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Description  |
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BACKGROUND OF THE INVENTION
This invention generally relates to a dilatation catheter suitable for
percutaneous transluminal angioplasty procedures which can perfuse blood
distally of the dilatation balloon during the inflation thereof.
In typical percutaneous transluminal coronary angioplasty (PTCA)
procedures, a guiding catheter having a preformed distal tip is
percutaneously introduced into the cardiovascular system of a patient
through tee brachial or femoral arteries and advanced therein until the
distal tip thereof is in the ostium of the desired coronary artery. A
guidewire and a dilatation catheter having a balloon on the distal end
thereof are introduced through the guiding catheter with the guidewire
slidably disposed within an inner lumen of the dilatation catheter. The
guidewire is first advanced into the patient's coronary vasculature until
the distal end thereof crosses the lesion to be dilated and then the
dilatation catheter is advanced over the previously introduced guidewire
until the di1atation balloon is properly positioned across the lesion.
Once in position across the lesion, the flexible, relatively inelastic
balloon is inflated to predetermined size with radiopaque liquid at
relatively high pressures (e.g., greater than 8 atmospheres) to radially
compress the atherosclerotic plaque of the lesion against the inside of
the artery wall to thereby dilate the lumen of the artery. The balloon is
then deflated so that the dilatation catheter can be removed and blood
flow resumed through the dilated artery.
Further details of angioplasty procedures and the devices used in such
procedures can be found in U.S. Pat. Nos. 4,332,254 (Lundquist); 4,323,071
(Simpson-Robert); 4,439,185 Lundquist); 4,468,224 (Enzmann et al.)
4,516,972 (Samson); 4,538,622 (Samson et al.); 4,554,929 (Samson et al.);
and 4,616,652 (Simpson) which are hereby incorporated herein in their
entirety.
Steerable dilatation catheters with built-in or fixed guidewires or guiding
elements are used with greater frequency because the deflated profile of
such catheters is generally smaller than conventional dilatation catheters
with movable guidewires or elements having the same inflated balloon size.
Further details of low-profile steerable, dilatation catheters may be
found in U.S. Pat. Nos. 4,582,181 (Samson), 4,619,263 (Frisbie et al.),
4,641,654 (Samson et al.), and 4,664,113 (Frisbie et al.) which are hereby
incorporated in its entirety by reference thereto. The lower profile of
these catheters allows them to cross tighter lesions and to be advanced
much deeper into the patient's coronary anatomy. Moreover, the use of
steerable low-profile dilatation catheters shortens considerably the time
for the angioplasty procedure because there is no need to first advance a
guidewire across a lesion and then slide a conventional dilatation
catheter over the previously advanced guidewire to position the balloon
thereof across the lesion.
When the balloon is inflated during typical angioplasty procedures, all
blood flow through the artery is blocked. While it is widely believed that
long term dilation of the stenosis will increase the probability that the
stenosis wi11 remain open after dilation and will also reduce the risk of
re-stenosis, presently used typical dilation times range from about 15 to
60 seconds because longer periods would result in dangerous ischemic
conditions distally of the inflated balloon in a coronary region which may
already be in jeopardy.
Efforts have been made to develop dilatation catheters which perfuse blood
through the catheter or by the balloon of the catheter when the balloon is
inflated during angioplasty procedure in order to avoid ischemic
conditions distally of the balloon. For example the dilatation catheters
described in U.S. Pat. Nos. 4,581,017 (Sahota) and 4,423,725 (Baran et
al.) both describe means to perfuse blood distally when the dilatation
balloon is inflated to facilitate longer inflation periods, but
unfortunately both dilatation catheters are very complicated structurally
and are expensive to manufacture. Additionally, any guidewire utilized
with these catheters was disposed in the same lumen through which the
blood must flow, thereby reducing the flow, unless the guidewire is
withdrawn prior to the dilations to a location proximal to the perfusion
inlet holes in the catheter body.
What has been needed and heretofore unavailable is a steerable dilatation
catheter which provides for the distal perfusion of blood during
angioplasty procedures through a lumen separate from the lumen receiving
the guidewire to thereby allow for longer term dilations. The present
invention satisfies that need.
SUMMARY OF THE INVENTION
This invention is directed to a steerable dilatation catheter which
provides for the distal perfusion of blood through an inner lumen which
passes through the balloon thereof when the balloon is inflated during
angioplasty procedures.
The catheter in accordance with the invention generally comprises a
flexible, elongated tubular member, a perfusion body, and a balloon member
disposed about and sealingly secured to the perfusion body. The flexible
tubular member has an inner lumen extending along the length thereof and
is adapted to receive a guidewire therein. The perfusion body, which is
secured to the distal extremity of the tubular member, has two inner
lumens, a first lumen in fluid communication with the inner lumen of the
tubular member and a second lumen having a much larger diameter than the
first lumen and having inlet and discharge ports to facilitate the passage
of blood therethrough when the balloon element disposed about the
perfusion body is inflated. The first lumen is preferably adapted to
receive a guidewire from the inner lumen of the tubular member.
In a presently preferred embodiment, the balloon member encases the
perfusion body and has at least one inlet port in fluid communication with
the inlet port of the second lumen of the perfusion body and at least one
discharge port in fluid communication with the discharge port of the
second lumen of the perfusion body. The perfusion body has an inflation
/deflation port in the upper portion thereof in fluid communication with
the first lumen therein which opens into the interior of the balloon
member to provide inflation fluid thereto. The balloon is sealingly
secured about the periphery of the perfusion body distally and proximally
of the inflation/deflation port to prevent loss of fluid.
A guiding element or guidewire is disposed within the inner small diameter
lumen of the catheter so that the catheter can be more easily steered to
the desired location within the patient's coronary vasculature. The core
of the guidewire is disposed within the inner lumen of the tubular member,
passes through the small diameter first lumen of the perfusion body and
extends out the distal end thereof. A helical coil or other flexible body
is disposed about and secured to the portion of the guidewire core
extending out of the perfusion body. The core wire of the guidewire
extends proximally through the inner lumen of the tubular member and the
proximal end thereof is secured to a torquing means, such as a knob, to
rotate the guidewire when it is advanced through the patient's vasculature
to thereby steer the catheter to the desired location. The distal end of
the perfusion body is sealingly secured about the core of the guiding
element to prevent loss of inflation fluid.
The operation of the steerable catheter of the invention is similar to that
of conventional steerable dilatation catheters, except that when the
dilatation balloon is inflated, blood is forced to flow distally through
the larger second lumen of the perfusion body to the distal end of the
catheter and thereby prevent ischemic conditions in tissue distal to the
dilatation balloon. These and other advantages of the invention will
become more apparent from the following detailed description thereof when
taken in conjunction with the accompanying exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal sectional view of a dilatation catheter embodying
features of the invention;
FIG. 2 is a transverse sectional view of the catheter shown in FIG. 1 taken
along the lines of 2--2;
FIG. 3 is a transverse sectional view of the catheter shown in FIG. 1 taken
along the lines 3--3;
FIG. 4 is a transverse sectional view of the catheter shown in FIG. 1 taken
along the lines 4--4; and
FIG. 5 is a transverse sectional view of the catheter shown in FIG. 1 taken
along the lines 5--5.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a perfusion dilatation catheter 10 embodying features of
the invention which generally comprises an elongated, flexible tubular
member 11, a perfusion body 12, and a balloon member 13 disposed about the
perfusion body and sealingly secured about the periphery thereof at
locations 14 and 15 to prevent loss of liquid during the balloon
inflation.
The tubular member 11 has an inner lumen 16 extending along the length
thereof which is in fluid communication with the interior of balloon
member 13 to direct inflation fluid thereto and which is also adapted to
receive a guidewire 17. The proximal end of tubular member 11 is secured
to an adapter 18 and the distal end is secured to the proximal end of the
perfusion body 12.
The perfusion body 12 has two interior lumens, a first relatively small
diameter lumen 20 which is in fluid communication with inner lumen 16 of
tubular member 11 and which receives guidewire 17 and a second relatively
large diameter lumen 21 having an entry port 22 at the proximal end and a
discharge port 23 at the distal end for the passage of blood therethrough.
Preferably, the ratio of the large diameter lumen 21 to small diameter
lumen 20 is greater than 3:1. The interior of the inner lumen 20 may be
enlarged within the interior of the balloon member 13 as shown in FIG. 4.
An inflation/deflation port 24 is provided in the upper surface of
perfusion body 12 in fluid communication with the first small diameter
lumen 20 to direct inflation fluid to and from the interior of balloon
member 13. The distal end of the perfusion body 12 is sealingly secured
about the core member 25 of the guidewire 17 but with sufficient clearance
to allow the guidewire to rotate.
The balloon member 13 is disposed about the perfusion body 12 and is
sealingly secured by adhesive, heat shrinking or other suitable means
about the periphery thereof at locations 14 and 15. The proximal end of
balloon member 13 is sealingly secured to either the distal end of tubular
member 11 or the proximal end of perfusion body 12 or both. The distal end
of the balloon 13 is disposed about coil 27 on the distal extremity of the
guidewire 17 with sufficient clearance to allow rotation of the guidewire
therein.
The lower portions of the balloon member 13 extending proximal to sealing
location 14 and distal to sealing location 15 are provided with entry and
discharge ports 30 and 31, respectively, which are in fluid communication
with the entry and discharge ports 22 and 23 of large lumen 21 in the
perfusion body.
Means (not shown) may be provided to allow for the passage of air from the
interior of the balloon during the inflation with liquid but which blocks
the passage of inflation liquid therefrom, as described in U.S. Pat. Nos.
4,582,181 (Samson), 4,692,200 (Powell) and copending applications Ser. No.
000,651 filed Jan. 6, 1987, and Ser. No. 000,648 all of which have been
assigned to the present assignee, and which are incorporated herein by
reference thereto.
The adapter 18 on the proximal extremity of the catheter 10 has a first arm
32 which is in fluid communication with the lumen 16 of the tubular member
11 to supply inflation fluid therethrough to the interior of the balloon
member 13. The proximal extremity of the core member 25 of guidewire 17
extends through the second arm 33 of adapter 18 and has a torquing knob 34
secured thereto for rotating the guidewire 17 to thereby facilitate
steering the distal end of the catheter 10 during the advancement thereof
through a patient's vasculature. Details of suitable torquing knobs are
found in U.S. Pat. Nos. 4,619,263, 4,641,654 and 4,664,113 previously
mentioned. A flexible helical coil 27 preferably formed of radiopaque
materials is disposed about the portion of the guidewire 17 extending
through the distal end of balloon member 13 and is secured thereto by
suitable means, such as soldering or brazing or welding. In the presently
preferred embodiment, the distal portion of the core element 25 of the
guidewire 17 is tapered and the distal tip thereof is secured to plug 35
which is usually formed of suitable radiopaque material. However, if a
more flexible distal tip is desired, the guidewire 17 can be provided with
a floppy design (not shown) wherein the core 25 terminates proximal of the
plug 35 and a shaping ribbon extends from the distal end of the core to
the plug as illustrated in U.S. Pat. Nos. 4,554,929 and 4,538,622.
The catheter of the invention can be advanced through a patient's vascular
system to a desired location therein in a conventional fashion as with
prior steerable catheters. Knob 34 on the proximal end of adapter 18 is
rotated to rotate the flexible coil 27 on the distal tip of the guidewire
17 and thereby direct the tip into the desired arterial branches. Once in
position across a lesion, the balloon 13 is inflated with radiopaque
liquid which passes through arm 32, inner lumen 16, first lumen 20, and
inflation/deflation port 24 to the interior of balloon 13. In dilating a
stenosis, the inflated balloon 13 occludes the artery, but blood proximal
to the balloon passes through entry ports 30 in the balloon member and
entry port 22 of the perfusion body 12, through the large diameter second
lumen 21 therein and then is discharged through port 23 and ports 31 in
the balloon 13. In this manner, the balloon 13 can be inflated within an
artery for long periods of time with little risk in creating ischemic
conditions in tissue distal to the balloon 13. Dilatation of arterial
stenosis with the catheter of the invention for periods of up to 30
minutes or more are believed to provide long-term protection against
re-stenosis and little risk that a dilated artery will collapse when the
balloon is deflated. In the event that a dilated stenosis closes down when
the balloon 13 is deflated, the catheter of the invention can be
reinflated across the lesion and thereby in effect act as a temporary
stent to maintain blood flow across the lesion until by-pass surgery or
other corrective action can be taken on the blockage.
The tubular member 11 can be formed of suitable thermoplastic material such
as polyethylene, polyvinylchloride and the like or from stainless steel
(i.e. hypotubing) or it can be of composite structure such as described,
in copending application Ser. No. 241,047 filed 9-6-88. In this latter
application, the composite structure comprises a tubular substructure
formed from material such as polyimide with an outer coating of resin
impregnated fibrous material which has been wound or braided into the
tubular substructure to provide a relatively stiff proximal portion and a
relatively flexible but diametrically rigid distal portion. The balloon
may be irradiated polyethylene, polyethylene terephthalate, or other
suitable flexible but relatively inelastic materials. The perfusion body
12 can be made from flexible thermoplastic or thermoset plastics, such as
polyethylene, polyvinylchloride, polyurethane, and the like.
Typical dimensions of the catheter include an overall length of about 135
to about 175 cm, a tubular member outer diameter of about 0.035 to about
0.45 inch (0.635-1.14 mm) and an inner diameter of about 0.1 to about 0.3
inch (0.254-0.762 mm). The perfusion body has an overall length of about
1.5 to 3.5 inches (3.8-8.9 cm) and an outer diameter at its thickest
section of about 0.04 to about 0.075 inch (1.02-1.91 mm). The diameter of
the proximal portion of the small inner lumen 20 of the perfusion body 12
is approximately the same as the inner diameter 16 of the tubular member
11 and is greater or smaller depending on whether the proximal end of the
perfusion body is secured outside or inside the distal end of the tubular
member. However, the diameter thereof may be reduced in the distal
direction. The diameter of the large lumen 21 in the perfusion body is
sufficiently large to handle the amount of expected blood flow and is
usually much larger, i.e., at least 1.5 times the diameter of the first
lumen 20. The balloon member 13 generally is of approximately the same
length or slightly larger than the perfusion body 12. The entry and
discharge ports 30 and 31 in the balloon member 13 are sized to provide
adequate blood flow at the blood pressures normally found, e.g., 70 cc/min
at 80 mm Hg. The size and number of these apertures can be varied to
provide the flow desired. The diameter of the proximal portion of
guidewire 17 can range from 0.008 to about 0.018 inch (0.203-0.457 mm)
with the distal end of the core member thereof tapering toward the distal
end in a conventional manner. The outer diameter of coil 27 is generally
smaller than the inner diameter of the tubular member 11 and the inner
lumen 20 over essentially all of the length thereof except at the distal
extremity which is necked down about the core 25 to prevent the loss of
inflation fluid.
While the perfusion catheter of the invention has been described in terms
of certain presently preferred embodiments, it should be apparent that
modifications may be made. For example, the balloon member and the
perfusion body are described herein as separate members which are secured
together with the tubular member to form the catheter assembly. However,
either of these members may be formed in a unitary structure with the
tubular member if desired. Other modifications and improvements can be
made without departing from the scope of the invention.
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