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Claims  |
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I claim:
1. A catheter comprising:
a guidewire extending from a proximal end to a distal end;
an inflatable dilitation balloon having a wall defining the interior of the
balloon and with at least a portion of said balloon wrapped around a
portion of the guidewire proximate the distal end of the guidewire without
any portion of said guidewire being in said interior of said balloon; and
means for inflating the balloon.
2. A catheter as in claim 1 further comprising means for securing the
balloon wrapped around the guidewire to enable insertion into a vessel.
3. A catheter as in claim 2 wherein the balloon comprises an inflatable
elongate member having a generally tapered shape attached along at least a
portion of its exterior length to the guidewire.
4. A catheter as in claim 2 wherein the means for securing comprises means
for securing a first region of the balloon to a second region of the
balloon to thereby maintain the balloon wrapped around the guidewire.
5. A catheter comprising:
an inflatable dilitation balloon with at least a first region of said
balloon positioned adjacent a second region to define a lumen of a size to
accommodate a guidewire;
means for inflating said balloon; and
means for providing a temporary bond between the first and second regions,
which bond breaks when the balloon is inflated.
6. A catheter as in claim 1 wherein the means for inflating comprises
longitudinal channel means extending from the balloon toward the proximal
end of the guidewire, the channel communicating with the balloon.
7. A catheter as in claim 1 wherein the longitudinal channel means
comprises at least two channels extending from the balloon toward the
proximal end of the guidewire.
8. A catheter as in claim 1 further comprising an elongate housing adapted
to be inserted into a vessel through which housing the guidewire extends.
9. A catheter comprising:
an inflatable dilitation balloon with at least a first region of said
balloon positioned adjacent a second region to define a lumen;
means for inflating said balloon;
an elongate housing adapted to be inserted into a vessel, said balloon
being attached to the distal end of said housing; and
wherein the housing includes a longitudinal slot extending from a distal
end thereof.
10. A catheter as in claim 8 wherein the elongate housing extends from the
proximal to the distal end of the catheter.
11. A catheter as in claim 8 wherein the elongate housing extends from the
distal end of the catheter a selected distance.
12. A catheter as in claim 1 further comprising a cover adapted to cover
the dilitation balloon and at least a portion of the distal end of the
guidewire.
13. A catheter as in claim 1, further comprising a cover adapted to cover
the dilitation balloon, wherein the cover surrounds the dilitation balloon
to prevent it from inflating.
14. A catheter as in claim 13 wherein the cover comprises an elongate body
having an opening therethrough within which the dilitation balloon is
disposed.
15. A catheter, as claimed in claim 4, wherein said means for securing
comprises at least a first ultrasonic weld between part of said first
region of the balloon and part of said second region of the balloon.
16. A catheter, as claimed in claim 5, wherein said means for providing a
temporary bond comprises an ultrasonic weld between at least parts of the
first and second regions.
17. A catheter, as claimed in claim 9, further comprising means for
providing a temporary bond between parts of said first and second regions
of said balloon, which bond breaks when the balloon is inflated.
18. A catheter, as claimed in claim 17, wherein said means for providing a
temporary bond comprises an ultrasonic weld between parts of said first
region and said second region.
19. A catheter, as claimed in claim 1, further comprising stiffener means
attached to said wall of said balloon.
20. A catheter, as claimed in claim 5, further comprising stiffener means
attached to a wall of said balloon.
21. A catheter, as claimed in claim 9, further comprising stiffener means
attached to a wall of said balloon.
22. A catheter, as claimed in claim 1, further comprising a deformable
stint adjacent to said balloon.
23. A catheter, as claimed in claim 5, further comprising a deformable
stint adjacent to said balloon.
24. A catheter, as claimed in claim 9, further comprising a deformable
stint adjacent to said balloon.
25. A catheter, comprising:
a guidewire extending from a proximal end to a distal end; and
a dilitation balloon inflatable from a first uninflated configuration to a
second inflated configuration, wherein at least a portion of said balloon
is wrapped around a portion of said guidewire when said balloon is in said
uninflated condition, and wherein said guidewire and said balloon part
when said balloon is in said inflated condition, such that said guidewire
is substantially not surrounded by said balloon.
26. A catheter, comprising:
a guidewire extending from a proximal end to a distal end;
a dilitation balloon inflatable from a first uninflated configuration to a
second inflated configuration, said balloon having a wall defining the
interior of the balloon;
at least a portion of said balloon in said uninflated condition wrapped
around a portion of the guidewire proximate the distal end of the
guidewire;
means for inflating the balloon;
means for securing a first region of the balloon to a second region of the
balloon by ultrasonic welding to maintain the balloon wrapped around the
guidewire when said balloon is in said uninflated condition, wherein said
ultrasonic weld breaks when said balloon is inflated to said inflated
condition;
an elongate housing adapted to be inserted into a vessel through which
housing the guidewire extends, said elongate housing having a longitudinal
slot extending from a distal end thereof;
said elongate housing defining a first and a second channel extending from
the balloon toward the proximal end of the guidewire, said first channel
for flushing said catheter, and said second channel usable for venting and
for flushing said catheter; and
a cover comprising an elongate body having an opening therethrough within
which the dilitation balloon is disposed to prevent the balloon from
inflating.
27. A catheter, comprising:
an elongate housing adapted to be inserted into a vessel, said housing
defining a lumen having a first diameter and having a proximal end and a
distal end;
a dilitation balloon having a wall defining the interior of the balloon,
the wall having an exterior surface and an interior surface, the balloon
being inflatable from a first uninflated configuration to a second
inflated configuration attached proximate the distal end of the housing;
means for inflating the balloon;
said balloon wall exterior surface, while said balloon is in said
uninflated condition, defining a lumen of a size to accommodate a
guidewire and substantially coaxial with said housing lumen.
28. A catheter, as claimed in claim 27, wherein said balloon in said
uninflated condition has a diameter greater than said diameter of said
housing lumen.
29. A catheter, comprising:
an elongate housing adapted to be inserted into a vessel, defining a lumen
with a first diameter;
a dilitation balloon attached to the distal end of the housing, said
balloon being inflatable from a first uninflated condition to a second
inflated condition;
said balloon in said uninflated condition with at least a first region of
said balloon positioned adjacent a second region to define a balloon lumen
having a second diameter less than said first diameter; and
a guidewire having a proximal end and a distal end, a portion of said
guidewire tapering in a direction toward said distal end, a portion of
said guidewire disposed in said housing lumen, at least a part of said
tapered portion of said guidewire disposed in said balloon lumen.
30. A catheter, comprising:
a guidewire extending from a proximal end to a distal end;
an inflatable dilitation balloon with at least a portion of said balloon
wrapped around a portion of the guidewire proximate the distal end of the
guidewire;
stiffening means attached to said balloon and spaced from said guidewire;
and
means for inflating the balloon.
31. A catheter, comprising:
an elongate housing having a distal end and a proximate end, adapted to be
inserted into a vessel;
an inflatable dilitation balloon attached to said distal end of said
housing with at least a first region of said balloon positioned adjacent
said second region to define a lumen of a size to accommodate a guidewire;
first channel means in said housing for flushing said catheter; and
second channel means in said housing for venting said catheter, wherein
said second channel means is configurable as a second means for flushing.
32. A method for inflating a balloon of a catheter, comprising:
providing a guidewire extending from a proximal to a distal end;
providing an inflatable dilitation balloon having a wall defining the
interior of the balloon with at least a portion of said balloon wrapped
around a portion of the guidewire proximate the distal end of the
guidewire;
providing flushable channel means in fluid communication with said interior
of said balloon; and
flushing said flushable channel means to inflate said inflatable balloon to
an inflated condition, wherein substantially no portion of said guidewire
is in said interior of said balloon.
33. A catheter, as claimed in claim 13, wherein said cover includes a
cone-shaped surface for threading the guidewire. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to catheters, and in particular to dilitation
balloon catheters, for use in the performance of percutaneous transluminal
procedures including peripheral angioplasty, coronary angioplasty and
valvuloplasty. The configuration of the catheter permits the introduction
of a relatively large caliber balloon across a severe intraluminal
stenosis with relative facility.
2. Description of the Prior Art
In 1977 Dr. Andreas Greuntzig first used a balloon-tipped flexible catheter
to percutaneously dilitate a region of stenosis within a coronary artery
of a patient with atherosclerotic heart disease. Since that time, the
incidence of percutaneous transluminal coronary angioplasty has increased
exponentially. Over the course of the past three to four years, the
performance of this procedure has become routine within many major medical
centers throughout the world. With the advent of improved technology and
operator skill, the indications for this procedure have also increased
substantially.
At the outset of a routine percutaneous transluminal coronary angioplasty
procedure, a preshaped angioplasty guiding catheter containing a balloon
catheter equipped with a flexible intracoronary guidewire is engaged
within the ostium of a coronary vessel containing the lesion to be
dilitated. Once suitably engaged (within the left main or right coronary
ostium), the guidewire is advanced within the lumen of the appropriate
vessel and manipulated across the region of stenosis. By rotating the
guidewire, which contains a slight bend within its distal aspect, the
operator can control the course of the wire, selecting the appropriate
coronary lumen as the wire is advanced.
Once the wire is positioned across the region of stenosis (narrowing), the
angioplasty dilitation balloon catheter is advanced over the guidewire and
positioned across the stenotic lesion. The angioplasty is accomplished by
inflating the dilitation catheter to a high pressure, typically 6 to 10
atmospheres. Generally, 3 to 4 dilitations are required for each region of
stenosis. Balloon inflation is maintained for 30 to 90 seconds during each
dilitation, depending upon anatomic considerations and operator
preference.
Following the final dilitation, the guidewire and balloon catheter are
withdrawn leaving the guiding catheter in place. (Frequently, an exchange
wire is installed within the lumen of the coronary artery via the guiding
catheter prior to removal of the balloon catheter. This ensures
intraluminal access in the event of a complication.) Selective coronary
angiography then is performed to evaluate the cosmetic appearance of the
vessel following the angioplasty and to determine the severity of the
residual stenosis.
At present, the major obstacle to the performance of an angioplasty
procedure involves the manipulation of the angioplasty dilitation balloon
catheter across the region of stenosis within the coronary artery.
Although the guidewire can frequently be advanced across the region of
stenosis with relative facility in vessels which are anatomically amenable
to the performance of an angioplasty (see FIG. 1A), manipulation of the
balloon catheter across the stenosis often proves difficult because the
cross-sectional profile of the deflated balloon affixed to the distal
aspect of the dilitation catheter is considerably greater than the
corresponding profile of the intracoronary guidewire. Advancing the
relatively large caliber angioplasty catheter within a significant
stenosis commonly results in disengagement of the guiding catheter from
the coronary ostium. Once the guiding catheter becomes disengaged, the
angioplasty catheter frequently prolapses within the sinus of Valsalva
immediately cephaled to the aortic valve, precluding further advancement
of the angioplasty catheter (see FIG. 1B). The guiding catheter disengages
in this circumstance because it is moderately flexible. It must be
flexible because insertion of this catheter requires that it be advanced
over a guidewire up the aorta, which is relatively straight, and then over
the aortic arch, which is, as the name implies, curvilinear.
One approach to circumvent this problem involves the development of
angioplasty dilitation balloon catheters that impart less resistance
during manipulation across a coronary stenosis relative to conventional
profile dilitation catheters. The approach to the development of these
angioplasty catheters has, in essence, involved the miniaturization of
conventional balloon catheters. These "low profile" catheters have
substantially contributed to the feasibility of performing angioplasty
individuals with severe coronary stenoses previously considered unsuitable
for percutaneous transluminal coronary angioplasty.
FIG. 2 illustrates the basic configuration of a conventional angioplasty
balloon catheter. The catheter consists of a lumen to accommodate a
guidewire, an inflation channel, as well as a small dilitation balloon
affixed to the distal aspect. Attempts to miniaturize these conventional
catheter systems has resulted in several disadvantages, given the
constraints imposed by current technology and material availability. For
example, the balloons of these "low profile" systems tend to have a
correspondingly smaller inflated diameter relative to conventional
balloons. This circumstance derives from the fact that the most suitable
material for the construction of dilitation balloons must be relatively
inelastic. Thus, the use of these "low profile" catheters frequently
obligates the operator to install one or more dilitation balloon catheters
of sequentially larger caliber. In addition to the added expense,
radiation exposure and operative time that this approach involves, the
complication rate for an intravascular procedure is in direct proportion
to the number of catheters employed during the procedure, as well as the
time required to complete the operation.
Despite extensive research and development, the deflated profile of these
"low profile" catheters remains substantial, hence the resistance imparted
by these devices during manipulation within a coronary stenosis remains
considerable. Furthermore, the introduction of a "low profile" catheter of
conventional configuration within a region of stenosis commonly deforms
the deflated balloon resulting in the development of wrinkles which
further contribute to the resistance generated by the catheter (see FIGS.
2C and 2D).
To circumvent the problems intrinsic to miniaturizing the balloon component
of the catheter, the Hartzler system was developed wherein the caliber of
the guidewire was reduced relative to the other components of the system.
Because this results in a fragile guidewire, the system was designed such
that the guidewire could not be removed from the protective confines of
the dilitation balloon catheter lumen. Disadvantages of this system
include the inability to accommodate conventional guidewires that afford
relatively superior directional control and the maintenance of a guidewire
within the coronary artery during the process of exchanging dilitation
balloon catheters.
The configuration of the Hartzler system does permit rotation of the
guidewire about the axis of the catheter and this feature affords some,
albeit suboptimal, directional control to the catheter system. The
configuration of the Hartzler system, however, does not permit (1)
360.degree. rotation of the guidewire, and (2) independent movement of the
guidewire relative to the catheter along the axis of the system. Because
the caliber of the Hartzler balloon is relatively small, when fully
inflated, use of this device frequently mitigates the use of one or more
subsequent dilitation balloon catheters of sequentially larger caliber in
order to achieve an optimal result. Because the Hartzler system does not
accommodate an exchange wire, the operator must completely renegotiate the
course of the diseased coronary artery with another intracoronary
guidewire before advancing the subsequent larger caliber angioplasty
dilitation balloon catheter across the region of stenosis. This inability
to use an exchange wire enhances the difficulty of the procedure and thus
predisposes the patient to increased risk. Many operators prefer to
install an exchange wire within a coronary artery during the process of
exchanging dilitation balloon catheters to ensure intraluminal access in
the event that a complication occurs during the process. The use of the
Hartzler system does not permit this.
Although conventional "low profile" catheter systems can accommodate an
exchange wire, there exist some intrinsic disadvantages to these catheter
systems relative to the Hartzler system. The deflated profile of
conventional low profile systems tends to exceed the corresponding profile
of the Hartzler system. Hence, it is frequently more difficult to advance
one of the these catheters across a region of critical stenosis relative
to the Hartzler system. Secondly, the lumen of low profile catheters
cannot accommodate the larger caliber intracoronary guidewires. Given the
fact that torque control and hence, directional control are directly
related to the caliber of the guidewire, the use of conventional low
profile catheter systems requires the use of guidewires with suboptimal
directional control. This feature further limits the likelihood of success
in the performance of an angioplasty of a complete coronary occlusion
(wherein the use of a low profile catheter system would be optimal). Most
operators prefer to use relatively large caliber (0.018 inch)
intracoronary guidewires in the performance of an angioplasty of a
complete coronary occlusion because of the enhanced column strength that
this increased caliber affords, and small caliber guidewires tend to
buckle in this circumstance. While one would prefer to use a low profile
system in this situation, the fact that these systems do not accommodate a
stiff wire tends to mitigate against their use in this circumstance.
SUMMARY OF THE INVENTION
The angioplasty dilitation balloon catheter of the preferred embodiment of
my invention provides numerous advantages relative to prior art catheters.
In particular, the configuration of the catheter permits the introduction
of a relatively large caliber balloon across a severe stenosis with
relative facility by maximizing the ratio of the inflated balloon
cross-sectional profile to the corresponding deflated profile of the
distal dilitation balloon. Relative to prior art dilitation catheters, the
distal deflated profile is considerably smaller. As a result, the
resistance imparted by the balloon during catheter manipulation within a
coronary is considerably less than the corresponding resistance of prior
art "low profile" catheters, yet the inflated caliber of the balloon is
substantially greater than the corresponding profile of conventional "low
profile" catheters. Thus, the use of this catheter frequently eliminates
the need to install exchange wires, and subsequent larger caliber
dilitation catheters, thus precluding the complications associated with
these additional procedures. As a result, use of this device substantially
contributes to the efficiency and safety of performing an intraluminal
dilitation procedure (e.g., peripheral angioplasty, coronary angioplasty,
valvuloplasty, ureteral stenosis dilitation, etc.).
In a preferred embodiment, the catheter includes an inflatable balloon
disposed on the distal aspect of the catheter, a channel to accommodate a
guidewire, extending from the proximal end to the balloon, and a means to
inflate the balloon. Typically, the balloon is wrapped around the
guidewire, thus forming a channel to accommodate the guidewire contained
therein. This wrapped configuration affords several advantages. It
provides a very compact streamlined means for disposing the balloon in the
deflated state that permits the maximization of the balloon
cross-sectional inflation/deflation profile ratio while circumventing the
use of elastic elements in the construction of the balloon to accomplish
this end.
The wrapped balloon configuration permits considerable reduction in the
deflated cross section balloon profile relative to the corresponding
profile of prior art catheters because this configuration (1) precludes
the development of flanges within the balloon itself that extend radially
from the distal aspect of the catheter (see FIG. 2C); (2) precludes the
development of wrinkles at the junction of the balloon and guidewire
housing; (3) precludes the development of wrinkles within the flanges of
the balloon during manipulation of the catheter across a stenosis (see
FIG. 3B); and (4) eliminates the bulk intrinsic to the bond of the balloon
to the guidewire housing that contribute to the deflated profile of the
prior art catheters.
The wrapped configuration further imparts column strength to the balloon,
thus eliminating the need to extend the guidewire catheter housing within
the confines of the balloon. This permits further reduction in the
deflated cross-sectional balloon profile of the catheter of my design. The
wrapped balloon configuration has particular application to the
performance of valvulopasty. In this circumstance, this configuration
permits the introduction of a relatively large caliber balloon (requisite
to the performance of a valvuloplasty) within the vasculature via a
relatively small arteriotomy of hematomas, hemophage, and peripheral
arterial trauma that frequently complicate conventional valvuloplasty
procedures. Furthermore, the wrapped configuration permits the
introduction of a large caliber balloon within the heart without the risk
of inducing intracardial trauma consequent with balloon inflation (a
problem intrinsic to dilitation balloon catheters of the prior art)
because the distal aspect of the balloon becomes blunt on full inflation
(see FIG. 4D).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic diagram illustrating the normal configuration of a
Judkin's guiding catheter within the aorta following engagement with the
ostium of the left main coronary artery and introduction of a dilitation
balloon catheter over an intracoronary guidewire to within the proximity
of a lesion contained within the left anterior descending coronary artery;
FIG. 1B illustrates the distortion in the configuration of the guiding
catheter that frequently results from attempts to advance a dilitation
catheter across a stenosis;
FIG. 2A is a cross-sectional side view of a conventional prior art
angioplasty dilitation balloon catheter;
FIG. 2B illustrates the prior art catheter fully inflated;
FIG. 2C illustrates the catheter when deflated;
FIG. 2D illustrates the development of wrinkles within the deflated balloon
of the prior art consequent with introduction of the dilitation catheter
across a region of stenosis;
FIGS. 3, 3A, 3B, and 3C are side, top and end views of a preferred
embodiment of the catheter;
FIG. 3D illustrates the catheter in perspective view with the dilitation
balloon unwrapped;
FIG. 3E is a perspective view of the catheter with the dilitation balloon
wrapped around an intracoronary guidewire;
FIGS. 4A-4D are a sequence of views illustrating the inflation of the
dilitation balloon;
FIG. 4E illustrates a catheter with a stint encompassing the deflated
wrapped dilitation balloon;
FIGS. 5A-5C illustrate three different embodiments of the catheter in which
the guidewire housing is changed;
FIGS. 6A and 6B illustrate a removable protective cover for the dilitation
balloon designed to prevent unwrapping of the dilitation balloon during
flushing and preparation of the catheter for introduction into the body;
and
FIG. 7A illustrates the use of a flushing syringe for flushing the channels
of a dual lumen catheter.
FIG. 7B illustrates the use of an inflating syringe with the dual lumen
catheter of FIG. 7A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although it is acknowledged at the outset that the configuration of the
catheter described herein has application to the performance of a variety
of dilitation procedures including peripheral angioplasty, valvuloplasty
and dilitation of ureteral stenosis. For the purpose of clarity, the
balance of the text will be confined to a discussion of the application of
this device to the performance of percutaneous transluminal coronary
angioplasty.
FIGS. 3A, 3B and 3C are a longitudinal sectional, top and end view,
respectively, of the cutaway angioplasty dilitation balloon catheter of a
preferred embodiment of my invention. An inset has been provided for the
purpose of orientation with respect to FIG. 3A. A guidewire has been
included in FIGS. 3A and 3E for orientation. As shown in FIG. 3, the
catheter includes a housing 21 extending from a proximal end (not shown)
to a distal end 22 creating a lumen 23 to accommodate an intracoronary
guidewire 30. The balloon typically is formed from an inelastic material
so it will inflate uniformly to a predetermined configuration.
FIG. 3B illustrates the housing 21, communicating channels 45, and balloon
40 from above. The balloon is shown in an unwrapped deflated condition.
FIG. 3B also illustrates an optional feature of the catheter,
specifically, a stiffening element 44 disposed longitudinally along the
length of the balloon to provide additional column strength to the
balloon. FIG. 3C is a "phantom" end view of the catheter illustrating the
disposition of channels 45 within the confines of the catheter housing.
The communicating channels 45 provide a means for both flushing air out of
the catheter prior to introduction into the body as well as inflating the
dilitation balloon 40 once the catheter has been positioned across a
region of stenosis.
FIG. 3D is a perspective view of the dilitation balloon 40, in an unwrapped
deflated condition and optional stiffening element 44. For clarity,
guidewire 30 is not shown in FIG. 3D. FIG. 3E is a perspective view of the
dilitation balloon 40 and guidewire 30 illustrating the manner in which
the dilitation balloon may be wrapped around the guidewire. Relative to
prior art catheters, this configuration permits the disposition of a
relatively large inelastic balloon along the course of a guidewire with a
minimal cross-sectional profile. (The guidewire is shown larger than to
scale for illustration.) Typically, the balloon will be wrapped around the
guidewire at the time of manufacture and will not be unwrapped until it is
inflated within the region of the stenosis. Both the lumen 23 in housing
20 and the lumen created by wrapping balloon 40 are of sufficient caliber
to permit unimpaired longitudinal and rotational movement of guidewire 30
within the confines of the catheter. Notwithstanding the small insertion
diameter, on inflation, the balloon unwraps from the guidewire and
provides the full capability of existing angioplasty dilitation balloons.
A slot 26 at the end of the housing 21 allows the balloon to be inflated
near the end of housing 21 without unduly stressing the guidewire 30. The
configuration of the balloon 40 can be modified to optimize the taper that
develops along the leading edge of the catheter on wrapping the balloon
around the guidewire as illustrated in FIG. 3E.
Because the balloons used in the construction of conventional catheters
have very thin walls, the wrapping of a relatively large balloon around a
guidewire does not lead to a significant increase in the overall deflated
cross-sectional diameter of the catheter relative to the corresponding
profile of a catheter containing a smaller caliber dilitation balloon.
Hence, this configuration of the preferred embodiment provides a catheter
of lower deflated profile that contains a relatively larger balloon than
prior art catheters. Because the use of the catheter described herein
permits the initial introduction of a balloon of optimal caliber within a
severe stenosis with minimal resistance (relative to conventional prior
art low-profile catheters), without the need to introduce and inflate
several additional dilitation catheters across the region of stenosis the
use of this system reduces the difficulty, expense, duration, and risk of
the dilitation procedure. Because the catheter readily accommodates 0.018
inch (large caliber) guidewires and exchange wires, the use of this
catheter does not compromise directional control for miniaturization as do
currently available low profile systems. Furthermore, the catheter permits
the maintenance of a previously installed exchange wire within the
coronary artery following balloon dilitation in the event that the
operator desires to maintain intraluminal access, an option not feasible
with the Hartzler system. For all of these reasons, the use of my catheter
enhances the safety, feasibility, efficiency and economy of an
intraluminal dilitation procedure.
To provide additional column strength to manipulate the catheter across a
tight stenosis, the lumen of the balloon may be made smaller than the
guidewire lumen of the catheter housing. In this circumstance, a tapered
guidewire allows the operator to manipulate the balloon across the
stenosis by applying pressure to the guidewire itself. In this
circumstance, the column strength of the guidewire contributes to the
column strength of the catheter. On inflation of the balloon, the
guidewire and catheter part. The addition of an optional stiffener 44, as
illustrated in FIGS. 3A, 3B and 3D contributes to the column strength of
the balloon.
FIGS. 4A-4D illustrate the manner in which the wrapped balloon unwraps
during inflation. When first manipulated across a stenosis, balloon 40 is
wrapped in the manner of FIG. 4A. This configuration is maintained by a
temporary bond designed to tolerate the stresses usually applied to this
segment of the catheter during introduction across a coronary stenosis and
yet release when subjected to the forces that develop during inflation of
the balloon. This bonding may be achieved using any well known technique
including, for example, ultrasonic bonding. As shown in FIGS. 4B and 4C,
as the balloon is progressively inflated by fluid inserted through the
channels, the bond (or bonds) breaks, allowing the balloon to unwrap from
the guidewire 30. Once it is completely unwrapped, as shown in FIG. 4D,
the guidewire is no longer encompassed by the balloon.
In an alternate embodiment shown in FIG. 4E, a stint 48 is used to maintain
the balloon 40 in a wrapped position. When the balloon 40 is inflated, the
stint 48 is deformed to an enlarged shape and remains within the artery to
hold the lumen open. Thus, the catheter functions as an optimal device to
introduce stints into the vasculature.
FIGS. 5A, 5B and 5C illustrate three different embodiments for the design
of the housing 20 of the catheter. In FIG. 5A, the guidewire 30 is shown
together with a full length housing 21 and balloon 40. An adapter 50 is
shown attached to the catheter to communicate with channel 45 to enable
flushing the air out of the channel and inflation of the balloon.
In FIG. 5B the housing 21 extends only along a fraction of the length of
the catheter. In one embodiment the housing and dilitation balloon extend
about 25 centimeters back from the distal aspect of the catheter. This
embodiment offers two advantages relative to conventional catheters.
First, it eliminates the need for exchange wires which tend to be
particularly cumbersome. Second, this embodiment allows for extracorporeal
fixation of the intracoronary guidewire during manipulation of the
catheter within the heart because both extracorporeal elements are
independent. Fixation of the guidewire minimizes motion of the wire within
the coronary artery as the angioplasty dilitation balloon catheter is
advanced within the heart and thus minimizes some of the intra-arterial
trauma that develops as a result of the inadvertent guidewire movement.
This embodiment also eliminates the need for a second angiographer to
stabilize the guidewire during this aspect of an angioplasty.
In the embodiment of FIG. 5C the only aspect of the catheter that
encompasses the guidewire is the balloon itself. The midportion of the
catheter of this embodiment simply consists of one or more adjacent or
coaxially disposed channels 45 extending from the flush/infusion fitting
50 to the balloon 40. Although the least stable configuration of the
three, this embodiment affords the smallest caliber for the angioplasty
dilitation balloon catheter. This permits the introduction of this
catheter within a guiding catheter of proportionately smaller caliber. The
use of a smaller guiding catheter allows the performance of a smaller
arteriotomy, permitting the performance of a percutaneous dilitation
procedure with minimal risk for peripheral vascular complications and
hemorrhage. This design also permits complete separation of the catheter
from the guidewire, following inflation of the balloon, substantially
minimizing the likelihood of dislodging the guidewire during subsequent
withdrawal of the deflated dilitation catheter.
The catheter system of my invention offers several advantages over both the
Hartzler system and conventional low profile catheter systems. The
deflated cross-sectional profile of my catheter is substantially smaller
than the corresponding profile of all currently available catheter
systems. By eliminating the tubing that constitutes the housing for the
guidewire within the confines of the balloon at the distal aspect of the
catheter, a considerable amount of the bulk that contributes to the
deflated cross-sectional profile of the catheter is eliminated. Also
eliminated is the need to attach the deflated (and hence planar) balloon
to the circumference of the tubing, a geometrical incongruity that
frequently leads to the development of wrinkles. The wrinkles contribute
to the deflated cross-sectional profile of all currently available low
profile angioplasty dilitation balloon catheters. The wrapped
configuration provides a means of disposing a dilitation balloon of larger
caliber when inflated than corresponding prior art low profile catheters.
This feature allows an operator, using this device, to introduce a
dilitation balloon, of optimal (inflated) caliber, across a stenosis at
the outset, with relative facility, without resorting to the installation
and inflation of additional dilitation balloon catheters of sequentially
larger caliber.
By reducing the length of the guidewire housing, the need to use long and
frequently cumbersome exchange wires, the installation of which requires
the participation of two operators, is eliminated. It should be recognized
that an exchange wire is simply a guidewire that is twice the length of a
regular intracoronary guidewire. The additional length the wire is used
during the exchange of conventional prior art dilitation catheters. Thus,
the wire must extend from the heart to the distal aspect of an angioplasty
dilitation catheter when the catheter has been fully removed from the
body.
FIG. 6A illustrates in cross section a cover 60 adapted to fit over the
wrapped balloon 40 and guidewire 30. Cover 60 protects the balloon 40
during shipment and facilitates preparation of the catheter by providing a
cone-shaped surface 65 for threading the guidewire 30 into housing 21. As
will be described in conjunction with FIG. 7, the cover also facilitates
flushing of the catheter. FIG. 6B is a perspective view showing the cover
60 encompassing the balloon following introduction of the guidewire into
the catheter lumen.
The preparation of a conventional catheter involves the flushing of the
system with Renograffin-76, a conventional radiographic contrast agent
diluted with normal saline. This flushing is to eliminate any air bubbles
that might be trapped within the system. This procedure results in full
inflation of the angioplasty dilitation balloon before it is ever
introduced within the body. Clearly, in the case of the catheter of my
invention, this approach would be counterproductive because premature
inflation of the balloon results in disruption of the bond which maintains
the wrapped configuration of the balloon and unwraps the balloon itself
from the guidewire. To avoid this, the catheter is distributed with a
protective cover, similar to the protective cover 60 shown in FIG. 7A, in
place. The housing prevents inflation of the balloon during the flushing
procedure. Because the balloon is tightly wrapped at the outset, it will
not contain air. Hence, to adequately prepare the catheter described
herein for introduction into the body, it remains necessary only to flush
the air out of channel(s) 45, and this can be accomplished by means of a
venting system illustrated in FIG. 7A. Cover 60 then is removed prior to
insertion of the catheter.
With respect to flushing of catheters in general, there exist three
different approaches. Preparation of systems that contain no venting
system depend upon the brute force of the operator to generate a
substantial vacuum within the system prior to the introduction of any
fluid. Preparation of these systems is frequently time consuming, awkward
and invariably results in the introduction of some air into the system.
Low profile systems are commonly constructed without a venting system.
A second approach to flushing involved the introduction of a venting tube
(contained within the dilitation catheter) within the confines of the
balloon to vent the system. Once the catheter has been vented, the tube is
withdrawn and closed. This approach is time-consuming and cumbersome.
Furthermore, the vent tube contributes to the cross-sectional profile of
the catheter as well as the dead space of the system, once the catheter
has been flushed.
The third and clearly superior approach involves catheter that contains two
lumens, in addition to the lumen for the guidewire. Such a catheter is
depicted in FIGS. 7A and 7B. At the outset one of the lumens functions as
a flush port and one functions as a vent port for the system. Once the
catheter has been flushed, the extracorporeal vent is eliminated and the
vent port is converted to an additional flush port. This approach offers
several advantages. The system provides a vent for the catheter, thus
minimizing both the amount of air trapped in the system, as well as the
amount of force required to prepare the system. The configuration does not
entail any dead space. Also, once the system has been flushed, both
channels function to inflate and deflate the balloon. Because the
resistance incurred during the inflation and deflation of the dilitation
balloon is proportional to the cross-sectional profile of the infusion
channel(s), the use of two channels allows the operator to inflate and
deflate the balloon more rapidly relative to a single channel (and hence,
smaller caliber) flush port system.
The partition 48 separating the flush channel from the vent channel does
not extend the entire length of the flush/vent port. To flush the system,
one need only insert a preshaped syringe into only the flush port and
inject fluid. In this circumstance, the vent port is open to air. Once the
vent port has filled with fluid, the catheter is fully flushed. The
preshaped syringe is removed and the catheter attached to a standard
inflation device, typically a syringe. Because the coupling of the
inflation device does not extend deep within the lumen of the flush/vent
port, both channels are exposed to hydrostatic pressure on inflation of
the balloon and hence, both channels function as flush channels.
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