U.S. patent application number 12/026067 was filed with the patent office on 2008-12-18 for vascular sealing device and method using clot enhancing balloon and electric field generation.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to William J. Drasler, Tracee Eidenschink, Mark L. Jenson, Anu Sadasiva, Joseph M. Thielen.
Application Number | 20080312645 12/026067 |
Document ID | / |
Family ID | 39427660 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080312645 |
Kind Code |
A1 |
Drasler; William J. ; et
al. |
December 18, 2008 |
Vascular Sealing Device and Method Using Clot Enhancing Balloon and
Electric Field Generation
Abstract
An apparatus and method for closing an opening in a blood vessel
wall is disclosed. The apparatus includes at least one member which
is extended through a tissue tract formed through the epidermis and
subcutaneous layer of skin and through the opening in the blood
vessel. The member includes a proximal end and a distal end with
the distal end being positionable proximate to the opening in the
blood vessel wall. A positive electrode is positioned next to the
distal end with a negative electrode being positioned next to the
proximal end When the electrodes are energized an electric field is
created therebetween, blood cells are attracted to the positive
electrode, and a thrombus is formed at the opening in the blood
vessel wall. The member may include a balloon at the distal end to
temporarily occlude blood flow from the blood vessel to the tissue
tract to facilitate formation of the thrombus. In addition, the
shape of the balloon may be tailored to facilitate the formation of
the thrombus including, but not limited to, the creation of pockets
and self-supporting balloons
Inventors: |
Drasler; William J.;
(Minnetonka, MN) ; Eidenschink; Tracee; (Wayzata,
MN) ; Thielen; Joseph M.; (Buffalo, MN) ;
Jenson; Mark L.; (Greenfield, MN) ; Sadasiva;
Anu; (Maple Grove, MN) |
Correspondence
Address: |
MILLER, MATTHIAS & HULL
ONE NORTH FRANKLIN STREET, SUITE 2350
CHICAGO
IL
60606
US
|
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
39427660 |
Appl. No.: |
12/026067 |
Filed: |
February 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60888202 |
Feb 5, 2007 |
|
|
|
Current U.S.
Class: |
606/28 ; 606/194;
606/50 |
Current CPC
Class: |
A61B 2017/00654
20130101; A61N 1/18 20130101; A61B 17/0057 20130101; A61N 1/32
20130101; A61B 18/14 20130101 |
Class at
Publication: |
606/28 ; 606/194;
606/50 |
International
Class: |
A61B 18/14 20060101
A61B018/14; A61M 29/02 20060101 A61M029/02 |
Claims
1. An apparatus fbi closing an opening in a blood vessel,
comprising: a balloon catheter having a proximal end positionable
at an epidermis of the patient, and a distal end positionable at a
blood vessel wall of the patient; a first electrode positioned on
tissue of the patient distant from the opening in the blood vessel;
and a second electrode at the distal end the balloon catheter
2. The apparatus of claim 1, further including a sheath extending
from the epidermis of the patient to the blood vessel wall, the
sheath having a proximal end positionable at the epidermis of the
patient, and a distal end at the blood vessel wall of the
patient
3. The apparatus of claim 1, wherein the first electrode is
negatively charged and the second electrode is positively
charged.
4. The apparatus of claim 1, wherein the balloon catheter includes
a balloon at the distal end, the balloon being toroidal in
cross-section shape
5. The apparatus of claim 4, wherein the balloon forms a pocket
against an interior surface of the blood vessel wall, the pocket
facilitating formation of a thrombus.
6. The apparatus of claim 1, further including a second set of
positive and negative electrodes.
7. The apparatus of claim 3, further including a second positive
electrode, the second positive electrode being positioned on one of
the balloon catheter and the sheath at a distance closer to the
negative electrode than the first positive electrode
8. The apparatus at claim 1, wherein the balloon catheter includes
a balloon at the distal end, the balloon being substantially
T-shaped in cross-section
9. The apparatus of claim 1, wherein the balloon catheter includes
a balloon at the distal end, the balloon being substantially
teardrop-shaped
10. The apparatus of claim 1, wherein the balloon catheter includes
a balloon adapted to extend between diametrically opposed interior
surfaces of the blood vessel while still allowing perfusion through
the blood vessel
11. The apparatus of claim 1, wherein the first and second
electrodes are formed by one of coiled wire, metal bands, foil,
conductive ink, and gold micro-extrusion
12. The apparatus of claim 1, wherein the balloon is a tolling
membrane balloon.
13. The apparatus of claim 1, further including a heat-source at
the distal end of one of the sheath and balloon catheter
14. An apparatus for closing an opening in a blood vessel,
comprising: a member for extending between an epidermis of a
patient and a blood vessel wall of the patient, the member
including a proximal end positionable at the epidermis, and a
distal end positionable at the blood vessel wall; a first electrode
at the member proximal end; and a second electrode at the member
distal end.
15. The apparatus of claim 10, wherein the first electrode is
negatively charged and the second electrode is positively
charged.
16. The apparatus of claim 10, further including a backstop at the
member distal end.
17. The apparatus of claim 16, wherein the backstop is a
balloon.
18. The apparatus of claim 16, wherein the backstop is a membrane
covered wall
19. The apparatus of claim 17, wherein the balloon is a lolling
membrane balloon.
20. The apparatus of claim 17, wherein the balloon is substantially
toroidal in cross-sectional shape.
21. The apparatus of claim 17, wherein the balloon is substantially
T-shaped in cross-section.
22. A method of closing an opening in a blood vessel, comprising:
inserting a sheath into a tissue tract within a patient extending
between an epidermis and a blood vessel wall; extending a balloon
catheter into the sheath, the balloon catheter having a shaft
terminating in a balloon, the balloon catheter being inserted until
the balloon is fully within the blood vessel, one of the sheath or
balloon catheter having a positive electrode thereon, one of the
sheath and balloon catheter having a negative electrode thereon;
inflating the balloon; retracting the balloon catheter until the
inflated balloon engages an interior surface of the blood vessel
wall; and creating an electric field between the negative and
positive electrodes, blood cells thereby being attracted to the
positive electrode and forming a thrombus at the blood vessel
wall
23. The method of claim 22, wherein inflating and retracting the
balloon causes a pocket to form between the balloon and the blood
vessel wall.
24. The method of claim 22, wherein inflating the balloon causes
the balloon to engage the blood vessel wall at at least two
diametrically opposed points
25. The method of claim 22, wherein the balloon is self-supporting
when inflated.
26. A method of closing an opening in blood vessel, comprising:
inserting a member between an epidermis of a patient and the
opening of the blood vessel wall of the patient, the member having
a positive electrode and negative electrode thereon; and creating
an electric field between the negative and positive electrodes,
blood cells being attracted to the positive electrode and forming a
thrombus at the blood vessel wall.
27. The method of claim 26, wherein the member is a balloon
catheter.
28. The method of claim 26, wherein the member is a rolling
membrane balloon
29. The method of claim 28, wherein the rolling member is inserted
by directing a pressurized fluid into the rolling balloon
30. The method of claim 28, wherein the rolling membrane balloon is
inserted and retracted using a mechanical extension and withdrawal
rod.
31. The method of claim 26, wherein the member is a working
sheath.
32. The method of claim 31, further including extending a balloon
catheter through the working sheath until a balloon extending from
a shaft of the balloon catheter is fully within the blood vessel,
inflating the balloon, and retracting the balloon until it engages
an interior surface of the blood vessel wall, before the electric
field is created.
33. The method of claim 32, further including forming a pocket
between the balloon and the blood vessel wall to facilitate
formation of the thrombus.
34. The method of claim 32, further includes inflating the balloon
such that it engages at least two diametrically opposed points on
the interior surface of the blood vessel wall.
35. The method of claim 26, further including heating the distal
end of the member.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a non-provisional patent application
claiming priority under 35 USC .sctn. 119(e) to U.S. provisional
patent application Ser. No. 60/888,202 filed on Feb. 5, 2007.
FIELD OF THE DISCLOSURE
[0002] The present disclosure generally relates to medical devices
and, more particularly, relates to apparatus and methods for
closing openings in blood vessels.
BACKGROUND OF THE DISCLOSURE
[0003] In many medical procedures, such as balloon angioplasty and
the like, it is known how to create an opening in a blood vessel,
known as an arteriotomy, to allow for the insertion of various
medical devices which can be navigated through the blood vessel to
the site to be treated. Typically, the opening is formed in the
femoral artery at a point proximate the groin and a series of
medical devices are inserted in sequence. For example, a guide wire
may first be inserted through the tissue tract created between the
skin or the epidermis of the patient down through the subcutaneous
tissue and into the opening formed in the blood vessel The guide
wire is then navigated through the blood vessel to the site of the
occlusion, the heart, or any other area to be treated. Once the
guide wire is in place, a working sheath can be slid over the guide
wire to form a wider, more easily accessible, tract between the
epidermis and the opening into the blood vessel If an angioplasty
needs to be per formed, the balloon catheter can then be introduced
over the guide wire again through the working sheath, through the
opening in the femoral artery, and then up to the blood vessel to
the site of the occlusion.
[0004] Once the procedure is performed, the guide wire, balloon
catheter and any other equipment introduced can be retracted
through the blood vessel, out through the opening in the blood
vessel wall, out through the working sheath, and out of the body
entirely. The working sheath can then be removed whereby the
physician or other medical technician is presented with the
challenge of trying to close the opening both in the femoral artery
and the tissue tract formed in the epidermis and subcutaneous
tissue Most importantly, the opening in the blood vessel must be
closed as soon as possible.
[0005] Over the years that these procedures have been performed, a
number of apparatus and methods have been created fbi closing the
opening in the blood vessel. Traditionally, and still commonly
today, the opening is closed simply by the application of manual
pressure If sufficient pressure is applied, the blood vessel is
constricted until a clot or thrombus forms whereupon the pressure
can be removed and eventually the patient can become ambulatory
once again However, a number of drawbacks are associated with such
a method For one, the process is very time consuming often taking
many hours fbi the thrombus to fully form, during which time the
patient is required to be stationary. In addition, the mere
application of such significant pressure to the groin is often
quite uncomfortable for the patient.
[0006] In light of these difficulties, a number of proposals have
been introduced to potentially alleviate such drawbacks. In one
approach, an anchor is inserted through the tissue tract and the
blood vessel with a filament extending therefrom and connected to a
sealing plug by a pulley arrangement. Once the anchor engages an
interior surface of the blood vessel the filament can be used to
pull the sealing plug securely into the tissue tract. While this
approach does more quickly close the opening in the blood vessel
than manual pressure application, it also results in the
unfavorable characteristic of leaving a foreign body in the patient
after the procedure is completed.
[0007] Another approach uses a resistive heating coil inserted into
the opening in the blood vessel. Upon energization of the heating
coil, the blood in the vicinity of the opening is caused to
coagulate given the rise in temperature. This can be accomplished
in combination with the introduction of a procoagulant into the
site to again expedite the creation of the coagulation While this
approach has also met with some level of success, it also results
in the introduction of a foreign body and/or substance into the
tissue of the patient.
[0008] A still further approach involves the introduction of a
collagen plug into the site of the opening. Such a plug is sized to
be frictionally engaged by the sides of the opening in the blood
vessel and thus held in place until coagulation of blood forms
around the collagen plug. The collagen plug is biodegradable and
eventually is dispersed into the blood flow and eliminated from the
body. However, just the introduction of such a foreign substance
into the body can sometimes be, at the very least, inflammatory and
uncomfortable for the patient
[0009] In one collagen plug approach, a balloon catheter is
inserted into the blood vessel, inflated, and then pulled back
against an interior surface of the blood vessel wall to serve as a
backstop. The collagen plug in such an approach is shaped and sized
as to closely match the opening in the blood vessel wall and is
pushed down into the tissue tract until it engages the inflated
balloon. The inflated balloon can then be deflated and withdrawn
leaving the collagen plug in place.
[0010] In another collagen plug approach, a delivery sheath wider
than the opening in the blood vessel wall is used and then a
collagen plug corresponding to the size of the inner diameter of
the delivery sheath is pushed through the sheath so as to engage
the outer surface of the blood vessel wall The plug can then be
tamped or compressed down against the exterior surface of the blood
vessel wall such that a portion of the collagen extends into the
opening of the blood vessel wall
[0011] While each of the foregoing approaches have been met with
some level of success, it can be seen that each also has
substantial drawbacks. Accordingly, it would be advantageous for
the art to provide an apparatus and method which can quickly close
the opening in the blood vessel wall, minimizes any decrease in
blood flow through the blood vessel during the closure procedure,
forms a thrombus which reliably remains in place after formation,
minimizes patient discomfort, introduces no foreign body or
substance into the blood vessel and leaves no foreign bodies behind
after the procedure is completed.
SUMMARY OF THE DISCLOSURE
[0012] According to one aspect of the disclosure, an apparatus is
disclosed for closing an opening in a blood vessel. The apparatus
may include a sheath extending from the epidermis of a patient to a
blood vessel, the sheath having a proximal end positionable at the
epidermis of the patient and a distal end positionable at the blood
vessel wall of the patient. The apparatus further includes a
balloon catheter inserted through the sheath with the balloon
catheter having a proximal end positionable at the epidermis of the
patient and a distal end positionable within the blood vessel of
the patient. The apparatus further includes first and second
electrodes with the first electrode being at the proximal end of
the sheath and balloon catheter, and the second electrode being at
the distal end of the balloon catheter.
[0013] In accordance with another aspect of the disclosure, an
apparatus for closing an opening in a blood vessel is disclosed
which comprises a member for extending between an epidermis of a
patient and a blood vessel wall of a patient, a first electrode,
and a second electrode. The member includes a proximal end
positionable at the epidermis and distal end positionable at the
blood vessel wall with the first electrode being at the member
proximal end and the second electrode being at the member distal
end.
[0014] In accordance with another aspect of the disclosure, a
method of closing an opening in a blood vessel is disclosed
comprising inserting a sheath into a tissue tract of a patient
extending between an epidermis and a blood vessel wall, extending a
balloon catheter into the sheath, the balloon catheter having a
shaft extending into a balloon, the balloon catheter being inserted
until the balloon is entirely within the blood vessel, at least one
of the sheath and balloon catheter having a positive electrode
thereon, at least one of the sheath and balloon catheter having a
negative electrode thereon, inflating the balloon, retracting the
balloon until the inflated balloon engages an interior surface of
the blood vessel wall, and creating an electric field between the
negative and positive electrodes, cells thereby being attracted to
the positive electrode and forming a thrombus at the blood vessel
wall.
[0015] In accordance with another aspect of the disclosure, a
method of closing an opening in a blood vessel is disclosed which
comprises inserting a member between the epidermis of the patient
and the opening of the blood vessel wall of the patient, the member
having a positive electrode and negative electrode thereon, and
creating a electric field between the negative and positive
electrodes, cells thereby being attracted to the positive electrode
and forming a thrombus at the blood vessel wall. The member
includes proximal and distal ends with the distal end being
positionable at the blood vessel wall, and the positive electrode
being provided at the member distal end
[0016] These and other aspects and features of the disclosure will
become mole apparent upon reading the following detailed
description when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a cross-sectional view of a blood vessel,
subcutaneous layer, and epidermis layer with a tissue tract formed
between the epidermis, through the subcutaneous layer, and to the
blood vessel wall;
[0018] FIG. 2 is a sectional view similar to FIG. 1, but with a
working sheath/sleeve extended through the tissue tract;
[0019] FIG. 3 is a view similar to FIG. 2, but with an uninflated
balloon catheter being extended through the introducer sheath;
[0020] FIG. 4 is a view similar to FIG. 3, but with the balloon
catheter inflated;
[0021] FIG. 5 is a view similar to FIG. 4, but with the balloon
catheter inflated and retracted to be against the inner surface of
the blood vessel wall;
[0022] FIG. 6 is a view similar to FIG. 5, but with electrodes
creating an electric field and thereby drawing cells to the
positive electrode;
[0023] FIG. 7 is a view similar to FIG. 6, after a thrombus has
formed and prior to the balloon catheter and working sheath being
retracted;
[0024] FIG. 8 is a view similar to FIG. 7, but with the thrombus
fully formed after the balloon catheter and working sheath are
withdrawn;
[0025] FIG. 9 is a sectional view of an alternative embodiment
depicting a toroidal-shaped balloon;
[0026] FIG. 10 is a sectional view similar to the previous views
but depicting a self supporting balloon;
[0027] FIG. 11 is a sectional view of FIG. 10, taken along line
11-11 of FIG. 10, showing the self-supporting balloon extending
across the blood vessel at two diametrically opposed points;
[0028] FIG. 12a is a sectional view of an alternative embodiment
using a rolling membrane balloon and depicted in an un-deployed
configuration;
[0029] FIG. 12b is a sectional view of the alternative embodiment
of FIG. 12a but depicted in a partially deployed configuration;
[0030] FIG. 12c is a sectional view of the alternative embodiment
of FIG. 12a but depicted in a deployed configuration;
[0031] FIG. 13 is a sectional view of another alternative
embodiment showing a removal sheath;
[0032] FIG. 14 is a sectional view of another alternative
embodiment showing an everting balloon; and
[0033] FIG. 15 is a sectional view showing another alternative
embodiment including a sealing plug.
[0034] While the present disclosure is susceptible to various
modifications and alternatives constructions, certain illustrative
embodiments have been shown in the drawings and will be described
below in detail. It should be understood, however, that there is no
intention to limit the present invention to the specific forms
disclosed, but on the contrary, the intention is to cover all
modifications, alternative constructions, and equivalents falling
within the spirit and scope of the present invention.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0035] Referring now to the drawings and with specific reference to
FIG. 1, a blood vessel 20 is depicted with an opening 22 therein
after the completion of a medical procedure such as, but not
limited to, a balloon angioplasty. As stated above with respect to
the background, in such a procedure, an opening or arteriotomy 22
is provided in a wall 23 of the blood vessel 20 to allow access
into and passage through the blood vessel of the various medical
devices needed for the medical procedure. After such medical
devices are used and removed from the opening and through a tissue
tract 24 extending between a blood vessel 20 and a subcutaneous
layer 26, and an epidermis layer 28, the opening 22 and tract 24
need to be closed. The pending disclosure is primarily directed to
an apparatus and method for closing the opening 22 in the blood
vessel wall 23.
[0036] Referring now to FIG. 2, a first step according to the
present disclosure is to insert a working sheath 30 into the tissue
tract 24 substantially to the opening 22 in the blood vessel wall
23. The working sheath 30 may include a main cylindrical body 32. A
circumferential flange 34 can be movably located around the sheath
30 to provide a flange electrode located on the skin. Other
electrode designs can also be used to allow for current flow. The
working sheath 30 may be provided in any number of different forms
and may or may not include the flange 34 or could be provided with
other indicia on the main body 32 informing the physician or other
medical technician the distance the working sheath should be
introduced into the tract 24. In addition, the working sheath 30
may be slid along a guide wire (not shown) and extended through the
tract 24 and into the blood vessel 20. However, for the purpose of
illustration, and ease of understanding, the guide wire is not
depicted.
[0037] Referring now to FIG. 3, a next step is depicted where a
balloon catheter 36 is extended into the working sheath 30. The
balloon catheter includes a shaft 38 from which a balloon 40
extends The balloon catheter 36 is extended through the working
sheath 30 in an uninflated state. The balloon catheter 36 is
extended to a distance necessary to allow the balloon 40 to be
fully received within the blood vessel 20. Alternatively, the
apparatus could work in conjunction with a conventional introducer
sheath wherein the balloon catheter is slid through an introducer
sheath and the working sheath is then slid through the introducer
sheath In such an embodiment, the negative electrode mentioned
later herein could be located in the working sheath.
[0038] Referring now to FIG. 4, it is seen that the balloon 40 is
then inflated, i.e., by the introduction of air or fluid into the
balloon shaft and ultimately the interior of the balloon 40. The
balloon 40 is of such a size that even when inflated, blood flow
through the blood vessel 20 is not fully occluded, but does allow
for a certain degree of perfusion therethrough. After the balloon
40 is fully inflated, the balloon catheter 36 is retracted away
from the center of the blood vessel 20 such that an upper surface
41 of a balloon 40 engages an inner surface 42 of the blood vessel
wall 23 In so doing, it will be readily understood by one of
ordinary skill in the art that the opening 22 is substantially
sealed preventing any significant level of blood flow between the
blood vessel 20 and the tissue tract 24.
[0039] Once the physician reaches the position depicted in FIG. 5,
as determined based on the degree of resistance felt when
retracting the balloon 40 and lack of blood flow out of the tissue
t act 24, the physician or other medical technician can energize
first electrode 44 and second electrode 46. In so doing, an
electric field 48 is created between the first and second
electrodes 44 and 46 as shown in FIG. 6. In addition to the layout
of FIG. 6, additional electrode configurations are available within
the scope of this disclosure to create multiple fields and further
aid in thrombus formation By positioning the electrodes
appropriately, the blood cells within the tissue tract 24 are
attracted to a position where it is desired to have a thrombus 50
formed More specifically, the platelets of the blood are attracted
to the positive electrode, even in blood which has been treated
with a blood thinner or other anti-coagulant, such as heparin Since
such blood cells are attracted to a positive electrode, by
positioning the positive electrode appropriately, a thrombus can be
formed in a desired location Thus in the depicted embodiments, the
first electrode 44 is negatively charged and the second electrode
46 is positively charged, with the second electrode being provided
at a position proximate the blood vessel wall 23 The thrombus 50 is
therefore formed as shown in FIGS. 6, 7, and 8 at the juncture
between the blood vessel wall 23 and the tissue tract 24
Alternatively, the positively charged electrode can be located
along the shaft of the balloon catheter, at the distal end of the
shaft, or on a portion of the balloon. By the same token, the
negative electrode can be located on the skin of the patient.
[0040] After the thrombus 50 fully forms in the tract 24 around the
shaft 38, the balloon 40 can be deflated and fully withdrawn
through a center opening 52 within the thrombus 50 as shown in FIG.
7. The working sheath 30 can be removed at the same time as well. A
minimal amount of manual pressure or bandaging 53 can then be
provided over the tract 24 to minimize blood loss until the opening
52 within the thrombus 50 fully closes as shown in FIG. 8. Using
such a method, it has been determined that the closure of the
opening 22 can be accomplished in less then five minutes at
relatively low voltages and amperages, thus minimizing the
discomfort to the patient as well. In addition, in order to lessen
the likelihood of the thrombus being dislodged when the balloon 40
is retracted, a tank tread or rolling membrane balloon may be
employed as depicted in FIGS. 12a-12c and described in further
detail herein.
[0041] Referring again to FIGS. 5 and 6, it can be seen that more
than one set of positive and negative electrodes are depicted. A
first set of electrodes 44, 46 may be provided at proximal and
distal ends of the balloon catheter 36, with a second set of
electrodes 44a and 46a being provided on proximal and distal ends
of the working sheath 30. Other combinations of one electrode on
one element, and one electrode on another element ate possible as
well. In addition, as the positive electrode is of importance in
dictating the location of the resulting thrombus, if more than one
thrombus is desired it is possible to position one positive
electrode at a distal end of the balloon catheter or working sheath
30, and a second positive electrode at a position on the balloon
catheter or working sheath closet to the negative electrode than
the first positive electrode. Accordingly, a second thrombus (not
shown) can be formed at an intermediate position within the middle
of the tissue tract 24 for example as a secondary means of closure
if it is desired In such an embodiment, it would be possible to
only provide a single negative electrode with that one single
negative electrode creating electric fields between it and both
positive electrodes.
[0042] Referring now to FIGS. 9-11, alternative embodiments of the
balloon are depicted. In order to facilitate the formation of the
thrombus 50, the inventors have found that it is beneficial to
create a pocket 54 between the upper surface 56 of a balloon 58 and
the inner surface 42 of the blood vessel wall 20. The pocket 54
forms a natural recess into which the thrombus 50 can be formed
when the electrodes are energized. In order to form the pocket 54
one version of the balloon 58 is provided in a toroidal shape in
cross section.
[0043] In addition to the pocket 54, it may be beneficial to
provide "self-supporting" balloon such as that depicted in FIGS. 10
and 11 As shown therein, the balloon 60 has a substantially
T-shaped configuration in cross-section having an upper expanse 62
from which a leg 64 extends. The balloon 60, including its expanse
62 and leg 64 has a dimension so as to extend across the entire
diameter of the blood vessel 20 and contact the inner surface 42 of
the blood vessel 20 in at least two diametrically opposed locations
denoted as points 66 and 68 in FIGS. 10 and 11. As also depicted in
FIG. 11, it can also be seen that the T-shaped configuration of the
balloon 60 does not substantially occlude the flow of blood through
the blood vessel 20, but rather provides ample space 70 for such
blood flow even when balloon 60 is inflated Such a
"self-supporting" balloon provides significant strength as a
backstop in that it engages the rear of the blood vessel, as well
as the wall of the blood vessel proximate the opening
Alternatively, the self-supporting balloon can be teardrop-shaped
among other shapes.
[0044] Referring now to the aforementioned FIGS. 12a-12c, a rolling
membrane balloon 80 is depicted. The previously mentioned balloons
can be thought of as "pre-formed" balloons having a balloon located
at a distal end of a straight shaft. The balloon is inserted in a
deflated condition, inflated, used as a backstop and locator while
the thrombus is formed, deflated, and then retracted from the
tissue tract. While effective, if it is desired to reduce the
pulling force applied to the thrombus as the balloon catheter is
retracted, and thus lessen the likelihood of the thrombus being
dislodged thereby, the rolling membrane balloon can be used. With
such a rolling membrane, the balloon 80 can be extended from a
shortened, rolled-up configuration depicted in FIG. 12c to the
configuration of FIG. 12b and ultimately to the configuration of
FIG. 12a This extension and retraction can be achieved through the
use of pressurized fluid and/or a mechanical rod. As shown in the
figures, the balloon 80 may be connected to a manifold 82 and in
turn to a pressurized fluid source 84 When the source 84 is in
communication with the balloon 80, the balloon is caused to
"roll-out" much like a tank tread from the position shown in FIG.
12c to that depicted in FIG. 12a. In turn when the balloon 80 is to
return to the position shown in FIG. 12c, the balloon "rolls-up"
thereby peeling away from the surface of the thrombus gradually, as
opposed to simultaneously. This reduction in force may allow the
thrombus to more likely remain in position. As shown, a push/pull
or withdrawal rod 86 may be used to manually extend (roll-out) and
retract (roll-up) the balloon 80 as opposed to relying solely on
fluid pressure
[0045] Two other approaches which can be used to facilitate removal
of the balloon are depicted in FIGS. 13 and 14. In FIG. 13, a
sheath 100 is placed in close proximity to the shaft 38 of the
balloon so as to aid removing the balloon without disrupting the
thrombus 50. In FIG. 14, an everting balloon 140 is shown The
balloon 140 is similar to balloon 40 but for having a fiber or
filament 142 extending through the shaft 138 and being connected to
a bottom wall 144 of the balloon 140. Accordingly, when the
filament 142 is pulled out of the patient in the direction of arrow
146, the balloon everts on itself, pulling away from within and
peeling its outer surface 148 gradually away from the thrombus
[0046] In any of the foregoing embodiments, the thrombus may be
even more effectively formed by using a heat source in combination
with the electrodes In such embodiments a resistive coil 88 or the
like can be positioned at the distal end of one of the components
of the apparatus, with coil 88 being shown as attached to the rod
86 in FIGS. 12a-12c as an example. The resulting rise in
temperature of the blood and surrounding tissue facilitates
coagulation as well Thrombus formation may also be aided by adding
a biodegradable plug 200, such as collagen or fibrin, as shown in
FIG. 15. The plug 200 could be positioned at a junction 202 of the
subcutaneous tissue 26 and the blood vessel wall 42 In so doing, a
surface for the thrombus 50 to attach to is provided The volume of
material forming the plug 200 will reduce the time needed to create
the thrombus mass adequate to ensure hemostasis and prevent
hematoma.
[0047] With respect to the parameters of the electrical field
generated by the electrodes, the inventors have found that the clot
formation rate is dependent on a number of parameters including the
type, intensity, duration, and other stimulation parameters of the
electrode design. In addition, based on other requirements such as
the time allotted for the thrombus to form, the size of the clot to
form, the size of the wound to close, the contact impedance, etc,
the electrical stimulation signal can be modified or chosen. For
example, the electric field may be an alternating current, direct
current, pulsed alternating current or pulsed direct current The
intensity of the field can be adjusted based on amplitude, net
energy, charged delivery, frequency, duty cycle, or other
parameters. One particularly effective approach the inventors found
was to use a DC positive signal continuously delivered to the
thrombus site. The rate of clot formation increased with increased
amplitude of the signal.
[0048] Based on the foregoing, it can be seen that the present
disclosure provides an apparatus and method for effectively closing
an opening in a blood vessel through the creation of an electric
field in the area of the opening By appropriately positioning the
positive electrode forming a portion of the electric field, blood
cells are attracted to the positive electrode and a thrombus is
quickly formed thereabout.
* * * * *