U.S. patent application number 11/996416 was filed with the patent office on 2009-01-15 for devices and methods for perfusing an organ.
Invention is credited to Adam Lucas Bilney, David Martin Kaye, Mark L. Mathis, John Melmouth Power.
Application Number | 20090018526 11/996416 |
Document ID | / |
Family ID | 37771174 |
Filed Date | 2009-01-15 |
United States Patent
Application |
20090018526 |
Kind Code |
A1 |
Power; John Melmouth ; et
al. |
January 15, 2009 |
Devices and Methods for Perfusing an Organ
Abstract
The present invention provides devices and methods for use in
the perfusion of organs and anatomical regions. In one aspect the
present method provides a percutaneously deliverable device for
supporting a vessel in a human or animal subject including means
for supporting the vessel during delivery of a fluid thereto or
collection of a fluid therefrom. In another aspect the invention
provides a method for delivery or collection of a fluid to or from
an organ or anatomical region in a human or animal subject, the
method including the step of supporting a vessel associated with
the organ or anatomical region. The devices and methods may be used
to deliver, remove or recirculate a therapeutic agent to an organ
or anatomical region.
Inventors: |
Power; John Melmouth;
(Victoria, AU) ; Mathis; Mark L.; (Fremont,
CA) ; Kaye; David Martin; (Victoria, AU) ;
Bilney; Adam Lucas; (Victoria, AU) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
37771174 |
Appl. No.: |
11/996416 |
Filed: |
August 25, 2006 |
PCT Filed: |
August 25, 2006 |
PCT NO: |
PCT/AU2006/001234 |
371 Date: |
June 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60753478 |
Dec 22, 2005 |
|
|
|
60711298 |
Aug 25, 2005 |
|
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|
Current U.S.
Class: |
604/508 ;
623/1.11 |
Current CPC
Class: |
A61M 29/02 20130101;
A61M 25/01 20130101; A61M 25/09 20130101; A61M 2025/09183 20130101;
A61M 2025/1052 20130101; A61M 25/10 20130101; A61F 2/82
20130101 |
Class at
Publication: |
604/508 ;
623/1.11 |
International
Class: |
A61M 25/01 20060101
A61M025/01; A61F 2/84 20060101 A61F002/84 |
Claims
1. A percutaneously deliverable device for supporting a vessel in a
human or animal subject including means for supporting the vessel
during delivery of a fluid thereto or collection of a fluid
therefrom.
2. A device according to claim 1 wherein the means for supporting
the vessel is capable of maintaining patency of the vessel during
delivery of the fluid thereto or collection of the fluid
therefrom.
3. A device according to claim 1 wherein the means for supporting
the vessel is capable of maintaining patency of the vessel where
the fluid pressure in the vessel is less than the minimum pressure
normally found in the vessel.
4. A device according to claim 1 including a collection catheter
component.
5. A device according to claim 4 wherein where the device includes
a collection catheter component, and the collection catheter
component is attached to a pump, the pressure around the intake of
the pump is equal to or less than about -90 mmHg.
6. A device according to claim 4 wherein where the device includes
a collection catheter component, and the collection catheter
component is attached to a pump, the pressure around the intake of
the pump is equal to or less than about -100 mmHg to -115 mmHg
7. A device according to claim 4 wherein where the device includes
a collection catheter component, and the collection catheter
component is attached to a pump, the pressure around the intake of
the pump is equal to or less than about -115 mmHg.
8. A device according to claim 4, wherein the device includes a
collection catheter component, and the collection catheter
component is attached to a pump, the device is capable of
preventing or delaying cavitation in the collection catheter
component, or the pump, or a line connecting the collection
catheter to the pump.
9. A device according to claim 1, wherein the means for supporting
the vessel is capable of maintaining patency of the vessel under
conditions of high fluid flow rate in the vessel.
10. A device according to claim 9 wherein the fluid flow rate in
the vessel is equal to or greater than a value selected from the
group consisting of about 20 ml_per minute, 160 ml. per minute, 180
mL per minute., 200 ml_per minute, and 220 mL per minute.
11. A device according to claim 9 wherein the fluid flow rate
substantially matches the rate of flow of fluid into the vessel
from an anatomical region or organ.
12. A device according to claim 1, wherein the means for supporting
the vessel includes an expandable member deliverable in a collapsed
condition to the vessel and expandable to support the vessel during
delivery of fluid thereto or collection of fluid therefrom.
13. A device according to claim 12 wherein the expandable member is
radially expandable.
14. A device according to claim 12 wherein the expandable member
includes one or more loop portions, each of the one or more loop
portions being attached at a first loop end to a distal end of a
lumen, and at a second loop end to a stem extending through the
lumen, the one or more loop portions having a collapsed condition
in which they are substantially within the lumen, and wherein the
one or more loop portions are controllably expandable by advancing
the stem to eject the one or more loop portions from the lumen.
15. A device according to claim 14 including 2, 3, 4, 5, 6 or more
loop portions.
16. A device according to claim 12, wherein the expandable member
has a configuration substantially as illustrated with reference to
any one of the embodiments shown in accompanying FIGS. 1a to 3 and
5 to 8c.
17. A device according to claim 12, wherein the expandable member
is formed substantially of a material having shape memory
properties.
18. A device according to claim 12, wherein the expandable member
is formed of a material having substantially super-elastic
properties.
19. A device according to claim 12, further including retention
means to retain the expandable member in an expanded condition.
20. A device according to claim 4, including means for
substantially occluding flow from the vessel thereby allowing the
collection catheter to collect substantially all flow entering the
vessel.
21. A device according to claim 4, including means for retaining
the collection catheter at a distance from the vessel wall such
that the lumen of the catheter is prevented from contacting the
vessel wall thereby preventing trauma to the vessel wall and/or
occlusion of the lumen of the catheter.
22. A device according to claim 21 wherein the means for retaining
the collection catheter at a distance from the vessel wall is the
means for supporting a vessel.
23. A device according to claim 12, wherein the expandable member
is capable of anchoring the device at a fixed location in the
vessel thereby substantially preventing movement of the device.
24. A device according to claim 1, further including an atraumatic
guiding tip for guiding the expandable member into the vessel, such
that in use the atraumatic tip makes substantially atraumatic
contact with the vessel wall.
25. A device according to claim 24 wherein the atraumatic tip is
provided 0.25 to 5 centimeters from a distal end of the expandable
member.
26. A device according to claim 24 wherein the atraumatic tip is
flexible, such that in use the tip deforms or deflects upon contact
with a wall of the vessel such that trauma to the vessel wall is
substantially avoided.
27. A device according to claim 24, wherein the atraumatic tip is
shaped, such that in use and upon contacting the vessel wall,
trauma to the vessel wall is substantially avoided.
28. A device according to claim 24, wherein the atraumatic tip is
curved, such that in use and upon contacting the vessel wall,
trauma to the vessel wall is substantially avoided.
29. A device according to claim 24, wherein the atraumatic tip
includes, is made from or is coated with a material having a low
coefficient of friction.
30. A device according to claim 12, wherein the expandable member
is capable of being coupled to a distal region of a guidewire, and
an atraumatic tip is provided at a distal end of the guidewire.
31. A device according to claim 30 wherein in use, a proximal end
of the expandable member is fixedly coupled to the guidewire and a
distal end of the expandable member is movable relative to the
guidewire.
32. A device according to claim 12, wherein in use, a distal end of
the expandable member is fixedly coupled to the guidewire and a
proximal end of the expandable member is movable relative to the
guidewire.
33. A device according to claim 30 wherein the expandable member is
integral with the guidewire structure.
34. A device according to claim 30 wherein a proximal end of the
expandable member is coupled to a first length of a guidewire, and
a distal end of the expandable member is coupled to a second length
of the guidewire.
35. A device according to claim 1, wherein the vessel is a blood
vessel.
36. A device according to claim 35 wherein the blood vessel is a
vein.
37. A device according to claim 36 wherein the vein is selected
from the group consisting of a coronary vein (including the
coronary sinus), an internal jugular vein, hepatic vein, a renal
vein, a cephalic vein, an inferior vesical vein, a pulmonary vein,
an internal iliac vein, a portal vein, a splenic vein, a femoral
vein, a saphenous vein, a subclavian vein, an intercostal vein, an
axillary vessel, a testicular vein, an ovarian vein and tributaries
thereof.
38. A device according to claim 36 wherein the vein is associated
with an organ selected from the group consisting of the heart,
lung, liver, kidney, brain, intestine, testicle, ovary, spleen,
stomach, prostate, and pancreas.
39. A device according to claim 36 wherein the vein is associated
with an anatomical region selected from the group consisting of a
limb, the pelvis, the chest, the breast and the mesenteric
system.
40. A device according to claim 1, including: a plurality of
support members disposed in an array having an expanded state and a
collapsed state, wherein in the collapsed state, the array is sized
for delivery to the vessel through a lumen of a catheter, and
wherein in the expanded state, the array is sized to be greater
than an internal dimension of the catheter, wherein the support
members are biased to the expanded state,
41. A device according to claim 40 wherein in the expanded state,
the support members are substantially parallel to a longitudinal
axis of the catheter.
42. A method for delivery or collection of a fluid to or from an
organ or anatomical region in a human or animal subject, the method
including the step of supporting a vessel associated with the organ
or anatomical region.
43. A method according to claim 42 wherein the vessel is maintained
substantially patent during delivery of fluid thereto or collection
of fluid therefrom.
44. A method according to claim 42 wherein the fluid pressure in
the vessel is less than the minimum pressure normally found in the
vessel.
45. A method according to claim 42, including the step of placing a
collection catheter in the vessel, and attaching a pump to the
collection catheter.
46. A method according to claim 45 wherein the pressure around the
intake of the pump is equal to or less than about -90 mmHg.
47. A method according to claim 45 wherein the pressure around the
intake of the pump is equal to or less than about -100 mmHg to -115
mmHg
48. A method according to claim 45 wherein the pressure around the
intake of the pump is equal to or less than about -115 mmHg.
49. A method according to claim 45, wherein cavitation in the
collection catheter component, or the pump, or a line connecting
the collection catheter to the pump is substantially prevented or
delayed.
50. A method according to including the use of high fluid flow rate
in the vessel.
51. A method according to claim 50 wherein the fluid flow rate in
the vessel is equal to or greater than a value selected from the
group consisting of about 20 ml_per minute, 160 ml_per minute, 180
mL per minute, 200 ml_per minute, and 220 mL per minute.
52. A method according to claim 50 wherein the fluid flow rate
substantially matches the rate of flow of fluid into the vessel
from an anatomical region or organ.
53. A method according to claim 45, including the step of
substantially occluding flow from the vessel thereby allowing the
collection catheter to collect substantially all flow entering the
vessel.
54. A method according to claim 42, wherein the vessel is a blood
vessel.
55. A method according to claim 54 wherein the blood vessel is a
vein.
56. A method according to claim 55 wherein the vein is selected
from the group consisting of a coronary vein (including the
coronary sinus), an internal jugular vein, hepatic vein, a renal
vein, a cephalic vein, an inferior vesical vein, a pulmonary vein,
an internal iliac vein, a portal vein, a splenic vein, a femoral
vein, a saphenous vein, a subclavian vein, an intercostal vein, an
axillary vessel, a testicular vein, an ovarian vein and tributaries
thereof.
57. A method according to claim 54 wherein the blood vessel is an
artery.
58. A method according to claim 57 wherein the artery is selected
from the group consisting of a coronary artery, a left or right
vertebral artery, a left or right internal carotid artery, an
inferior vesicle artery, an internal iliac artery, a renal artery,
a gastric artery, a splenic artery, a superior or inferior
mesenteric artery, an internal iliac artery, an internal mammary
artery, an intercostal artery, a right or left testicular artery, a
left or right ovarian artery, a pulmonary artery or tributaries
thereof.
59. A method according to claim 54, wherein the blood vessel is
associated with an organ selected from the group consisting of the
heart, lung, liver, kidney, brain, intestine, testicle, ovary,
spleen, stomach, prostate, and pancreas.
60. A method according to claim 54, wherein the blood vessel is
associated with an anatomical region selected from the group
consisting of a limb, the pelvis, the chest, the breast and the
mesenteric system.
61. A method according to claim 42, including the step of
percutaneously delivering a device according to any one of 1 to
41.
62. A method of recovering fluid from a vessel having a net flow
direction, the method including the steps of: placing a catheter
into the vessel with an exposed central lumen of the catheter
facing a direction of ongoing fluid flow in said blood vessel and
with the catheter lumen connected to a source for drawing fluid out
of the vessel; placing a support member in the vessel in close
proximity to a distal tip of the catheter with the support member
configured to oppose a wall of the vessel with a force sufficient
to prevent collapse of the wall in response to pressures generated
at the catheter tip.
63. A method according to claim 62 wherein the support member
includes an array of elongate support arms, the method including
placing the support device in the vessel with the arms
substantially parallel to an axis of the catheter or vessel at the
catheter tip with the arms opposing a length of the vessel
wall.
64. A method according to claim 62 wherein the step of placing the
support member in the vessel in close proximity to a distal tip of
the catheter includes retaining part of the support member within
the catheter.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a support device for
supporting a vessel of a human or animal subject. The support
device can be used, for example, during procedures in which a fluid
is collected from an organ or anatomical region via an associated
blood vessel.
BACKGROUND TO THE INVENTION
[0002] Many therapeutic procedures can be performed percutaneously.
Such procedures include investigative and diagnostic methods as
well as medical and surgical treatments. Percutaneous techniques
are advantageous because they are minimally invasive, and therefore
present a reduced risk to the patient when compared with invasive
surgeries requiring open access to tissues within the patient's
body.
[0003] Catheters and sheaths are typically used to access internal
sites by entering the patient's body through an incision or other
entry point to the peripheral vasculature and navigating through
the torturous paths of the vascular system to the target site.
Tools, cameras illumination sources and transducers can be deployed
through the catheters and sheaths enabling a physician to inspect
the site, take biopsies, implant devices, repair damage and perform
numerous other tasks often on an outpatient basis.
[0004] Minimally invasive percutaneous approaches have also
presented an opportunity for localized delivery of therapeutic
agents. Localization facilitates improved treatment since the agent
may be delivered directly to a target site, (for example, an organ)
thereby avoiding "first pass" degradation in the liver. The agent
may therefore exhibit an improved therapeutic effect when compared
with the same agent administered orally, intravenously or via the
intramuscular route. Moreover, where the therapeutic agent has
benefit to the target site but is likely to be toxic to other
organs or tissues, localized delivery can minimize the exposure and
hence the risk presented to cells in other parts of the body. An
example is where a cytotoxic drug is to be delivered to a cancerous
organ, but it is desired to minimize or prevent exposure of healthy
organs to the drug.
[0005] Various devices and methods to facilitate the percutaneous
delivery and collection of fluids to organs and tissues of the
human body have been described in the art. Typically, these devices
and methods include a first catheter to deliver a fluid to an organ
or tissue and a second catheter to collect fluid exiting the organ
or tissue. The collected fluid may be returned to the organ, or
discarded as waste outside the body.
[0006] While devices and methods of the prior art appear to address
the theoretical requirements of percutaneous delivery and
collection of fluids, Applicant has found that they are of little
practical use in the clinic. In particular, difficulties are
encountered in maintaining sufficient flow rates of fluid through a
collection catheter. As will be appreciated by the skilled person,
where a collection catheter is positioned in a vein, venous
pooling, tissue damage and possible death of the subject can result
from low flow rates. Low flow rates via a collection catheter may
also severely limit the ability to deliver the therapeutic agent
via a delivery catheter given that in order to maintain fluid
balance the volume of fluid entering and exiting should be
substantially equal.
[0007] Applicants have identified a further problem with devices
and methods of the prior art in that damage to vessel walls may
also be noted after catheterization of vessels. Where the catheter
is a collection catheter, partial or complete occlusion is
sometimes observed during use. Yet a further problem exists in that
catheters often move from the position in which they are
deployed.
[0008] It is an aspect of the present invention to overcome or
alleviate a problem of the prior art by providing devices and
methods capable of maintaining the flow of fluid via the collection
catheter. The methods and devices may also minimize vessel wall
damage, occlusion of the catheter lumen, and movement of a catheter
after placement.
[0009] The discussion of documents, acts, materials, devices,
articles and the like is included in this specification solely for
the purpose of providing a context for the present invention. It is
not suggested or represented that any or all of these matters
formed part of the prior art base or were common general knowledge
in the field relevant to the present invention as it existed before
the priority date of each claim of this application.
SUMMARY OF THE INVENTION
[0010] In one aspect the present invention provides a
percutaneously deliverable device for supporting a vessel in a
human or animal subject including means for supporting the vessel
during delivery of a fluid thereto or collection of fluid
therefrom. Without wishing to be limited by theory, Applicant
proposes that collapse of the vessel wall is at least partly
responsible for the low flow rates that are problematic in the
percutaneous collection of fluids from an organ or tissue of the
body. The support devices described herein have the effect of
maintaining patency of the vessel via which fluid is being
collected, while also preventing collision of the collection
catheter with the vessel wall. Maintenance of patency of the
collection vessel allows for useful flow rates to be established,
thereby reducing the risk of venous pooling. Where the invention
further includes delivery of a fluid to a tissue or organ, flow
rates of the fluid into the tissue or organ are also improved.
[0011] In one embodiment of the method the means for supporting the
vessel is capable of maintaining patency of the vessel during
delivery of the fluid thereto or collection of the fluid therefrom.
Movement of fluids into and out of a vessel can cause deformations
in the wall of the vessel leading to collapse. The collapse of the
vessel wall can lead to complete obstruction of the vessel thereby
preventing any further flow of fluid. In particular drawing fluid
out of a vessel during collection can lead to a decrease in
pressure in the vessel which in turn leads to vessel collapse.
Vessels have a normal range of pressures under which they function
in the body. The normal range is that noted in a healthy subject,
and may vary from subject to subject and also from vessel to vessel
within a given subject. Pressure less than normal can be noted
during techniques used to perfuse an organ, and especially on the
collection side of the organ where the removal of fluid from a vein
can lead to lower than normal intravascular pressure.
[0012] It may be desirable to support vessels in a number of
procedures. One procedure involves simply drawing fluid out of the
vessel using a pump during, for example, perfusion of an organ.
Perfusion typically involves the use of one or more pumps to
transport fluid into an organ, and to draw fluid away from the
organ. The perfusate may or may not be returned to the organ. Under
typical perfusion conditions, the rate at which fluid is drawn out
of the vessel may need to be sufficiently high such that the vessel
walls cannot maintain patency and subsequently collapse. The cause
of vessel collapse may be due to a combination of high flow rates
and low pressure on the collection side of the organ. The vessel
may collapse either partially, where the vessel wall deforms in
such a way that flow into a collection catheter is impeded, or the
vessel may collapse completely where flow into the catheter is
prevented entirely.
[0013] Vessel collapse is particularly prevalent in flaccid vessels
such as veins. A particularly problematic case is where the
coronary sinus is used to collect fluid perfusing through the
coronary circulation of the heart. The coronary sinus can be
difficult to deal with when collecting fluid using a collection
lumen located within the sinus. This is in part due to the fact
that the coronary sinus wall is flaccid and prone to collapse when
contacted by a collection catheter tip. This problem is intensified
as a result of the low pressures which are generated at the
catheter tip as fluid is drawn out of the sinus and these low
pressures, in combination with inadequate flow into the sinus, can
cause the vessel wall to collapse.
[0014] Further, because of the curvature of the coronary sinus,
there is a natural tendency for a catheter tip approaching from the
right atrium to contact the sinus wall, thus increasing the risk of
collapse and damage to the sinus wall e.g. by perforation. Collapse
of the coronary sinus can cause venous pooling in the coronary
veins and may therefore be fatal. Use of a support device to
maintain patency of the coronary sinus and distance the catheter
tip from the vessel walls, in accordance with some embodiments of
the present invention, minimizes the risk of these complications
eventuating. Other veins of the body may also assume a curved
course thereby increasing the likelihood of catheter contact and
obstruction during collection of blood or perfusate.
[0015] The inventive device and methods, in their various
embodiments, at least partly overcome the problems referred to
above by providing an expandable member which is percutaneously
deliverable and is adapted to expand when located inside a target
vessel, thereby preventing the vessel from collapsing and thereby
maintaining patency. A further advantage of the support device is
provided where the support device maintains the catheter tip
through which the fluid is drawn or delivered substantially
centrally of the vessel, or at least maintains the tip at a
distance from the vessel wall. This prevents the tip from
aspirating into the vessel wall and occluding the lumen. Further,
the support device may act as an anchor when in contact with the
vessel wall, limiting movement of the catheter as fluid is
collected or delivered.
[0016] Perfusion methods incorporate one or more pumps to deliver
fluid into or collect fluid from an organ. In one embodiment of the
device where the device includes a collection catheter component,
and the collection catheter component is attached to a pump, the
pressure around the intake of the pump is equal to or less than
about -90 mmHg. In some cases, pressures this low will lead to
collapse of a vessel wall. Vessel collapse becomes more likely when
the pressure at the pump is equal to or less than about -100 mmHg
to -115 mmHg, or lower.
[0017] Where a pump exerts a very large negative pressure on a
perfusion line, cavitation may occur. Under this situation,
perfusion must be halted, and the low pressures in the line
returned closer to normal. Applicant has found that cavitation is a
substantial difficulty in the perfusion of organs, and have found
that inclusion of a support device can negate this problem.
Accordingly, in another embodiment of the device, where the device
includes a collection catheter component, and the collection
catheter component is attached to a pump, the device is capable of
preventing or delaying cavitation in the collection catheter
component, or the pump, or a line connecting the collection
catheter to the pump. While cavitation may not be completely
prevented it may be at least delayed such that the problem does not
occur until a higher flow rate or lower pressure is reached. The
presence of the means for supporting the vessel will at least
provide that a higher flow rate is necessary to trigger cavitation
as compared with the situation where no means for support is
present.
[0018] In another embodiment of the invention the means for
supporting the vessel is capable of maintaining patency of the
vessel under conditions of high fluid flow rate in the vessel. In
one form of the invention, the fluid flow rate in the vessel is
equal to or greater than a value selected from the group consisting
of about 20 mL per minute, 160 mL per minute, 180 mL per minute,
200 mL per minute, and 220 mL per minute.
[0019] Typically, the fluid flow rate substantially matches the
rate of flow of fluid into the vessel from an anatomical region or
organ. By maintaining this balance, the organ, anatomical region
and their associated vessels will have less chance of damage due to
the build up of excess fluid or desiccation.
[0020] The support device may be deployed in a vessel associated
with a number of different organs or anatomical regions of the
subject's body including but not limited to the heart, lungs,
brain, liver, kidney, pancreas, intestine, mesenteric system, the
upper and lower limbs, thorax, pelvic region and the like. While
the present invention is proposed to be used primarily for
intravascular applications, it is to be understood that use of the
device in non-vascular applications is also possible. For example,
the support device may be deployed in any vessel of the body
capable of carrying a fluid and prone to collapse such as a lymph
vessel, ureter or urethra, bile duct, pancreatic duct, fallopian
tube, intestine, oesophagus, or a spermatic duct.
[0021] Preferably, the device is adapted to support the vessel
during collection of substantially all fluid entering the vessel
from an organ or region during a fluid collection procedure. To
assist in this regard, occluding means such as an occluding balloon
may be utilized to prevent flow from the vessel to other organs or
regions. This enables the collection catheter to collect
substantially all of the flow entering the vessel. The collection
catheter may extend through the occluding balloon although other
arrangements may be contemplated. Preferably, the expandable member
is adapted to support the vessel during collection of fluid at a
rate which substantially matches a rate of fluid flow into the
vessel from a region or organ.
[0022] The expandable member may also be adapted for use with a
delivery catheter during delivery of fluid to a vessel in which
there is a propensity for the delivery catheter to move, for
example, into branched tributaries of the vessel. Such vessels may
include arteries, particularly smaller arteries, or vessels in
which there is turbulent blood flow.
[0023] The support device may also include an atraumatic guiding
tip adapted to make atraumatic contact with the vessel wall when
guiding the expandable member into position within the target
vessel. Thus, as the expandable member is positioned within the
vessel, perforation, bruising, laceration or other trauma is
substantially avoided upon contact between the atraumatic tip and
the vessel. Once positioned within the vessel, the expandable
member can be released from a delivery catheter or sheath and
expanded. The atraumatic tip may be curved or shaped to
substantially avoid trauma to the vessel wall. Thus, the atraumatic
tip may include a "J-shaped" portion, a pigtail portion, a loop
portion or a substantially straight portion with a flexible end
adapted for atraumatic contact with the vessel wall. The atraumatic
tip may also have a smooth surface to encourage deflecting or
sliding along the vessel wall. A lubricious or low coefficient of
friction coating may be utilized to encourage deflection or
sliding.
[0024] In one embodiment, the expandable member of the support
device is a radially expanding member. Radial expansion may be
achieved using any suitable means. In one preferred form, the
expandable member includes a framework formed from a material
having super-elastic and/or shape memory properties, enabling the
device to self-expand to a particular shape when released from a
delivery catheter. In other forms, the expandable member may
include a framework which is designed to be controllably expanded
e.g. by mechanical means, when positioned within the vessel.
[0025] Preferably, the support device includes a radiopaque or
other marker for use with an imaging system known in the art for
positioning the device within the blood vessel. The marker may be
incorporated into the atraumatic tip. Alternatively, there may be
one or more marker regions incorporated into the expandable member
itself. In another embodiment, markers are incorporated into the
atraumatic tip and the expandable member.
[0026] The expandable member may be coupled to a stem or shaft
(such as a guidewire) for delivery of the expandable member to a
deployment site within the vessel. In one embodiment, the distal
end of the expandable member may be movably coupled to the stem,
whereas the proximal end of the member is fixedly coupled to the
stem. In this arrangement, the distal end of the member slides
along the guidewire enabling the member to expand and collapse.
This configuration may alternatively be provided in the reverse,
where the distal end of the expandable member is fixedly coupled to
the guidewire with the proximal end movably coupled to the
guidewire, although additional modification may be required to
facilitate recapture of the expandable member for removal from the
vessel.
[0027] In a further embodiment, the expandable member is integral
with the stem. Thus, a distal region of the stem provides a
plurality of pre-shaped segments or struts, adapted together to
form an expandable member under certain conditions. For example,
when released from a delivery catheter into the target vessel.
Preferably, the pre-shaped segments or struts are filamentous and
composed of a substantially superelastic, shape memory or other
material which may be subjected to deformation (for collapsed
delivery to the target site) and recover to an expanded condition
when released from a catheter.
[0028] In another embodiment, the expandable member includes one or
more loop portions with each of the loop portions attached at a
first loop end to a distal end of a lumen, and at a second loop end
to a control stem extending through the lumen. The one or more loop
portions have a collapsed condition in which they are substantially
within the delivery lumen, and are controllably expandable by
advancing the control stem to eject one or more of the loops
therefrom. An atraumatic guiding tip may be incorporated into one
or more of the loop portions. Alternatively, a separate atraumatic
tip may be provided in communication with the control stem.
[0029] The expandable member may have 2, 3, 4, 5, 6 or more loop
portions. Determination of the number of loop portions may be based
on the size of the vessel being supported, and/or the stiffness of
the vessel, where more loop portions may be required to support a
vessel having particularly flaccid walls. The support device may
also include retention means to retain the expandable member in an
expanded condition. Retention means may include, for example, an
outer stem on the support device. The proximal end of the outer
stem may be fastened to an anchor point outside the subject's body
to prevent collapse of the expanded member during collection of
fluid from the vessel, especially where very low pressures are
generated.
[0030] The atraumatic tip may be provided at any suitable distance
from the distal end of the expandable member, as may be
necessitated by the anatomy of the vessel being supported. For
example, the atraumatic tip may be provided 0.25 to 5 centimeters
from a distal end of the expandable member when it used in the
coronary sinus. However, it is to be understood that these values
are examples only and that the atraumatic tip may be provided at
any suitable distance from the expandable member, as may be
influenced by the size and shape of the target vessel and the
surrounding structures.
[0031] Preferably, the atraumatic tip is made from, includes or is
coated with a lubricious material or a material having a low
coefficient of friction to encourage the tip to "slide" off the
vessel wall on making contact. Some suitable materials which may be
considered to have sufficiently low coefficient of friction
properties may include but are not limited to biocompatible high
density polyethylene (HDPE), Teflon.RTM., polypropylene,
polyethylene, Microglide.TM., low friction chromium and silicon
[0032] In a further embodiment of the invention there is provided a
device including: a plurality of support members disposed in an
array having an expanded state and a collapsed state, wherein in
the collapsed state, the array is sized for delivery to the vessel
through a lumen of a catheter, and wherein in the expanded state,
the array is sized to be greater than an internal dimension of the
catheter, wherein the support members are biased to the expanded
state. In one embodiment of the device, in the expanded state, the
support members are substantially parallel to a longitudinal axis
of the catheter.
[0033] Embodiments of the present invention may be used to support
a range of blood vessels servicing different organs of the body
including the heart, lung, liver, kidney, brain, intestine,
testicle, ovary, spleen, stomach, prostate and pancreas. The
present invention may also be used to support blood vessels
servicing an entire anatomical region such as a limb, the pelvis,
the chest, the breast and the mesenteric system. The skilled person
will possess sufficient knowledge to decide the appropriate vessel
or vessels to target according to which organ or anatomical region
is to be catheterized.
[0034] For example, where the organ is the heart the arterial
catheter may be placed in the coronary artery. A venous catheter
may be placed in the coronary vein, typically in the coronary
sinus. Where the organ is the liver, an arterial catheter may be
placed in the hepatic artery and a venous catheter may be placed in
the hepatic vein. This may be performed with a reduction of flow in
the portal vein utilizing acute administration of, for example,
Octreotide or Terlipressin.
[0035] Where the organ is the brain, arterial catheters may be
placed in the left and right vertebral arteries, and also the left
and right internal carotid arteries. Venous catheters may be placed
in the left and right internal jugular veins.
[0036] Perfusion of the kidney may be performed by locating an
arterial catheter in the renal artery. A venous catheter may be
placed in the renal vein. Where the organ is the stomach, an
arterial catheter may be placed in the gastric artery. A venous
catheter may be placed in the portal vein or the hepatic veins.
[0037] Perfusion of the spleen may be achieved by placing an
arterial catheter may in the splenic artery, and a venous catheter
in the splenic vein, the portal vein, or the hepatic veins. To
perfuse the intestines, an arterial catheter may be placed in the
superior and/or inferior mesenteric artery. A venous catheter may
be placed in the portal vein or hepatic veins.
[0038] Where the anatomical region is the pelvis, an arterial
catheter may be placed in the internal iliac artery. Where the
organ is a testicle or an ovary, an arterial catheter may be placed
in the right or left testicular or ovarian artery. A venous
catheter may be placed in the right or left testicular or ovarian
vein. To perfuse the prostate, an arterial catheter may be placed
in the inferior vesicle artery or the internal iliac artery. A
venous catheter may be placed in the inferior vesical vein or the
internal iliac vein.
[0039] Where the organ is a lung, an arterial catheter may be
placed in the pulmonary artery. A venous catheter may be placed in
one or both pulmonary veins. In one embodiment, selective delivery
can be provided to one lung only, or only one lobe of a lung. Thus,
the arterial catheter may be located in the relevant branch of the
pulmonary artery and the venous catheter would be located in the
relevant (i.e. upper or lower) pulmonary vein, depending on the
lobe being treated. To perfuse the breast, an arterial catheter may
be placed in the internal mammary artery and the intercostal
arteries. A venous catheter may be placed in the intercostal
veins.
[0040] The devices described herein are proposed to be useful in
delivering and/or collecting fluids from organs and anatomical
regions of the body. Accordingly, in a further aspect the present
invention provides a method for percutaneous delivery and/or
collection of a fluid to or from an organ or an anatomical region
of a subject, the method including the step of supporting a vessel
of the organ or the anatomical region. The vessel is maintained
substantially patent during delivery or collection of fluid to or
from the organ or anatomical region, especially where the fluid
pressure in the vessel is less than the minimum pressure normally
found in the vessel. Under normal perfusion conditions, and where
the fluid pressure in a vessel decreases to a sub-normal level,
vessel wall collapse may ensue leading in turn to cavitation in
perfusion lines. In one embodiment of the method, cavitation in the
collection catheter component, or the pump, or a line connecting
the collection catheter to the pump is substantially prevented or
delayed.
[0041] The method may include the step of placing a collection
catheter in the vessel and attaching a pump to the collection
catheter. While any suitable pump may be used, typically a
peristaltic pump is used. The collection catheter may be placed in
an outflow vessel of the organ or anatomical region. The method may
also include the step of placing a delivery catheter in an inflow
vessel of the organ or anatomical region, for example where it is
desired to introduce a fluid into the organ or anatomical region or
to recirculate a fluid through the organ or anatomical region.
Again, a pump is typically attached to the delivery catheter to
assist delivery of the fluid into the subject organ or anatomical
region.
[0042] In another form of the method the collection catheter
collects fluid from the target region at the outflow vessel such
that the collected fluid is substantially prevented from entering
the general circulation. A higher level of isolation is provided
whereby the method further includes the step of substantially
occluding flow from the outflow vessel to the general circulation.
The occlusion step allows the collection catheter to collect
substantially all flow entering the vessel. In one form of the
method the step of occluding is performed by inflating an occluding
balloon around the collection catheter placed in the outflow
vessel. Optionally, an occluding flange is placed around the
collection catheter.
[0043] As discussed infra the present invention allows for
perfusion at flow rates that would normally lead to collapse of
vessels associated with the organ being perfused, or cavitation
occurs in the perfusion circuit. Accordingly, one form of the
method includes the use of high fluid flow rate in the vessel. The
fluid flow rate in the vessel may be equal to or greater than a
value selected from the group consisting of about 20 mL per minute,
160 mL per minute, 180 mL per minute, 200 mL per minute, and 220 mL
per minute.
[0044] In some situations it may be desired to recirculate a fluid
through an organ or anatomical region of a subject. Accordingly,
one embodiment of the method further includes the step of
connecting a re-perfusion circuit between the delivery and
collection catheters and recirculating the collected fluid. If
fluid is lost in the course of reperfusion then the method may
include the further step of adding a replenishing fluid to the
re-perfusion circuit. Where recirculation is implemented the method
may include the further step of oxygenating blood collected from
the inflow vessel prior to re-perfusing it into the organ or
anatomical region.
[0045] It is to be understood that while embodiments of the present
invention have been described in the context of anterograde
circulation and perfusion, it will be apparent that the methods may
also be suitable for retrograde perfusion of an organ or an
anatomical region. Typically, for anterograde perfusion the inflow
vessel is an artery, and the outflow vessel is a vein. Where
retrograde perfusion is desired the inflow vessel is a vein, and
the outflow vessel is an artery.
[0046] The present methods may be used in respect of any organ or
anatomical region where support of an associated vessel is
necessary or desirable due to a propensity for collapse of the
vessel. Exemplary organs include the heart, lung, liver, kidney,
brain, intestine, testicle, ovary, spleen, stomach, prostate, and
pancreas. The anatomical region may be a limb, the pelvis, the
chest, the breast or the mesenteric system.
[0047] The vein may be any vein of the body requiring support
including, but not limited to a coronary vein (including the
coronary sinus), a left or right internal jugular vein, a hepatic
vein, a renal vein, a cephalic vein, an inferior vesical vein, a
pulmonary vein, an internal iliac vein, a portal vein, a splenic
vein, a femoral vein, a saphenous vein, a subclavian vein, an
intercostal vein, an axillary vessel, a left or right testicular
vein, a left or right ovarian vein, a pulmonary vein or tributaries
thereof.
[0048] The artery may be any artery of the body requiring support
including, but not limited to a coronary artery, a left or right
vertebral artery, a left or right internal carotid artery, an
inferior vesicle artery, an internal iliac artery, a renal artery,
a gastric artery, a splenic artery, a superior or inferior
mesenteric artery, an internal iliac artery, an internal mammary
artery, an intercostal artery, a right or left testicular artery, a
left or right ovarian artery, a pulmonary artery or tributaries
thereof.
[0049] The method may further include the step of using an imaging
technique to position the delivery catheter and/or collection
catheter in the inflow and outflow vessels of the target region,
the imaging technique including one or more of deployment of
radiographic contrast, deployment of nuclear medical probes,
deployment of in vivo probes sensitive to oxygen, hydrogen, pH or
the like and deployment of labelled micro- or nano-particles.
[0050] It is proposed that the devices described herein are useful
in the percutaneous delivery and/or collection of therapeutic and
diagnostic agents to a discrete tissue of the body. Accordingly, a
further aspect of the invention provides a method for percutaneous
delivery and/or removal of a therapeutic or diagnostic agent to a
target organ or anatomical region of a subject, the method
including the step of supporting an inflow or an outflow vesse. In
one embodiment the method includes the use of a percutaneously
deliverable device as described herein. The therapeutic agent may
be, or may be carried by the fluid referred to herein. Examples of
therapeutic agents deliverable in the context of the present
methods and devices includes a chemotherapy pharmaceutical, an
antibiotic, a vasodilator, a vasoconstrictor, a peptide, a hormone,
a stem cell, a cytokine, an enzyme, a gene therapy agent, a
polynucleotide, blood, and serum.
[0051] An advantage of the present devices and methods is that it
is possible to substantially isolate the circulation of an organ or
anatomical region and administer (and optionally recirculate) a
therapeutic agent. By collecting substantially all therapeutic
agent leaving the outflow vessel, it is possible to prevent
exposure of the systemic circulation to the agent. This is of
significant advantage where the agent is toxic (such as a
chemotherapeutic agent), or where it is otherwise undersirable to
expose other tissues (for example a gene therapy agent). Similarly,
where the agent is only available in limited quantities,
administering the agent to only the target tissue is clearly
desirable. It follows that since a smaller quantity of the
therapeutic agent is used in a highly localized manner, the present
invention provides a cost reduction for the therapy.
[0052] For treatment of organs and anatomical regions the inventive
methods and devices may be used to deliver a therapeutic or
diagnostic agent such as a small molecule, a gene or a cell for the
treatment of conditions including but not limited to diabetic
nephropathy, renal fibrosis, glomerulonephritis, contrast-induced
nephropathy, and renal transplant rejection, renal cancer (for the
kidney); emphysema, cystic fibrosis, pulmonary fibrosis, pneumonia,
lung malignancy and pulmonary hypertension, pulmonary embolism (for
the lungs); neurodegenerative diseases such as Alzheimer's disease,
Parkinson's disease and Huntington's disease, cerebral ischemia,
epilepsy and brain tumor (for the brain); viral hepatitis,
autoimmune hepatitis, cirrhosis, hepatocellular carcinoma,
hepatitic metastasis, and fatty liver (for the liver); myocardial
infarction, angina, coronary heart disease, congestive heart
failure, myocarditis and ventricular hypertrophy (for the heart);
diabetes and pancreatic cancer (for the pancreas); deep vein
thrombosis, limb ischemia (for limb); inflammatory bowel disease
and bowel cancer (for the intestines).
IN THE FIGURES
[0053] The present invention will now be described in greater
detail with reference to the accompanying drawings. It is to be
understood that the particularity of the accompanying drawings does
not supersede the generality of the preceding description of the
invention.
[0054] FIGS. 1a to 1c illustrate a support device according to an
embodiment of the present invention. FIG. 1a shows the expandable
member in an expanded condition. FIG. 1b shows the expandable
member in a collapsed condition with in a catheter for delivery to
a vessel. FIG. 1c shows the expandable member after deployment from
the catheter into the vessel.
[0055] FIG. 2 illustrates a support device according to another
embodiment of the present invention, where the expandable member is
in communication with a stem or shaft such as a guidewire.
[0056] FIG. 3 illustrates the support device of FIGS. 1a to 1c, in
the expanded configuration, with the addition of an occluding
balloon, inflated around the catheter.
[0057] FIGS. 4a and 4b illustrate variations of an atraumatic
guiding tip for use with embodiments of the present invention.
[0058] FIG. 5 illustrates a support device according to another
embodiment of the invention, incorporating stops to limit movement
of the expandable member.
[0059] FIGS. 6a and 6b illustrate a support device having 4
expandable loop portions, according to an embodiment of the present
invention.
[0060] FIGS. 7a and 7b illustrate an alternative support device
having 3 expandable loop portions, according to another embodiment
of the present invention.
[0061] FIGS. 8a to 8c illustrate various expandable members having
different geometric designs.
[0062] FIG. 9 illustrates a cross section of a catheter for use
with embodiments of the present invention.
[0063] FIG. 10 illustrates an expandable member according to
another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0064] While the support device of the present invention may be
used in a range of different vessels, including blood vessels, it
has particular application in procedures where an organ or
anatomical region is undergoing localized perfusion with a
therapeutic, diagnostic or other agent. For simplicity, these
agents will be hereinafter referred to as therapeutic agents.
However, it is to be understood that the term "therapeutic" is not
to be construed as limiting, and that it includes, without
limitation, therapeutic, diagnostic, prophylactic and other agents
not specifically identified herein, but which would be considered
by the relevant skilled addressee to be suitable for perfusion to
an organ or anatomical region.
[0065] Perfusion may be total perfusion, where the entire organ is
totally or substantially isolated from the systemic flow, or
partial perfusion where only a portion of the organ is
substantially isolated. Localized perfusion of this kind presents
advantages by improving efficacy and the time exposure of the
therapeutic agent to the relevant cells. It also limits exposure
and hence toxicity to non-target cells as described in brief above.
However, it is to be understood that the present invention may also
be used simply to collect or drain fluid from an organ or region.
Collected fluid may be removed from the subject and re-circulated
into the organ, filtered and/or treated, or discarded.
[0066] In some organs, it may be difficult to achieve total
isolation, so partial isolation and perfusion may be performed, for
example to the right or left lobe of the liver. Despite partial
perfusion being capable of delivering therapeutic agent to merely a
part of the organ, significant therapeutic benefit may still be
achieved.
[0067] Particular benefit may be achieved where perfusate is
collected after perfusing the target organ, so as to prevent
subsequent circulation of the therapeutic agent to other regions of
the body where toxic effects may be observed, or the therapeutic
agent wasted. The benefit may be improved further where collected
perfusate is re-circulated into the target organ utilizing any
therapeutic agent which remains after a first pass through the
target organ. This may be achieved using the approach described in
published patent application WO2005/082440, the entire contents of
which are herein incorporated by reference.
[0068] As discussed infra, when fluid is collected from vessels
draining from a target organ or region, one or more of these
vessels may require cannulation with a collection catheter. When
fluid is drained through these collection catheters, the vessels in
which they are positioned become susceptible to collapse as the
pressure inside decreases. While some vessels may be more
susceptible to collapse than others, the support device of the
present invention can provide advantages by supporting and
stabilizing the vessel and even anchoring the collection catheter
in position. The support device of the present invention may
facilitate or at least improve the performance of perfusion. In
some instances, the advantages of the present invention have been
found to be essential to maintaining adequate positioning of
collection catheters and flow rates within the vessel during
perfusion.
[0069] The right and left lobes of the liver have been identified
as possible target regions and in this context, the support device
may be deployed in one of the hepatic veins to support and maintain
patency of the vein as fluid (e.g. perfusate) is collected from the
liver. However, it is to be understood that fluid from many other
organs or regions may be accessed in this way.
[0070] Deploying the support device may also protect the vessel
wall by maintaining the tip of the catheter substantially centrally
of the vessel or at least at a distance from the vessel walls to
prevent aspiration or cavitation. Deployment of the device may
refer to partial or complete deployment. In complete deployment,
the entire expandable member is released from the catheter and
expanded to its full extent. In partial deployment, part of the
expandable member is retained within the catheter and the amount of
expansion is limited by the diameter of the catheter opening.
Partial deployment may be useful where, for example, during
deployment it is found that the diameter of the expandable member
may exceed the vessel diameter by an unsafe amount and complete
deployment is likely to damage the vessel wall. Limiting expansion
of the device by partial deployment may avoid vessel damage.
[0071] Partial deployment may also stabilize the expandable member
by limiting its movement relative to the catheter tip. Thus by
retaining part of the expandable member within the catheter,
torsional, axial and lateral movement of the member, relative to
the catheter is prevented or at least minimized by the struts of
the expandable member being in abutment with the internal surface
of the catheter. Alternatively, the expandable member may be
modified at the proximal end, for example by incorporating a lead,
a link or other means to limit the extent of movement possible
between the catheter tip and the expandable member once deployed.
As a further positioning aid, markings may be provided at the
proximal end of the control stem/shaft, outside the patient's body.
As the device is released into the vessel, the markings may be
utilized to indicate the distance of device deployment, past the
catheter tip.
[0072] During collection of fluid from the vessel, low pressures
may develop at the collection device tip, particularly where a
roller/peristaltic pump or the like is used to draw fluid from the
target organ out of the vessel. This may be indicated by pressures
in a lumen feeding into the pump as low as, for example, -190 mmHg,
although clearly these pressures are variable depending on the
vessel type, health and age of the subject, characteristics of the
perfusion circuit and the like. In the absence of the inventive
support device, these pressures can cause the vessel to collapse.
Not only would vessel collapse affect the perfusion procedure,
vessel collapse can also cause venous pooling in the organ and
irreversible tissue damage.
[0073] The advantages and benefits of the present invention will be
expanded upon in the following detailed description presenting some
of the preferred embodiments of the invention, and the specific
Examples which follow. It is to be understood that the embodiments
and examples provided herein are intended to indicate how the
present invention may be performed and are not intended to be
limiting on the scope of protection sought as is defined in the
claims appended hereto.
[0074] FIG. 1a shows an example of an expandable member, in its
expanded condition, suitable for supporting a vessel. Expandable
member 104 is provided in the form of an expandable framework and
is adapted to be percutaneously deliverable to the blood vessel in
a collapsed condition. FIG. 1b shows the expandable member in a
collapsed condition within a catheter 110, in which ends 105, 107
have been drawn apart to radially reduce the member. When collapsed
within catheter 110, atraumatic tip 101 may protrude from the
catheter to assist in guiding the support device into the vessel
prior to deployment. When the expandable member has been guided
into the target blood vessel, the catheter 110 is retracted (or the
expandable member is pushed out of the catheter), deploying the
device into the vessel where it expands. FIG. 1c shows the support
device fully deployed from the catheter, with the expandable member
in its fully expanded condition.
[0075] A guidewire or stem 106 extends within the catheter 110 and
is used to deliver the device from a point of entry through the
peripheral vasculature to the target vessel. Atraumatic tip 101
coupled to the expandable member 104, is adapted to make atraumatic
contact with vessel walls during placement of the device by
deforming or deflecting off the vessel wall on contact. This can be
achieved by incorporating flexibility into the tip so that it
deforms upon contact with the vessel wall. Alternatively or
additionally, the tip may be shaped or curved to avoid trauma.
[0076] The atraumatic tip may take any one of a number of forms. In
the examples illustrated in FIGS. 1 to 3, the atraumatic tip 101,
201 is J-shaped. However, other shapes are considered to be
suitable, including but not limited to those illustrated in FIG. 4.
For example, the atraumatic tip may have a cross section which is
enlarged relative to the guidewire radius, and have a smooth
surface so as to avoid causing perforation when the tip comes into
contact with the vessel wall. One such example is shown in FIG. 4a
where the atraumatic tip 401 is tear-shaped. Alternatively, the
atraumatic tip may include a portion having a pigtail shaped curve
402 (FIG. 4b), or an angled tip (not shown).
[0077] Preferably, the expandable member is formed from a
biocompatible superelastic material, or alternatively from a shape
memory material or a material which exhibits both of these
properties, being capable of recovery after deformation for
delivery in a collapsed or compressed state within a catheter.
Devices manufactured using these materials can be collapsed for
percutaneous delivery to a deployment site and then resume a known
shape on deployment. A range of biocompatible materials may be
suitable such as alloys of nickel and titanium (e.g. Nitinol).
Other suitable biocompatible materials include but are not limited
to polymers and plastics such as hydrophilic plastics, ceramics and
the like.
[0078] FIG. 3 illustrates the support device of FIGS. 1a to 1c,
with an occluding balloon inflated around catheter 110. The
occluding balloon 114 may be utilized during collection of fluid
from an organ or region of the body in isolation, where
substantially all of the fluid flowing out of the organ or region
is collected by the catheter 110. The occluding means substantially
prevents blood, therapeutic agent and/or other fluids entering the
vessel from flowing on to other organs or regions, and permits
collection of substantially all of the fluid entering the vessel.
Collected fluid may then be analyzed and/or re-oxygenated and/or
perfused through the organ, discarded or handled otherwise. The
occlusion means may include an occluding balloon, flange, disc or
other means.
[0079] Catheter 110 is delivered to the vessel with the balloon 114
in a deflated condition. The expandable member is delivered,
through the catheter, and deployed inside the vessel. The balloon
is then inflated around the catheter and substantially all the
fluid in the vessel flows through the catheter and into a perfusion
set or reservoir to which it is connected.
[0080] A pump, syringe or other means may be incorporated into the
perfusion set to draw fluid out of the vessel, through the
catheter, at a rate which substantially maintains the required flow
through the organ or region, or through a re-perfusion circuit. As
fluid is drawn out of the vessel through the catheter, the expanded
support structure supports the vessel walls, preventing collapse or
cavitation which might otherwise result from the low pressures or
high flow rates generated at the catheter tip, maintaining patency
and ensuring flow in the circuit. The expandable member may also
anchor the device in position within the vessel, substantially
precluding movement of the device and ensuring that the catheter is
retained in an optimal location for collection of fluid.
[0081] The expandable member may take a range of different shapes
when in an expanded (or collapsed) configuration, and may provide
any number of supporting filaments or struts. The design of the
expandable member may be based on a range of criteria including but
not limited to the size and strength of the vessel wall and the
flow rates and pressures likely to be generated near the device.
Some of these embodiments are illustrated in FIGS. 8a to 8c
although these are examples only and are not intended to limit the
scope of the invention as broadly described herein. FIGS. 8a to 8c
illustrate expandable members having elongate portions in the
supporting struts adapted for contact with the vessel wall. In the
example in FIG. 8b, the supporting struts are slightly rounded to
reduce trauma to the vessel walls. FIG. 8c provides additional
struts when compared with FIG. 8a, as may be necessitated in
particularly flaccid vessels requiring more substantial
support.
[0082] Embodiments illustrated herein provide expandable members
with a substantially elongate structure adapted for coaxial
insertion into and placement within the vessel. The elongate
structure supports the vessel over a length on the elongate
portions of the struts substantially parallel to and in contact
with the vessel wall. These elongate portions may be substantially
straight, or may be curved (e.g. FIG. 8b). Supporting the vessel
wall over a length of the support device, compared with the point
of supports of the prior art, improves the capacity of the device
to maintain patency, even when very low pressures and high flow
rates are generated at the catheter tip, and also reduces the
likelihood of the device causing damage to the vessel wall.
[0083] The elongate portions may have a length which is about the
same as or greater than the diameter of the vessel being supported,
or some multiple of the vessel diameter, or for example from 1 mm
up to 30 mm depending on the vessel size and structure. The length
of the elongate portion may be selected according to the vessel
being supported, the size of the catheter being used and the flow
rates and pressures likely to be generated at the catheter tip.
[0084] Preferably, the elongate portions of the expandable member
which contact the vessel wall, are just adjacent the distal tip of
the catheter when the device is fully deployed. Thus, a proximal
end of one or more of the elongate portions may commence, for
example, within 0.1 to 25 mm of the catheter tip, or at least at a
distance which is less than the diameter of the catheter opening.
This prevents the vessel wall from being drawn into the space
between the catheter tip and the start of the elongate portion of
the expandable member which contacts the vessel wall.
[0085] Further, the device may be configured so that when it is in
an expanded condition, the distance between adjacent elongate
portions is sufficiently small to prevent the vessel wall from
being drawn into gaps between them. For example, the distance
between adjacent elongate portions may be less than the diameter of
the catheter. Alternatively, the distance between the adjacent
elongate portions may be less than, for example, 3, 2.5, 2, 1.5, 1
or 0.5 mm, depending on the size and type of the target vessel, and
the diameter of the collection catheter being used.
[0086] Preferably, the support device possesses sufficient
mechanical strength to maintain patency during collection of fluid,
withstanding the deformation forces which may occur in response to
suction or low pressures produced at the collection catheter tip.
In some embodiments however, it may also be desirable for the
device to exhibit some flexibility, and conform to the shape of the
vessel when deployed. Thus, the support device is capable of
providing support and maintaining patency along a length of the
vessel, even where there is a curve in the vessel wall.
[0087] An alternative embodiment of a support device 200 is
illustrated in FIG. 2. Proximal end 205 of the expandable member
204 is fixedly attached to a stem or shaft 206, whereas distal end
203 of the expandable member is movable and able to slide over part
of the shaft. This enables the member to collapse radially for
delivery inside a delivery catheter, and also facilitates recapture
of the device.
[0088] FIG. 5 illustrates another alternative embodiment of a
support device shown at 500 in an expanded condition. In this
embodiment, both the proximal end 505 and the distal end 503 of the
expandable member are movable along a stem or shaft 506 used to
deliver the device to the vessel. Stops 508a, 508b are provided at
fixed locations on a distal portion of the shaft, arranged between
ends 503,505 of the expandable member. These stops may consist of a
small ring, crimp or node of increased diameter, relative to the
shaft diameter, and prevent the ends of the expandable member from
moving across the stop. This facilitates deployment and retrieval
of the expandable member from a catheter.
[0089] FIG. 10 illustrates a support device 151 consisting of an
expandable framework 155 having a woven or braided, basket-like
configuration when in the expanded condition. In this arrangement,
the support device may also include occluding means in the form of
a thin flow-proof coating 156 on the inner and/or outer surface of
framework 155 to prevent flow of liquid from the vessel. Thus,
substantially all fluid in the vessel may be collected by catheter
160. The flow-proof coating may be made from biocompatible silicon,
elastomer or flow-proof polymer.
[0090] Preferably, the support device includes a radiopaque or
other marker so that it can be positioned within the target vessel
using an imaging system such as those generally known in the art.
This enables the physician to position and deploy the expandable
member into the blood vessel accurately. The marker may be
incorporated into the expandable member and/or into an atraumatic
guiding tip which may be incorporated into the support device.
[0091] Preferably, the atraumatic tip is manufactured from,
includes or is coated with a lubricant and/or a material having a
low coefficient of friction. Many materials having low coefficient
of friction properties may be used including but not limited to
biocompatible high density polyethylene (HDPE), Teflon.RTM.,
polypropylene, polyethylene, Microglide.TM., low friction chromium
and silicon to name a few.
[0092] This improves the performance of the atraumatic tip, so that
it "slides" along the vessel wall upon making contact, thereby
substantially avoiding trauma. Use of an atraumatic guiding tip
improves the safety and ability to position the expandable member
in the target vessel. Moreover, since the atraumatic tip may
exhibit greater flexibility than the rest of the device, the device
is easier to manipulate into position.
[0093] The atraumatic tip may be provided at a distance from the
distal end of the expandable member which enables a physician to
guide the expandable member into position within the target vessel.
This distance may be anywhere from, for example, 0.25 to 5
centimeters from the distal end of the expandable member when in an
expanded condition, although it is to be understood that larger or
smaller distances may be utilized, depending on the location of the
target vessel and the anatomy surrounding it.
[0094] Referring now to FIGS. 6a and 6b, another example of a
support device 600 is shown. A lumen 602 has a control stem 601
extending therein. Four loop portions 603 are provided. Each loop
portion is attached at a first loop end to a distal end 604 of the
lumen, and at a second loop end to the control stem at 605. The
loop portions are controllably expandable by advancing the control
stem within the lumen in the direction shown by arrow 606 (FIG.
6b). The support device is percutaneously deliverable with the
plurality of loop portions housed substantially within the lumen
602 as illustrated in FIG. 6a and expandable as illustrated in FIG.
6b.
[0095] Whilst the embodiment illustrated in FIGS. 6a and 6b
provides 4 loop portions, it is to be understood that any number of
loop portions may be used. The number of loop portions incorporated
into the device may depend on, for example, the anatomy of the
vessel being supported, and/or the size of the catheter used to
deliver the device. FIGS. 7a and 7b illustrate another example of a
support device 700 which provides 3 loop portions 703 attached to
control stem 701 at juncture 705. The 3 loop portions are contained
during delivery substantially within lumen 702 (FIG. 7a), and are
controllably expandable to maintain patency within the blood vessel
by advancing control stem 701 in the direction of arrow 706 (FIG.
7b). The rounded edges of the loop portions present a reduced risk
of damaging the vessel walls, e.g. by perforation or bruising
during delivery.
[0096] The one or more loop portions may be attached to or near the
distal end of the delivery lumen in any suitable manner. The point
of attachment may be inside or outside the lumen. The loops may be
manufactured from any suitable material such as a metal, metal
alloy, plastic, polymer, or other filamentous material or
composite. The one or more loop portions may be attached at a
second loop end to the control stem by soldering, fusing, an
adhesive, or any other suitable means. In another embodiment, the
loop portions may be attached to a first and a second loop end to
the control stem.
[0097] The support structure of FIGS. 6a, 6b, 7a and 7b may further
include an atraumatic guiding tip of the kind described above to
aid in positioning the support structure within the blood vessel.
Alternatively, parts of the loop portions which may protrude from
the lumen when the loop portions are in their collapsed state may
be used to guide the support structure into the blood vessel. One
or more of the loop portions may be provided with a radiopaque or
other marker to assist in this regard.
[0098] Retention means may also be provided with the support
structure to retain the expandable member in an expanded condition
within the vessel. The retention means may be in the form of a
clamp, clip, thumb-slide or the like accessible from outside the
patient's body, and may facilitate adjustment of a deployed
expandable member during a procedure. Retention means may also
impart additional rigidity and strength to the expandable member.
Thus, the retention member may be used to counteract excessively
low pressures which may otherwise cause the expanded member to
fail.
[0099] A support structure of the kind illustrated in the Figures
may be delivered within a multilumen catheter 900 of the kind
illustrated in cross section in FIG. 9. Using this catheter, the
support device 910 can be delivered through a first internal lumen
901 without interfering with flow in a second lumen 902. A third
lumen 903 may be provided for monitoring flow rates and pressures,
for blood analysis or for delivering other percutaneous tools or
devices to the vessel or as an inflation lumen for an occlusion
balloon.
[0100] It is to be understood that in the various embodiments of
the present invention, the expanded member does not require
constant contact with the vessel walls to provide the required
support. For example, the diameter of the expanded member may be
less than the diameter of the vessel so that the expanded member
only contacts the vessel wall when the vessel begins to collapse.
Patency is considered to be maintained as long as the support
device keeps the vessel open to a degree which is sufficient to
maintain continuous flow.
[0101] To avoid causing turbulence or other undesirable blood flow
effects within the vessel, and to optimize flow in the vessel it
may be desirable to substantially match the diameter of the
expanded member to the diameter of the vessel. Alternatively the
expandable member may be shaped, e.g. as a coil or helix, to have
minimal effect on the flow in the vessel.
[0102] In one embodiment, the expandable member may have a slightly
larger expanded diameter than the relaxed vessel to create an
anchoring effect. Depending on the size of the outflow vessel from
which blood and perfusate is collected from the target region,
there may be a natural tendency for the collection catheter tip to
move about and contact the vessel, thus increasing the risk of
vessel collapse or invagination of the catheter tip into the vessel
wall. This can cause pooling of fluid in the isolated target region
and may cause serious and permanent damage to the organ or region
of the patient being treated. Use of a support structure in
conjunction with the collection catheter to maintain patency of the
outflow vessel, in accordance with embodiments of the present
invention can minimize the risk of these complications eventuating.
Thus, a collection catheter associated with the expanding member
can be retained in position during fluid collection. This minimizes
movement of the catheter tip, ensures that it is substantially
centered relative to the vessel walls and improves withdrawal of
fluid out of the vessel.
[0103] At completion of the procedure, it is desirable that the
expanded member is collapsed or compressed and recaptured,
preferably in the catheter from which it was deployed. This
facilitates removal of the support device from the patient. A
reinforcing tip may be provided on the catheter end to strengthen
it for re-capture. Alternatively or additionally, the tip may be
coated with a lubricant and/or material having a low coefficient of
friction to facilitate smooth recapture of the expandable member.
The catheter may also have an internal coating of lubricant and/or
a material having a low coefficient of friction to assist
translation of support device along its interior during delivery
and removal of the device from the patient.
[0104] Although the present invention has been described in terms
of the presently preferred embodiments, it is to be understood that
the disclosure is not to be interpreted as limiting. Various
alterations and modifications will no doubt become apparent to
those skilled in the art after having read the above disclosure and
it is intended that the present disclosure be interpreted as
covering all alterations and modifications as fall within the true
spirit and scope of the invention.
EXAMPLES
Example 1
Effect of Support Device on Flow Rates and Pressures Achievable
During Recirculation in Sheep Right Hepatic Vein, Cephalic Vein,
Coronary Sinus and Renal Vein During Recirculation
[0105] A 0.014'' diameter superelastic nitinol wire stem of 1.35 m
length was used, coupled to an expandable member having 6
pre-shaped elliptical loop portions welded to the stem. A 0.024''
OD atraumatic tip of 2 cm length attached to the distal end of the
expandable member was used to position the device in the blood
vessel. A balloon occlusion catheter was positioned in the vessel
and the expandable member deployed at the tip of the catheter. The
balloon was inflated to isolate and capture flows in the vessel and
the catheter was connected to a standard extracorporeal circuit for
blood circulation.
TABLE-US-00001 TABLE 1 Perfusion of the right hepatic and cephalic
veins. pressure (mmHg) Flow right hepatic vein cephalic vein
(mL/min) device no device device no device 20 -200 40 -10 -13 -11
.dwnarw. 60 -20 -19 -18 no flow 80 -30 -23 achievable 100 -30 -47
-32 120 -40 -75 -43 140 -48 -96 -60 160 -60 -112 -71 180 -75 -142
-97 200 -94 | -139 220 -115 | | 250 -200 | | 220 .dwnarw. | | 200
-92 | | 180 .dwnarw. | 160 -115 .dwnarw. 140 -180 (Bold values
indicate cavitation has occurred)
TABLE-US-00002 TABLE 2 Perfusion of coronary sinus and renal vein.
pressure (mmHg) pressure (mmHg) coronary sinus renal vein RPM
device no device RPM device no device 30 -7 -8 30 40 -19 -30 40
-200 50 -33 -45 50 no flow 60 -52 -106 60 achievable 70 -67 -154 70
80 -84 -203 80 90 -137 | 90 100 -192 | 100 18 90 -137 | 150 -14 80
| 200 -30 70 | 250 -55 60 .dwnarw. 300 -80 no 350 recovery 400 -120
no cavitation (Bold values indicate cavitation has occurred)
[0106] Negative pressures were observed in perfusion lines draining
the coronary sinus, renal vein, right hepatic vein and cephalic
vein during recirculation both with and without a support device.
These data show that cavitation is prevented at certain pressures
in the vessels tested where a support device is used, but is not
prevented where the support device is absent in the vessel at those
pressures. Although cavitation may occur even with the support
device, it occurs at higher flows. Also, cavitation ceases sooner
where the support device was employed allowing flow to return to
normal. In the coronary sinus, recovery from cavitation was not
possible without the support device, emphasizing the importance of
the device in the procedure. The data further demonstrates that
vessel collapse can be irreversible in the absence of a support
structure. However, where a support structure is present, the
vessel collapse may be reversed by increasing pressure in the
vessel or by slowing or reversing the flow rate of fluid through
the vessel.
[0107] More specifically, considering the data for the right
hepatic vein, flow rates of up to 250 mL per minute may be achieved
before cavitation occurs where a support device is present in the
vessel. Under the same conditions but where there is no support
device, flow rates of only up to 180 mL per minute are possible. A
more striking example of the advantages of the support device is
seen for the cephalic vein where no flow is achievable without the
device. When the vessel wall is supported by the device flow rates
of up to 200 mL per minute are noted before cavitation occurs. When
the vessel wall is supported flow rates of up to 200 mL per minute
are noted before cavitation occurs.
* * * * *