Therapeutic medical instrument for insertion into body

This invention provides a cylindrical plastic catheter of the type having a distal end portion movable over a guide wire to a treatment site such as a stenosis in the cardiovascular system, wherein the catheter shape gradually changes from a tubular configuration with a cylindrical skin defining an interior inflating lumen. The skin configuration and internal lumen changes shape gradually along the catheter length for insertion of the wire into a resident guide lumen resident only in the distal end portion without bends or kinks in the wire and retaining a generally parallel disposition to the catheter axis from which it departs to penetrate the catheter. Thus a guiding groove in the skin gradually transforms into a crescent partly surrounding the guide wire before changing into a toroidal body defining a guide wire lumen. The diameter of the catheter is thus kept constant and small with consistent axial stiffness throughout its length for supporting withdrawal and intrusion from external axial forces. The balloon mounts on the catheter body cylinder for a better, more secure seal and the axial forces along the catheter are balanced about the axis so that there is no tendency to buckle or veer with entry or withdrawal forces. By supplying a groove along the length of the catheter body to receive nested therein a parallel guide wire, the outer circumferencial dimension of the combination guide wire-catheter body may be reduced for entry into vessels of restricted size.

TECHNICAL FIELD 
This invention relates to instruments and methods of therapeutic treatment 
of the body at internal body sites and more particularly it relates to 
dilatation catheters movable along coronary blood vessels upon a guide 
wire to position an uninflated balloon at a site for treating stenosis by 
subsequent inflation of the balloon, or the like. 
BACKGOUND ART 
The art balloon dilatation catheters for treatment of stenosis in coronary 
blood vessels is well developed. Representative U.S. patented art includes 
the following briefly discussed catheters: 
G. T. Schejeldahl, et al., U.S. Pat. No. 4,413,989 Nov. 8, 1983 was 
concerned with long treatment periods in a balloon catheter inserted over 
a guide wire and thus provides for dilation without interruption of the 
blood supply with a lumen for bypassing blood. 
A. Kuhl, U.S. Pat. No. 4,439,186 provides for pulsating pressure for 
expansion and contraction of the balloon to permit blood flow past the 
balloon. 
J. J. Leary, U.S. Pat. No. 4,545,390 is concerned with steering the balloon 
and thus provides a steerable end to the guide wire upon which the balloon 
rides. 
M. J. Horzewski, et al., U.S. Pat. No. 4,748,982 June 7, 1988 provides a 
balloon dilatation catheter with a short distal end portion moving along a 
guide wire with the feature of decreasing stiffness of the catheter body 
from the proximal extremity to the distal extremity in order to overcome 
difficulties in pushing prior catheters to a treatment site. 
T. Bonzel, U.S. Pat. No. 4,762,129, Aug. 9, 1988 provides a stiffener wire 
in a separate balloon dilating lumen positioned parallel to the guide wire 
except at the distal end to aid in pushing the balloon to the treatment 
site. 
There still reamin many unsolved problems in the art of treatment of a site 
within the body with instrumentation located in part outside the body. In 
the dilatation catheter art, for example, there are problems of pushing 
catheters into position at the treatmenmt site through restricted body 
vessels. Any unbalance of thrust forces or bends or kinks in te catheter 
can interfere with insertion or withdrawal. Critical is the friction 
encountered in moving a catheter along a guide wire. While considerable 
friction is removed by inserting the guide wire only at a distal end 
region of the catheter, the adds criticality by introducing a tendency to 
tilt or veer in the presence of slightly off axis thrust forces or 
unbalances of size, strength or axial stiffness of the catheter body. This 
is particularly evident at entrance point of the wire into the catheter 
body, where it is common to bend or distort the path of the guide wire, 
thereby adding unwanted friction and guiding problems. An example of this 
is given by the sharp bending zone in the guidewire set forth in the 
Horzewski patent. 
Furthermore with dilatation balloon structure affixed to the catheter body 
and subjected to dilating by means of injecting fluid at high pressure, 
there are sealing and inflation problems. Thus, because of the high 
inflation pressures, any attempt to seal on a non-cylindrical surface 
produces a tendency to either produce leakage by tearing away the sealing 
joint or an uneven inflation of the balloon structure causing weak points 
or misshaping. Shaping is critical for passage into stenosis areas, and 
leakage or pressure limitations critical to the treatment and safety of 
the patient. 
Another problems area is the abrupt transition of a catheter tubing body or 
lumen at transition areas for entry of a guide wire or mounting of a 
balloon. This can for example tend to cause damage to vesel sidewalls or 
as heretofore discussed by causing the short distal end rider type of 
catheter geneally preferable to reduce friction on insertion between the 
catheter and the guide wire or its connection tubing to bend, veer, buckle 
or bind on the guide wire in response to pushing or pulling axial forces 
exerted along the catheter axis to insert or withdraw the catheter. 
The distal end profile of a balloon is critical particularly if it needs to 
be forced through a stenosis. The flexibility of the balloon for dilation 
is inconsistent with the initial need for penetration of restricted 
passageways to position the balloon at a treatment site for dilation. As a 
matter of fact any abrupt transition from one material to another or from 
one shape to another as it occurs if two separate lumens--one for 
inflation of the balloon and one for guidance of the wire--cause an abrupt 
joint between the lumens such as in the catheter suggested by Bonzel, 
supra, such abrupt changes provide problems of insertion, positioning and 
reliability. 
Particularly for coronary blood vessel treatment, small diameters, known as 
low profile, for insertion into branch vessels and flexibility to bend 
around sharp corners is critical. Thus balloons attached to stiff tubings 
or those unadapted to bend around a vessel curve are of limited use as 
well as those requiring significant room resulting in greater diameters of 
the catheter body for mounting elements affixing the balloon structure 
upon the catheter. 
Very critical to coronary vessel treatment is the quick interchange of 
dilatators of different size. Thus a smaller diameter dilatator balloon 
may be used for penetration of the stenosis and enlargement enough to 
accommodate a larger diameter balloon necessary to restore a reasonably 
normal working diameter in the vessel. 
It is therefore a particular object of this invention to provide an 
improved dilatation catheter particularly adapted for angioplasty and 
treatment of coronary vessels that resolves the foregoing problems in the 
prior art. 
A more general object is to provide improved instrumentation and treatment 
methods for therapeutic treatment at sites within the body from the 
outside. 
Other objects, features and advantages of the invention will be found 
throughout the following description, and in the accompanying drawings and 
claims. 
DISCLOSURE OF THE INVENTION 
This invention provides therapeutic instrumentation and treatment methods 
for treatment inside the body of the type that is passed over a guide wire 
of positioning at the treatment site. A specific example is an inflatable 
dilatation catheter specially adapted for arteriosclerotic vessel 
treatment of stenosis or angioplasty. The catheter is of the type riding 
on a guide wire only at a short distal end portion. Novel features of this 
catheter include the transition of the catheter tubing, typically plastic 
having a cylindrical thin skin-like wall surrounding a single inflation 
lumen for dilating and accompanying balloon to accommodate a second guide 
wire lumen at a predetermined length of the catheter body near the distal 
end. 
Thus the configuration of a conventional cylindrical catheter tubing with 
outer plastic wall defining a single internal lumen changes gradually 
while passing through successive configurations at the more distal 
(balloon) end. Thus the generally substantially cylindrical outer wall, 
becomes grooved to guide a substantially parallel guide wire alongside 
toward the interior of the catheter without any substantial bending of the 
wire. The catheter groove then progressively leads into a crescent shaped 
wall-lumina configuration which partially encompasses the guide wire 
before becoming cylindrical to surround the guide wire as a toroid. In 
parallel to this grooving and encompassing process, the inner lumen of the 
catheter changes its shape as well from round towards more of a C-shaped 
configuration. This unique and novel feature contributes significantly to 
smaller total diameter of dilatation catheters despite the same mechanical 
strength for pushing the catheter forward, compared to conventional 
arrangement with two parallel cylindrical lumens. The distal end lumen and 
body structure finally tapers into a low profile solid nose adapted for 
working its way through stenosis before the balloon affixed to the 
cylindrical length of the catheter body is placed at the stenosis. The 
wall of the inflating-deflating tube is apertured at the site of the 
balloon to connect the balloon via the inflating-deflating lumen within 
the catheter body to the outside of the human body for operation of the 
balloon by fluid injection under pressure. This provides a short low 
friction rider of limited length and of small diameter substantially 
cylindrical. This cylindrical diameter extends along the entire length of 
the distal catheter body that it can be introduced into smaller vessels in 
the coronary system for treatment. 
The novel structure permits construction at the entry position of the guide 
wire into the catheter body at a position having a common shape and 
consistent still axial strength with the rest of the catheter body to 
facilitate feeding into a treatment site. A lateral modulus of elasticity 
sufficient to permit bending about sharp curves is provided within the 
plastic catheter body devoid of stiffener wires. The bending is enhanced 
around curves by the novel form of the inflating lumen as a C-shaped 
lumen, which bends readily as the catheter is inserted. It also readily 
permits withdrawal and replacement of small diameter catheters in small 
passagesways with progressively increasing balloon sizes when needed. 
When a catheter and a guide wire are inserted into an arterial vessel of 
sufficient size over an introducer sheet, the diameter of the dilatation 
catheter plus that of a guide wire lying outside the catheter is not 
critical to the possibility to introduce the system into the human body. 
But there are conditions where severely diseased and narrowed vessels make 
the size of the introducer sheet critical to the success of insertion. In 
those cases, the overall diameter of the dilation catheter and the guide 
wire together can be decreased if a groove is present along the entire 
catheter structure forwards of the outside of the body. By this means the 
guide wire is situatied within the circumferential groove in the dilation 
catheter enabling small size introducer sheets.

THE PREFERRED EMBODIMENT 
In the present invention , the catheter can be given special and critical 
properties by means of treatment of plastic materials from which the 
catheter is formed. For example, silicones, polyethylenes, polyurethanes, 
polyvinylchlorides and like synthetic plastic materials are readily formed 
into desired shapes by injection molding techniques, and may be after 
treated by thermal molding. 
The distal rider end of the catheter afforded by a preferred embodiment of 
this invention also is molded from a suitable plastic material to have a 
gradual transformation along the axial length from an initial 
substantially round cylindric shape to a modified shape of the dilatation 
fluid lumen without abrupt changes from a generally cylindrical 
configuration of constant diameter for penetration of a guide wire into a 
gradually created second guide wire lumen formed inside the catheter body. 
The catheter body comprises an outer body skin defining an internal 
cylindrical dilation fluid lumen which is gradually conformed along a 
predetermined portion of the length into a riding saddle over the guide 
wire. 
Along this length, which permits the guide wire to remain along its length 
with a substantially parallel axis with the catheter body, the catheter 
body wall gradually progresses from a groove into a crescent shaped wall 
and internal lumen which at least partly surrounds the guide wire. The 
crescent closes toroidally about the guide wire to form a guide wire lumen 
which gradually extends toward the axis of the catheter body as the 
dilating lumen and outer configuration tapers into a terminal nose of 
solid plastic material. The generally cylindrical body shape is maintained 
at a constant diameter, with a cylindrical outer region positioned between 
the entry point of the guide wire and the nose for attachment of a 
circumferential dilatation balloon. Communication between the balloon and 
dilation fluid in the dilation lumen results from apertures in the body 
wall. 
Throughout the transition portion of the length catheter axial stiffness is 
maintained constant to facilitate entry and withdrawal of the catheter. 
Lateral bending elasticity is provided by the material and shaping of the 
lumen without substantially departing from the initial cylindric shape in 
order to facilitate bending in conformation with body vessels. 
The balloon or balloon mounting vicinity of the catheter may be radiation 
tempered. The C-shaped lumen may be reinforced by shaping or adding 
reinforcement means internal to the lumen at any points of critical stress 
under pressure caused by non-round lumen shaping. The tempered portions of 
the catheter can be treated to give a lateral bending modulus for 
similarly bending around curves without significant effect to the axial 
pushing stiffness required for positioning and withdrawing the catheter 
over a substantially parallel guide wire. Preferably the balloon at the 
distal end terminates near a solid plastic nose section tapered to provide 
less friction in penetrating a stenosis area for example to position the 
balloon for dilatation. Also preferably the balloon exterior perimeter 
tapers at both ends and has no disruptions. 
By having a common circumferential plastic body about the dilatation lumen 
cavity smoothly an progressively changing along the catheter length into 
an interior guide wire lumen without abutments or steps in the catheter 
diameter, many problems of exerting distortion forces on the catheter or 
balloon surface for reaching treatment sites are eliminated. This all 
results in a more reliable, low friction, easy to insert balloon dilation 
catheter with a smaller diameter catheter in the region of the balloon 
than known in the prior art. 
As may be seen in FIGS. 1 and 2, the catheter of this invention is ideally 
suited for treament of cardiac disease such as stenosis 32 of arterial 
vessel wall 31. The catheter 20 is inserted into the cardiovascular system 
typified by vessel 31 over a previously inserted guide wire 21 which runs 
parallel outside the catheter until it reaches a distal end region 23 for 
guiding the catheter to carry instrumentation such as a dilatation balloon 
located near its distal end to a treatment site 32. 
This catheter is of the type that as it nears the distal end 23, the guide 
wire 21 is gradually more and more encompassed and thus little friction 
between the guide wire and catheter is present to impede insertion or 
withdrawal of the catheter from a position outside the body. The catheter 
at region 2--2 of this embodiment is generally of cylindrical shape having 
an internal inflation lumen 42 for fluid under pressure to expand a 
dilatation balloon in the distal end region 22. The catheter body is 
formed of a plastic material 26 having enough axial stiffness to push the 
distal end 23 over the guide wire 21 and through small or stenosis 
restricted cardiovascular blood vessels into a treatment site without 
buckling or restricting the lumen 42 diameter, as aforesaid. 
The catheter throughout the distal end regions 4--4 to 10--10, as shown in 
cross section in corresponding FIG. 4 through 10, undergoes smoothly 
progressing changes of shape of the wall 26 and lumen 42. The distal 
terminal end at FIG. 10 is of solid plastic which tapers to a penetration 
shape, which helps to advance the balloon more easily over an already 
positioned guide wire through high degree narrowings so that the balloon 
section of FIG. 9 may be placed into position for dilatation as shown in 
FIG. 2 within the blood vessel 31 at stenosis site 32. The guide wire 
facilitates withdrawal of the catheter 20 along the guide wire 21 and 
allows its replacement with one having a larger diameter head end portion 
allowing a greater degree of dilatation. Because of the easy insertion of 
the guide wire into the novel guiding lanes and of the limited length of 
guidance of the wire in the balloon possible with this invention, initial 
treatment with a smaller balloon can readily be followed by a subsequent 
treatment with a larger balloon without the need for extensive guiding of 
the new catheter over a guide wire of more than double the length of the 
catheter. 
The smoothly changing shape of the catheter along its axial length at the 
balloon site critical to this invention allows for an exchange of 
catheters without significant friction thus facilitating easy and fast 
pull back and advance of subsequent catheter structure over a guide wire. 
This can be visualized as related to the cross sections of FIGS. 3 to 10. 
Thus the catheter plastic body wall 26 becomes more deeply grooved at 40 
for guiding the guide wire toward its final position, in this embodiment 
coaxial with the balloon as shown in FIG. 10. Thus guide wire 21 enters 
the catheter body axially from left to right (FIG. 1) through a groove, a 
crescent shaped semi-enveloping configuration, FIGS. 5 and 6, and then 
completely surrounded as in FIGS. 7 through 10. Thus the catheter is 
transformed from a single lumen catheter into two lumens, adding one for 
the guide wire, all without changing substantially the outer cylindrical 
body configuration or its diameter. Furthermore, the guide wire gradually 
enters its new guiding lumen through several changes of guidance within a 
groove, and thus incurs no kinking or sharp bending as mandatory for low 
friction removal or advance of the catheter over the guide wire. 
Also the lumen shape changes gradually within the catheter 20 as seen 
through the progression of FIGS. 3 to 9, for this embodiment. Note that 
the balloon 90 has an outer skin 91 which is distendable in the presence 
of fluid in the inflating lumen 42 under increased pressure into an 
expanded diameter 90 shown in phantom view. This balloon is affixed to the 
outer cylindrical catheter surface at each end. That is critical in that 
high internal pressures are minimized and equalized about the joint, 
resulting in more reliability and operation at greater safety margins. 
The small diameter of the catheter 20, especially at zone 23, permits good 
lateral flexibility to bend around curves in the cardiovascular vessels. 
At the tip 100, a special material with some pliability is preferred for 
use in penetration of a stenosis region and this may be achieved by 
thermal or radiation treatment. 
The smooth progressive change of shape of the catheter body 26 and its 
internal inflating lumen 25 to convert the single lumen catheter to one 
having an additional internal guide wire lumen 45 without substantially 
changing the direction of travel of the guide wire and the constant outer 
catheter diameter throughout is typified by the sequence in the FIGS. 3 to 
10. Thus the catheter body 26 of FIG. 3 becomes grooved at FIG. 4, with 
the body 26 and internal lumen 42 becoming crescent shaped at FIGS. 4 and 
5. The internal lument 415 is formed at FIG. 7 so that the balloon 90 may 
be glued or otherwise affixed to the outer cylindrical periphery of the 
catheter body 26 at 91 in FIGS. 2 and 8. The aperture 95 in the catheter 
body 26 of FIG. 9 permits balloon 90 to be dilated from fluid in lumen 42 
to the inflated balloon condition 90. The lumen 42 is tapered toward the 
nose 100 shown in FIG. 10 to provide a low profile solid penetrating probe 
end. During this entire transition, the catheter maintains its cylindrical 
shape and diameter. 
Accordingly it is seen heretofore and in the appended claims that this 
invention has advanced the state of the art with those novel features 
defined in the claims for examplifying the nature and spirit of the 
invention.