U.S. patent application number 10/108245 was filed with the patent office on 2002-10-31 for aortic filter catheter.
Invention is credited to Leary, James J., Macoviak, John A., Samson, Wilfred J..
Application Number | 20020161394 10/108245 |
Document ID | / |
Family ID | 22027475 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020161394 |
Kind Code |
A1 |
Macoviak, John A. ; et
al. |
October 31, 2002 |
Aortic filter catheter
Abstract
A aortic filter catheter is used to capture potential emboli
within the aorta during heart surgery and cardiopulmonary bypass.
An expandable embolic filter assembly having fine filter mesh for
capturing macroemboli and microemboli is mounted on a catheter
shaft having a perfusion lumen with perfusion ports located
upstream of the filter. The embolic filter assembly can be actively
or passively deployed within the ascending aortic. The embolic
filter assembly includes an aortic occlusion device, which may be a
toroidal balloon, an expandable balloon or a selectively deployable
external catheter flow control valve. The combined device allows
percutaneous transluminal administration of cardiopulmonary bypass
and cardioplegic arrest with protection from undesirable embolic
events.
Inventors: |
Macoviak, John A.; (La
Jolla, CA) ; Leary, James J.; (Sunnyvale, CA)
; Samson, Wilfred J.; (Saratoga, CA) |
Correspondence
Address: |
Gunther Hanke
Fulwider Patton Lee & Utecht
P.O. Box 22615
Long Beach
CA
90801-5615
US
|
Family ID: |
22027475 |
Appl. No.: |
10/108245 |
Filed: |
March 26, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10108245 |
Mar 26, 2002 |
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09158405 |
Sep 22, 1998 |
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6361545 |
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60060117 |
Sep 26, 1997 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61B 17/12136 20130101;
A61F 2230/0069 20130101; A61F 2002/30092 20130101; A61B 17/12172
20130101; A61F 2/014 20200501; A61F 2210/0019 20130101; A61F
2250/0098 20130101; A61F 2250/0023 20130101; A61F 2210/0033
20130101; A61F 2230/0067 20130101; A61B 17/221 20130101; A61F
2230/0006 20130101; A61B 17/12109 20130101; A61F 2/013 20130101;
A61F 2230/008 20130101; A61F 2250/0003 20130101; A61F 2002/018
20130101; A61B 17/12022 20130101; A61F 2002/3008 20130101; A61F
2/011 20200501; A61B 2017/22067 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
What is claimed is:
1. An aortic filter catheter comprising: an elongated catheter
shaft, an embolic filter assembly mounted on said catheter shaft,
said embolic filter assembly including a porous filter mesh, said
embolic filter assembly being expandable to engage an inner surface
of a patient's aorta, and an aortic occlusion device mounted on
said elongated catheter shaft.
2. The aortic filter catheter of claim 1, wherein said aortic
occlusion device is mounted on said elongated catheter shaft
upstream of said embolic filter assembly.
3. The aortic filter catheter of claim 1, wherein said aortic
occlusion device comprises a toroidal balloon occlusion device,
said toroidal balloon occlusion device having an uninflated state,
a first inflated state in which said toroidal balloon occlusion
device engages the inner surface of the aorta and in which said
toroidal balloon occlusion device has an open central passage
permitting fluid flow therethrough, and a second inflated state in
which said central passage of said toroidal balloon occlusion
device closes preventing fluid flow therethrough.
4. The aortic filter catheter of claim 1, wherein said aortic
occlusion device comprises an inflatable balloon expandable to
occlude the aortic lumen.
5. The aortic filter catheter of claim 4, wherein said inflatable
balloon is mounted on said elongated catheter shaft upstream of
said embolic filter assembly.
6. The aortic filter catheter of claim 1, wherein said aortic
occlusion device comprises an external catheter flow control valve
expandable to occlude the aortic lumen.
7. The aortic filter catheter of claim 6, wherein said external
catheter flow control valve is mounted on said elongated catheter
shaft upstream of said embolic filter assembly.
8. The aortic filter catheter of claim 1, wherein said embolic
filter assembly is configured to expand passively in response to
blood flow in the aorta.
9. The aortic filter catheter of claim 1, wherein said embolic
filter assembly is resiliently biased toward the expanded
state.
10. The aortic filter catheter of claim 1, further comprising a
perfusion lumen within said elongated catheter shaft, said
perfusion lumen being fluidly connected to a perfusion port located
on said elongated catheter shaft upstream of said filter mesh and
downstream of said aortic occlusion device.
11. The aortic filter catheter of claim 10, further comprising a
distal lumen within said elongated catheter shaft, said distal
lumen being fluidly connected to a distal port on said elongated
catheter shaft upstream of said aortic occlusion device.
12. The aortic filter catheter of claim 1, wherein said embolic
filter assembly is configured with a conical upstream section and
an approximately cylindrical extension extending downstream of said
conical upstream section.
13. The aortic filter catheter of claim 1, wherein said embolic
filter assembly includes a means to actively expand said embolic
filter assembly within the aorta.
14. The aortic filter catheter of claim 13, wherein said means to
actively expand said embolic filter assembly comprises a plurality
of actuation members connected to an outer periphery of said
embolic filter assembly.
15. The aortic filter catheter of claim 14, wherein said actuation
members comprise a plurality of actuation wires slidably received
within at least one actuation wire lumen within said elongated
catheter shaft, said actuation wires having distal ends connected
to the outer periphery of said embolic filter assembly.
16. The aortic filter catheter of claim 13, wherein said means to
actively expand said embolic filter assembly comprises an
extendable and retractable support wire circumscribing an outer
periphery of said embolic filter assembly.
17. The aortic filter catheter of claim 16, wherein said support
wire has a distal end advanceable and retractable through a channel
circumscribing said outer periphery of said embolic filter
assembly.
18. The aortic filter catheter of claim 16, wherein said support
wire forms an expandable and retractable loop circumscribing said
outer periphery of said embolic filter assembly.
19. The aortic filter catheter of claim 16, wherein said elongated
catheter shaft is approximately tangential to said outer periphery
of said embolic filter assembly when said embolic filter assembly
is in an expanded state.
20. The aortic filter catheter of claim 1, wherein said embolic
filter assembly has an outer periphery and said elongated catheter
shaft is approximately tangential to said outer periphery of said
embolic filter assembly when said embolic filter assembly is in an
expanded state.
21. The aortic filter catheter of claim 20, wherein said elongated
catheter shaft has a distal end that is curved toward a center of
an inlet end of said embolic filter assembly.
22. The aortic filter catheter of claim 1, further comprising a
light emitting means for directing a beam of light through a wall
of the aorta.
23. The aortic filter catheter of claim 22, wherein said light
emitting means is positioned on an outer periphery of said embolic
filter assembly.
24. The aortic filter catheter of claim 1, wherein said embolic
filter assembly comprises a first portion of porous filter mesh
having a first porosity and a second portion of porous filter mesh
having a second porosity different from said first porosity.
25. The aortic filter catheter of claim 24, wherein said first
portion of porous filter mesh is an upstream portion of the porous
filter mesh and said second portion of porous filter mesh is a
downstream portion of the porous filter mesh.
26. The aortic filter catheter of claim 24, wherein said first
portion of porous filter mesh is separated from said second portion
of porous filter mesh along a longitudinally oriented dividing
line.
27. The aortic filter catheter of claim 1, wherein said filter mesh
has a convoluted configuration when said embolic filter assembly is
in the expanded state.
28. The aortic filter catheter of claim 27, wherein said filter
mesh has a circumferentially convoluted configuration.
29. The aortic filter catheter of claim 27, wherein said filter
mesh has a longitudinally convoluted configuration.
30. The aortic filter catheter of claim 27, wherein said filter
mesh has a helically convoluted configuration.
31. An aortic filter catheter comprising: an elongated catheter
shaft, an embolic filter assembly having a porous filter mesh
mounted on said catheter shaft, said embolic filter assembly being
expandable to engage an inner surface of a patient's aorta, said
embolic filter assembly having an inlet end that is open to fluid
flow when said embolic filter assembly is in an expanded state, and
a toroidal balloon occlusion device mounted at said inlet end of
said embolic filter assembly, said toroidal balloon occlusion
device having an uninflated state, a first inflated state in which
said toroidal balloon occlusion device engages the inner surface of
the aorta and in which said toroidal balloon occlusion device has
an open central passage permitting fluid flow therethrough, and a
second inflated state in which said central passage of said
toroidal balloon occlusion device closes preventing fluid flow
therethrough.
32. The aortic filter catheter of claim 31, wherein said elongated
catheter shaft is approximately tangential to said inlet end of
said embolic filter assembly when said embolic filter assembly is
in the expanded state.
33. The aortic filter catheter of claim 31, wherein said inlet end
of said embolic filter assembly is connected to said elongated
catheter shaft by a plurality of struts.
34. The aortic filter catheter of claim 31, further comprising a
perfusion lumen within said elongated catheter shaft, said
perfusion lumen being fluidly connected to a perfusion port located
on said elongated catheter shaft upstream of said filter mesh and
downstream of said toroidal balloon occlusion device.
35. The aortic filter catheter of claim 34, further comprising a
distal lumen within said elongated catheter shaft, said distal
lumen being fluidly connected to a distal port on said elongated
catheter shaft upstream of said toroidal balloon occlusion
device.
36. A method comprising: introducing an elongated tubular shaft of
an aortic filter catheter into a patient's aorta; positioning an
embolic filter assembly having a porous filter mesh mounted on said
elongated tubular shaft within the patient's ascending aorta;
expanding said embolic filter assembly to engage an inner surface
of the patient's ascending aorta; and occluding the patient's
ascending aorta with an aortic occlusion device mounted on said
elongated tubular shaft.
37. The method of claim 36, wherein said aortic occlusion device is
mounted on said elongated catheter shaft upstream of said embolic
filter assembly.
38. The method of claim 36, further comprising perfusing oxygenated
blood through a perfusion lumen within said elongated tubular shaft
into the patient's aorta.
39. The method of claim 36, further comprising perfusing oxygenated
blood through a perfusion lumen within said elongated tubular shaft
into the patient's aorta upstream of said porous filter mesh and
downstream of said aortic occlusion device.
40. The method of claim 36, further comprising introducing a
cardioplegic agent into the patient's coronary arteries to induce
cardioplegic arrest by infusing the cardioplegic agent into the
patient's aorta upstream of said aortic occlusion device.
41. The method of claim 36, further comprising monitoring the
position and deployment state of said aortic filter catheter by
directing a beam of light from said aortic filter catheter through
a wall of the patient's aorta and observing the transmitted light
beam external to the aorta.
42. The method of claim 36, wherein said aortic occlusion device
comprises an inflatable balloon expandable to occlude the aortic
lumen.
43. The method of claim 36, wherein said aortic occlusion device
comprises an external catheter flow control valve expandable to
occlude the aortic lumen.
Description
CROSS REFERENCE TO OTHER APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 09/158,405, filed Sep. 22, 1998, now U.S. Pat. No.
6,361,545, which claims the benefit of U.S. Provisional
Application, serial No. 60/060,117, filed Sep. 26, 1997, which are
hereby incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a catheter or
cannula for infusion of oxygenated blood or other fluids into a
patient for cardiopulmonary support and cerebral protection. More
particularly, it relates to an arterial perfusion catheter with a
deployable embolic filter for protecting a patient from adverse
effects due to emboli that are dislodged during cardiopulmonary
bypass.
BACKGROUND OF THE INVENTION
[0003] Over the past decades tremendous advances have been made in
the area of heart surgery, including such life saving surgical
procedures as coronary artery bypass grafting (CABG) and cardiac
valve repair or replacement surgery. Cardiopulmonary bypass (CPB)
is an important enabling technology that has helped to make these
advances possible. Recently, however, there has been a growing
awareness within the medical community and among the patient
population of the potential sequelae or adverse affects of heart
surgery and of cardiopulmonary bypass. Chief among these concerns
is the potential for stroke or neurologic deficit associated with
heart surgery and with cardiopulmonary bypass. One of the likely
causes of stroke and of neurologic deficit is the release of emboli
into the blood stream during heart surgery. Potential embolic
materials include atherosclerotic plaques or calcific plaques from
within the ascending aorta or cardiac valves and thrombus or clots
from within the chambers of the heart. These potential emboli may
be dislodged during surgical manipulation of the heart and the
ascending aorta or due to high velocity jetting (sometimes called
the "sandblasting effect") from the aortic perfusion cannula. Air
that enters the heart chambers or the blood stream during surgery
through open incisions or through the aortic perfusion cannula is
another source of potential emboli. Emboli that lodge in the brain
may cause a stroke or other neurologic deficit. Clinical studies
have shown a correlation between the number and size of emboli
passing through the carotid arteries and the frequency and severity
of neurologic damage. At least one study has found that frank
strokes seem to be associated with macroemboli larger than
approximately 100 micrometers in size, whereas more subtle
neurologic deficits seem to be associated with multiple microemboli
smaller than approximately 100 micrometers in size. In order to
improve the outcome of cardiac surgery and to avoid adverse
neurological effects it would be very beneficial to eliminate or
reduce the potential of such cerebral embolic events.
[0004] Several medical journal articles have been published
relating to cerebral embolization and adverse cerebral outcomes
associated with cardiac surgery, e.g.: Determination or Size of
Aortic Emboli and Embolic Load During Coronary Artery Bypass
Grafting; Barbut et al.; Ann Thorac Surg 1997;63; 1262-7; Aortic
Atheromatosis and Risks of Cerebral Embolization; Barbut et al.; J
Card & Vasc Anesth, Vol 10, No 1, 1996: pp 24; Aortic Atheroma
is Related to Outcome but not Numbers of Emboli During Coronary
Bypass; Barbut et al.; Ann Thorac Surg 1997;64;454-9; Adverse
Cerebral Outcomes After Coronary Artery Bypass Surgery; Roach et
al.; New England J of Med, Vol 335, No 25, 1996: pp 1857-1863;
Signs of Brain Cell Injury During Open Heart Operations: Past and
Present; Aberg; Ann Thorac Surg 1995;59; 1312-5; The Role of CPB
Management in Neurobehavioral Outcomes After Cardiac Surgery;
Murkin; Ann Thorac Surg 1995;59;1308-11; Risk Factors for Cerebral
Injury and Cardiac Surgery; Mills; Ann Thorac Surg 1995;59;1296-9;
Brain Microemboli Associated with Cardiopulmonary Bypass: A
Histologic and Magnetic Resonance Imaging Study; Moody et al.; Ann
Thorac Surg 1995;59;1304-7; CNS Dysfunction After Cardiac Surgery:
Defining the Problem; Murkin; Ann Thorac Surg 1995;59;
1287+Statement of Consensus on Assessment of Neurobehavioral
Outcomes After Cardiac Surgery; Murkin et al.; Ann Thorac Surg
1995;59;1289-95; Heart-Brain Interactions: Neurocardiology Comes of
Age; Sherman et al.; Mayo Clin Proc 62:1158-1160, 1987; Cerebral
Hemodynamics After Low-Flow Versus No-Flow Procedures; van der
Linden; Ann Thorac Surg 1995;59;1321-5; Predictors of Cognitive
Decline After Cardiac Operation; Newman et al.; Ann Thorac Surg
1995;59;1326-30; Cardiopulmonary Bypass: Perioperative Cerebral
Blood Flow and Postoperative Cognitive Deficit; Venn et al.; Ann
Thorac Surg 1995;59; 1331-5; Long-Term Neurologic Outcome After
Cardiac Operation; Sotaniemi; Ann Thorac Surg 1995;59;1336-9; and
Macroemboli and Microemboli During Cardiopulmonary Bypass; Blauth;
Ann Thorac Surg 1995;59;1300-3.
[0005] The patent literature includes several references relating
to vascular filter devices for reducing or eliminating the
potential of embolization. These and all other patents and patent
applications referred to herein are hereby incorporated herein by
reference in their entirety.
[0006] The following U.S. patents relate to vena cava filters: U.S.
Pat. Nos. 5,549,626, 5,415,630, 5,152,777, 5,375,612, 4,793,348,
4,817,600, 4,969,891, 5,059,205, 5,324,304, 5,108,418, 4,494,531.
Vena cava filters are devices that are implanted into a patient's
inferior vena cava for capturing thromboemboli and preventing them
from entering the right heart and migrating into the pulmonary
arteries. These are generally designed for permanent implantation
and are only intended to capture relatively large thrombi,
typically those over a centimeter in diameter, that could cause a
major pulmonary embolism. As such, these are unsuitable for
temporary deployment within a patient's aorta or for capturing
macroemboli or microemboli associated with adverse neurological
outcomes. Vena cava filters are also not adapted for simultaneously
providing arterial blood perfusion in connection with
cardiopulmonary bypass.
[0007] The following U.S. patents relate to vascular filter
devices: U.S. Pat. Nos. 5,496,277, 5,108,419, 4,723,549, 3,996,938.
These filter devices are not of a size suitable for deployment
within a patient's aorta, nor would they provide sufficient filter
surface area to allow aortic blood flow at normal physiologic flow
rates without an unacceptably high pressure drop across the filter.
Furthermore, these filter devices are not adapted for
simultaneously providing arterial blood perfusion in connection
with cardiopulmonary bypass devices.
[0008] The following U.S. patents relate to aortic filters or
aortic filters associated with atherectomy devices: U.S. Pat. Nos.
5,662,671, 5,769,816. The following international patent
applications relate to aortic filters or aortic filters associated
with atherectomy devices: WO 97/17100, WO 97/42879, WO 98/02084.
The following international patent application relates to a carotid
artery filter: WO 98/24377. This family of U.S. and international
patents includes considerable discussion on the mathematical
relationship between blood flow rate, pressure drop, filter pore
size and filter area and concludes that, for use in the aorta, it
is desirable for the filter mesh to have a surface area of 3-10
in.sup.2, more preferably 4-9 in.sup.2, 5-8 in.sup.2 or 6-8
in.sup.2, and most preferably 7-8 in.sup.2. While these patents
state that this characteristic is desirable, none of the filter
structures disclosed in the drawings and description of these
patents appears capable of providing a filter surface area within
these stated ranges when deployed within an average-sized human
aorta. Accordingly, it would be desirable to provide a filter
structure or other means that solves this technical problem by
increasing the effective surface area of the filter mesh to allow
blood flow at normal physiologic flow rates without an unacceptably
high pressure drop.
SUMMARY OF THE INVENTION
[0009] In keeping with the foregoing discussion, the present
invention takes the form of a perfusion filter catheter or cannula
having an embolic filter assembly mounted on an elongated tubular
catheter shaft. The elongated tubular catheter shaft is adapted for
introduction into a patient's ascending aorta either by a
peripheral arterial approach or by a direct aortic puncture. A fine
filter mesh for capturing macroemboli and/or microemboli is mounted
on the embolic filter assembly. The embolic filter assembly has an
undeployed state in which the filter is compressed or wrapped
tightly around the catheter shaft and a deployed state in which the
embolic filter assembly expands to the size of the aortic lumen and
seals against the inner wall of the aorta. The embolic filter
assembly can be passively or actively deployable. Various
mechanisms are disclosed for both passive and active deployment of
the embolic filter assembly. Optionally, an outer tube may cover
the embolic filter assembly when it is in the undeployed state.
Radiopaque markers and/or sonoreflective markers, may be located on
the catheter and/or the embolic filter assembly. Preferably, a
perfusion lumen extends through the elongated tubular catheter
shaft to one or more perfusion ports upstream of the embolic filter
assembly. Oxygenated blood is perfused through the perfusion lumen
and any embolic materials that might be dislodged are captured in
the deployed embolic filter assembly.
[0010] In order to provide a sufficient flow rate of oxygenated
blood for support of all critical organ systems through the filter
without excessive pressure drop, it is preferred that the surface
area of the filter mesh be greater than twice the cross-sectional
area of the aortic lumen, more preferably three, four, five or six
times greater than luminal cross section of the aorta. Preferably,
the embolic filter assembly is also configured to hold at least a
majority of the filter mesh away from the aortic wall when deployed
to maximize the effective filter surface area. Several possible
configurations are described for the embolic filter assembly that
meet these parameters. The embolic filter assembly configurations
described include an elongated cone, a frustum of a cone, a
trumpet-shape, a modified trumpet-shape, and helically,
circumferentially and longitudinally convoluted shapes. Further
configurations are described having standoff members for centering
the embolic filter assembly within the aorta and for holding at
least a majority of the filter mesh away from the aortic walls when
deployed.
[0011] Embodiments are also described that combine the perfusion
filter catheter with an aortic occlusion device, which may be a
toroidal balloon, an expandable balloon or a selectively deployable
external catheter flow control valve. The combined device allows
percutaneous transluminal administration of cardiopulmonary bypass
and cardioplegic arrest with protection from undesirable embolic
events. An embodiment of the perfusion filter catheter is described
having an aortic transillumination system for locating and
monitoring the position and the deployment state of the catheter
and the embolic filter assembly without fluoroscopy.
[0012] In use, the perfusion filter catheter is introduced into the
patient's aorta with the embolic filter assembly in a collapsed
state either by a peripheral arterial approach or by a direct
aortic puncture. The embolic filter assembly is advanced across the
aortic arch and into the ascending aorta. When the embolic filter
assembly is positioned in the ascending aorta between the aortic
valve and the brachiocephalic artery, the embolic filter assembly
is either actively or passively deployed. The position of the
catheter and the deployment state of the embolic filter assembly
may be monitored using fluoroscopy, ultrasound, transesophageal
echography (TEE) or aortic transillumination. Once the embolic
filter assembly is deployed, oxygenated blood may be infused into
the aorta through the perfusion lumen. Any potential emboli are
captured by the embolic filter assembly and prevented from entering
the neurovasculature or other branches downstream. After use, the
embolic filter assembly is returned to the collapsed position and
the catheter is withdrawn from the patient.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1-3 show a perfusion filter catheter configured for
retrograde deployment via a peripheral arterial access point.
[0014] FIG. 1 is a cutaway perspective view of the perfusion filter
catheter deployed within the aorta via femoral artery access.
[0015] FIG. 2 shows the distal end of the catheter with the embolic
filter assembly in a deployed state.
[0016] FIG. 3 shows the distal end of the catheter with the embolic
filter assembly in a collapsed state for insertion or withdrawal of
the device from the patient.
[0017] FIGS. 4-6 show a method of passively deploying an embolic
filter assembly on a perfusion filter catheter.
[0018] FIGS. 7, 7A, 8 and 8A show a flow-assisted method of
passively deploying an embolic filter assembly on a perfusion
filter catheter.
[0019] FIGS. 9-11 show a method of passively deploying a
self-expanding and self-supporting embolic filter assembly on a
perfusion filter catheter.
[0020] FIGS. 12-14 show a method of actively deploying an embolic
filter assembly with a collapsible outer hoop and a plurality of
actuation wires.
[0021] FIGS. 15-17 show a method of actively deploying an embolic
filter assembly with an inflatable filter support structure.
[0022] FIGS. 18-20 show a method of actively deploying a spiral
fluted embolic filter assembly by twisting or furling the embolic
filter assembly around an inner catheter shaft.
[0023] FIGS. 21-23 show a method of actively deploying a
circumferentially pleated embolic filter assembly on a perfusion
filter catheter.
[0024] FIG. 24 shows a perfusion filter catheter adapted for
retrograde deployment via subclavian artery access.
[0025] FIGS. 25-27 show a perfusion filter catheter adapted for
antegrade deployment via direct aortic puncture.
[0026] FIGS. 28 and 29 show a perfusion filter catheter having an
embolic filter assembly with a graded porosity filter screen.
[0027] FIGS. 30 and 30A show a perfusion filter catheter having a
longitudinally fluted embolic filter assembly.
[0028] FIGS. 31 and 31A show a perfusion filter catheter having a
longitudinally ribbed embolic filter assembly.
[0029] FIG. 32 shows a perfusion filter catheter having an embolic
filter assembly that is surrounded by a cage of longitudinally
oriented standoff members.
[0030] FIG. 33 shows a perfusion filter catheter having an embolic
filter assembly that is surrounded by a cage of coiled wire
standoff members.
[0031] FIG. 34 shows a perfusion filter catheter having an embolic
filter assembly that is surrounded by a cage of coarse netting.
[0032] FIG. 35 shows a cutaway view of a perfusion filter catheter
having an embolic filter assembly that is surrounded by a fender
made from a porous foam or a fibrous network.
[0033] FIGS. 36 and 37 show an alternate embodiment of a perfusion
filter catheter with a passively deployed embolic filter
assembly.
[0034] FIGS. 38-41 show an alternate embodiment of a perfusion
filter catheter with an actively deployed embolic filter assembly
having a filter support structure with a preshaped, superelastic
actuation wire.
[0035] FIGS. 42 and 43 show another alternate embodiment of a
perfusion filter catheter with an actively deployed embolic filter
assembly having a filter support structure with a preshaped,
superelastic wire purse string loop.
[0036] FIGS. 44 and 45 show another alternate embodiment of a
perfusion filter catheter with an actively deployed inflatable
embolic filter assembly.
[0037] FIGS. 46-50 show the operation of an embodiment of a
perfusion filter catheter that combines an embolic filter assembly
with a toroidal balloon aortic occlusion device.
[0038] FIG. 51 shows an embodiment of a perfusion filter catheter
that combines an embolic filter assembly with an inflatable balloon
aortic occlusion device.
[0039] FIG. 52 shows an embodiment of a perfusion filter catheter
that combines an embolic filter assembly with a selectively
deployable external catheter flow control valve.
[0040] FIG. 53 shows an embodiment of a perfusion filter catheter
with an embolic filter assembly having areas of different filter
porosity.
[0041] FIG. 54 shows an embodiment of a perfusion filter catheter
with a fiberoptic system for aortic transillumination.
DETAILED DESCRIPTION OF THE INVENTION
[0042] FIGS. 1-3 show a perfusion filter catheter 100 according to
the present invention configured for retrograde deployment via a
peripheral arterial access point. FIG. 1 is a cutaway perspective
view of the perfusion filter catheter 100 deployed within the aorta
of a patient via femoral artery access. FIG. 2 shows the distal end
of the catheter 100 with the embolic filter assembly 102 in a
deployed state. FIG. 3 shows the distal end of the catheter with
the embolic filter assembly 102' in a collapsed state for insertion
or withdrawal of the device from the patient.
[0043] Referring now to FIG. 1, the perfusion filter catheter 100
includes an elongated tubular catheter shaft 104 with a proximal
end 108 and distal end 110. The catheter shaft 104 is preferably
extruded of a flexible thermoplastic material or a thermoplastic
elastomer. Suitable materials for the catheter shaft 104 include,
but are not limited to, polyvinylchloride, polyurethane,
polyethylene, polypropylene, polyamides (nylons), and alloys or
copolymers thereof, as well as braided, coiled or counterwound wire
or filament reinforced composites. The tubular catheter shaft 104
may have a single lumen or multilumen construction. In the
exemplary embodiment shown, the catheter 100 has a single perfusion
lumen 106 extending from the proximal end 108 to the distal end 110
of the catheter shaft 104. The perfusion lumen 106 is open at the
distal end 110 of the catheter shaft 104. The distal end 110 of the
catheter shaft 104 may have a simple beveled or rounded distal
edge, as shown, or it may include additional side ports or a flow
diffuser to reduce jetting when oxygenated blood is infused through
the perfusion lumen 106. The proximal end 108 of the elongated
tubular catheter shaft 104 is adapted for connecting the perfusion
lumen 106 to a cardiopulmonary bypass pump or other source of
oxygenated blood using standard barb connectors or other
connectors, such as a standard luer fitting (not shown).
Preferably, the catheter shaft 104 is made with thin walled
construction to maximize the internal diameter and therefore the
flow rate of the perfusion lumen 106 for a given outside diameter
and length of the catheter shaft 104. Thin walled construction also
allows the outside diameter of the catheter shaft 104 to be
minimized in order to reduce the invasiveness of the procedure and
to reduce trauma at the insertion site. The perfusion lumen 106
should be configured to allow sufficient blood flow to preserve
organ function without hemolysis or other damage to the blood. For
standard cardiopulmonary support techniques, a catheter shaft 104
of 18-24 French size (6-8 mm outside diameter) is sufficient to
deliver the requisite 3-4 liters of oxygenated blood to preserve
organ function. For low flow cardiopulmonary support techniques,
such as described in commonly owned, copending patent application
Ser. No. 60/084,835, filed May 8, 1998 which is hereby incorporated
by reference, the size of the catheter shaft 104 can be reduced to
9-18 French size (3-6 mm outside diameter) for delivering 0.5-3
liters of oxygenated blood to preserve organ function. The catheter
shaft 104 should have a length sufficient to reach from the
arterial access point where it is inserted to the ascending aorta
of the patient. For femoral artery deployment, the catheter shaft
104 preferably has a length from approximately 80-120 cm.
[0044] A deployable embolic filter assembly 102 is located just
proximal to the distal end 110 of the catheter shaft 104. The
embolic filter assembly 102 includes a filter screen 112 made of a
fine mesh material. In this exemplary embodiment and each of the
other embodiments described below, the fine mesh material of the
filter screen 112 may be a woven or knitted fabric, such as Dacron
polyester or nylon mesh, or other textile fabrics, or it may be a
nonwoven fabric, such as a spun bonded polyolefin or expanded
polytetrafluoroethylene or other nonwoven materials. The fine mesh
material of the filter screen 112 may be woven, knitted or
otherwise formed from monofilament or multifilament fibers. The
fine mesh material of the filter screen 112 may also be a fine wire
mesh or a combination of wire and textile fibers. Alternatively,
the fine mesh material of the filter screen 112 may be an open cell
foam material. The fine mesh material of the filter screen 112 must
be nontoxic and hemocompatible, that is, non-thrombogenic and
non-hemolytic. Preferably, the fine mesh material of the filter
screen 112 has a high percentage of open space, with a uniform pore
size. The pore size of the filter screen 112 can be chosen to
capture macroemboli only or to capture macroemboli and microemboli.
In most cases the pore size of the filter screen 112 will
preferably be in the range of 1-200 micrometers. For capturing
macroemboli only, the pore size of the filter screen 112 will
preferably be in the range of 50-200 micrometers, more preferably
in the range of 80-100 micrometers. For capturing macroemboli and
microemboli, the pore size of the filter screen 112 will preferably
be in the range of 1-100 micrometers, more preferably in the range
of 5-20 micrometers. In other applications, such as for treating
thromboembolic disease, a larger pore size, e.g. up to 1000
micrometers (1 mm) or larger, would also be useful. In some
embodiments, a combination of filter materials having different
pore sizes may be used.
[0045] Alternatively or additionally the material of the filter
screen in each embodiment of the filter catheter may be made of or
coated with an adherent material or substance to capture or hold
embolic debris which comes into contact with the filter screen
within the embolic filter assembly. Suitable adherent materials
include, but are not limited to, known biocompatible adhesives and
bioadhesive materials or substances, which are hemocompatible and
non-thrombogenic. Such materials are known to those having ordinary
skill in the art and are described in, among other references, U.S.
Pat. Nos. 4,768,523, 5,055,046, 5,066,709, 5,197,973, 5,225,196,
5,374,431, 5,578,310, 5,645,062, 5,648,167, 5,651,982, and
5,665,477. In one particularly preferred embodiment, only the
upstream side of the elements of the filter screen are coated with
the adherent material to positively capture the embolic debris
which comes in contact with the upstream side of the filter screen
after entering the filter assembly. Other bioactive substances, for
example, heparin or thrombolytic agents, may be impregnated into or
coated on the surface of the filter screen material or incorporated
into an adhesive coating.
[0046] The embolic filter assembly 102 is movable between a
collapsed state, as shown in FIG. 3, and an expanded or deployed
state, as shown in FIGS. 1 and 2. The filter screen 112 may be
attached directly to the catheter shaft 104 and it may constitute
the entire embolic filter assembly 102, particularly if the filter
screen 112 is made of a resilient or semirigid fabric that has
enough body to be self-supporting in the deployed state. Generally,
however, the embolic filter assembly 102 will also include a filter
support structure 114, particularly if a highly flexible or flaccid
material is used for the filter screen 112. The filter support
structure 114 attaches and supports the filter screen 112 on the
catheter shaft 104. In the illustrative embodiment of FIGS. 1-3,
the filter support structure 114 is constructed with an outer hoop
116 and a plurality of struts 118 which extend approximately
radially from a ring-shaped hub 126 that is mounted on the catheter
shaft 104. In this case four struts 118 are shown, however, two,
three or more struts 118 may be used. The open distal end 122 of
the filter screen 112 is attached to the outer hoop 116 and the
proximal end 120 of the filter screen 112 is sealingly attached to
the catheter shaft 104. When the embolic filter assembly 102 is
deployed, the outer hoop 116 of the filter support structure 114
holds the open distal end 122 of the filter screen 112 against the
inner wall of the aorta, as shown in FIG. 1. To accommodate most
normal adult aortas, the outer hoop 116 of the filter support
structure 114 and the distal end 122 of the filter screen 112 have
a diameter of approximately 2.5 to 4 cm, plus or minus 0.5 cm.
Larger and smaller diameter filter support structures 114 may be
made to accommodate patients with distended or Marfan syndrome
aortas or for pediatric patients.
[0047] The embolic filter assembly 102 may be deployed by a passive
means or by an active means. Passive means for deploying the
embolic filter assembly 102 could include using the elastic memory
of the filter screen 112 and/or the filter support structure 114 to
deploy the embolic filter assembly 102, and/or using pressure from
the blood flow in the aorta to deploy the embolic filter assembly
102. By contrast, active means for deploying the embolic filter
assembly 102 could include one or more actuation members within the
catheter shaft 104 for mechanically actuating the filter support
structure 114 to deploy the embolic filter assembly 102 from the
proximal end 108 of the catheter 100. Shape memory materials may
also be used as actuation members for deploying the embolic filter
assembly 102. Alternatively, active means for deploying the embolic
filter assembly 102 could include one or more lumens within the
catheter shaft 104 for hydraulically actuating the filter support
structure 114 to deploy the embolic filter assembly 102. Passive
means may be used to augment the action of the active deployment
means. As shown in FIG. 3, an outer tube 124 may be provided to
cover the embolic filter assembly 102 when it is in the collapsed
state in order to create a smooth outer surface for insertion and
withdrawal of the catheter 100 and to prevent premature deployment
of the embolic filter assembly 102, particularly if passive
deployment means are used.
[0048] The perfusion filter catheter 100 is prepared for use by
folding or compressing the embolic filter assembly 102 into a
collapsed state within the outer tube 124, as shown in FIG. 3. The
distal end 110 of the catheter 100 is inserted into the aorta in a
retrograde fashion. Preferably, this is done through a peripheral
arterial access, such as the femoral artery or subclavian artery,
using the Seldinger technique or an arterial cutdown.
Alternatively, the catheter 100 may be introduced directly through
an incision into the descending aorta after the aorta has been
surgically exposed. The embolic filter assembly 102 is advanced up
the descending aorta and across the aortic arch while in the
collapsed state. The position of the catheter 100 may be monitored
using fluoroscopy or ultrasound, such as transesophageal echography
(TEE). Appropriate markers, which may include radiopaque markers
and/or sonoreflective markers, may be located on the distal end 110
of the catheter 100 and/or the embolic filter assembly 102 to
enhance imaging and to show the position of the catheter 100 and
the deployment state of the embolic filter assembly 102. When the
distal end 110 of the catheter 100 is positioned in the ascending
aorta between the aortic valve and the brachiocephalic artery, the
outer tube 124 is withdrawn and the embolic filter assembly 102 is
deployed, as shown in FIG. 3. Optionally, a distal portion of the
catheter shaft 104 may be precurved to match the curvature of the
aortic arch to aid in placement and stabilization of the catheter
100 and the embolic filter assembly 102 within the aorta. Once the
embolic filter assembly 102 is deployed, oxygenated blood may be
infused through the perfusion lumen 106 to augment cardiac output
of the beating heart or to establish cardiopulmonary bypass so that
the heart can be arrested. Any potential emboli are captured by the
filter screen 112 and prevented from entering the neurovasculature
or other branches downstream. After use, the embolic filter
assembly 102 is returned to the collapsed position and the catheter
100 is withdrawn from the patient.
[0049] Preferably, the embolic filter assembly 102 is configured so
that, when it is in the deployed state, at least a majority of the
filter screen 112 is held away from the aortic walls so that flow
through the pores of the filter screen 112 is not occluded by
contact with the aortic wall. In addition, this also assures that
blood flow into the side branches of the aorta will not be
obstructed by the filter screen 112. In this way, each side branch
of the aorta will receive the benefit of flow through the full
surface area of the filter screen 112 so that blood flow is not
restricted by the area of the ostium of each side branch. In the
illustrative embodiment of FIGS. 1-3, the filter screen 112 has a
roughly conical shape with an open distal end 122. The conical
shape holds the fine mesh material of the filter screen 112 away
from the aortic walls and away from the ostia of the side branches
so that blood can flow freely through the pores of the filter
screen 112.
[0050] Deployment of the embolic filter assembly 102 can be
accomplished passively or actively. FIGS. 4-11 show various methods
of passively deploying the embolic filter assembly 102 and FIGS.
12-23 show various methods of actively deploying the embolic filter
assembly 102. FIGS. 4-6 show one method of passively deploying the
embolic filter assembly 102. In this exemplary embodiment, the
outer hoop 116 and the struts 118 of the filter support structure
114 are made of an elastic or superelastic metal or polymer, for
example a superelastic nickel/titanium alloy, which is easily
deformed into the collapsed state and which expands passively from
the collapsed state to the deployed state. To place the embolic
filter assembly 102 in the collapsed position shown in FIG. 4, the
struts 118 are folded back in the proximal direction and the outer
hoop 116 is folded against the catheter shaft 104 along with the
material of the filter screen 112. The outer tube 124 is placed
over the folded embolic filter assembly 102 to hold it in the
collapsed position. Once the perfusion filter catheter 100 is in
position within the patient's aorta, the outer tube 124 is pulled
back, as shown in FIG. 5, to release the folded embolic filter
assembly 102. The outer hoop 116 and struts 118 expand the filter
screen 112 to its deployed position, shown in FIG. 6, and hold the
open distal end 122 of the filter screen 112 against the inner wall
of the aorta, as shown in FIG. 1. After use, the embolic filter
assembly 102 is returned to the collapsed position by advancing the
outer tube 124 distally over the filter screen 112 and the filter
support structure 114, then the catheter 100 is withdrawn from the
patient.
[0051] FIGS. 7, 7A, 8 and 8A show another method of passively
deploying an embolic filter assembly 132 on a perfusion filter
catheter 130. In this embodiment, the filter support structure
includes a plurality of struts 136 which are hinged or flexibly
attached at their inner, proximal ends to the catheter shaft 134.
The struts 136 may be made of either a metal or a polymer. The
distal end 138 of the filter screen 140 is attached to the struts
136 along an outer, distal portion of the struts 136. The proximal
end 146 of the filter screen 140 is sealingly attached to the
catheter shaft 134. The portion of the filter screen 140 attached
to the struts 136 forms a skirt 142 along the distal edge of the
filter assembly 132. The remaining portion of the filter screen 140
forms a filter pocket 144 along the proximal end of the filter
assembly 132. The skirt 142 and the filter pocket 144 may be made
of the same filter material or they may be made of different filter
materials having different porosities. The skirt 142 of the filter
screen 140 may even be made of a nonporous material.
[0052] The embolic filter assembly 132 is folded into the collapsed
position shown in FIG. 7 by folding the struts 136 in the distal
direction so they lie against the catheter shaft 134. FIG. 7A is a
cutaway view of the catheter 130 with the embolic filter assembly
132 in the collapsed position. The material of the filter screen
140 is folded around or in between the struts 136. The outer tube
148 is placed over the folded embolic filter assembly 132 to hold
it in the collapsed position. Once the perfusion filter catheter
130 is in position within the patient's aorta, the outer tube 148
is pulled back, as shown in FIG. 8, to release the folded embolic
filter assembly 132. Blood flow within the aorta catches the skirt
142 of the filter screen 140 and forces the embolic filter assembly
132 to open into the deployed position shown in FIG. 8. FIG. 8A is
a cutaway view of the catheter 130 with the embolic filter assembly
132 in the deployed position. Optionally, the struts 136 may be
resiliently biased toward the deployed position to assist in
passive deployment of the embolic filter assembly 132. As the
embolic filter assembly 132 is passively opened by the blood flow,
the skirt 142 of the filter screen 140 naturally and atraumatically
seals against the aortic wall. The passive deployment of the skirt
142 also naturally compensates for patient-to-patient variations in
aortic luminal diameter. The filter pocket 144 of the embolic
filter assembly 132 is held away from the aortic walls and away
from the ostia of the side branches so that blood can flow freely
through the pores of the filter screen 140.
[0053] FIGS. 9-11 show another method of passively deploying an
embolic filter assembly 152 on a perfusion filter catheter 150. In
this embodiment, the filter screen 154 is self-expanding and
self-supporting, so no separate filter support structure is needed.
Preferably, the embolic filter assembly 152 includes resilient
wires or filaments 156 that are interwoven with the fibers of the
filter screen 154. Alternatively, the resilient wires or filaments
156 may be attached to the interior or exterior surface of the
filter screen 154 fabric. The resilient wires or filaments 156 may
be made of either a polymer or a metal, such as an elastic or
superelastic alloy. In one preferred embodiment, the resilient
wires or filaments 156, and preferably the fibers of the filter
screen 154 as well, are woven at an angle to the longitudinal axis
of the embolic filter assembly 152, so that the embolic filter
assembly 152 can expand and contract in diameter by changing the
angle of the wires or filaments 156. Generally, as the embolic
filter assembly 152 expands in diameter, the angle between the
wires or filaments 156 and the longitudinal axis of the embolic
filter assembly 152 increases and the embolic filter assembly 152
may also foreshorten. The resilient wires or filaments 156 urge the
embolic filter assembly 152 to expand to the deployed position. The
proximal end 158 of the filter screen 154 is sealingly attached to
the catheter shaft 162.
[0054] The perfusion filter catheter 150 is shown in FIG. 9 with
the embolic filter assembly 152 compressed into the collapsed
position. The embolic filter assembly 152 compresses in diameter
smoothly without folding as the resilient wires or filaments 156
and the fibers of the filter screen 154 decrease their angle with
respect to the longitudinal axis of the embolic filter assembly
152. An outer tube 164 holds the embolic filter assembly 152 in the
collapsed position. Once the perfusion filter catheter 150 is in
position within the patient's aorta, the outer tube 164 is pulled
back, which allows the embolic filter assembly 152 to expand, as
shown in FIG. 10. As the embolic filter assembly 152 expands, the
angle between the wires or filaments 156 and the longitudinal axis
of the embolic filter assembly 152 increases and the embolic filter
assembly 152 foreshortens slightly. FIG. 11 shows the embolic
filter assembly 152 fully expanded in the deployed position. The
resilient wires or filaments 156 are preformed so that, when
deployed, the filter screen 154 has a roughly conical shape with an
open distal end 160. The conical shape holds the filter screen 154
away from the aortic walls and away from the ostia of the side
branches so that blood can flow freely through the pores of the
filter screen 154. The distal end 160 of the embolic filter
assembly 152 seals against the aortic wall. The self-expanding
aspect of the embolic filter assembly 152 naturally compensates for
patient-to-patient variations in aortic luminal diameter.
[0055] In alternate embodiments, the resilient wires or filaments
156 may be preformed to other geometries so that the filter screen
154 of the embolic filter assembly 152 assumes a different
configuration when deployed, including each of the other
configurations discussed within this patent specification.
[0056] FIGS. 12-14 show one method of actively deploying an embolic
filter assembly 168 on a perfusion filter catheter 166. In this
exemplary embodiment, the filter support structure 170 includes a
collapsible outer hoop 172 and a plurality of actuation wires 174.
The distal end 176 of the filter screen 180 is attached to the
outer hoop 172 and the proximal end 182 of the filter screen 180 is
sealingly attached to the catheter shaft 184. The actuation wires
174 are slidably received within actuation wire lumens 186 located
in the outer wall of the catheter shaft 184. The actuation wires
174 exit the actuation wire lumens 186 through side ports 188
located near the distal end of the catheter shaft 184. The
actuation wires 174 and the outer hoop 172 are each made of a
resilient polymer or a metal, such as stainless steel,
nickel/titanium alloy or the like.
[0057] The perfusion filter catheter 166 is shown in FIG. 12 with
the embolic filter assembly 168 compressed into the collapsed
position. The actuation wires 174 are withdrawn into the actuation
wire lumens 186 through the side ports 188 and the outer hoop 172
is folded or collapsed against the catheter shaft 184. The material
of the filter screen 180 is folded or collapsed around the catheter
shaft 184. An outer tube 190 covers the embolic filter assembly 168
in the collapsed position to facilitate insertion of the catheter
166. Once the perfusion filter catheter 150 is in position within
the patient's aorta, the outer tube 190 is pulled back to expose
the embolic filter assembly 152. Then, the actuation wires 174 are
advanced distally to expand the outer hoop 172 and the filter
screen 180, as shown in FIG. 13. FIG. 14 shows the embolic filter
assembly 168 fully expanded in the deployed position. In this
exemplary embodiment, the filter screen 180 is configured as a
frustum of a cone with an open distal end 176. The outer hoop 172
at the distal end 176 of the filter screen 180 seals against the
aortic wall.
[0058] FIGS. 15-17 show another method of actively deploying an
embolic filter assembly 202 on a perfusion filter catheter 200. In
this embodiment, the filter support structure 204 includes an outer
hoop 206 and a plurality of struts 208, which are all
interconnected hollow tubular members. Preferably, the outer hoop
206 and the struts 208 are made of a flexible polymeric material.
The filter support structure 204 is connected to an inflation lumen
210, which parallels the perfusion lumen 218 within the catheter
shaft 212. At its proximal end, the inflation lumen 210 branches
off from the catheter shaft 212 to a side arm 214 with a luer
fitting 216 for connecting to a syringe or other inflation device.
By way of example, this embodiment of the embolic filter assembly
202 is shown with a trumpet-shaped filter screen 220. The filter
screen 220 includes a skirt portion 222 extending distally from a
proximal, filter pocket 224. The skirt portion 222 is in the shape
of a frustum of a cone with an open distal end, which is attached
to the outer hoop 206. The filter pocket 224 is roughly cylindrical
in shape with a closed proximal end, which is sealingly attached to
the catheter shaft 212. The skirt 222 and the filter pocket 224 may
be made of the same filter material or they may be made of
different filter materials having different porosities. The skirt
222 of the filter screen 220 may even be made of a nonporous
material.
[0059] The perfusion filter catheter 200 is shown in FIG. 17 with
the embolic filter assembly 202 folded into a collapsed position.
The outer hoop 206 and the struts 208 of the filter support
structure 204 are deflated and the material of the filter screen
220 is folded or collapsed around the catheter shaft 212. An outer
tube 226 covers the embolic filter assembly 202 in the collapsed
position to facilitate insertion of the catheter 200. Optionally,
the outer tube 226 may have a slit or a weakened longitudinal tear
line along its length to facilitate removal of the outer tube 226
over the side arm 214 at the proximal end of the catheter 200. Once
the perfusion filter catheter 200 is in position within the
patient's aorta, the outer tube 226 is pulled back to expose the
embolic filter assembly 202. Then, the embolic filter assembly 202
is deployed by inflating the outer hoop 206 and the struts 208 with
fluid injected through the inflation lumen 210 to actively expand
the filter support structure 204, as shown in FIG. 16. When the
embolic filter assembly 202 is deployed, the outer hoop 206 of the
filter support structure 204 seals against the inner wall of the
aorta, as shown in FIG. 15. Preferably, at least the outer wall of
the outer hoop 206 is somewhat compliant when inflated in order to
compensate for patient-to-patient variations in aortic luminal
diameter.
[0060] FIGS. 18-20 show another method of actively deploying an
embolic filter assembly 232 on a perfusion filter catheter 230. In
this embodiment, the filter support structure 234 includes an outer
hoop 236 and a plurality of struts 238, which are connected to an
inner catheter shaft 240. The outer hoop 236 and the struts 238 may
be made of a resilient polymer or metal, for example a superelastic
nickel/titanium alloy. The distal end 242 of the filter screen 244
is attached to the outer hoop 236. The proximal end 246 of the
filter screen 244 is sealingly attached to an outer catheter shaft
250. The inner catheter shaft 240 is slidably and rotatably
received within the outer catheter shaft 250. Preferably, the
filter screen 244 has one or more spiral grooves or flutes 248 that
wind helically around the filter screen 244.
[0061] The embolic filter assembly 232 is folded into the collapsed
position shown in FIG. 20 by extending and rotating the inner
catheter shaft 240 in a first direction with respect to the outer
catheter shaft 250. This collapses the filter support structure 234
back against the inner catheter shaft 240 and furls the filter
screen 244 around the inner catheter shaft 240. The spiral flutes
248 in the filter screen 244 help it to collapse smoothly around
the inner catheter shaft 240. An outer tube 252 covers the embolic
filter assembly 232 in the collapsed position to facilitate
insertion of the catheter 230. Once the perfusion filter catheter
230 is in position within the patient's aorta, the outer tube 252
is pulled back to expose the embolic filter assembly 232. Then, the
embolic filter assembly 232 is deployed by rotating the inner
catheter shaft 240 in the opposite direction with respect to the
outer catheter shaft 250 and allowing it to retract slightly, as
shown in FIG. 19. The filter support structure 234 and the filter
screen 244 will expand within the aorta and the distal end 242 of
the filter screen 244 will seal against the aortic wall, as shown
in FIG. 18. When it is in the deployed position, the spiral flutes
248 of the embolic filter assembly 232 hold most of the filter
screen 244 away from the aortic walls and away from the ostia of
the side branches so that blood can flow freely through the pores
of the filter screen 244. After use, the embolic filter assembly
232 is returned to the collapsed position as described above and
the catheter 230 is withdrawn from the patient.
[0062] The coaxial arrangement of the inner catheter shaft 240 and
the outer catheter shaft 250 in this embodiment of the perfusion
filter catheter 230 creates an annular space that can optionally be
used as a lumen 258 to aspirate potential emboli that are captured
by the filter screen 244. To facilitate this, a side arm 254 with a
luer fitting and a sliding hemostasis valve 256 may be added to the
proximal end of the outer catheter shaft 250, as shown in FIG.
18.
[0063] FIGS. 21-23 show another method of actively deploying an
embolic filter assembly 262 on a perfusion filter catheter 260. In
this embodiment, the filter support structure 234 includes an outer
hoop 266 and a plurality of struts 268, which are connected to an
inner catheter shaft 270. The outer hoop 266 and the struts 268 may
be made of a resilient polymer or metal, for example a superelastic
nickel/titanium alloy. The distal end 272 of the filter screen 274
is attached to the outer hoop 266. The proximal end 276 of the
filter screen 274 is sealingly attached to an outer catheter shaft
280. The inner catheter shaft 270 is slidably received within the
outer catheter shaft 280. Preferably, the filter screen 274 has a
series of circumferential pleats 278 that give the filter screen
274 an accordion appearance.
[0064] The embolic filter assembly 262 is folded into the collapsed
position shown in FIG. 23 by extending the inner catheter shaft 270
distally with respect to the outer catheter shaft 280. This
collapses the filter support structure 264 back against the inner
catheter shaft 270 and collapses the circumferential pleats 248 of
the filter screen 274 against the inner catheter shaft 270. An
outer tube 282 covers the embolic filter assembly 262 in the
collapsed position to facilitate insertion of the catheter 260.
Once the perfusion filter catheter 260 is in position within the
patient's aorta, the outer tube 282 is pulled back to expose the
embolic filter assembly 262. Then, the embolic filter assembly 262
is deployed by retracting the inner catheter shaft 270 proximally
with respect to the outer catheter shaft 280, as shown in FIG. 22.
The filter support structure 264 and the filter screen 274 will
expand within the aorta and the distal end 272 of the filter screen
274 will seal against the aortic wall, as shown in FIG. 21. When it
is in the deployed position, the circumferential pleats 278 of the
embolic filter assembly 262 hold the majority of the filter screen
274 away from the aortic walls and away from the ostia of the side
branches so that blood can flow freely through the pores of the
filter screen 274. After use, the embolic filter assembly 262 is
returned to the collapsed position as described above and the
catheter 260 is withdrawn from the patient.
[0065] As with the previous embodiment, the coaxial arrangement of
the inner catheter shaft 270 and the outer catheter shaft 280 in
this embodiment of the perfusion filter catheter 260 creates an
annular space that can optionally be used as a lumen 288 to
aspirate potential emboli that are captured by the filter screen
274. To facilitate this, a side arm 284 with a luer fitting and a
sliding hemostasis valve 286 may be added to the proximal end of
the outer catheter shaft 280, as shown in FIG. 21.
[0066] Active deployment of the embolic filter assembly can also be
accomplished with any of the preceding embodiments by using shape
memory materials, such as a nickel/titanium alloy, to construct the
filter support structure and/or the actuation members. The
transition temperature of the shape memory material should be
chosen to be close to normal body temperature so that extreme
temperature variations will not be necessary for deployment. The
shape memory material of the filter support structure should be
annealed in the deployed position to confer a shape memory in this
configuration. Then, the embolic filter assembly should be cooled
below the transition temperature of the shape memory material, so
that the filter support structure is malleable and can be shaped
into a collapsed position. Depending on the transition temperature,
this can be done at room temperature or in iced saline solution. If
desired, an outer tube can be placed over the embolic filter
assembly to facilitate catheter insertion and to avoid premature
deployment. Once the perfusion filter catheter is in position
within the patient's aorta, the outer tube is pulled back to expose
the embolic filter assembly and the filter support structure is
heated above the transition temperature to deploy the embolic
filter assembly. Depending on the transition temperature of the
shape memory material, the filter support structure can be
passively heated by body heat (accounting, of course, for decreased
body temperature during hypothermic cardiopulmonary support
methods) or it can be self-heated by applying an electrical current
through the filter support structure. When heated, the filter
support structure expands to its annealed configuration within the
aorta. After use, the embolic filter assembly is returned to the
collapsed position by advancing the outer tube distally over the
filter screen and the filter support structure, then the catheter
is withdrawn from the patient.
[0067] The foregoing examples of the perfusion filter catheter of
the present invention showed retrograde deployment of the device
within the aorta via femoral artery access. Each of the described
embodiments of the perfusion filter catheter can also be adapted
for retrograde deployment via subclavian artery access or for
antegrade or retrograde deployment via direct aortic puncture.
[0068] FIG. 24 shows a perfusion filter catheter 290 which is
adapted for retrograde deployment via subclavian artery access. In
this exemplary embodiment, the perfusion filter catheter 290 is
depicted with a trumpet-style, passively-deployed embolic filter
assembly 292. Because it is intended for subclavian artery access,
the perfusion filter catheter 290 has a tubular catheter shaft 294
with a length of approximately 60-90 cm. Because of the shorter
length, as compared to the femoral version of the catheter, the
outside diameter of the catheter shaft 294 can be reduced to 12-18
French size (4-6 mm outside diameter) for delivering the 3-4 liters
of oxygenated blood needed to preserve organ function. The reduced
diameter of the catheter shaft 294 is especially advantageous for
subclavian artery delivery of the catheter 290. To further reduce
the size of the catheter system for subclavian or femoral artery
delivery, the outer tube 296 may be adapted for use as an
introducer sheath by the addition of an optional hemostasis valve
298 at the proximal end of the outer tube 296. This eliminates the
need for a separate introducer sheath for introducing the catheter
290 into the circulatory system.
[0069] In use, the perfusion filter catheter 290 is introduced into
the subclavian artery with the embolic filter assembly 292 in a
collapsed state within the outer tube 296, using the Seldinger
technique or an arterial cutdown. The embolic filter assembly 292
is advanced across the aortic arch while in the collapsed state.
The position of the catheter 292 may be monitored using fluoroscopy
or ultrasound, such as transesophageal echography (TEE). Radiopaque
markers and/or sonoreflective markers, may be located on the
catheter 290 and/or the embolic filter assembly 292 to enhance
imaging and to show the position of the catheter 290 and the
deployment state of the embolic filter assembly 292. When the
distal end of the catheter 290 is positioned in the ascending aorta
between the aortic valve and the brachiocephalic artery, the outer
tube 296 is withdrawn and the embolic filter assembly 292 is either
actively or passively deployed, as shown in FIG. 24. Once the
embolic filter assembly 292 is deployed, oxygenated blood may be
infused into the aorta through the tubular catheter shaft 294. Any
potential emboli are captured by the embolic filter assembly 292
and prevented from entering the neurovasculature or other branches
downstream. After use, the embolic filter assembly 292 is returned
to the collapsed position and the catheter 290 is withdrawn from
the patient.
[0070] Retrograde deployment of the perfusion filter catheter 290
via direct aortic puncture is quite similar to introduction via
subclavian artery access, except that the catheter 290 is
introduced directly into the descending aorta after it has been
surgically exposed, for example during open-chest or minimally
invasive cardiac surgery. Because of the direct aortic insertion,
the length and the diameter of the catheter shaft 294 may be
further reduced.
[0071] FIGS. 25-27 show a perfusion filter catheter 300 which is
adapted for antegrade deployment via direct aortic puncture. In
this exemplary embodiment, the perfusion filter catheter 300 is
depicted with a hybrid-style embolic filter assembly 302, which is
a compromise between the conical filter screen and the
trumpet-style filter screen previously described. Because the
catheter 300 is introduced directly into the ascending aorta, the
catheter shaft 304 can be reduced to a length of approximately
20-60 cm and an outside diameter of approximately 12-18 French size
(4-6 mm outside diameter) for delivering the 3-4 liters of
oxygenated blood needed to preserve organ function during
cardiopulmonary bypass. An important modification that must be made
to the catheter 300 for antegrade deployment is that the perfusion
port or ports 306 which connect to the perfusion lumen 308 must
exit the catheter shaft 304 proximal to the filter screen 310 so
that fluid flow will come from the upstream side of the embolic
filter assembly 302. The catheter shaft 304 need not extend all the
way to the distal end of the filter screen 310. The filter screen
310 may be entirely supported by the filter support structure 312,
particularly if the embolic filter assembly 302 is to be passively
deployed. Alternatively, a small diameter filter support member 314
may extend from the catheter shaft 304 to the distal end of the
filter screen 310. If the embolic filter assembly 302 is intended
to be actively deployed, the filter support member 314 may be
slidably and/or rotatably received within the catheter shaft 304.
Either of these configurations allows the embolic filter assembly
302 to be folded or compressed to a size as small as the diameter
of the catheter shaft 304 to facilitate insertion of the catheter
300. Optionally, an outer tube 316 may be placed over the folded
embolic filter assembly 302 to hold it in the collapsed
position.
[0072] In use, the ascending aorta of the patient is surgically
exposed, using open-chest or minimally invasive surgical
techniques. A purse string suture 318 is placed in the ascending
aorta and an aortotomy incision is made through the aortic wall.
The catheter 300, with the embolic filter assembly 302 in the
collapsed position within the outer tube 316, is inserted through
the aortotomy and advanced antegrade into the aortic arch. When the
proximal end of the embolic filter assembly 302 is positioned in
the ascending aorta between the aortic valve and the
brachiocephalic artery, the outer tube 316 is withdrawn and the
embolic filter assembly 302 is either actively or passively
deployed, as shown in FIG. 25. Once the embolic filter assembly 302
is deployed, oxygenated blood may be infused into the aorta through
the tubular catheter shaft 304. Any potential emboli are captured
by the embolic filter assembly 302 and prevented from entering the
neurovasculature or other branches downstream. After use, the
embolic filter assembly 302 is returned to the collapsed position,
the catheter 300 is withdrawn from the patient, and the purse
string suture 318 is tightened to close the aortotomy.
[0073] In general, each of the passive and active deployment
methods described above may be used interchangeably or together in
combinations with each of the embodiments of the perfusion filter
catheter and each of catheter insertion methods which are described
above and below. Likewise, many of the features of the embodiments
described may be used in various combinations with one another to
create new embodiments, which are considered to be a part of this
disclosure, as it would be too cumbersome to describe all of the
numerous possible combinations and subcombinations of the disclosed
features.
[0074] Following are a number of alternate embodiments of the
perfusion filter catheter of the present invention illustrating
additional features and variations in the configuration of the
invention. In general, each of the described embodiments may be
passively or actively deployed by the methods described above. Each
embodiment of the perfusion filter catheter described can also be
adapted for retrograde deployment via peripheral arterial access,
such as femoral or subclavian artery access, or for antegrade or
retrograde deployment via direct aortic puncture.
[0075] FIGS. 28 and 29 show a perfusion filter catheter 320 having
an embolic filter assembly 322 with a graded porosity filter screen
324. The filter screen 324 is attached to a filter support
structure 326 mounted on a catheter shaft 328 for antegrade or
retrograde deployment. The filter screen 324 may be made in each of
the configurations disclosed herein or any other convenient shape.
By way of example, the filter screen 324 in this embodiment is
depicted as being in the shape of a frustum of a cone. The filter
screen 324 has an upstream end 330 and a downstream end 332. The
upstream end 330 of the filter screen 324 has a finer filter mesh
than the downstream end 332. Depending on the capabilities of the
fabrication process used, the pore size of the filter screen 324
may make a gradual transition from the upstream end 330 to the
downstream end 332 or there may be two or more discrete zones of
varying pore size. In one preferred embodiment, the filter mesh on
the upstream end 330 has a pore size of approximately 5-50
micrometers for capturing microemboli and macroemboli and the
filter mesh on the downstream end 332 has a pore size of
approximately 50-100 micrometers for capturing macroemboli only.
The pore size of the filter screen 324 has been greatly exaggerated
in FIG. 28 for clarity of illustration.
[0076] In use, the perfuision filter catheter 320 is introduced
into the aorta with the embolic filter assembly 322 in a collapsed
state within an outer tube 334, using one of the methods described
above. The embolic filter assembly 322 is advanced across the
aortic arch while in the collapsed state. When the upstream end 336
of the catheter 320 is positioned in the ascending aorta between
the aortic valve and the brachiocephalic artery, the outer tube 334
is withdrawn and the embolic filter assembly 322 is either actively
or passively deployed, as shown in FIG. 29. Preferably, the embolic
filter assembly 292 is dimensioned so that when it is deployed, the
upstream end 330 of the filter screen 324 is positioned in the
vicinity of the ostia for the brachiocephalic artery and the left
common carotid artery and the downstream end 332 of the filter
screen 324 is positioned downstream of this position, preferably in
the descending aorta. This configuration assures that all of the
perfusate which is destined for the neurovasculature must pass
through the finer, upstream end 330 of the filter screen 324 to
remove all microemboli and macroemboli. Whereas, the perfusate
which is destined for the viscera and the lower limbs, which are
more tolerant of small emboli, need only pass through the
downstream end 332 of the filter screen 324, so as to remove at
least the macroemboli.
[0077] FIG. 30 shows a perfusion filter catheter 340 having a
longitudinally fluted embolic filter assembly 342. The embolic
filter assembly 342 has a filter screen 344 that is attached at its
open distal end 352 to a filter support structure 346 mounted on a
catheter shaft 348 for antegrade or retrograde deployment. The
filter screen 344 has a plurality of longitudinally oriented folds
or flutes 350. FIG. 30A is a cutaway section of the embolic filter
assembly 342 cut along line 30A in FIG. 30 in order to better show
the longitudinal flutes 350. The longitudinal flutes 350 provide
additional surface area to the filter screen 344 to reduce pressure
drop from blood flow across the embolic filter assembly 342. The
longitudinal flutes 350 also serve to hold a majority of the filter
screen 344 away from the aortic wall and away from the ostia of the
arch vessels. The longitudinally fluted embolic filter assembly 342
can be adapted for passive or active deployment by any of the
methods described above.
[0078] FIG. 31 shows a perfusion filter catheter 360 having a
longitudinally ribbed embolic filter assembly 362. The embolic
filter assembly 362 has a filter screen 364 that is attached at its
open distal end 372 to a filter support structure 366 mounted on a
catheter shaft 368 for antegrade or retrograde deployment. The
filter screen 364 may be configured as a conical, trumpet,
longitudinally fluted or other style of filter screen. The embolic
filter assembly 362 has a plurality of longitudinally oriented ribs
370 positioned around the exterior of the filter screen 364. FIG.
31A is a cutaway section of the embolic filter assembly 362 cut
along line 31A in FIG. 31 in order to better show the
longitudinally oriented ribs 370. The longitudinal ribs 370 serve
as standoff members to center the filter screen 364 within the
aorta so as hold a majority of the filter screen 364 away from the
aortic wall and away from the ostia of the arch vessels. The
longitudinally ribbed embolic filter assembly 362 can be adapted
for passive or active deployment by any of the methods described
above.
[0079] FIG. 32 shows a perfusion filter catheter 380 having an
embolic filter assembly 382 that is surrounded by a cage 394 of
standoff members 396. The embolic filter assembly 382 has a filter
screen 384 that is attached at its open distal end 392 to a filter
support structure 386 mounted on a catheter shaft 388 for antegrade
or retrograde deployment. The filter screen 384 may be configured
as a conical, trumpet, longitudinally fluted or other style of
filter screen. The embolic filter assembly 382 further includes a
plurality of standoff members 396 that form a cage 394 surrounding
the filter screen 384. The standoff members 396 may be made of a
resilient polymer or metal, such as an elastic or superelastic
alloy, or a shape-memory material. The geometry of the standoff
members 396 is quite variable. By way of example, FIG. 32 depicts
the standoff members 396 as a plurality of longitudinally oriented
wires which, together, form a roughly cylindrical cage 394. Other
possible configurations include circumferential members, diagonal
members, and combinations thereof. The standoff members 396 of the
cage 394 serve to center the filter screen 384 within the aorta so
as hold a majority of the filter screen 384 away from the aortic
wall and away from the ostia of the arch vessels. The embolic
filter assembly 382 and the standoff members 396 of the cage 394
can be adapted for passive or active deployment by any of the
methods described above.
[0080] FIG. 33 shows a perfusion filter catheter 400 having an
embolic filter assembly 402 that is 10 surrounded by a cage 414 of
coiled wire standoff members 416. The embolic filter assembly 402
has a filter screen 404 that is attached at its open distal end 412
to a filter support structure 406 mounted on a catheter shaft 408
for antegrade or retrograde deployment. The filter screen 404 may
be configured as a conical, trumpet, longitudinally fluted or other
style of filter screen. The embolic filter assembly 402 further
includes a plurality of loosely coiled wire standoff members 416
which form a cage 414 surrounding the filter screen 404. The coiled
standoff members 416 may be made of a resilient polymer or metal,
such as an elastic or superelastic alloy, or a shape-memory
material. The coiled standoff members 416 of the cage 414 serve to
center the filter screen 404 within the aorta so as hold a majority
of the filter screen 404 away from the aortic wall and away from
the ostia of the arch vessels. The embolic filter assembly 402 and
the standoff members 416 of the cage 414 can be adapted for passive
or active deployment by any of the methods described above.
[0081] FIG. 34 shows a perfusion filter catheter 420 having an
embolic filter assembly 422 that is surrounded by a cage 434 of
coarse netting 436. The embolic filter assembly 422 has a filter
screen 424 that is attached at its open distal end 432 to a filter
support structure 426 mounted on a catheter shaft 428 for antegrade
or retrograde deployment. The filter screen 424 may be configured
as a conical, trumpet, longitudinally fluted or other style of
filter screen. The embolic filter assembly 422 further includes a
coarse netting 436, which forms a roughly cylindrical cage 434
surrounding the filter screen 424. The netting 436 may be made of a
resilient polymer or metal, such as an elastic or superelastic
alloy, or a shape-memory material. The netting 436 of the cage 434
serves to center the filter screen 424 within the aorta so as hold
a majority of the filter screen 424 away from the aortic wall and
away from the ostia of the arch vessels. The embolic filter
assembly 422 and the coarse netting 436 of the cage 434 can be
adapted for passive or active deployment by any of the methods
described above.
[0082] FIG. 35 shows a cutaway view of a perfusion filter catheter
440 having an embolic filter assembly 442 that is surrounded by a
fender 454 made from a porous foam or a fibrous network 456. The
embolic filter assembly 442 has a filter screen 444 that is
attached at its open distal end 452 to a filter support structure
446 mounted on a catheter shaft 448 for antegrade or retrograde
deployment. The filter screen 444 may be configured as a conical,
trumpet, longitudinally fluted or other style of filter screen. The
embolic filter assembly 442 further includes a roughly cylindrical
fender 454 made from a highly porous foam or a fibrous network 456,
which surrounds the filter screen 444. The fender 454 may be made
of a highly porous open cell polymer foam or a network of polymeric
fibers. The fender 454 serves to center the filter screen 444
within the aorta so as hold a majority of the filter screen 444
away from the aortic wall and away from the ostia of the arch
vessels. The embolic filter assembly 442 and the fender 454 can be
adapted for passive or active deployment or a combination
thereof.
[0083] FIGS. 36 and 37 show an alternate embodiment of a perfusion
filter catheter 460 with a passively deployed embolic filter
assembly 462. The embolic filter assembly 462 has a filter screen
464 that is attached at its open distal end 474 to a filter support
structure 466 mounted on a catheter shaft 468 for antegrade or
retrograde deployment. The proximal end 476 of the filter screen
464 is sealingly attached to the catheter shaft 468. The filter
screen 464 may be configured as a conical, trumpet or other style
of filter screen. The filter support structure 466 has an outer
hoop 470 which is attached by a perpendicular leg 472 to the
catheter shaft 468. Preferably, the outer hoop 470 is made of a
resilient polymer or metal, such as an elastic or superelastic
alloy, or possibly a shape-memory material. The filter support
structure 466, in this embodiment, has no struts. Optionally, the
distal end 478 of the catheter shaft 468 may be curved toward the
center of the outer hoop 470 to help center the perfusion port 480
located at the distal end of the catheter shaft 468 within the
aorta when the catheter 460 is deployed. Also, the perfusion port
480 may optionally include additional side ports or a flow
diffuser, as shown, to reduce jetting when oxygenated blood is
infused through the perfusion lumen 482.
[0084] The perfusion filter catheter 460 is prepared for use by
bending the outer hoop 470 in the proximal direction or wrapping it
around the catheter shaft 468, then folding or wrapping the
material of the filter screen 464 around the catheter shaft 468. An
outer tube 484 is placed over the embolic filter assembly 462 to
hold it in the collapsed position, as shown in FIG. 37. The
catheter 460 is introduced and the embolic filter assembly 462 is
advanced across the aortic arch while in the collapsed state. When
the distal end 474 of the embolic filter assembly 462 is positioned
in the ascending aorta between the aortic valve and the
brachiocephalic artery, the outer tube 484 is withdrawn and the
resilient outer hoop 470 expands to deploy the embolic filter
assembly 462, as shown in FIG. 36. The outer hoop 470 and the
distal end 474 of the filter screen 464 will seal against the
aortic wall. After use, the embolic filter assembly 462 is returned
to the collapsed position by advancing the outer tube 484 distally
over the filter screen 464 and the filter support structure 466,
then the catheter 460 is withdrawn from the patient.
[0085] FIGS. 38-41 show an alternate embodiment of a perfusion
filter catheter 490 with an actively deployed embolic filter
assembly 492. The embolic filter assembly 492 has a filter screen
494 with a sewn tubular channel 496 which extends circumferentially
around the open distal end 498 of the filter screen 494. The distal
end 498 of the filter screen 494 is attached on one side to the
catheter shaft 504, and the proximal end 506 of the filter screen
494 is sealingly attached to the catheter shaft 504. The filter
screen 494 may be configured as a conical, trumpet or other style
of filter screen. The filter support structure in this embodiment
consists of a preshaped, superelastic actuation wire 500, which,
when the embolic filter assembly 492 is in the collapsed state,
resides in a second lumen 502 within the catheter shaft 504.
Preferably, the actuation wire 500 has a bead or small loop 508 at
its distal end to create a blunt, non-piercing tip. The second
lumen 502 of the catheter shaft 504 communicates with the tubular
channel 496 at the distal end 498 of the filter screen 494. When
the actuation wire 500 is extended, it forms a hoop as it passes
through the tubular channel 496 of the filter screen 494.
[0086] Optionally, the distal end 510 of the catheter shaft 504 may
be curved toward the center of the embolic filter assembly 492 to
help center the perfusion port 510 located at the distal end of the
catheter shaft 504 within the aorta when the catheter 490 is
deployed. Also, the perfusion port 510 may optionally include
additional side ports or a flow diffuser, as shown, to reduce
jetting when oxygenated blood is infused through the perfusion
lumen 512 during cardiopulmonary bypass.
[0087] The perfusion filter catheter 490 is prepared for use by
withdrawing the actuation wire 500 into the second lumen 502, then
folding or wrapping the flexible material of the filter screen 494
around the catheter shaft 504. Optionally, an outer tube 514 may be
placed over the embolic filter assembly 492 to hold it in the
collapsed position, as shown in FIG. 38. The catheter 490 is
introduced and the embolic filter assembly 492 is advanced across
the aortic arch while in the collapsed state. When the distal end
498 of the embolic filter assembly 492 is positioned in the
ascending aorta between the aortic valve and the brachiocephalic
artery, the outer tube 514 is withdrawn, which allows the filter
screen 494 to unwrap from the catheter shaft 504, as shown in FIG.
39.
[0088] Then, the preshaped, superelastic actuation wire 500 is
advanced distally so that it begins to form a hoop as it passes
through the tubular channel 496 at the distal end 498 of the filter
screen 494, as shown in FIG. 40. The actuation wire 500 is further
advanced until it forms a complete hoop, as shown in FIG. 41,
thereby sealing the distal end 498 of the filter screen 494 against
the aortic wall. After use, the embolic filter assembly 492 is
returned to the collapsed position as described above, then the
catheter 490 is withdrawn from the patient.
[0089] FIGS. 42 and 43 show another alternate embodiment of a
perfusion filter catheter 520 with an actively deployed embolic
filter assembly 522. The embolic filter assembly 522 has a filter
screen 524 with a sewn tubular channel 526 which extends
circumferentially around the open distal end 528 of the filter
screen 524. The distal end 528 of the filter screen 524 is attached
on one side to the catheter shaft 534, and the proximal end 536 of
the filter screen 524 is sealingly attached to the catheter shaft
534. The filter screen 524 may be configured as a conical, trumpet
or other style of filter screen. The filter support structure in
this embodiment consists of a preshaped, elastic or superelastic
wire loop 530. The wire loop 530 passes through the tubular channel
526 at the distal end 528 of the filter screen 524. When the
embolic filter assembly 522 is in the collapsed position, the wire
loop 530 is withdrawn into a second lumen 532 within the catheter
shaft 534, as shown in FIG. 42. In the collapsed position, the wire
loop 530 acts as a purse string to close the filter screen 524
tightly around the catheter shaft 534. When the wire loop 530 is
advanced distally, it forms a hoop that holds the distal end 528 of
the filter screen 524 open, as shown in FIG. 43.
[0090] Optionally, the distal end 540 of the catheter shaft 534 may
be curved toward the center of the embolic filter assembly 522 to
help center the perfusion port 542 located at the distal end of the
catheter shaft 534 within the aorta when the catheter 520 is
deployed. Also, the perfusion port 540 may optionally include
additional side ports or a flow diffuser, as shown, to reduce
jetting when oxygenated blood is infused through the perfusion
lumen 544 during cardiopulmonary bypass.
[0091] The perfusion filter catheter 520 is prepared for use by
withdrawing the wire loop 530 into the second lumen 532, then
folding or wrapping the flexible material of the filter screen 524
around the catheter shaft 534. Optionally, an outer tube 538 may be
placed over the embolic filter assembly 522 to hold it in the
collapsed position. The catheter 520 is introduced and the embolic
filter assembly 522 is advanced across the aortic arch while in the
collapsed state. When the distal end 528 of the embolic filter
assembly 522 is positioned in the ascending aorta between the
aortic valve and the brachiocephalic artery, the outer tube 538 is
withdrawn, and the preshaped, superelastic wire loop 530 is
advanced distally so that it forms a hoop that holds the distal end
528 of the filter screen 524 open and seals against the aortic
wall. The inherent adjustability of the wire loop 530 used to
deploy the embolic filter assembly 522 naturally compensates for
patient-to-patient variations in aortic luminal diameter. After
use, the embolic filter assembly 522 is returned to the collapsed
position by withdrawing the wire loop 530 into the second lumen
532. This closes the filter screen 524 like a purse string to
capture any potential emboli that are in the embolic filter
assembly 522. Then, the catheter 520 is withdrawn from the
patient.
[0092] FIGS. 44 and 45 show another alternate embodiment of a
perfusion filter catheter 550 with an actively deployed embolic
filter assembly 552. The embolic filter assembly 552 has a filter
screen 554 with an open distal end 558 that is attached to a
toroidal balloon 560. The toroidal balloon 560 is attached on one
side to the catheter shaft 564 and it is fluidly connected to an
inflation lumen 562 within the catheter shaft 564. The proximal end
566 of the filter screen 554 is sealingly attached to the catheter
shaft 564. The filter screen 554 may be configured as a conical,
trumpet or other style of filter screen. Optionally, the distal end
570 of the catheter shaft 564 may be curved toward the center of
the embolic filter assembly 552 to help center the perfusion port
572 located at the distal end of the catheter shaft 564 within the
aorta when the catheter 550 is deployed. Also, the perfusion port
570 may optionally include additional side ports or a flow
diffuser, as shown, to reduce jetting when oxygenated blood is
infused through the perfusion lumen 574 during cardiopulmonary
bypass.
[0093] The perfusion filter catheter 550 is prepared for use by
deflating the toroidal balloon 560, then folding or wrapping the
deflated toroidal balloon 560 and the filter screen 554 around the
catheter shaft 564. Optionally, an outer tube 564 may be placed
over the embolic filter assembly 552 to hold it in the collapsed
position, as shown in FIG. 44. The catheter 550 is introduced and
the embolic filter assembly 552 is advanced across the aortic arch
while in the collapsed state. When the distal end 558 of the
embolic filter assembly 552 is positioned in the ascending aorta
between the aortic valve and the brachiocephalic artery, the outer
tube 564 is pulled back to expose the embolic filter assembly 552.
Then, the embolic filter assembly 202 is deployed by inflating the
toroidal balloon 560 with fluid injected through the inflation
lumen 562, as shown in FIG. 45. When the embolic filter assembly
552 is deployed, the toroidal balloon 560 seals against the inner
wall of the aorta. Preferably, at least the outer wall of the
toroidal balloon 560 is somewhat compliant when inflated in order
to compensate for patient-to-patient variations in aortic luminal
diameter. After use, the toroidal balloon 560 is deflated and the
catheter 550 is withdrawn from the patient.
[0094] Ideally, it is preferable that the embolic filter assembly
of the perfusion filter catheter be deployed continuously
throughout the entire period of cardiopulmonary bypass or
extracorporeal perfusion. It is most critical, however, that the
embolic filter assembly be deployed during periods when the
potential for embolization is the highest, such as during
manipulations of the heart and the aorta, during clamping and
unclamping of the aorta and during the initial period after the
heart is restarted following cardioplegic arrest. It has been
previously stated that, for continuous deployment of a filter
device in the aortic lumen, it is desirable for the filter mesh to
have a surface area of 3-10 in.sup.2. The shallow, cone-shaped
aortic filter devices illustrated in the known prior art only
manage to provide surface areas at the lower end of this desired
range in the largest of human aortas (approximately 3.0-3.9
in.sup.2 in aortas of 3.5-4.0 cm diameter estimated based on the
drawings and descriptions in the prior art disclosures) and in no
cases are there embodiments disclosed which could provide surface
areas in the middle and upper end of this range or that could even
meet the minimum limit of this desired range in more typically
sized aortas in the range of 2.5-3.5 cm diameter. Consequently, it
is the opinion of the present inventors that the prior art does not
provide an adequate solution to the technical problem that it
illuminates.
[0095] The solution to this dilemma is to provide a filter assembly
that has a greater ratio of filter surface area to the
cross-sectional area of the aortic lumen. (The cross-sectional area
of the aortic lumen being approximately equal to the area of the
open upstream end of the embolic filter assembly at its deployed
diameter within the aorta.) Preferably, the embolic filter assembly
should provide a ratio of the filter surface area to the
cross-sectional area of the aortic lumen of greater than
approximately 2, more preferably greater than 3, more preferably
greater than 4, more preferably greater than 5 and most preferably
greater than 6. With these ratios of the filter surface area to the
cross-sectional area of the aortic lumen, it is possible to achieve
a filter mesh surface area of 3-10 in.sup.2 or greater in all
typical adult human aortas ranging from 2.0 to 4.0 cm in diameter.
Furthermore, given the embolic filter assembly structures that have
been disclosed herein, it is envisioned that ratios of the filter
surface area to the cross-sectional area of the aortic lumen of 8,
10, 12 and even greater are readily achievable. Higher ratios such
as these are desirable as they allow a very fine filter mesh to be
utilized to effectively capture both macroemboli and microemboli
without compromising the aortic blood flow. Along with this, it is
preferable to utilize an embolic filter assembly structure or other
means that maximizes the effective surface area of the filter mesh
by holding at least a majority of the filter mesh away from the
aortic wall or any other structures that might potentially obstruct
flow through the filter mesh.
[0096] To further illustrate this point, the following are given as
examples of embolic filter assemblies exhibiting the desired range
of ratios of the filter surface area to the cross-sectional area of
the aortic lumen. These examples are merely illustrative of some of
the possible embodiments of the embolic filter assembly and should
not be interpreted as limiting in any way to the scope of the
present invention. Turning first to FIGS. 1-3, there is illustrated
an embolic filter assembly that is approximately conical in shape.
In order to achieve a ratio of the filter surface area to the
cross-sectional area of the aortic lumen of greater than
approximately 2, a conical filter assembly must have a filter
length L of greater than the aortic diameter D. To achieve a ratio
of the filter surface area to the cross-sectional area of the
aortic lumen of greater than approximately 4, a conical filter
assembly must have a filter length L of greater than twice the
aortic diameter D. To achieve a ratio of the filter surface area to
the cross-sectional area of the aortic lumen of greater than
approximately 6, a conical filter assembly must have a filter
length L of greater than three times the aortic diameter D. With
these ratios of the filter surface area to the cross-sectional area
of the aortic lumen, it is possible to achieve a filter mesh
surface area of 3-10 in.sup.2 or greater in all typical adult human
aortas ranging from 2.0 to 4.0 cm in diameter. Greater length to
diameter ratios will provide more improved ratios of the filter
surface area to the cross-sectional area of the aortic lumen.
[0097] Turning next to FIGS. 7-8, 15-17 and 25-27, there are
illustrated embolic filter assemblies having an approximately
trumpet-shaped geometry that includes an approximately conical
upstream section connected to an approximately cylindrical
extension with a closed downstream end. This geometry provides an
improvement in the ratio of the filter surface area to the
cross-sectional area of the aortic lumen of approximately 15 to 50
percent compared with the simple conical geometry. Thus, even
greater ratios of the filter surface area to the cross-sectional
area of the aortic lumen are readily achieved using this
trumpet-shaped geometry. Further improvements of the ratio of the
filter surface area to the cross-sectional area of the aortic lumen
can be realized with the convoluted embolic filter assemblies
illustrated in FIGS. 18-20, 20-23 and 30. With these convoluted
geometries, ratios of the filter surface area to the
cross-sectional area of the aortic lumen of 2-12 or even greater
can be achieved.
[0098] Each of the embodiments of the invention described herein
may be used for administration of standard cardiopulmonary bypass
and cardioplegic arrest by combining the aortic filter catheter
with a standard aortic crossclamp and a standard arterial perfusion
cannula inserted into the ascending aorta between the crossclamp
and the embolic filter assembly. Where the aortic filter catheter
includes an integral perfusion lumen, the CPB system can be
simplified by the eliminating the separate arterial perfusion
cannula. The CPB system can be further simplified by incorporating
an aortic occlusion device into the aortic filter catheter and
eliminating the aortic crossclamp. Such a system would allow
percutaneous transluminal administration of cardiopulmonary bypass
and cardioplegic arrest with protection from undesirable embolic
events.
[0099] FIGS. 46-50 show the operation of an embodiment of a
perfusion filter catheter 600 that combines an embolic filter
assembly 602 with a toroidal balloon aortic occlusion device 604.
The embolic filter assembly 602 and the toroidal balloon aortic
occlusion device 604 are mounted on an elongated catheter shaft 606
that may be adapted for peripheral introduction via the femoral
artery or subclavian artery or for central insertion directly into
the ascending aorta. The toroidal balloon aortic occlusion device
604 is connected to an inflation lumen within the elongated
catheter shaft 606. A cardioplegia lumen, which may also serve as a
guidewire lumen, connects to a cardioplegia port 608 at the distal
end of the catheter shaft 606. A perfusion lumen connects to one or
more perfusion ports 610 located on the catheter shaft 606
downstream from the toroidal balloon aortic occlusion device 604,
but upstream of the embolic filter assembly 602.
[0100] FIG. 46 shows the perfusion filter catheter 600 in the
collapsed or undeployed state with the embolic filter assembly 602
and the toroidal balloon aortic occlusion device 604 collapsed or
folded about the elongated catheter shaft 606. The perfuision
filter catheter 600 is inserted in the collapsed state and advanced
into the patient's ascending aorta until the embolic filter
assembly 602 is positioned between the coronary ostia and the
brachiocephalic artery. The toroidal balloon aortic occlusion
device 604 is then inflated to expand and deploy the embolic filter
assembly 602, as shown in FIG. 47. The embolic filter assembly 602
may assume a simple conical shape or, more preferably, one of the
surface area increasing geometries described above. In addition,
the embolic filter assembly 602 may include a structure or other
means to hold the filter material apart from the aortic wall to
maximize the effective filter area. With the embolic filter
assembly 602 deployed, cardiopulmonary bypass with embolic
protection can be started through the perfusion ports 610.
[0101] When it is desired to initiate cardioplegic arrest, the
toroidal balloon aortic occlusion device 604 is further inflated
until it expands inward to occlude the aortic lumen, as shown in
FIG. 48. A cardioplegic agent is infused through the cardioplegia
port 608 and into the coronary arteries to arrest the heart.
Oxygenated blood continues to be infused through the perfusion
ports 610. After completion of the surgical procedure, the toroidal
balloon aortic occlusion device 604 is partially deflated, leaving
the embolic filter assembly 602 deployed, as shown in FIG. 49.
Oxygenated blood enters the coronary arteries to restart the heart
beating. If any embolic materials 612 are dislodged during
manipulation of the heart or when the heart resumes beating, they
will be captured by the embolic filter assembly 602. Once the
patient is weaned off of bypass, the toroidal balloon aortic
occlusion device 604 is deflated to collapse the embolic filter
assembly 602, as shown in FIG. 50. Any potential emboli are trapped
within the embolic filter assembly 602 and can be removed along
with the catheter 600.
[0102] FIG. 51 shows an embodiment of a perfusion filter catheter
620 that combines an embolic filter assembly 622 with an inflatable
balloon aortic occlusion device 624. The embolic filter assembly
622 may be any one of the actively or passively deployed embolic
filter assemblies described herein. Preferably, the inflatable
balloon aortic occlusion device 624 is an 5 elastomeric balloon of
sufficient inflated diameter to occlude the ascending aorta and is
mounted on the elongated catheter shaft 626 upstream of the embolic
filter assembly 622. Alternatively, the inflatable balloon aortic
occlusion device 624 may be positioned to occlude the inlet end of
the embolic filter assembly 622 to minimize the area of contact
between the perfusion filter catheter 620 and the aortic wall. The
inflatable balloon aortic occlusion device 624 is connected to an
inflation lumen within the elongated catheter shaft 626. A
cardioplegia lumen, which may also serve as a guidewire lumen,
connects to a cardioplegia port 628 at the distal end of the
catheter shaft 626. A perfusion lumen connects to one or more
perfusion ports 630 located on the catheter shaft 626 downstream
from the inflatable balloon aortic occlusion device 624, but
upstream of the embolic filter assembly 622. The operation of the
perfusion filter catheter 620 of FIG. 51 is quite similar to that
described for the embodiment of FIGS. 46-50.
[0103] FIG. 52 shows an embodiment of a perfusion filter catheter
640 that combines an embolic filter assembly 642 with a selectively
deployable external catheter flow control valve 644. The embolic
filter assembly 642 may be any one of the actively or passively
deployed embolic filter assemblies described herein. The
selectively deployable external catheter flow control valve 644 is
mounted on the elongated catheter shaft 646 upstream of the embolic
filter assembly 642. Alternatively, the selectively deployable
external catheter flow control valve 644 may be positioned to
occlude the inlet end of the embolic filter assembly 642 to
minimize the area of contact between the perfusion filter catheter
640 and the aortic wall. Selectively deployable external catheter
flow control valves suitable for this application are described in
commonly owned, copending U.S. patent applications Ser. Nos.
08/665,635, 08/664,361 and 08/664,360, filed Jun. 17, 1996, which
are hereby incorporated by reference in their entirety. The
elongated catheter shaft 646 may include one or more deployment
lumens as needed for actuating the external catheter flow control
valve 644. A cardioplegia lumen, which may also serve as a
guidewire lumen, connects to a cardioplegia port 648 at the distal
end of the catheter shaft 646. A perfusion lumen connects to one or
more perfusion ports 650 located on the catheter shaft 646
downstream from the external catheter flow control valve 644, but
upstream of the embolic filter assembly 622. The operation of the
perfusion filter catheter 640 of FIG. 52 is quite similar to that
described for the embodiment of FIGS. 46-50.
[0104] FIG. 53 shows an additional feature of the present invention
that may be used in combination with many of the features and
embodiments previously described. FIG. 53 shows an embodiment of a
perfusion filter catheter 660 with an embolic filter assembly 662
having areas of different filter porosity. The embolic filter
assembly 662 is mounted on an elongated catheter shaft 666 that may
be adapted for peripheral introduction via the femoral artery or
subclavian artery or for central insertion directly into the
ascending aorta. The embolic filter assembly 662 may resemble any
one of the actively or passively deployed embolic filter assemblies
described herein. Preferably, the embolic filter assembly 662
assumes one of the surface area increasing geometries described
above, such as a trumpet-style embolic filter assembly 662 as
shown. The embolic filter assembly 662 is divided along a
longitudinal dividing line into areas of different filter porosity.
In a preferred embodiment, the embolic filter assembly 662 has an
upper portion 664 of finer porosity facing toward the aortic arch
vessels and a lower portion 668 of courser porosity facing away
from the aortic arch vessels. Preferably, the elongated catheter
shaft 666 will have a preformed curve to help orient the upper
portion 664 and the lower portion 668 of the embolic filter
assembly 662 in the proper position once deployed. The filter mesh
of the upper portion 664 may be selected to exclude both
macroemboli and microemboli, and the filter mesh of the lower
portion 668 may be selected to exclude macroemboli only.
Alternatively, the upper portion 664 may be impermeable so as to
act like a shunt to direct potential emboli downstream away from
the aortic arch vessels.
[0105] Another feature that may be combined with the features and
embodiments of the present invention is an aortic transillumination
system for locating and monitoring the position of the catheter,
the filter and the optional occlusion devices without fluoroscopy
by transillumination of the aortic wall. Aortic transillumination
systems using optical fibers and/or light emitting diodes or lasers
suitable for this application are described in commonly owned,
copending U.S. patent application Ser. No. 60/088,652, filed Jun.
9, 1998, which is hereby incorporated by reference in its entirety.
By way of example, FIG. 54 shows an embodiment of a perfusion
filter catheter 670 with a fiberoptic system for aortic
transillumination. A first optical fiber 684 is positioned near a
distal end of the perfusion filter catheter 670, upstream of the
embolic filter assembly 672, so that it will emit a first laterally
directed beam of light. A second optical fiber 672 is positioned on
the outer rim of the filter support structure 674 so that it will
emit a second laterally directed beam of light. An optical coupling
682 at the proximal end of the perfusion filter catheter 670
connects the optical fibers 684, 672 to a light source 680 by way
of an optical cable 678. The light beams emitted by the optical
fibers 684, 672 are visible through the aortic wall and can be used
to locate and monitor the position and the deployment state of the
perfusion filter catheter 670 and the embolic filter assembly 672.
Similarly, in embodiments of the perfusion filter catheter
utilizing an aortic occlusion device, one or more optical fibers or
other light emitting devices may be positioned on the aortic
occlusion device to locate and monitor its position and state of
deployment.
[0106] Likewise, the features and embodiments of the present
invention may also be combined with a bumper location device for
facilitating catheter insertion and positioning by providing
tactile feedback when the catheter device contacts the aortic
valve. Bumper location devices suitable for this application are
described in commonly owned, copending U.S. patent application Ser.
Nos. 60/060,158, filed Sep. 26, 1997, and No. 60/073,681, filed
Feb. 4, 1998, which are hereby incorporated by reference in their
entirety.
[0107] While the present invention has been described herein with
respect to the exemplary embodiments and the best mode for
practicing the invention, it will be apparent to one of ordinary
skill in the art that many modifications, improvements and
subcombinations of the various embodiments, adaptations and
variations can be made to the invention without departing from the
spirit and scope thereof.
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