U.S. patent application number 14/157326 was filed with the patent office on 2014-05-15 for embolic protection device and methods of use.
This patent application is currently assigned to St. Jude Medical, Cardiology Division, Inc.. The applicant listed for this patent is St. Jude Medical, Cardiology Division, Inc.. Invention is credited to John R. Drontle, Andrew J. Dusbabek, Steven S. Hackett, Thomas F. Janecek, Peter T. Keith, Joel D. Phillips, Thomas V. Ressemann, Kyle L. Thunstrom, Chad W. Trembath, Eric S. Whitbrook.
Application Number | 20140135813 14/157326 |
Document ID | / |
Family ID | 37619169 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140135813 |
Kind Code |
A1 |
Hackett; Steven S. ; et
al. |
May 15, 2014 |
EMBOLIC PROTECTION DEVICE AND METHODS OF USE
Abstract
An evacuation sheath assembly and method of reducing or removing
a blockage within a vessel without permitting embolization of
particulate matter is provided. The evacuation sheath assembly
includes a first elongate tubular member, having proximal and
distal ends and a main lumen configured to be placed in fluid
communication with a blood vessel. An expandable member is provided
on a distal portion of the tubular member. The evacuation assembly
further includes a second elongate tubular member having an
inflation lumen configured to be placed in fluid communication with
the expandable member and a fluid inflator. The fluid inflator is
configured to be placed in fluid communication with the inflation
lumen in order to provide a regulated pressure fluid source for
inflating the expandable member.
Inventors: |
Hackett; Steven S.; (Maple
Grove, MN) ; Whitbrook; Eric S.; (St. Paul, MN)
; Janecek; Thomas F.; (Flagstaff, AZ) ; Trembath;
Chad W.; (Big Lake, MN) ; Dusbabek; Andrew J.;
(Dayton, MN) ; Drontle; John R.; (Buffalo, MN)
; Phillips; Joel D.; (Minneapolis, MN) ;
Ressemann; Thomas V.; (St. Cloud, MN) ; Thunstrom;
Kyle L.; (Eden Prairie, MN) ; Keith; Peter T.;
(Lanesboro, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
St. Jude Medical, Cardiology Division, Inc. |
St. Paul |
MN |
US |
|
|
Assignee: |
St. Jude Medical, Cardiology
Division, Inc.
St. Paul
MN
|
Family ID: |
37619169 |
Appl. No.: |
14/157326 |
Filed: |
January 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13532351 |
Jun 25, 2012 |
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|
|
14157326 |
|
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|
11177473 |
Jul 7, 2005 |
8221348 |
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13532351 |
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Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61M 2025/0037 20130101;
A61B 17/22032 20130101; A61M 25/005 20130101; A61M 2025/0034
20130101; A61M 25/10181 20131105; A61M 2205/8225 20130101 |
Class at
Publication: |
606/194 |
International
Class: |
A61B 17/22 20060101
A61B017/22 |
Claims
1. A fluid inflator comprising: a shuttle mechanism for controlling
fluid flow to an expandable member via an inflation lumen, the
shuttle mechanism comprising: a shuttle chamber having a pressure
chamber and a vacuum chamber; a shuttle movable within the shuttle
chamber between at least first and second positions; wherein the
shuttle is operable to alternately place the pressure chamber in
flow communication with a vacuum source, a pressurized fluid
source, and the inflation lumen.
2. The fluid inflator of claim 1, further comprising a tube coupled
to the inflation lumen and to the shuttle chamber, the expandable
member and inflation lumen being part of a balloon catheter.
3. The fluid inflator of claim 1, further comprising a puncturing
mechanism connected to the pressurized fluid source and including a
puncture spear and a lever for engaging the puncture spear.
4. The fluid inflator of claim 1, further comprising a mechanism
for removing fluid from an expandable member of the balloon
catheter.
5. The fluid inflator of claim 1, wherein the pressure chamber
further comprises an inlet port in fluid communication with the
pressurized fluid source for filling the pressure chamber with a
volume of fluid.
6. The fluid inflator of claim 2, further comprising: a housing; at
least one control switch positioned on the housing and operable to
control fluid flow within the inflation lumen.
7. The fluid inflator of claim 6, wherein the at least one control
switch further comprises an inflation button and a deflation button
operably connected to the shuttle mechanism.
8. The fluid inflator of claim 7, wherein the shuttle is operably
connected to the inflation and deflation buttons and the shuttle
mechanism further comprises: a series of seals mounted on the
shuttle and spaced apart to divide the shuttle chamber into the
pressure chamber and the vacuum chamber, wherein the vacuum chamber
has a one way bypass seal for venting fluid from the vacuum
chamber; a vacuum piston operably connected to the one way bypass
seal of the vacuum chamber; a translation output connected to the
inflation and deflation buttons for moving the shuttle
longitudinally within the shuttle chamber.
9. The fluid inflator of claim 8, wherein the series of seals are
o-ring seals.
10. The fluid inflator of claim 9, wherein the vacuum chamber is
formed by one o-ring seal and the one-way venting seal spaced apart
and the pressure chamber is formed by two or more o-ring seals
spaced apart.
11. The fluid inflator of claim 8, wherein the shuttle chamber
includes a high pressure resistance outlet port and a low pressure
resistance outlet port.
12. The fluid inflator of claim 11, wherein the translation output
for moving the shuttle longitudinally is configured to alternately
place the pressure chamber in fluid communication with the
pressurized fluid source and the high pressure resistance outlet
port.
13. The fluid inflator of claim 2, further comprising a venting
system for regulating the pressure of the fluid delivered to the
inflation lumen from the pressure chamber.
14. The fluid inflator of claim 13, wherein the venting system
further comprises at least one pressure relief valve for
maintaining a constant delivery pressure to the inflation
lumen.
15. The fluid inflator of claim 14, further comprising a second
pressure release valve.
16. The fluid inflator of claim 14, wherein the at least one
pressure valve comprises a spring-loaded poppet valve.
17. The fluid inflator of claim 14, wherein the pressure relief
valve further comprises a pressure indicator in fluid communication
with the inflation lumen.
18. The fluid inflator of claim 2, further comprising an in-line
filter for sterilizing the fluid before delivery to the inflation
lumen.
19. The fluid inflator of claim 1, wherein the pressurized fluid
source comprises a pressurized Carbon Dioxide.
20. A fluid inflator comprising: a shuttle mechanism comprising: a
shuttle chamber having a pressure chamber and a vacuum chamber; a
shuttle movable within the shuttle chamber; wherein the shuttle is
operable between a first position in which the pressure chamber is
in flow communication with a vacuum source, a second position in
which the pressure chamber is in flow communication with a
pressurized fluid source, and a third position in which the
pressure chamber is in flow communication with an inflation lumen
of a vascular closure device.
Description
RELATED APPLICATIONS
[0001] This is a divisional application of U.S. patent application
Ser. No. 13/532,351, filed 25 Jun. 2012, and entitled EMBOLIC
PROTECTION DEVICE AND METHODS OF USE, pending, which is a
divisional application of U.S. patent application Ser. No.
11/177,473, filed on 7 Jul. 2005, now U.S. Pat. No. 8,221,348,
issued 17 Jul. 2012, and entitled EMBOLIC PROTECTION DEVICE AND
METHODS OF USE, the disclosures of which are incorporated, in their
entireties, by this reference.
FIELD OF THE INVENTION
[0002] The present invention relates to apparatus and methods used
to prevent the introduction of emboli into the bloodstream during
and after surgery performed to reduce or remove blockage in blood
vessels.
BACKGROUND OF THE INVENTION
[0003] Narrowing or occlusion of blood vessels, such as the walls
of an artery, inhibits normal blood flow. Such blockages, whether
partial or full, can have serious medical consequences, depending
upon their location within a patient's vascular system. Narrowing
or blockage of the coronary vessels that supply blood to the heart,
a condition known as atherosclerosis, may cause damage to the
heart. Heart attacks (myocardial infarction) may also result from
this condition. Other vessels are also prone to narrowing,
including carotids, renals, cerebrals, and other peripheral
arteries.
[0004] Various surgical procedures are currently used to reduce or
remove the blockage in blood vessels. Such procedures include
balloon angioplasty, which involves inserting a balloon catheter
into the narrowed or occluded area, expanding the balloon in the
narrow or occluded area, and if necessary, placing a stent in the
now expanded area to keep it open. Another common procedure used is
atherectomy where the lesion is cut away and removed from the
vessel, or abrasively ground, sending the small particulates
downstream. Other endovascular procedures make use of thrombectomy,
drug delivery, radiation, stent-grafts, and various diagnostic
devices.
[0005] Another alternative is bypass surgery in which a section of
vein is removed from, for example, the patient's leg, e.g., a
saphenous vein, to be used as a graft to form a pathway to bypass
the occluded area. The saphenous vein graft (SVG), however, is also
susceptible to becoming occluded in a manner similar to that of the
bypassed vessel. In such a case, angioplasty (with or without the
use of a stent) or atherectomy is often used on the SVG to remove
or reduce the blockage.
[0006] Each of the above described procedures carries with it the
risk that some of the treated plaque, or other obstructive material
such as thrombus, will be disrupted, resulting in embolic
particulates released in the bloodstream. These emboli, if allowed
to flow through the vascular system, may cause subsequent
infarctions or ischemia in the patient. SVGs treated by angioplasty
or atherectomy carry a particularly high risk of this result, but
such problems are also encountered in the other types of procedures
mentioned, such as carotids, or native coronary arteries,
particularly those whose lesions include thrombus, such as those
associated with acute myocardial infarction (AMI).
[0007] Several systems to prevent emboli being released into the
bloodstream during such procedures have been tried. One system uses
a balloon to totally occlude the artery distal (downstream) to the
area of blockage to be treated. In this system, a guide wire with a
balloon is introduced into the narrowed or occluded area, and
passes through the narrowed or occluded area to a position
downstream of the blockage. The balloon is inflated, the blockage
is reduced or removed, and then the blood proximal to the balloon
is withdrawn from the blood vessel to remove any particles or
emboli which have resulted from the reduction of the blockage.
While this system has shown a decrease in emboli related
complications in patients undergoing such treatments, the event
rate remains significant. One particular problem with this system
is passing the guidewire and balloon through the narrowed or
occluded area prior to occlusion with the balloon, creating the
risk that emboli will be produced as the balloon passes through the
blockage. Thus, any particulate or plaque disturbed during this
passage which forms emboli prior to inflation of the balloon is
free to flow through the vascular system, increasing the risk for
infarction or ischemia. Also, any debris or embolic particulate
matter which gathers around the edges of the balloon may slip
downstream during deflation and retrieval of the balloon. In
addition, this system requires that blood flow be totally occluded
in the vessel for relatively prolonged intervals that may induce
adverse cardiac events. Although this may not be a problem
clinically, many patients perceive the occlusion of blood flow for
this period of time as problematic.
[0008] Another system used to prevent emboli being released into
the bloodstream during surgical intervention is a filter. As with
the occlusion balloon, the filter must pass through the narrowed or
occluded area and is deployed distal (downstream) to the blockage.
The filter then catches any particulate material generated during
the removal of the blockage. The filter offers the benefit that
blood flow is not totally occluded. However, because the filter
must pass through the blockage, it suffers from the same drawback
as the previous system--risk of the creation of emboli during
passage of the filter through the blockage. In addition, it is
difficult to deploy the filter securely against the walls of the
vessel to prevent flow around the filter and any debris or
particulate matter which gathers around the edges of the filter may
slip downstream during its retrieval. Also, in order to allow blood
flow during the procedure, the pores of the filter should be at
least 100 microns in diameter. The majority of emboli have a
diameter between about 40 microns and about 100 microns. Thus, the
filter will not catch the majority of emboli, which may flow
downstream and cause an infarction or ischemia. The filter also
cannot prevent the passage of certain neurohumoral or vasoactive
substances which are released into the blood during the procedure
and may contribute to generalized vasospasm of the distal coronary
tree.
[0009] Thus, there is a need for an improved system and method of
treating occluded vessels which can reduce the risk of distal
embolization during vascular interventions. There is also a need
for a system which reduces the amount of time that total occlusion
of the blood flow is necessary.
SUMMARY OF THE INVENTION
[0010] In accordance with the invention, methods and apparatuses
for reducing or removing a blockage within a vessel without
permitting embolization of particulate matter are provided. The
methods and apparatuses occlude blood flow for a minimal amount of
time and capture particulate matter created during each step of the
surgical process.
[0011] According to one aspect of the present invention, an
evacuation sheath assembly is provided. The evacuation sheath
assembly includes a first elongate tubular member having main
lumen, wherein the main lumen is configured to be placed in fluid
communication with the blood stream so that embolic particulate
matter may be evacuated, contrast, saline or other therapeutic
fluid may be infused or interventional devices may be delivered to
a blood vessel. The evacuation sheath further includes an
expandable sealing member configured to form a seal with a blood
vessel and a second elongate tubular member with distal and
proximal ends and an inflation lumen extending therebetween,
wherein the inflation lumen is configured to be placed in fluid
communication with the expandable member at the distal end. The
evacuation sheath further includes gas inflator having a pressure
regulating mechanism, wherein the gas inflator is configured to be
connected to the proximal end of the inflation lumen to deliver
provide a regulated pressure gas source for inflating the
expandable member. The Patent expandable member may be a balloon,
alternatively the expandable member may be any suitable expandable
sealing member.
[0012] In an alternative embodiment, the evacuation sheath assembly
may further include a soft tip mounted on the distal end of the
first elongate tubular member. Such a soft tip may further be
secured to the distal end of first elongate tubular member and the
distal end of the expandable member in order to provide a flexible,
conical shape capable of can deforming and dilating to facilitate
folding up a "winged out" balloon of an interventional device as it
is withdrawn back through the main lumen of the evacuation
sheath.
[0013] In an alternate embodiment, the first elongate tubular
member may further be surrounded by a kink resistant structure, for
example a kink resistant braid or a kink resistant coil. The kink
resistant coil may be comprised of a ribbon wire and may have
further be secured at the proximal and distal ends of the coil to
prevent uncoiling by one or more laser welds joining one or more
adjacent turns of the coil. In such an embodiment, the second
elongate tubular member may then be secured to the first elongate
member by mounting the second, elongate tubular member to the kink
resistant structure.
[0014] In addition, it is further contemplated that the second
elongate tubular member and the first elongate tubular member
surrounded by the kink resistant coil may further be enclosed by an
encapsulation layer. The encapsulation layer may be made of PEBAX
or another suitable material. The encapsulation layer may then be
melted down to conform and bond to the surfaces of the first and
second elongate members. In such a manner a single, flexible,
multi-lumen tube comprising a main lumen and an inflation lumen may
be formed.
[0015] According to another aspect of the present invention, the
evacuation sheath may be sized to have an outer diameter
substantially the same size as the inner diameter of a guide
catheter, such as a 6 French guide catheter, alternatively a 7
French guide catheter, alternatively an 8 French guide catheter or
any other size guide catheter. In an alternative embodiment, the
outer diameter of the evacuation sheath may be covered with a
lubricious coating. Additionally, the expandable member of
evacuation assembly may also be covered with a lubricious
coating.
[0016] According to another aspect of the present invention, the
evacuation sheath assembly may further include a third elongate
tubular member slidably insertable through the main lumen of the
first elongate tubular member and extendable from the aperture of
the main lumen for positioning beyond the distal end of the main
lumen, wherein the third elongate tubular member has a proximal
end, a distal end, a lumen extending therebetween. The lumen of the
third elongate member further includes an aperture disposed at the
distal end for communicating said lumen with the bloodstream and is
connected at the proximal end of the tube with an infusion means
for delivering a fluid into the blood stream.
[0017] According to another aspect of the present invention, a gas
inflator for inflating and deflating the expandable member is
provided. The gas inflator includes a shuttle mechanism for
delivering a bolus of gas to an expandable member via an inflation
lumen having one or more outlet ports in communication with the
inflation lumen and a high pressure gas source having an inlet port
in fluid communication with the shuttle mechanism. The gas inflator
may further include a housing and one or more control switches on
the housing for controlling gas flow within the inflation lumen,
for example an inflation and a deflation button operably connected
to the shuttle mechanism. In an alternative embodiment, the gas
inflator may further include a mechanism for removing gas from the
expandable member, which also may be connected to one or more
control switches within the housing. In addition, the gas inflator
may further include a tube operably sized to connect with the
proximal end of an inflation lumen and place the inflation lumen in
fluid communication with the one or more outlet ports.
[0018] According to another aspect of the present invention, the
gas inflator may further comprise a puncturing mechanism connected
to the high pressure gas cartridge, having a puncture spear and a
lever for engaging the puncture spear. The high pressure gas
cartridge contains a suitable high pressure gas for inflating the
expandable member, for example Carbon Dioxide, Nitrous
[0019] Dioxide or Helium. Additionally, the gas inflator may
further comprises an in line filter for sterilizing the gas before
delivery to the inflation lumen.
[0020] According to another aspect of the present invention, a
shuttle mechanism of the gas inflator may be operably connected to
inflation and deflation buttons on the housing and may further
include a cylindrical shuttle chamber in fluid communication with
the one or more outlet ports and the high pressure gas source,
wherein a series of seals, for example o-ring seals, are mounted on
the shuttle and spaced apart to divide the shuttle chamber into a
pressure chamber and a vacuum chamber, wherein the vacuum chamber
has a one way bypass seal for venting gas from the vacuum chamber,
and a vacuum piston operably connected to the one way bypass seal
of the vacuum chamber. The shuttle mechanism further includes
translation output connected to the inflation and deflation buttons
for moving the shuttle longitudinally within the shuttle chamber to
alternately place the vacuum and pressure chambers in fluid
communication with a shuttle chamber outlet port and the pressure
chamber in fluid communication with a high pressure gas source. In
addition, the pressure chamber may further comprise an inlet port
in fluid contact with the high pressure gas source for filling the
pressure chamber with a bolus of gas. Additionally, the shuttle
mechanism may further comprise both a high pressure resistance
outlet port and a low pressure resistance outlet port.
[0021] In an alternative embodiment, the vacuum chamber may be
formed by one o-ring seal and the one-way venting seal spaced apart
to define a chamber and the pressure chamber is formed by two or
more o-ring seals spaced apart to define a chamber.
[0022] In an alternative embodiment, the gas inflator may further
comprises a venting system for regulating the pressure of the gas
delivered to inflation lumen from the outlet port. Such a venting
system may include at least one pressure relief valve for
maintaining a constant delivery pressure to the inflation lumen.
Alternatively, the venting system may comprise a second pressure
release valve. The pressure relief valves may be spring-loaded
poppet valves. In addition, one of the pressure relief valves may
further comprises a pressure indicator in fluid communication with
the inflation lumen, wherein the housing further comprises a window
for viewing the pressure indicator.
[0023] According to another aspect of the invention, a method for
treating a diseased blood vessel is provided. The method includes
advancing an elongate tubular member into the blood vessel through
the lumen of the guide catheter, positioning the elongate tubular
member within the diseased blood vessel, inflating the expandable
sealing member located on the distal end of the of the elongate
tubular member to form a seal between the region of interest of the
diseased blood vessel and the distal end of the guide catheter; and
applying a vacuum to the elongate tubular member to cause
retrograde blood flow in the blood vessel and to carry fluid into
the lumen of the elongate tubular member.
[0024] According to another aspect of the invention, a method for
treating a diseased blood vessel is provided. The method includes
advancing an elongate tubular member into the blood vessel through
the lumen of the guide catheter, positioning the elongate tubular
member within the diseased blood vessel, inflating the expandable
sealing member located on the distal end of the of the elongate
tubular member to occlude normal ante grade blood flow in the blood
vessel proximal to the region of interest, and applying a vacuum to
the elongate tubular member to cause retrograde blood flow in the
blood vessel and to carry fluid into the lumen of the elongate
tubular member. In addition, the method may further include the
step of removing the elongate tubular member from the blood
vessel.
[0025] According to another aspect of the invention, a method for
treating a diseased blood vessel is provided. The method includes
advancing a guide catheter proximal to the blood vessel, advancing
an elongate tubular member into the blood vessel through the lumen
of the guide catheter and beyond the distal opening, wherein the
proximal end of the elongate tubular member extends proximally
outside the patient during use, positioning the elongate tubular
member within the diseased blood vessel, inflating the expandable
sealing member located on the distal end of the of the elongate
tubular member to occlude normal ante grade blood flow in the blood
vessel proximal to the region of interest, and applying a vacuum to
the elongate tubular member to cause retrograde blood flow in the
blood vessel and to carry fluid into the lumen of the elongate
tubular member.
[0026] In addition, the method of treating a blood vessel may
further include the steps of advancing an infusion catheter through
the evacuation lumen and introducing fluid into the blood stream
via the infusion catheter while the expandable member is
inflated.
[0027] In another alternative embodiment, the method of treating a
blood vessel may further include the steps of injecting contrast
dye through the lumen of the elongate tubular member to verify the
occlusion of the blood vessel.
[0028] In addition the method of treating a blood vessel may
further include the step of applying a second vacuum to the
evacuation sheath assembly to re-initiate retrograde flow in the
blood vessel and to carry remaining embolic material from the blood
vessel into the lumen of the elongate tubular member. In another
embodiment, the method may further include the step of applying a
vacuum to the gas inflator to deflate the expandable member.
[0029] According to another aspect of the present invention the
step of inflating the expandable member may further comprises the
steps of puncturing a high pressure gas cartridge within the gas
inflator, filling a pressure chamber in the gas inflator with a
bolus of high pressure gas, depressing a pressure button on the gas
inflator to advance a shuttle in the gas inflator, wherein the
shuttle transports the pressure chamber into communication with a
high pressure resistance output port and wherein the high pressure
resistance output port is in communication with the inflation lumen
via a tube extending from the gas inflator, regulating the flow of
the high pressure gas from the high pressure resistance output port
via at least one pressure relief valve, and delivering a low
pressure volume of gas to the tube in communication with the
inflation lumen and thereby inflating the expandable member.
[0030] In an alternative embodiment, the step of inflating the
expandable member may also include the step of priming the
inflation lumen to remove the ambient air from the inflation lumen
and the expandable member prior to advancing the evacuation
assembly through the guide catheter. Priming the inflation lumen
may further comprise the steps of activating a piston in the gas
inflator, wherein the piston in operably connected to a seal with a
one way bypass which defines the opening of a vacuum chamber in the
gas inflator, releasing the piston and creating a vacuum in a
vacuum chamber, depressing a vacuum button on the gas inflator to
advance a shuttle mechanism within the gas inflator and place the
vacuum chamber in fluid communication with a low pressure
resistance output port wherein the low pressure resistance output
port is in communication with the inflation lumen, and suctioning
the gas from the inflation lumen and the expandable member via the
low resistance valve output.
[0031] According to another aspect of the present invention the
step of deflating the expandable member may further include
activating a piston in the gas inflator, wherein the piston in
operably connected to a seal with a one way bypass which defines
the opening of a vacuum chamber in the gas inflator, releasing the
piston and creating a vacuum a vacuum chamber, depressing a vacuum
button on the gas inflator to advance a shuttle mechanism within
the gas inflator and place the vacuum chamber in fluid
communication with a low pressure resistance output port wherein
the low pressure resistance output port is in communication with
the inflation lumen, suctioning the gas from the inflation lumen
and the expandable member via the low resistance valve output.
[0032] In an alternative embodiment, the pressure in the inflation
lumen may be monitored as the expandable member is being inflated
and/or deflated.
[0033] Additional objects and advantages of the invention will be
set forth in part in the description which follows, and in part
will be obvious from the description, or may be learned by practice
of the invention. The objects and advantages of the invention will
be realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0034] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1A is a side view of an embodiment of a full length
evacuation sheath according to the present invention.
[0036] FIG. 1B is a side view of the proximal end of an embodiment
of a full length evacuation sheath according to the present
invention.
[0037] FIG. 1C is a side view of the distal end of an embodiment of
a full length evacuation sheath according to the present
invention.
[0038] FIG. 1D illustrates a cross sectional view of an embodiment
of a full length evacuation sheath taken along plane A-A according
to the present invention.
[0039] FIG. 1E illustrates a side view of an embodiment of a third
elongate tubular member for use in an alternate embodiment of an
evacuation sheath according to the present invention.
[0040] FIG. 2 illustrates a schematic diagram of an embodiment of
the device in use according to the present invention.
[0041] FIG. 3A illustrates an embodiment of a kink resistant coil
for use in the present invention.
[0042] FIG. 3B illustrates an embodiment of welds for use in
securing a kink resistant coil to the elongate tubular member of a
device according to the present invention.
[0043] FIG. 4 illustrates an embodiment of a sealing mechanism for
use in the present invention.
[0044] FIG. 5 illustrates an overview of an embodiment of a gas
inflator according to the present invention.
[0045] FIG. 6A illustrates a cross-sectional view of an embodiment
of a gas inflator according to the present invention.
[0046] FIG. 6B illustrates a cross-sectional view of an embodiment
of the high pressure gas source and gas delivery mechanism of a gas
inflator according to the present invention.
[0047] FIG. 6C illustrates a cross-sectional view of an embodiment
of a pressure relief valve/pressure indicator and an inflation
communication outlet of a gas inflator according to the present
invention.
[0048] FIG. 7 illustrates an embodiment of a control switch for
controlling movement of the shuttle mechanism and regulating gas
flow within a gas inflator according to the present invention.
[0049] FIG. 8A-H illustrate a schematic diagram of an embodiment of
a shuttle mechanism in use according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0050] The present invention provides a system and method for
evacuating emboli, particulate matter and other debris from a blood
vessel, and particularly from an occluded blood vessel. As used
herein, an "occlusion," "blockage," or "stenosis" refers to both
complete and partial blockages of the vessels, stenoses, emboli,
thrombi, plaque, debris and any other particulate matter which at
least partially occludes the lumen of the blood vessel.
[0051] This method and apparatus are particularly suited to be used
in diseased blood vessels that have particularly fragile lesions,
or vessels whereby the consequences of even small numbers of small
emboli may be clinically significant. Such blood vessels include
diseased SVGs, carotid arteries, coronary arteries with thrombus
such as associated with AMI, and renal arteries. However, it is
contemplated that the method and apparatus may also be applied to
peripheral, neuro, and other vascular and non-vascular
applications.
[0052] FIG. 1A illustrates an embodiment of an evacuation sheath
assembly 100. As shown, the evacuation sheath assembly 100 includes
a multi-lumen elongate tubular member 102 having a main lumen 106
extending essentially the full length of the elongate tubular
member 102 and an expandable member 104 mounted at the distal end
105 of the elongate tubular member. As shown in FIGS. 1B, 1C and
1D, the multi-lumen elongate tubular member 102 further includes an
inflation lumen 110 (most easily seen in FIGS. 1C and 1D) connected
at the proximal end 103 to a gas inflator 120 (shown in FIG. 2) and
extending distally to connect with the expandable member 104
mounted at the distal end 105 of the elongate tubular member 102.
The evacuation sheath assembly further includes a soft tip 114 at
the distal end and is connected to a manifold 130 at the proximal
end.
[0053] As shown in FIG. 1B, the manifold includes an inflation
connector tube 122, which when connected to the inflation system
(not shown) defines a pathway for inflation of the expandable
member 104 via an inflation lumen 110 in the multi-lumen elongate
tubular member 102. The manifold includes an aspiration tube 131,
which is in fluid communication with the evacuation lumen. 106. A
stopcock 132 is preferably connected to the aspiration tube 130,
which facilitates the use of the main lumen 106 for evacuation of
embolic particulate matter and/or infusion of fluids there through
to the vasculature. In use, as depicted in FIG. 2, the aspiration
tube 131 and stopcock 132 may be connected to both an evacuation
syringe 210 which would be alternately used to draw the embolic
particulate matter from the main lumen and an inflation syringe 211
which would alternately be used to deliver fluids, for example
radiopaque contrast agent for angiography, saline or therapeutic
agents through the main lumen 106.
[0054] In an alternative embodiment, the evacuation sheath assembly
may include a third elongate tubular member 140, as depicted in
FIG. 1E, slidably insertable through the main lumen and extendable
from the aperture of the main lumen for positioning beyond the
distal end of the main lumen. In this embodiment, the third
elongate tubular member 140 has a proximal end 141, a distal end
142, a lumen 144 extending therebetween, and an aperture 143
disposed at the distal end for communicating said lumen 144 with
the bloodstream. In use, the third elongate tubular member may be
delivered to a blood vessel through the main lumen of the
multi-lumen tube so that the distal end of the lumen is in fluid
communication with the blood stream. The proximal end of the third
elongate tubular member may then be connected at the with an
inflation syringe or other infusion means for delivering a fluid
such as saline or another therapeutic fluid into the blood
stream.
[0055] As shown in FIG. 2, the proximal end of the evacuation
sheath assembly 100 may be used with a lip seal 240 for isolating
fluid communication between the multi-lumen elongate tubular member
102 and the guide catheter 204. The distal end of the lip seal 240
includes a male luer fitting 242 which connects to the female luer
fitting 243 at the proximal end of the guide catheter 204. FIG. 4
shows an embodiment of a lip seal according to this invention in
more detail. The lip seal 240 includes a diaphragm 244 with an
opening 246 operably sized to allow passage of the multi-lumen
elongate tubular member 102 therethrough, a stationary base 248, a
tubular actuator 250 and a male luer adaptor 242 at the distal end
for securing to a female luer fitting at the proximal end of a
guide catheter. In use, when the actuator 250 is depressed, it
pushes the diaphragm 244 against the stationary base 248 and causes
the opening 246 in the diaphragm to expand. While the opening 246
is expanded, the multi-lumen elongate tubular member 102 can easily
be slid through the tubular actuator 250, and diaphragm opening
246, and into the lumen of the guide catheter 204. Once the
actuator 250 is released, the opening in the diaphragm 244
retracts, forming a seal around the multi-lumen elongate tubular
member 102 and isolating fluid communication from the guide
catheter, to prevent back-bleeding out of the guide catheter 204,
or to prevent air ingress into the lumen of the guide catheter 204.
Since the evacuation lumen in the multi-lumen elongate tubular
member 102 may be used for delivery of interventional catheters, or
fluids such as saline, contrast dyes or therapeutic agents, it is
possible to completely isolate the guide catheter from fluid
communication with the manifold of the evacuation sheath assembly
100. As shown in FIG. 2, once the elongate tubular member 102 is
inserted in the lip seal 240, the main lumen 106 becomes the lumen
through which particulate matter is evacuated, contrast infusions
are delivered and blood pressures are monitored, and the lumen of
the guide catheter 204 is not used for these functions.
[0056] As shown in FIG. 1D, in an embodiment of the multi-lumen
elongate tube 102 two PTFE tubes comprising a main liner tube 107
and an flattened oval inflation tube 111 are provided. These tubes
may be chemically etched to make them more bondable. These tubes
may then be covered with an encapsulation material, for example,
PEBAX, to create the composite, multi-lumen elongate tubular member
102 depicted in FIG. 1A. In this embodiment, the encapsulation
layer may be a PEBAX tube 112 that is loaded over the assembly of
the main tube 107 and the inflation tube 111. In an alternative
embodiment, the encapsulation material covering the main tube may
be different for the distal and proximal regions of the main tube,
for example PEBAX 72D may be used to cover the proximal region of
the tube while PEBAX 55D may be used to cover the distal region of
the tube 107. In such an embodiment, the distal region of the tube
may be 32 cm in length, alternatively, the distal region may be
20-45 cm in length. In addition main tube 107 may further comprise
a kink resistant coil 108 surrounding the main tube 107. The PEBAX
tube 112 may then be melted down to fill around the inflation tube
111, and impregnate the coil 108 and melt to the outside of the
main tube 107. This process is sometimes called "reflowing". The
melted PEBAX may then bond to the etched surfaces. Alternatively,
the melting of the PEBAX encapsulation may be facilitated by the
use of a separate heat shrink tubing (not shown) which is loaded
over the initial PEBAX tube, and the whole thing is put into an
oven. Here, the heat shrink will shrink at a temperature above the
melt temp of the PEBAX and the melted Pebax will be forcibly
squeezed around the entire outside of the inflation tube 111 and
into the coil 108, resulting in a composite, mutli-lumen elongate
tubular member.
[0057] It is contemplated that the multi-lumen tube 102 may be
sized to fit within a 6 French guide catheter, alternatively a 7
French guide catheter, alternatively an 8 French guide catheter or
other sized guide catheters. In an embodiment sized to fit with in
a 6 French guide catheter, the main liner tube 107 may have, for
example, an inner diameter of 0.052 inches and a wall thickness of
0.0015 inches, alternatively the inner diameter may range from
0.048 to 0.056 inches and/or the wall thickness may range from
0.001 to 0.004 inches. In such an embodiment, the inflation tube
111 may have an inner diameter of 0.006 inches, flattened to an
oval shape with an inner diameter of 0.0025 inches and a wall
thickness of 0.0015 inches, alternatively, the wall thickness may
range from 0.001 to 0.004 inches and/or the inner diameter may
range from 0.003 to 0.10 inches which may have no flattening or be
flattened to an oval shape with as small as 0.002 inner diameter.
In such an embodiment, the encapsulation layer 112 may have a
thickness such that the outer diameter of the multi-lumen tube 107
is 0.064 inches, alternatively the outer diameter may range from
0.060-0.070 inches. In an embodiment sized to fit within a 7
French, 8 French or other sized guide catheter, it is further
contemplated that ranges for the dimensions of the elements of the
multi-lumen tube would be adjusted corresponding to the inner
dimension of the guide catheter.
[0058] As depicted in FIGS. 3A and 3B, the kink resistant coil 108,
comprising for example ribbon wire, may be wound directly onto the
main tube 107 or expanded from a wound state and slidingly placed
over the main tube 107. Here, the proximal and distal ends of coil
108 may then be wound so that the coil wraps are touching and
welded together by one or more laser welds, for example as depicted
herein three laser welds 308, to secure each end of the coil 108
and prevent it from unwinding. The kink resistant provides for the
elongate tubular member to be highly flexible as well as kink
resistant. The main tube 107, including the surrounding kink
resistant coil 108, may then be bonded with an inflation tube as
described above to create a multi-lumen elongate tubular member for
use in the evacuation sheath assembly. In an alternative
embodiment, the kink resistant structure may be a braid.
[0059] FIG. 1C illustrates in more detail the distal end of the
evacuation sheath assembly 100. The soft distal tip 107 is secured
to the distal end of the main tube 107 and the distal end of the
expandable member 104 by suitable means such as thermal bonding.
The soft tip 107 is preferably formed of a relatively soft PEBAX
such as 35D and loaded with radiopaque material such as Barium
Sulfate. Such a tip allows interventional devices such as stent
delivery balloon catheters to be easily withdrawn back through the
tip after their balloons have been inflated and subsequently
deflated and "winged out". During retraction of the "winged out"
balloon, the soft tip 107 can deform and dilate to help fold up the
"winged out" balloon into the main lumen 106 of the evacuation
sheath assembly 100.
[0060] The expandable member 104 is preferably blow-molded and
attached to the multi-lumen elongate tubular member 102 with
suitable means such as thermal bonding. Further details of
preferred balloon materials and methods of fabrication may be found
is U.S. patent application Ser. No. 10/214,712, filed on Aug. 9,
2002 and published as US2003/0050600, U.S. patent application Ser.
No. 09/940,896, filed on Aug. 29, 2001 and published as
US2002/0165574 and U.S. patent application Ser. No. 09/845,162,
filed on May 1, 2001 and published as US2002/0165598 all of which
are incorporated in their entirety, herein.
[0061] As shown in FIG. 2, the multi-lumen elongate tubular member
102 is sized to fit inside a guide catheter 204 and to have a
distal end 105 advanced beyond the distal opening of the guide
catheter into a patient's blood vessel 200 while the proximal end
103 remains extending outside of the patient during use. The outer
surface of the elongate tubular member 102 may be coated with a
lubricious coating to facilitate movement through the lumen of the
guide catheter 204. The lubricious coating may cover the distal 10
cm in length of the elongate tubular member, alternatively the
coating may cover 20 cm, alternatively 30 cm, alternatively 40 cm
and up to the entire length of the elongate tubular member. In an
alternative embodiment, the outer surface of the expandable member
102 may also be coated with a lubricious coating to further
facilitate delivery through the lumen of catheter 204. Note that
FIG. 2 illustrates the embolic protection system at a particular
point in time, namely after a stent has been positioned in the
region of interest 206.
[0062] In use, the multi-lumen elongate tubular member 102 may be
advanced through a guide catheter 204 over a guide wire 202 to
extend distally from distal end of the guide catheter 204 into a
patients blood vessel 200, in a fashion similar to that described
in cross referenced U.S. patent application Ser. No. 10/214,712,
Ser. No. 09/940,896 and Ser. No. 09/845,162 previously incorporated
herein by reference. The guide wire 202 preferably only extends
initially to the region of interest 206 (e.g. the blockage or
lesion), but alternately the guide wire 202 may be advanced beyond
the region of interest 206 initially. The multi-lumen elongate
tubular member 102 is further advanced until the expandable member
104 is proximal to the region of interest 206. The expandable
member may then be expanded to occlude blood flow in the region of
interest 206. Once occluded, contrast may be infused via the main
lumen 106 into the blood vessel. An inflation syringe 211 may be
attached to the manifold 130 of the main lumen 106 via an
aspiration tube 131 and stopcock 132 to provide a contrast agent or
other fluids, such as saline or therapeutic agents, to the region
of interest via the main lumen 106. An interventional catheter such
as a stent delivery catheter may be introduced over the guide wire
202, through the main lumen 106 to deliver a stent to the region of
interest 206. The interventional catheter may then be removed from
the main lumen 106. A vacuum may be induced within the main lumen
106 of the multi-lumen elongate tubular member 102 using a
evacuation syringe 210 connected to the main lumen 106 via the
stopcock 132 and aspiration tube 131 on the manifold 130. The
vacuum will draw the embolic particulate matter 207 from the blood
vessel 200 and through the main lumen 106 into the evacuation
syringe 210. After the embolic particulate matter is removed, the
expandable member 104 may be deflated and the Multi-lumen elongate
tubular member 102 may be withdrawn from the blood vessel 200.
Alternatively, a contrast dye may be introduced into the region of
interest via the previously described method to insure that all of
the embolic particulate matter was removed and that the region of
interest is sufficiently treated before deflating the expandable
member and removing the multi-lumen elongate tubular member
102.
[0063] An unrecognized advantage of this design, wherein the main
lumen 106, which is used for evacuation, extends the full length of
the elongate tubular member 102, vs. "short lumen" designs wherein
the evacuation lumen was partially defined by the guiding catheter,
as described in U.S. patent application Ser. No. 10/214,712, Ser.
No. 09/940,896 and Ser. No. 09/845,162 previously incorporated
herein by reference, is that the evacuation lumen is less
obstructed. In this embodiment, the full length main lumen
typically houses only a guide wire 202 inside, and therefore
particulate doesn't catch and hang up on any of the protruding
surfaces while being evacuated through the main lumen. In the short
lumen designs, the particulate could hang up, particularly at
"crossovers" of the guide wire and the proximal shaft and be at
risk of redelivery into the circulation during subsequent contrast
injections. So even though this design uses the main lumen 106 of
the elongate tubular member 102 for the evacuation lumen, which has
a smaller full-length cross section for a given guiding catheter
compatibility (since none of the main lumen is defined by the guide
catheter lumen), it is more effective at particulate removal in the
clinical setting.
[0064] It is still desirable, however, to maximize the inner
diameter of the evacuation lumen 106 to the extent possible,
primarily for compatibility with larger stent delivery systems
being advanced through the evacuation lumen. For a particular guide
catheter compatibility, for example 6 French, 7 French or 8 French,
that means making the outer diameter of the elongate tubular member
102 close to the guide catheter inner diameter, adding lubricious
coating to the outer surface of the elongate tubular member 102,
and making the walls of the elongate tubular member 102 as thin as
possible. To help facilitate making the wall thin, a gas instead of
liquid is used to inflate the expandable member. Gas has a much
lower viscosity than a liquid and therefore enables use of a
smaller inflation lumen 110 in the elongate tubular member 102. As
shown in FIG. 1B and 2, a special gas inflation system 120 may be
connected to the inflation lumen 110 via a tubular member 122 to
quickly and safely accomplish delivery of a gas to the expandable
member. Here, the tubular member 122 of the gas inflator 120 has an
inner diameter corresponding to the diameter of the inflation lumen
110 for fluid communication therebetween.
[0065] In one embodiment, shown in FIG. 6, the gas inflation system
120 comprises a high pressure gas cartridge 600, a shuttle
mechanism 610, a first pressure relief mechanism 620 and a second
pressure relief mechanism 630. As depicted in FIG. 5, the gas
inflation system may be enclosed within a housing 650 and may
further include an inflation button 652 and a vacuum button 654 and
a pressure indicator window 655. The inflation button 652 and
vacuum button 654 are operably connected to the shuttle mechanism
610 for controlling movement of the shuttle mechanism 610 and
thereby controlling the flow of gas within the gas inflation
system, inflation lumen and expandable member. In addition, as
depicted in FIG. 5, an alternative embodiment of the gas inflation
system may further include an in-line filter 502 connected in-line
with a tube 122 leading from the gas inflation system 600 to the
inflation lumen of the expandable member. This serves to guard
against passage of contaminants such as spores, which may be
present in the gas cylinder, to the expandable member. This filter
is preferably a 0.20 micron mesh.
[0066] FIG. 6B shows the high pressure gas cartridge puncture
mechanism and the shuttle mechanism in more detail. The puncture
mechanism includes a lever 604 and a puncturing spear 602, which
are shown in the pre-puncture condition. The high pressure gas
cartridge is connected to the puncturing spear 602 and an inlet
port 606 in fluid communication with the shuttle mechanism 610.
Actuation of the lever 604 pushes the puncturing spear 602 into the
seal 601 of the gas cartridge 600. The spear includes a sharpened
conical tip, and a stem. The maximum diameter of the conical tip is
larger than the diameter of the stem. This allows free passage of
the gas past the sharpened tip once the tip has punctured and
passed through the seal of the cartridge, allowing the high
pressure gas to flow into the shuttle mechanism 610 via an inlet
port 606 in fluid communication with the shuttle mechanism 610. The
high pressure gas cartridge may contain CO.sub.2 gas,
alternatively, other gases such as nitrous oxide could be used. The
contents of the gas cartridge are typically maintained at a high
pressure, for example a CO.sub.2 cartridge may be maintained at 900
psi. At this pressure, much of the contents of the cartridge are
actually liquid CO.sub.2. An advantage of liquid CO.sub.2 is that
the CO.sub.2 is further compressed so that a larger volume of
CO.sub.2 may be stored in a smaller space. Thus, the o-ring 605 is
desirable in the puncture mechanism to prevent the high pressure
gas contents from leaking.
[0067] The shuttle mechanism 610 of the present embodiment, as
depicted in FIG. 6B, comprises a cylindrical shuttle chamber 612,
within which are the shuttle and a series of seals 614. The shuttle
chamber 612 is essentially the annular space between the shuttle
611 and the walls defining the shuttle chamber. The chamber of the
shuttle mechanism 612 further includes a series of seals 614 spaced
apart to divide the chamber into at least two primary chambers, a
pressure chamber 615 and a vacuum chamber 613. The pressure chamber
615 and vacuum chamber 613 are not in fluid communication and are
isolated from one another and from the outside by the seals 614a-f.
According to one aspect of the invention, the pressure chamber may
be defined by two spaced apart seals, for example o-ring seals.
Alternatively, as depicted in FIG. 6B, the pressure chamber may
further comprise one or more additional adjacent seals providing a
safe guard against leakage of the high pressure gas. The seals
614a-f may be o-ring seals. Alternatively, the seals may be any
suitable seal for isolating fluid communication between two defined
chambers. The seal 614f, defining the boundary of the vacuum
chamber 613, may alternatively be a one way bypass seal in order to
provide a means for removing the air from the chamber to create a
vacuum. In addition, three ports preferably access the shuttle
chamber, a cartridge inlet port 606 which allows the high pressure
gas from the cylinder to enter the shuttle chamber, a high
resistance outlet 616 which conveys the gas from the pressure
chamber to the pressure relief mechanisms 620 and 630, the
inflation lumen and the expandable member, and a vacuum port 617
through which gas is drawn out of the inflation lumen and
expandable member into the vacuum chamber 613 when a vacuum is
created therein.
[0068] In use, the shuttle mechanism 610 is transported
longitudinally to alternately place the pressure chamber 615 in
fluid communication with the cartridge inlet port and then the high
resistance outlet 616, as well as the vacuum chamber 613 in fluid
communication with the vacuum port 617. As shown in FIGS. 6A, an
embodiment of a shuttle transport mechanism may include an
inflation button 652 and deflation button 654 operably connected to
the shuttle mechanism 610 via cooperating connective elements
located on the shuttle mechanism and the inflation and deflation
buttons which are slidably coupled. For example, pins (shown on
FIG. 7) extending horizontally from holes 656 and 657 on the ends
of the shuttle mechanism 610 may be slidably housed within
corresponding biased grooves 658 and 659 in the inflation 652 and
vacuum 654 buttons. As depicted in FIG. 7, when button 654 is
actuated, it moves vertically.
[0069] As the button 654 moves, the biased groove 658 formed in the
side walls of the button will also move vertically, resulting in
the translation of horizontal location of the groove in any given
plane. Thus, the attached pins 660a and 660b of the shuttle
mechanism will be shifted longitudinally, corresponding to vertical
movement of the button 654, as it rides in the biased groove 659.
As the shuttle mechanism is translated longitudinally, the pressure
chamber 615 and vacuum chamber 613 are alternately placed in fluid
communication with the outlet port 616 and vacuum port 617 in order
to deliver a bolus of gas from the pressure chamber 615 via the
outlet port 616 or alternately, to draw any residual gas from the
inflation lumen and expandable member into the vacuum chamber 613
via the vacuum port 617. In addition, the vacuum button 654
depicted in FIG. 7 further includes an internal spring 662 and a
vacuum piston 664 for creating a vacuum in the vacuum chamber of
the shuttle mechanism. In use, as depicted in FIGS. 6B and 7, when
the vacuum button 654 is depressed, the vacuum piston 664 is also
displaced to force gas out of the vacuum chamber 613 via a one way
bypass seal 614. The spring 662 which was compressed during
actuation of the vacuum button 654 then expands, returning the
vacuum piston 664 to its initial location and creating a vacuum
within the vacuum chamber 613.
[0070] The outlet port 616 and vacuum port 617 are additionally in
fluid communication with at least one pressure relief valve 620.
Alternatively, a second pressure relief valve 630 may be provided.
Two relief valves provides a safety redundancy in the case of a
failure of a single relief valve, however, it is contemplated that
a single relief valve could also be utilized. Both relief valves
could be similar to the primary relief valve 630 described below,
or alternatively, as depicted in FIG. 6C and described herein, a
pressure indicator may be incorporated into one of the relief
valves, hereinafter referred to as an indicator relief valve 620.
The indicator relief valve 620 and a primary pressure relief valve
630 are both in communication with the shuttle chamber (not shown)
via outlet ports 616 and 617, as described above. The indicator
valve 620 and pressure relief valve 630 serve to regulate the gas
pressure within them by releasing excess gas volume above a desired
pressure, thereby enabling an inflation communication outlet 622
that is in fluid communication with valves 620 and 630 to deliver
gas to the expandable member at a controlled pressure. The pressure
relief mechanism thus assists the gas inflator system to
efficiently store the gas in a high pressure form then transform
the high pressure gas source into a controlled low pressure gas for
safe delivery to the expandable member.
[0071] As embodied herein, the indicator relief valve 620 includes
an indicator poppet 624, a sealing o-ring 626, a spring 628, and a
cap 629. When pressurized gas enters into the pressure relief
mechanism, it drives the indicator poppet 624 up, which compresses
the spring 628. Once the sealing o-ring rises above the bypass 627
excess gas will leak out, maintaining the gas within the pressure
relief mechanism at the desired pressure. In an embodiment as
depicted herein, the bypass may be created, for example, by an
expansion of the housing to create a gap between the o-ring seal
and the housing once the o-ring rises above the expanded section of
the housing. The movement of the indicator poppet 624 is also a
visual indicator that the pressure relief mechanism (and
subsequently the inflation lumen and inflatable member of the
catheter) is pressurized, as opposed to being at ambient pressure,
or negative vacuum pressure. The pressure at which the indicator
relief valve 620 will leak excess gas is determined by the spring
stiffness properties, as well as the dimensions of the poppet 624
and sealing o-ring 626. In addition, relatively small adjustments
may be made by adjusting the relative tightness of the cap 629,
which is screwed onto the housing.
[0072] The primary relief valve 630 includes a primary poppet 634,
o-ring 636, spring 638, and a cap 639. Unlike the indicator poppet
624, which requires the o-ring to actually rise above the bypass
before gas will leak, the primary poppet 634 preferably leaks
excess pressurized gas as soon as the poppet 634 begins to move
relative to the housing 640. The spring 638 is in a pre-compressed
condition against the primary poppet 634 and o-ring 636. When the
pressure force on the poppet exceeds the force of the compressed
spring 638, the poppet 634 will move slightly, resulting in leakage
until the pressure within the primary relief valve drops below the
desired pressure.
[0073] In use, the desired leak pressure of each relief valve can
be the same, or alternatively, the indicator relief valve 620 may
be set slightly lower than the primary relief valve 630. In this
manner, most or all of the excess pressurized gas will leak from
the primary relief valve 630. For example, in an embodiment of the
inflation system for use with the embolic protection catheter
embodiments described here, the primary relief valve may be set to
leak at about 2/3 atmosphere, and the indicator relief valve may be
set slightly higher, for example, approximately 0.5 to 1 psi
higher.
[0074] FIGS. 8A-H illustrate a schematic representation of the
shuttle mechanism and operation of the gas inflation system. Like
numbers depict the components as described in the gas inflation
system described above. As depicted herein, the shuttle mechanism
610 controls the inflation of the expandable member (not shown)
with a gas, for example CO.sub.2 or nitrous oxide or another
suitable gas, and subsequent deflation of the expandable member
when desired.
[0075] As previously described, the shuttle mechanism 610 comprises
a cylindrical shuttle chamber 612, within which are the shuttle 611
and a series of o-ring seals 614a-e. The shuttle chamber 612 is
essentially the annular space between the shuttle and the walls
defining the shuttle chamber. For ease in illustration, this "gap"
is shown rather large in these figures. The o-rings 614a-e are used
to divide the shuttle chamber into two primary chambers, the
pressure chamber 615 and the vacuum chamber 613. In addition, the
vacuum chamber is further defined by a one-way bypass seal attached
to a vacuum piston 664. Three ports access the shuttle chamber, a
cartridge inlet port 606 which allows the high pressure gas from
the cylinder (not shown) to enter, a high resistance outlet port
616 which conveys the gas from the pressure chamber 615 to the
pressure relief mechanism 620 and the expandable member (not
shown), and a vacuum port 617 through which gas is drawn out of the
expandable member into the vacuum chamber 613 when a vacuum is
created.
[0076] In FIG. 8A, the shuttle mechanism is in the initial
condition, wherein the pressure chamber 615, vacuum chamber 613 and
expandable member are all at ambient pressure. In FIG. 8B, the
pressure cartridge (not shown) has been punctured, which allows the
high pressure gas to enter and fill the pressure chamber 615 via
the cartridge inlet port 606. The pressure chamber 615B is shaded
to depict the bolus of high pressure gas filling the pressure
chamber. o-rings 614c and 614d keep the high pressure gas confined
to the pressure chamber 615. In an alternative embodiment, as
depicted herein, an additional o-ring 614b may be placed adjacent
to 614c to provide an additional safeguard against the high
pressure gas leaking from the pressure chamber. This additional
safeguard may be desired since CO.sub.2 cartridges, for example,
are typically pressurized to 900 psi, and include a portion of
liquid CO.sub.2 which keeps the pressure relatively constant as the
gas volume is consumed. Once the pressure chamber is placed within
fluid communication with the gas cartridge via inlet port 606, the
pressure chamber becomes pressurized to the same pressure as the
cylinder, typically about 900 psi. The shuttle mechanism may now be
ready to deliver the bolus of gas contained within the pressure
chamber 615 to the inflation lumen and expandable member via the
high resistance outlet port 616.
[0077] In an alternative embodiment, it may be desirable to "prep"
the inflation lumen and expandable member to remove most of the
ambient air in the expandable member and all gas passageways,
including the inflation lumen, in communication therewith. This
additional step of "prepping" the inflation lumen and expandable
member is depicted in FIGS. 8C and 8D. In FIG. 8C, the vacuum
piston 664 is advanced into the vacuum chamber 613. The one-way
bypass o-ring 619 allows the ambient pressure air to bypass or vent
out, indicated by the arrow. A return spring (not shown) draws back
the vacuum piston 664, creating a vacuum in the vacuum chamber,
shown in Figure D by the cross-hatch vacuum pattern in the pressure
chamber 613D. The vacuum chamber 613D is in fluid communication
with the inflation lumen and the expandable member via the high
resistance outlet 616 and the vacuum port 617, thus this vacuum may
draw out a significant portion of the air from the catheter balloon
and inflation lumen. A majority of the air is drawn out through the
pressure relief mechanism (not shown) and the vacuum port 617;
however, a small amount of air is also drawn through the high
resistance outlet 616, as this is in fluid communication with the
vacuum chamber at this time. After this step, the vacuum chamber
613, expandable member and all passageways therebetween will be
evacuated. In this embodiment, the dimensions of the vacuum chamber
were chosen such that a single actuation of the vacuum piston would
result in an acceptable strength vacuum. In an alternative
embodiment, the vacuum piston may be actuated multiple times to
enhance the strength of the vacuum.
[0078] To inflate the expandable member with gas, the shuttle
mechanism may be moved as shown in FIG. 8E. This translation
carries ("shuttles") the pressure chamber 615E into communication
with the high resistance outlet 616. The high pressure gas may then
pass through the high resistance outlet 616 into the pressure
relief mechanism 620 and into the expandable member. As previously
mentioned, the pressure relief mechanism guards against over
pressurization of the expandable member by venting excess gas
before it could over-inflate the expandable member. In addition,
the dimensions of the shuttle mechanism 610 may be designed such
that such that the volume of the pressure chamber 615E is
significantly smaller than the combined volume of the pressure
relief mechanism, expandable member, and all passageways
therebetween. This will minimize the volume of excess gas that must
be vented from the pressure relief mechanism, a further safety
feature for a gas inflator system. In an alternative embodiment,
the shuttle mechanism may be designed such that when the pressure
chamber delivers a volume of gas to the pressure relief mechanism,
little to no excess gas needs to be released to result in the
expandable member being pressurized to its target desired pressure,
in this case, preferably about 2/3 atmosphere gauge pressure.
[0079] The high resistance outlet 616 controls the flow rate of the
high pressure gas from the pressure chamber 615E such that the
pressure relief mechanism is not overwhelmed with an excessively
high pressure spike. After the expandable member is inflated to the
desired target pressure, the pressure chamber, pressure relief
mechanism, expandable member and inflation lumen are all at that
same relatively low pressure of approximately 2/3 atmosphere, and
filled with gas, as noted by the low pressure pattern in the FIG.
8E. During this step, the dead-spaces between some of o-rings 614b
and 614a may have also become pressurized, as indicated by the high
pressure pattern shown in FIG. 8E as a result of coming into fluid
communication with the cartridge inlet port 606. The right-most
o-ring 614a now prevents leakage of the high pressure cartridge
contents out the right side of the pressure chamber, and the double
o-rings 614b and 614c serve as a redundant barrier between the high
pressure cylinder and the expandable member at this time. If there
were only one o-ring there and it somehow failed, high pressure
CO.sub.2 could potentially over pressurize the expandable member
and cause rupture and excessive gas leakage.
[0080] To deflate the balloon and evacuate the CO.sub.2 gas, the
evacuation piston is advanced, as shown in FIG. 8F. In this step,
the piston 664 initially abuts the shuttle, resulting from the
prior translation of the shuttle to deliver the gas, as shown in
FIG. 8E. When the vacuum button (not shown) is depressed, the
translation of the piston 664 also translates the shuttle 611. The
pressurized expandable member (and inflation lumen, pressure relief
mechanism) will vent the gas once the vacuum port 617 is exposed to
the vacuum chamber 613. The gas may vent past the one-way bypass
o-ring 619 attached to the vacuum piston 664, resulting in the
vacuum chamber 613F, pressure relief mechanism and the expandable
member returning to ambient pressure. When the vacuum piston 664 is
released, a vacuum is again formed in the vacuum chamber 613G, and
the remaining ambient air in the expandable member and inflation
lumen may be drawn out via the vacuum port 617, as depicted in FIG.
8G. The action of translating the shuttle 611 also brings the
pressure chamber 615F/615G back to the position where it is in
fluid communication with the gas cartridge input port 606 and
thereby gets refilled with a bolus of high pressure gas by the
high- pressure gas cylinder.
[0081] To re-inflate the expandable member, the shuttle 611 is
translated again to the left, as shown in FIG. 8H. As in FIG. 8E,
the high pressure bolus in the pressure chamber 615H is brought
into communication with the pressure relief mechanism and the
inflation lumen leading to the expandable member via the high
resistance outlet 616. The expansion of the bolus of gas into a
larger volume and the venting of gas by the one or more pressure
relief valves results in a relatively low pressure inflation of the
expandable member, for example in this embodiment of about 2/3
atmosphere. In addition, repeated deflations and inflations may be
performed by repeating the steps depicted in FIGS. 8F, 8G, and
8H.
[0082] Relative to inflation of the expandable member in the
vasculature of the patient, it is preferable to carry out the
"prepping" steps depicted in FIGS. 8A-8D prior to introduction of
the catheter into the patient.
[0083] This places the balloon in a vacuum condition, which helps
minimize profile of the deflated balloon. However, in an
alternative method of use, it is also possible to carry out the
initial inflation and deflation of the expandable member, steps
corresponding to FIGS. 8E, 8F, and 8G, as well, prior to
introduction of the catheter into the patient. The reason is that
the inflation depicted in FIG. 8E is the first inflation of the
balloon. Here, there will be a small residual amount of air in the
balloon at this step, and if the balloon contents leak out, some
air also leaks out, which is undesirable. The amount of residual
air at this step is dependent on the relative volumes of the vacuum
chamber and the catheter balloon and the passageways leading
thereto, and may be clinically insignificant. However, after an
additional vacuum and pressurization step, the residual air in the
expandable member as of the inflation step of Fig. H will be
significantly less, as the expandable member has already been
"primed" with CO.sub.2 gas from the first inflation shown in Figure
E.
[0084] Having thus described a preferred embodiment of a device and
methods for embolic protection during vascular intervention , it
should be apparent to those skilled in the art that certain
advantages of the within system have been achieved. It should also
be appreciated that various modifications, adaptations and
alternative embodiments thereof may be made within the scope and
spirit of the present invention. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being defined by the
following claims.
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