Highly steerable dilatation balloon catheter system

A dilatation balloon catheter with a non-removable guidewire is disclosed in which the guidewire is joined to the catheter tube through a distortable element, preferably a twistable tube. The element provides a strong fluid-tight connection between the guidewire and catheter tube and yet permits the guidewire to be rotated relative to the catheter tube over a wide range of rotation, with little torsional stress on either the catheter tube, the balloon or any other element of the catheter construction. In preferred embodiments, the catheter construction further includes a column support tube inside the balloon, surrounding a segment of the guidewire toward its distal end, to prevent collapse of the balloon along its longitudinal axis as the balloon is advanced into a stenosis. In these embodiments, the distortable element is joined to the catheter tube through the column support tube which thus serves as an intermediate linkage.

This invention relates to catheters, and in particular to dilatation 
balloon catheters, including both intravascular dilatation balloon 
catheters which are percutaneously and intraoperatively installed and 
urologic dilatation balloon catheters. 
BACKGROUND OF THE INVENTION 
In 1977, Dr. Andreas Gruntzig first used a balloon-tipped flexible catheter 
to percutaneously dilate a region of stenosis within the coronary artery 
of a patient suffering from atherosclerotic heart disease. Since that 
time, the use of percutaneous transluminal coronary angioplasty has 
increased exponentially, and over the past eight to ten years, has become 
a routine procedure in many major medical centers throughout the world. 
With the advent of improved technology and operator skill, the indications 
for and use of this procedure have increased substantially. With such 
increased use, a need has developed for systems which have a low "crossing 
profile" (cross-sectional diameter of the balloon in the deflated state), 
low "shaft profile" (cross-sectional diameter of the catheter body), high 
"pushability" (resistance to collapse along the axial direction) and high 
"steerability" (directional control within the course of a body vessel). 
The reasons are as follows. 
Lower profile systems offer several advantages over their larger profile 
counterparts. Systems with lower crossing profiles offer lowered 
resistance during advancement within the vasculature, and consequently 
offer greater ease of installation across the confines of intravascular 
lesions relative to comparable systems of larger crossing profile. A 
further advantage is that these systems can be used in critical lesions 
that cannot accommodate catheters of larger profile crossing profile. 
Systems with lower shaft profiles provoke less interruption to the 
surrounding flow of fluids (i.e., blood, blood substitutes, contrast 
medium and medications) following introduction within the vasculature, and 
are thus less prone to provoke ischemia, impair the delivery of 
medications and compromise the resolution of intraoperative angiography, 
relative to comparable systems of larger crossing profile. 
Systems with greater pushability are easier to advance through regions of 
the vasculature that provoke resistance to catheter introduction relative 
to systems that provide inferior pushability. For purposes of this 
discussion, the term "pushability" will be used to denote the degree to 
which the catheter component of the system can be advanced into the 
vasculature without experiencing axial compression. Axial compression is 
the twisting, gathering or any other form of bending back of the balloon 
or shaft along the longitudinal axis of the system, which might occur in 
response to friction from the vasculature or, in the case of percutaneous 
transluminal coronary angioplasty, in response to friction from the 
guiding catheter which conducts the angioplasty catheter-guidewire system 
from the vascular access site to the origin of the coronary artery 
requiring treatment. 
Systems with greater steerability are easier to direct through tortuous 
regions of the vasculature requiring treatment relative to those with less 
steerability, and thus offer a variety of features to balloon-mediated 
intravascular dilatation, including enhanced safety, facility and 
efficiency. Thus, the ease of positioning a catheter system for use varies 
directly with its "steerability" and "pushability," and inversely with the 
"crossing" and shaft profile of the system. 
The shaft profile of a catheter-guidewire system varies with the number of 
channels contained within the catheter shaft. Other things being equal, 
multi-channel systems have larger profile shafts relative to 
single-channel systems. The pushability of a catheter system varies 
directly with the axial rigidity of the structural element (typically the 
guidewire mandrel or catheter body) that provides axial support to the 
system. Guidewire mandrels are constructed of stainless steel, which is 
less compliant than the polymeric materials commonly used in the 
construction of catheter bodies. For this reason, systems that rely upon 
the guidewire mandrel for column support (i.e., support of the balloon 
against axial compression) typically provide superior pushability relative 
to systems that rely upon the catheter body for this purpose. 
The steerability of a catheter-guidewire system, in general, depends on the 
ease with which the guidewire can be rotated within a body vessel. This 
rotational mobility of the guidewire in turn is directly related to the 
ease with which the guidewire can be rotated relative to the catheter 
component. The reason is that the catheter component in most 
guidewire-directed catheter systems is substantially larger in external 
profile than the guidewire, and hence more difficult to rotate within a 
body vessel. The extent to which the catheter component must rotate in 
order to achieve rotation of the guidewire component will therefore affect 
the rotational mobility of the guidewire. Hence, those systems in which 
the guidewire component rotates independently relative to the catheter 
component offer superior steerability. 
The original catheter conceived by Dr. Gruntzig is disclosed in Gruntzig, 
A., et al., U.S. Pat. No. 4,195,637, Apr. 1, 1980. Use of this device was 
abandoned in the early 1980's following the introduction of 
"over-the-wire" systems which offered both exchangeability and superior 
steerability. One such catheter is that disclosed by Simpson, J. B., et 
al., U.S. Pat. No. 4,323,071, Apr. 6, 1982. The term "exchangeability" 
denotes the ability of the guidewire and the catheter body to be separated 
while inside the vasculature for purposes of removing one or the other and 
replacing the removed component with a substitute component which differs 
in some respect, the exchange thereby taking place without the need to 
reestablish intraluminal access. 
Although over-the-wire devices remain popular, experience has shown that 
these devices frequently cannot be advanced through the confines of 
critical lesions and thus cannot be used to treat such lesions. This 
limitation led to the development of "non-over-the-wire" systems, which 
have lower crossing profiles and frequently superior pushability relative 
to over-the-wire systems, and can thus be advanced within the confines of 
critical lesions that will not readily accommodate over-the-wire systems. 
Non-over-the-wire systems include: (1) "semi-movable" catheter systems, (2) 
"fixed-wire" catheter systems, and (3) "balloon-on-a-wire" catheter 
systems. The guidewire components of these systems are permanently held 
inside the respective catheter tube and balloon components (i.e., the 
catheter components) of these systems. These systems differ among 
themselves however in the mobility of the guidewire components relative to 
the catheter components. An example is disclosed by Samson, W. J., et al, 
U.S. Pat. No. 4,616,653, Oct. 14, 1986. Fixed-wire catheters permit 
limited rotational and yet no coaxial mobility of the guidewire components 
relative to the catheter components. An example is disclosed by Samson, W. 
J., U.S. Pat. No. 4,582,181, Apr. 15, 1986. Balloon-on-a-wire systems 
permit no mobility of the guidewire components relative to the catheter 
components. An example of a balloon-on-a-wire device is disclosed by 
Crittenden, J. F., U.S. Pat. No. 4,917,088, Apr. 17, 1990. 
Non-over-the-wire systems offer several structural and functional 
advantages relative to over-the-wire systems. Non-over-the-wire systems 
are generally easier to prepare and easier to advance across critical 
lesions. Such systems furthermore contain pre-installed guidewires and 
thus do not require preparation with guidewires. Still further, such 
systems can be advanced more easily through the confines of critical 
stenoses due to the lower crossing profiles of these systems and their 
superior pushability. In some respects, non-over-the-wire systems also 
offer safety advantages due to their lower shaft profiles: (1) the systems 
are less prone to provoke ischemia; (2) they are less prone to impair the 
delivery of medications; and (3) they permit the performance of 
intra-operative angiography with enhanced resolution. 
These attributes have been achieved, however, at the expense of certain 
others. For example, none of these systems permit separation of the 
guidewire components from the catheter components. Hence, none of these 
systems are exchangeable and thus their use obligates sacrificing 
intraluminal access in the event of an exchange procedure. In the case of 
selected single-channel fixed-wire and balloon-on-a-wire systems, these 
attributes further have been achieved at the expense of steerability and 
structural integrity. 
The advantages and disadvantages of selected fixed-wire and 
balloon-on-a-wire systems vis-a-vis over-the-wire systems relate, in part, 
to the practice of bonding the catheter component (and in particular the 
distal balloon component) to the guidewire component in the construction 
of these systems. Samson, W. J., U.S. Pat. No. 4,582,181, Apr. 15, 1986, 
discloses a single-channel fixed-wire system that contains one such bond 
at the distal catheter-guidewire interface. Crittenden, J. F., U.S. Pat. 
No. 4,917,088, Apr. 17, 1990, similarly discloses a single-channel 
balloon-on-a-wire system that contains such a bond at the distal 
catheter-guidewire interface. In these and similar systems, the bond 
between the balloon and guidewire serves several functions: 
(1) It joins the distal aspect of the balloon to the guidewire; 
(2) It prevents fluid and gas leakage from the distal aspect of the 
hydraulic channel and balloon; and 
(3) It permits the guidewire to support the balloon against the possibility 
of axial collapse as the balloon is being advanced through a stenosis. 
In short, these bonds enable the construction of air-tight, hydraulically 
competent, guidewire-directed non-over-the-wire systems with single 
channels and guidewire-mediated column support. Stated differently, these 
bonds permit these devices to be constructed with lower shaft profiles and 
superior pushability relative to over-the-wire systems, which do not 
contain such bonds and rely upon the respective catheter bodies for column 
support. For these and other reasons, these bonds are fundamental to the 
structure and function of selected single-channel fixed-wire and 
balloon-on-a-wire devices. 
Bonding the balloon to the guidewire, however, comprises the steerability 
of fixed-wire and balloon-on-a-wire systems. This bond tethers the 
guidewire to the catheter tube as well, and as a result the rotational 
resistance of both the catheter tube and the balloon is transmitted to the 
guidewire. This in turn limits the ease with which the guidewire can be 
rotated within a body vessel, thereby compromising the steerability of the 
entire composite system. For practical purposes, therefore, the ease with 
which the guidewire can be rotated relative to the catheter tube in 
fixed-wire devices such as that disclosed by Samson, W. J., U.S. Pat. No. 
4,582,181, Apr. 15, 1986, is limited by the balloon's ability to 
accommodate torsion. Generally, these devices permit two or three complete 
(360.degree.) turns of the guidewire in each direction relative to the 
catheter tube. 
In addition to compromising steerability, the presence of a bond between 
the balloon and the guidewire compromises the structural integrity of 
single-channel fixed-wire and balloon-on-a-wire systems. In fixed-wire 
systems, the bond renders the device susceptible to over-wrapping of the 
balloon. When the guidewire in devices such as those disclosed by Samson, 
W. J., U.S. Pat. No. 4,582,181, Apr. 15, 1986, is given more than three 
complete turns in one direction relative to the catheter component, the 
balloon becomes tightly wrapped over the guidewire. Further rotation of 
the guidewire relative to the catheter component (and hence the balloon) 
generates increasing torsion within the balloon and guidewire. This raises 
the risk of causing tears in the balloon and fractures in the guidewire. 
To prevent such balloon wrapping and the occurrence of tears and 
fractures, torque limiters have been developed. An example is disclosed in 
U.S. Pat. No. 4,664,113 to Frisbie, J. S., et al., May 12, 1987. 
The presence of the bond similarly compromises the structural integrity of 
balloon-on-a-wire systems. These systems typically do not provide any 
mobility of the guidewire component relative to the catheter component. 
Directional control of these systems is accomplished by rotating the 
entire system. During the treatment of critical lesions, the balloon 
components of these systems can become "hung up" within the confines of a 
body vessel, and will thus resist rotation. If the operator continues to 
apply rotational torque to the guidewire in an attempt to overcome this 
resistance and thereby restore directional control to the system, 
sufficient torsion may accumulate in the region of the bond to fracture 
the delicate distal segment of the guidewire or to tear the thin walls of 
the balloon. 
From the foregoing, it is evident that there is a need for 
non-over-the-wire devices that have the crossing profile and pushability 
of a fixed-wire or balloon-on-a-wire device and yet afford greater 
guidewire rotational mobility and hence superior directional control and 
structural integrity than these systems presently offer, and that are 
simple in design and amenable to construction by mass production 
techniques. Such devices would enable one to perform an angioplasty within 
the confines of critically stenotic lesions with enhanced safety, 
facility, efficiency and finesse. These and other objects are addressed by 
the present invention. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a non-over-the-wire catheter 
system is provided in which the connecting structure between the guidewire 
and the catheter tube includes a distortable element which twists to 
accommodate the rotation of the guidewire within the catheter tube without 
interfering with the ability of the balloon to inflate or with the flow of 
fluids between the catheter lumen and the balloon. The distortable element 
comprises a length of flexible tubing, disposed over and coaxial to the 
guidewire component of the system, one end of which is secured to the 
guidewire component by a fluid-tight bond, while the other end is secured 
to the distal inner lumen of the balloon component, either directly or 
indirectly, by a fluid-tight bond. This distortable element constitutes a 
segment of the inner surface of the hydraulic channel of the system and 
functions to: (1) retain fluid under pressure, (2) permit limited 
rotational mobility of the guidewire component relative to the catheter 
component of the system, and (3) minimize the development of potentially 
damaging shear forces at the distal catheter-guidewire interface during 
guidewire rotation. The distortable element may be located anywhere along 
the length of the catheter, from the balloon interior to locations in the 
catheter lumen close to the catheter's proximal end without permitting 
loss of fluid and yet without interfering with the pressurization and 
depressurization of the balloon. The distortable element is thus comprised 
of liquid-permeable, and preferably both liquid- and gas-permeable, yet 
twistable material. 
In preferred embodiments, the distortable element is combined with a 
non-distortable tubular element to form a continuous length of tubing, 
with the non-distortable tubular element connected to the catheter tube. 
The connection between the distortable element and the catheter tube is 
thus an indirect one, with the non-distortable tube serving as an 
intermediate linkage. The non-distortable tube is one which is resistant 
to twisting (rotational distortion) and to column collapse (axial 
distortion), and in preferred embodiments is secured inside the catheter 
in such a way as to provide column support for the balloon, i.e., support 
against collapse of the balloon along the balloon's longitudinal axis, as 
the balloon is being advanced through a stenosis. The distortable and 
non-distortable tubular elements can be constructed from a single length 
of tubing, treated differently along its length to render the tubing 
distortable at one end and non-distortable at the other end, or from a 
plurality of tubular elements distinct from each other in composition and 
distortability, joined end-to-end by means of fluid-tight and pressure 
tolerant seals. In these embodiments, the guidewire is coaxial to, and 
extends through the confines of, the distortable and non-distortable 
elements. This combination of distortable and non-distortable elements 
preserves the hydraulic integrity of the system, provides rotational 
mobility to the guidewire, provides guidewire-enhanced column support to 
the balloon component and minimizes the development of shear forces 
consequent with guidewire rotation. 
Column support for the balloon can be provided in a variety of different 
ways in catheter systems that employ the present invention. For example, 
the non-distortable tubular element may extend through the length of the 
balloon element and be secured at one end to the distal aspect of the 
balloon and at the other to the distal end of the catheter tube proximal 
to the balloon. Bonded to the catheter in this manner, the non-distortable 
tubular element provides column support to the balloon by directly 
maintaining axial elongation of the balloon. In an alternative embodiment, 
the guidewire contains a stop which cooperates with a shoulder on the 
non-distortable element and thereby confers column support from the 
guidewire component to the distal aspect of the balloon, and thus axial 
elongation of the balloon. This embodiment provides superior pushability 
because column support is derived from the guidewire itself. The length of 
the non-distortable element in this embodiment is not critical to the 
column support, and the non-distortable element may therefore be reduced 
in length or eliminated entirely. The distortable element in this 
embodiment may be located either inside or outside the balloon. 
By varying the composition, structure and length of the distortable 
element, particularly when the distortable element is twistable tubing, 
one can vary the extent to which the guidewire can be rotated inside the 
catheter tube, and thereby attain a high degree of guidewire rotational 
mobility and catheter steerability. The distortable element permits this 
to occur with minimal shear force on the other components of the catheter. 
This is achieved, furthermore, with a shaft, guidewire, hydraulic channel 
and crossing profile that are comparable in size to those of comparable 
single-channel fixed-wire and balloon-on-a-wire systems of the prior art. 
In each of its various embodiments, therefore, the present invention 
permits one to construct air-tight, fluid-tight and pressure-tolerant 
catheter systems which have the advantageously narrow shaft profile of a 
single-channel non-over-the-wire system, the advantageously narrow 
crossing profile of a non-over-the-wire system, and the advantageously 
superior pushability of a non-over-the-wire system (which system relies 
upon the guidewire for coaxial support), and yet offer substantially 
enhanced rotational guidewire mobility, steerability, and structural 
integrity relative to air-tight systems of the prior art. Other features 
and advantages of the invention will be apparent from the description 
which follows.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 
FIG. 1 illustrates the application of the present invention to a particular 
fixed-wire catheter construction. This catheter (not shown to scale) 
includes a balloon 10, a guidewire with a tapered mandrel 11 (shown more 
clearly in FIG. 1B), an outer catheter shaft or tube 14, and a proximal 
adapter 15. The distal end of the guidewire passes through two tubular 
elements 21, 22 inside the outer catheter tube 14 and the balloon 10 and 
terminates in a tip coil 12 emerging from the catheter end. 
The balloon component 10 is formed of conventional high strength polymeric 
material. Such material provides a balloon which is both tolerant to high 
pressure and thin-walled. 
The outer catheter tube 14 is preferred embodiments of this invention is 
constructed in two or more butt-joined segments. The embodiment of FIG. 1A 
includes two such segments 18, 19 joined by a hydraulically competent 
bond. The distal end of the distal segment 19 is joined to the proximal 
end of the balloon 10. By selecting materials of differing flexibility for 
the different segments, one achieves a catheter of improved pushability 
(resistance to axial compression) and steerability (ease of advancement 
within the tortuous confines of the vasculature) relative to catheters 
with outer catheter tubes of uniform rigidity. The proximal segment 18 of 
the embodiment of FIG. 1A, for example, is more rigid than the distal 
segment 19. For catheters of the standard length of 130-140 cm, the distal 
segment 19 has a length Y which measures approximately 20-30 cm. 
Of the two inner tubular elements 21, 22, the more distal 22 of the two is 
relatively rigid and extends the full length of the balloon 10, while the 
more proximal element 21 is relatively flexible. The distal element 22 is 
the element providing column support for the balloon, while the proximal 
element 21, whose proximal end is bonded to the surface of the guidewire 
11, is the distortable element which twists to accommodate the turning of 
the guidewire relative to the outer catheter tube 14. In this embodiment, 
the distortable element 21 extends from the proximal end of the balloon to 
the most proximal taper 24 of the guidewire mandrel 11. For a catheter of 
the standard 120-140 cm length, this distance X measures 20-30 cm. This 
distance can be shortened or lengthened, however, to accommodate the 
requirements of the system. For similar reasons, the length of the 
distortable element 21 can be lengthened or shortened relative to the low 
profile (small diameter) segment of the guidewire mandrel 11. Detailed 
descriptions of various forms of the distortable and non-distortable 
elements appear below. A preferred material for the distortable element 21 
is PEBAX, a urethane-nylon composition manufactured by Atochem, Inc., of 
Glen Rock, N.J., while a preferred material for the column support tube 22 
is polyimide. 
In this embodiment, the distal end of the distortable element 21 is bonded 
to the proximal end of the column support element 22 at a joint 25, while 
the proximal end of the distortable element 21 is bonded to guidewire 
mandrel 11 at the first taper 24. The distal end of the column support 
element 22 is joined to the distal luminal surface of the balloon 10 at a 
joint 26. These joints and inner tubular elements, together with the 
exposed portion of the guidewire 11 proximal to the most proximal taper 
24, form the inner radial boundary of a closed annular hydraulic channel 
17, which is the space lying between these surfaces and the inner surface 
of the outer catheter shaft 14. The hydraulic channel 17 extends the 
length of the device and is in fluid communication with the interior of 
the balloon 10. The channel serves to convey hydraulic fluid and transmit 
hydraulic pressure along the length of the device. 
The column support element 22 is resistant both to twisting and to collapse 
along its longitudinal axis. At its proximal end, the column support 
element 22 abuts a support chip or flange 54 (visible in FIG. 1C) affixed 
to the guidewire mandrel in a manner that permits rotational mobility of 
the column support element 22 and yet resists coaxial mobility of the 
element relative to the guidewire mandrel. This configuration enables the 
guidewire to impart column support to the balloon component of the system 
without compromising the rotational mobility of the guidewire component 
relative to the catheter component, and thus the steerability of the 
composite system. In contrast to the column support element 22, the 
distortable element 21 is twistable and thereby provides rotational 
mobility of the guidewire mandrel 11 relative to the outer catheter tube 
14. The flexibility of the distortable element 21 permits it to wrap 
around its long axis in response to the application of torsional force. 
Since the distortable element 21 is not relied upon for providing column 
strength to the balloon and since it is supported by the underlying 
guidewire 11 during balloon inflation, the distortable element 21 can be 
constructed with particularly thin walls. 
The guidewire 11 terminates at its distal end in a radiopaque tip coil 12 
and shaping ribbon (not shown). The proximal end of the tip coil 12 and 
shaping ribbon are attached to the guidewire 11 at a location immediately 
distal to the balloon 10. The proximal end of the guidewire coils extend 
of the distal end of the catheter to provide a smooth transition between 
the catheter and guidewire, and yet one with sufficient clearance to 
permit rotational mobility of the guidewire relative to the catheter tube 
14. The distal end of the tip coil 12 is secured to the distal end of the 
shaping ribbon at a tip joint 23. The guidewire mandrel 11 and tip coil 12 
are rotationally mobile relative to the balloon 10 and the column support 
element 22. 
A marker band 27, which is radiopaque or of otherwise detectable material, 
is secured to the proximal end of the column support element 22. Thus 
positioned at opposite ends of the balloon, the marker band 27 and tip 
coil 12 permit one to precisely identify the location of the balloon 10 
during tracking of the catheter by fluoroscopic or otherwise appropriate 
methods. 
The proximal adapter 15, shown in reduced scale at the bottom of FIG. 1A, 
consists of a rotational element 29 and a stationary element 13 that are 
joined by means of a fluid-tight, high pressure tolerant interface 16 that 
limits intercomponent rotational mobility in either direction to a preset 
number of complete turns. An example of one such rotation limiter is 
disclosed in co-pending U.S. patent application Ser. No. 07/709,572, filed 
Jun. 3, 1991. Typical devices of this construction will accommodate 
approximately six to thirty complete turns in either direction. The 
rotational element 29 is bonded to the proximal aspect of the guidewire 
11. The operator rotates the rotational element 29 to rotate the guidewire 
and thereby steer the composite device within the confines of the 
vasculature. 
The stationary element 13 contains at least one sideport 28. The open end 
of this sideport is designed to mate with male Luer Lock components (not 
shown). The sideport 28 provides access to the hydraulic channel 17, and 
the balloon 10 is inflated by infusion of fluid into the sideport 28. A 
strain relief element 30 spans the interface between the proximal adapter 
and the outer surface of the outer catheter tube 18. The strain relief 
element is attached to the catheter tube and the stationary element 13 by 
means of a cap 31. 
FIG. 1B is a view of the distal aspect of the device shown in FIG. 1A, in 
full cross section. This figure illustrates the tapered configuration of 
the guidewire mandrel 11, as well as the structural relationship of the 
guidewire to the remaining components of the device. FIG. 1C is an 
enlargement of the "INSET" portion of FIG. 1B, indicating the spatial 
relationships of the column support element 22, the distortable element 
21, a shoulder 58 extending around the inner surfaces of the both the 
column support element 22 and the distortable element 21 at their 
juncture, the marker band 27, and the guidewire flange 54. 
To achieve column support, the balloon must be prevented from longitudinal 
collapse in the reverse axial direction (to the left in the view shown in 
the drawings) as the structure is advanced through a vasculature in the 
forward axial direction (to the right). Since both the balloon 10 and the 
distortable element 21 are sufficiently flexible to be vulnerable to this 
type of axial compression, the structure utilizes the guidewire 11 to 
maintain axial support of the distortable tubular element 21. This support 
is in turn transmitted to the balloon 10 by the column support element 22. 
Axial support of the distortable tubular element 21 is provided by the 
flange 54 which encircles the guidewire mandrel 11. The flange 54 abuts 
the shoulder 58 on the inner surfaces of the distortable and column 
support elements, thereby serving as a stop which prevents the tubular 
distortable element 21 from collapsing longitudinally toward the left. The 
flange 54 is capable of rotation relative to the shoulder 58, so that the 
guidewire remains free to rotate relative to the outer catheter tube, but 
the flange is incapable of axial movement past the shoulder. Column 
support is thus achieved without any kind of proximal bond, and with 
improved fluid communication between the annular hydraulic channel 17 of 
the catheter and the interior of the balloon 10. 
FIGS. 2A, 2B and 2C are detailed profile views of the distal aspect of a 
device like that of FIGS. 1A-1C, differing only in the taper configuration 
of the guidewire mandrel 11. All other parts of the system are identical 
to those of FIGS. 1A-1C. The distortable element 21, the column support 
element 22 and the marker band 27 are shown in full view rather than cross 
section in FIGS. 2A and 2C. FIG. 2B is a full cross section view 
illustrating the spatial relationships of the various components of this 
portion of the device, and particularly the relationship of the column 
support element 21 relative to the guidewire flange 54. FIG. 2C 
illustrates the change in configuration which the distortable element 21 
undergoes upon rotation of guidewire 11 relative to the catheter shaft 14. 
This change is a twisting of the distortable element about its 
longitudinal axis and the wrapping of the distortable element around the 
guidewire, in response to the torsional force caused by rotation of the 
guidewire. The torsional force required to twist the element in this 
manner is minimal. 
By utilization of the features illustrated in FIGS. 1A-2C, one can 
construct an air-tight, fluid-tight and pressure-tolerant low-profile 
fixed-wire dilatation balloon delivery system with advantages over 
single-channel fixed-wire systems of the prior art that contain adhesive 
bonds at the distal catheter-guidewire interface. These advantages 
include: 
(a) superior structural integrity, i.e., diminished propensity to sustain 
over-rotation of the balloon component, torsionally-mediated tears within 
the balloon walls and fratures within the guidewire mandrel, and 
(b) superior guidewire rotational mobility and hence superior steerability. 
These advantages are achieved while retaining pushability, shaft profile, 
crossing profile and hydraulic performance commensurate with the 
single-channel fixed-wire prior art systems. When comparing systems 
incorporating these features with over-the-wire systems of the prior art, 
further advantages are obtained. These include superior pushability, 
superior shaft profile and superior crossing profile. Furthermore, systems 
incorporating these features are simple to construct and amenable to 
manufacture with conventional mass production techniques. 
FIGS. 3A, 3B and 3C are similar profile views of the distal aspect of 
another dilatation balloon catheter-guidewire device within the scope of 
this invention, slightly different from the devices of FIGS. 1A-2C. In 
FIGS. 3A and 3C, the distortable element 21, the column support element 22 
and the marker band 27 are shown in full view rather than in cross 
section, with FIG. 3C illustrating the change in configuration which the 
distortable element 21 undergoes upon rotation of guidewire 11 relative to 
the catheter shaft 14 in the direction indicated by the arrow 37. FIG. 2B 
is a full cross section illustrating the spatial relationships of the 
various components. The device of FIGS. 3A, 3B and 3C differs from that of 
FIGS. 2A, 2B and 2C by virtue of: (1) the length of the column support 
element 22, (2) the spatial relationship of the guidewire flange 54 to the 
marker band 38, and (3) the spatial relationship of the marker band 38 to 
the distortable element 21. In the device of FIGS. 3A, 3B and 3C, the 
marker band 38 is disposed inside the distortable element 21 and is 
attached directly to the guidewire 11. 
In the structure shown in FIG. 4, the column support element 45 and the 
distortable tubular element 44 have been shortened. Both the distal end 47 
and the proximal end 48 of the distortable element 44 lie inside the 
balloon. In this embodiment, axial support of the balloon component is 
provided by shoulders 58 which are bonded to the inner luminal surfaces of 
the distortable and column support elements 44, 45, and which straddle the 
guidewire flange 54 in a manner that permits rotational mobility of the 
guidewire mandrel 11 relative to the tubular elements. A steerable 
fixed-wire catheter-guidewire system constructed in this manner offers a 
potentially lower crossing profile and potentially superior flexibility 
(and hence trackability) within the region of the balloon 10 relative to 
the systems described above. 
A further dilatation balloon catheter-guidewire device within the scope of 
this invention is shown in FIGS. 5A, 5B and 5C. The views correspond to 
those of FIGS. 2A-2C and FIGS. 3A-3C. The differences here are: (1) the 
length of the column support element 22 which here extends the full length 
of the confines of the balloon 10, (2) the presence of a bond 20 joining 
the proximal end of the column support element 22 to the luminal surface 
of the outer catheter tube 14 (which bond extends around only a portion of 
the circumference of the tube, thereby leaving room for fluid 
communication), and (3) the location of the marker band 27. Unlike the 
embodiments illustrated in FIGS. 3A-3C and 4, the balloon component of 
this device is supported axially by the outer catheter tubing 14 and not 
the guidewire mandrel 11. 
By using the arrangement of elements shown in FIGS. 5A-5C, one can 
construct highly steerable low-profile fixed-wire devices which afford 
catheter shaft-mediated pushability. This arrangement can also be used in 
the construction of semi-movable devices. As indicated above, semi-movable 
devices provide variable rotational and limited coaxial guidewire 
mobility. The use of an elastomeric material in the construction of the 
distortable element 21 of this embodiment provides the guidewire with 
limited mobility in both rotational and axial directions relative to the 
outer catheter tube 14. A suitable elastomeric material for this 
application is a urethane-nylon composition such as PEBAX, manufactured by 
Atochem, Inc., of Glen Rock, New Jersey. Like the distortable elements of 
the preceding figures, this elastomeric tubular segment 21 is interposed 
between the guidewire 11 and the column support element 22. 
The differences between typical semi-movable systems (not shown in the 
drawings hereto) and typical fixed-wire systems lie in the configuration 
of the proximal adapter (which is not shown in FIGS. 5A-5C) and in the 
number of marker bands. Unlike the fixed-wire system described previously, 
a semi-movable system may for example contain a marker band at the distal 
aspect of the balloon in addition to the marker band at the proximal 
aspect. The use of a pair of marker bands facilitates monitoring of the 
balloon location by fluoroscopy or other appropriate means as the catheter 
is being advanced through the vasculature. 
FIGS. 6A, 6B and 6C are profile views of the distal aspect of yet another 
embodiment of a catheter-guidewire system of the present invention. The 
views here as well correspond to those of FIGS. 2A-2C and FIGS. 3A-3C. The 
differences in this embodiment lie in the construction of the distortable 
and column support elements. Unlike the embodiments described above, the 
distortable and column support elements of this embodiment are constructed 
from a single length of tubing 56. In the case of this embodiment, the 
wall of one portion of the tubing 56 (the left half in the view shown in 
the drawings) has been thinned relative to the other to provide this 
segment with enhanced flexibility. 
FIGS. 7A and 7B are two profile view of the distal aspect of yet another 
embodiment of a catheter-guidewire system of the present invention. Like 
the embodiments described above, this embodiment also provides limited 
rotational and axial mobility of the guidewire relative to the catheter, 
but differs by providing axial mobility with enhanced ease. FIG. 7A shows 
the profile appearance of the distal aspect of the device with the 
guidewire fully retracted, while FIG. 7B shows the profile appearance of 
the device with the guidewire advanced relative to the catheter. While the 
device is similar in other respects to those of FIGS. 5A-5C and 6A-6C, the 
difference lies in the design and construction of the distortable element 
35. This element, which is preferably constructed of PET (polyethylene 
terephthalate), contains a series of corrugations which permit expansion 
and contraction of the element along its longitudinal axis, as well as 
rotation. These corrugations permit this expansion and contraction to 
occur with minimal force and with no risk of damage or fluid obstruction. 
In addition, upon the exertion of a torsional force, the element wraps 
easily around the guidewire. 
Any tubular element or tubular configuration that is fluid-tight, capable 
of withstanding elevated pressures without breakage, and that both twists 
rotationally and extends and contracts longitudinally, can be used in 
place of the corrugated construction of the element 35 shown in FIGS. 7A 
and 7B in the construction of a semi-movable device with a lower shaft 
profile than prior art devices. Consistent with the differences noted 
above between semi-movable and fixed-wire constructions, the semi-movable 
device of FIGS. 7A and 7B has a special proximal adapter (not shown) which 
permits the axial mobility of the guidewire, and two marker bands, one 27 
at the proximal aspect of the balloon and the other 28 at the distal 
aspect. 
FIGS. 8A and 8B are cross section profile views of another embodiment of a 
catheter-guidewire system of the present invention, this one, like that of 
FIGS. 7A and 7B, being another semi-movable device. FIG. 7A illustrates 
the appearance of the device with the guidewire in the fully retracted 
condition, while FIG. 7B illustrates the appearance of the device with the 
guidewire fully extended. The distortable element in this embodiment 
consists of a relatively rigid component 39 and a relatively flexible 
component 40, both tubular in form. The flexible component 40 affords both 
axial and rotational mobility to the guidewire mandrel 11. The flexible 
component 40 folds backward over itself as the guidewire is being advanced 
through the catheter, permitting mobility of the guidewire between the 
retracted position shown in FIG. 8A and the extended position shown in 
FIG. 8B. The column support element 22 is narrower but otherwise similar 
to that of FIGS. 7A and 7B. Note that in each of these configurations the 
rigid component 39 of the distortable element maintains a constant 
configuration and orientation, as do all other system components at the 
distal end of the catheter, and the hydraulic channel 17 remains fully 
sealed. 
Variations on the embodiment of FIGS. 8A and 8B are shown in FIGS. 9A, 9B, 
9C and 10. In these variations, the distortable element again consists of 
two components 61, 62, one of which 61 is both rotationally twistable and 
longitudinally stretchable, and the other 62 is relatively rigid. The 
twistable and stretchable component 61 may for example be constructed of 
an elastomeric material. The column support element 63 is analogous to 
that of the previous Figures. 
In the embodiment of FIGS. 9A-9C, FIG. 9A illustrates the distal aspect of 
the device with only the balloon 10, the catheter shaft 14 and the 
guidewire mandrel 11 in cross section. FIG. 9B shows the device in full 
cross section with the twistable and stretchable element 61 in a relaxed 
(neither twisted nor stretched) configuration, while FIG. 9C shows the 
device with only the balloon 10, catheter shaft 14, guidewire mandrel 11 
and rigid elements 62, 63 in cross section, to show the twistable and 
stretchable element 61 in a twisted condition caused by rotation of the 
guidewire in the direction indicated by the arrows 67. 
The embodiment of FIG. 10 is similar to that of FIGS. 9A-9C (in the same 
view as that of FIG. 9C) except for the length of the column support 
element 63, which is shortened sufficiently to place the distortable 
element 61 entirely within the confines of the balloon. 
The embodiment shown in FIG. 11 is analogous to that of FIGS. 9A-9C and 10, 
except that both components 61, 62 of the distortable element have been 
shortened as well, and there is no bond between any of the inner tubular 
elements and the catheter shaft 14, such as the bond 20 shown in FIGS. 
9A-9C and 10. In addition, the column support element has been eliminated 
entirely, and its function has been transferred to the rigid component 62 
of the distortable element. The twistable component 61 of the distortable 
element twists in response to the rotational force caused by rotation of 
the guidewire in the direction indicated by the arrow 67 but, unlike the 
corresponding components of the embodiments of FIGS. 9A-9C and 10, this 
component does not stretch axially. Column support for the balloon is thus 
achieved by the axial tension on the twistable component 61 as the 
guidewire 11 and the catheter shaft 14 are urged forward (to the right 
according to the view shown in the drawing). With the distortable element 
residing entirely inside the balloon, it is expected that the crossing 
profile of the device illustrated in this Figure will be lower than the 
crossing profiles of the devices illustrated in FIGS. 9A-9C and 10, where 
either all or part of the distortable element resides outside (at the 
proximal end of) the inflatable portion of the balloon. 
FIG. 12A illustrates a balloon-on-a-wire device which incorporates the 
present invention. FIG. 12B is an enlargement of the region at the 
proximal end of the balloon, labeled "INSET" in FIG. 12A, to illustrate in 
detail the structural relationships of the various components in this 
region. 
The balloon-on-a-wire device of FIGS. 12A and 12B includes a guidewire 
component which consists of a length of stainless steel hypodermic needle 
tubing 55, such as that sold under the trademark HYPOTUBE by Popper & 
Sons, Inc., New Hyde Park, N.Y., U.S.A., which is continuous with a 
guidewire mandrel 74, which in turn extends through the confines of the 
balloon 10 and terminates within the confines of the tip coil 12. 
Surrounding the mandrel 74 is a flange 54. The tip coil 12 is secured to 
the mandrel 74 by means of a solder joint 20, a ball tip 23 and a shaping 
ribbon (not shown) inside the tip coil. 
The catheter component includes a catheter tube 75, a balloon 10 secured to 
the distal end of the catheter tube 75, a column support tube 22, and a 
distortable element 21. The lumen 79 of the catheter tube 75 communicates 
with the interior of the balloon 10 and with the channel 53 of the 
stainless steel tubing. The column support tube 22 and the distortable 
element 21 are bonded together by means of a butt joint, and together 
constitute the inner tubular member of the device. The distal end of the 
column support tube 22 is secured to the distal end of the balloon 10 
whereas the proximal end of the distortable element 21 is secured to the 
guidewire mandrel 74 at some point proximal to the balloon 10 along the 
length of the mandrel 74. The column support tube 22 is rotationally 
disposed over the mandrel 74. Column support for the balloon 10 is 
provided by a flange 54 on the guidewire that engages a shoulder 58 which 
extends around the inside surface of the column support tube 22. 
At the proximal end of the device, the stainless steel tubing 55 is secured 
to a proximal adapter 76. This adapter is designed to receive a Luer-Lock 
component by an appropriate fitting 77, and contains a hydraulic channel 
60 which is continuous with the stainless steel tubing channel 53, and 
thus the catheter tube lumen 79 and the interior of the balloon 10. 
Direction control of the device is accomplished by rotating the entire 
device. In the event that the balloon becomes caught within the confines 
of a body vessel such that the catheter component fails to move when the 
guidewire is manipulated, it is anticipated that the distortable element 
22 will diminish the development of shear forces within the distal regions 
of the system. The distortable element thereby provides the system with 
superior structural integrity relative to systems that contain adhesive 
bonds at the distal catheter-guidewire interface. Inflation and deflation 
of the balloon 10 are accomplished by infusing and withdrawing fluid 
through the channel 53. 
Each of these embodiments and others within the scope of the invention 
offer the advantages of superior directional control over 
non-over-the-wire structures of the prior art, without loss of the 
benefits of the low crossing profiles, the option to prepare the device in 
dry condition, and the pushability, all of which are characteristic of 
such structures. The versatility and scope of the concept permit its 
application to semi-movable structures as well as fixed-wire and 
balloon-on-a-wire structures, and the invention as a whole enables one to 
perform angioplasty procedures with less effort and with greater 
efficiency, safety and finesse relative to the prior art. The embodiments 
are furthermore simple to construct and thus amenable to mass production. 
The foregoing descriptions are offered primarily for purposes of 
illustration. It will be readily apparent to those skilled in the art that 
the construction of the system, the materials, the type, arrangement and 
location of components, and other parameters of the system may be further 
modified or substituted in various ways without departing from the spirit 
and scope of the invention.