Catheter assembly

A catheter assembly including a first catheter having distal and proximal ends, and a second catheter which is positionable within the first catheter. The second catheter has a smaller diameter and is more flexible than the first catheter. The second catheter is positionable within the first catheter so that its distal end is extendable beyond the distal end of the first catheter. An expandable balloon or inflatable means is affixed to the outer surface of either the first or second catheters near the distal end thereof. When inflated, the inflatable means sealingly engages the interior walls of a body channel into which the catheter assembly has been inserted. The catheter assembly may also include associated fiber optics for viewing and removing obstructions.

The present invention relates generally to catheter assemblies, and more 
particularly to a catheter assembly for diagnostic use or for use in 
removing an obstruction in a blood vessel, body channel or body cavity. 
The American Heart Association has estimated that approximately four 
million people in the United States suffer from arteriosclerotic coronary 
artery disease. Many of these people are likely to suffer or die from a 
myocardial infraction, commonly known as a heart attack. Heart attacks are 
in fact the leading cause of death in the United States. Thrombosis in the 
coronary artery beyond the arteriosclerotic constriction is the usual 
cause of heart attacks. A procedure which can open arteriosclerotic 
constrictions, thereby permitting the normal flow of blood to the heart, 
may reduce the many deaths and disabilities caused by heart disease. 
Constrictions in the coronary artery are caused by a build-up of plaque, 
which may be "hard" or "soft". Plaque consists of calcium, fibrous and 
fatty substances. If the plaque is of recent origin or "soft", that is, it 
has a low concentration of calcium, a "Gruntzig" balloon catheter may be 
used to clear the artery. The "Gruntzig" catheter is inserted into the 
constricted area of the artery, and the balloon is inflated to expand and 
compress the plaque, thereby opening the artery and permitting an 
increased flow of blood through the artery. The "Gruntzig" balloon 
catheter is described in the following article: "Nonoperative Dilatation 
of Coronary-Artery Stenosis", A.R. Gruntzig, M.D., A. Senning, M.D., and 
W.E. Siegenthaler, M.D., The New England Journal of Medicine, Vol. 301, 
No. 2, July 12, 1979. See also U.S. Pat. No. 4,195,637, Gruntzig, et al., 
issued Apr. 1, 1980. 
The "Gruntzig" technique, however, does not work where the constriction in 
the artery is very tight, where the plaque is "old" and hard, or where the 
plaque forming the constriction has a high concentration of calcium and 
thus is very hard. It is estimated that the "Gruntzig" technique can be 
successfully used on only about 5% of the patients suffering from 
arteriosclerotic coronary disease. 
Accordingly, the present invention is directed to a catheter assembly which 
can remove (a) plaque, especially when hard, and (b) operate in a very 
constricted area of an artery. The catheter assembly of the present 
invention may also be used to remove obstructions from other blood vessels 
and body channels or cavities, as well as to view a region of a blood 
vessel or a non-vascular body channel. 
The present invention also provides a catheter assembly which is able to 
temporarily interrupt the flow of blood to an occluded or constricted 
region while such region is treated or observed. 
The catheter assembly of the present invention includes a first or outer 
catheter having distal and proximal ends, and a second or inner catheter 
which is positionable within the first catheter. The second catheter has a 
smaller diameter than the first catheter, and preferably, the second 
catheter is more flexible. The second catheter is positioned within the 
first catheter so that the second catheter can be shifted or moved with 
respect to the first catheter. Also, the distal end of the second catheter 
is extendable past the distal end of the first catheter. Inflatable means 
such as an expandable balloon is affixed to the outer surface of at least 
one of the catheters near the distal end thereof. When inflated, the 
balloon sealingly engages the interior walls of the blood vessel or the 
like in which the catheter assembly is inserted. This is done to stop the 
flow of blood into the area of the blood vessel in front of the distal end 
of the second catheter and thus to facilitate visualization of the 
obstructed or constricted region. 
A plurality of optical fibers extend through a portion of the second 
catheter and terminate at a point within the second catheter near its 
distal end. Usually one bundle of optical fibers is used for illuminating 
and another bundle of optical fibers is used for viewing the area in front 
of the distal end of the second catheter. 
Where the catheter assembly is to be used to remove an obstruction in a 
blood vessel, such as plaque material in the coronary artery or a clot, a 
special fiber capable of transmitting energy in the form of a laser beam 
extends through a portion of the second catheter and terminates near the 
distal end thereof. An appropriate lens may be attached to that end of the 
"laser fiber" located at the distal end of the second catheter. The lens 
focuses and intensifies the laser beam. In order to remove the 
obstruction, the laser has to deliver to the target area power sufficient 
to destroy, vaporize or soften the obstruction. 
Additionally, one or more channels may be provided within the catheter 
assembly for removal of combustion material generated during laser 
irradiation and for flushing of body fluids trapped between an occlusion 
and the adjacent catheter assembly. Suitable flushing fluids for this 
purpose are saline solutions, Ringer's solution, and the like. These 
channels may also be used to infuse a radio-opaque dye in the region. 
Appropriate positioning means may also be provided within the catheter 
assembly for positioning the laser fiber, and the viewing and illuminating 
optical fibers relative to the central axis of the catheter assembly. 
The catheter assembly embodying the present invention may include fiber 
optics for viewing and illuminating a body region, a fiber optic for 
transmitting a laser beam to a region within the patient's body, or both 
types of fiber optics, as desired. Alternatively, both types of fiber 
optics may be omitted and the catheter assembly of the present invention 
used to pretreat the plaque, occlusion or clot with a chemotherapeutic 
substance. In this later embodiment, the catheter assembly could be guided 
to the occlusion or clot by such means as fluoroscopy. Fluoroscopy could 
also be used to guide the catheter assembly to the target area where the 
assembly includes only a laser fiber optic.

The present invention will be described in conjunction with its most 
suitable use: the removal of plaque material from the coronary artery. The 
catheter assembly of the present invention, however, can also be used to 
remove occlusions, such as clots, in other arteries and veins. The present 
invention is especially useful in very constricted areas of blood vessels 
and for removing very hard material. Further, the catheter assembly could 
be used where it is necessary to temporarily stop the flow of blood to 
permit visual inspection and to achieve successful removal of an 
occlusion. The catheter assembly could also be used without its associated 
laser apparatus where it is simply desired to view an area of a blood 
vessel, some non-vascular body channel, or the interior of an organ or 
cavity. The present invention could also be used to remove obstructions 
from non-vascular body channels; for example, it could be used to remove 
bladder, kidney and gall stones. 
Referring now to the drawings, in which like components are designated by 
like reference numerals throughout the various figures, attention is first 
directed to FIGS. 1A through 1C. FIGS. 1A through 1C show catheter 
assembly 10 of the present invention positioned for use in removing plaque 
92 from coronary artery 90. Catheter assembly 10 comprises a guide or 
outer catheter 12 and a second or inner catheter 14. Guide catheter 12 has 
been inserted into an arm, leg or other artery 96 to extend near orifice 
94 of the coronary artery. The guide catheter is guided through such 
artery to the orifice by procedures well known in the art, such as 
fluoroscopy. Alternatively, catheter 12 may be an existing pre-formed 
catheter or articulated endoscope, adapted as described herein. 
Catheter 14 is positioned in coronary artery 90 by inserting it through 
guide catheter 12. Catheter 12 guides catheter 14 from the point of 
insertion, which is at the proximal end 12b of catheter 12, into coronary 
artery 90. To facilitate movement of catheter 14 within guide catheter 12, 
catheter 14 is more flexible than catheter 12. Catheter 14 also has a 
smaller outside diameter than the guide catheter. The outside diameter of 
catheter 12 is about 2.5 to 3.5 millimeters for use within the coronary 
artery. For other blood vessels or body channels, the outside diameter of 
catheter 12 may be selected accordingly. The outside diameter of catheter 
14 is approximately 1.5 to 2.5 millimeters. In instances, where the 
catheter assembly does not include optical fibers for viewing and 
illuminating, the outside diameter of catheter 14 can be as small as about 
1 to 2 millimeters. 
In use, catheter 14 is inserted in and pushed through the guide catheter 
until its distal end 14a extends beyond distal end 12a of the guide 
catheter, see FIGS. 1A through 1C. Inflatable means 16, discussed in more 
detail below, is affixed to inner catheter 14 at the distal end thereof. 
The inflatable means is collapsed as the inner catheter moves through the 
guide catheter, see FIGS. 1A and 1B. After distal end 14a of the inner 
catheter has been positioned near plaque buildup 92 by such means as 
fluoroscopy and the viewing and illuminating fiber optics, which are 
discussed below, inflatable means 16 is inflated as shown in FIG. 1C. 
Radio-opaque bands 56 may be located at distal end 14a so that the 
position of distal end 14a and inflatable means 16 can be precisely 
determined by use of the fluoroscope. 
To illuminate stenotic obstruction 92, an optical fiber bundle comprising a 
plurality of optical fibers 22 is provided within catheter 14, see FIGS. 2 
and 3. Optical fibers 22 originate at an exterior intense viewing light 
source, which is not illustrated, and extend from the proximal end 14b of 
catheter 14 to a point within the catheter near its distal end 14a. 
Optical fibers 22 are used to illuminate the area in front of the distal 
end of catheter 14. 
Catheter 14 further includes an optical fiber bundle 20 consisting of a 
plurality of optical fibers for viewing the area in front of distal end 
14a. Bundle 20 is connected to an appropriate eyepiece, which is not 
illustrated, and extends from the proximal end 14b of catheter 14 to 
terminate at a point within the catheter near distal end 14a. If desired, 
a protective transparent shield may be provided over the distal end of 
bundle 20. Viewing bundle 20 forms an image that is produced and viewed by 
conventional means as in a medical endoscope. Bundle 20, which is offset 
from central axis 17 of catheter 14, collects light through a tilted lens 
32. Lens 32 permits observation of the central portion of the artery, the 
surrounding area, and the occlusion. 
A laser-beam transmitting fiber 26 for transmission of laser energy from a 
laser source 34 is also carried by catheter 14. Laser-transmitting fiber 
26 extends from proximal end 14b of catheter 14 to a point inwardly of but 
near the distal end of catheter 14. Fiber 26 is preferably located along 
the central axis of catheter 14, and may also be covered by a transparent 
shield if desired. 
Laser 34 is coupled to laser-transmitting fiber 26 by a lens 36, which is 
either placed between the laser and the laser-transmitting fiber, as 
illustrated, or which is incorporated into the optical fiber. The exterior 
surface of laser transmitting fiber 26 is coated with an anti-reflective 
coating for the laser wavelength of interest. A shutter 38 between laser 
34 and lens 36 permits control of laser irradiation. Endoscopes used in 
conjunction with lasers for the performance of surgery are discussed in 
U.S. Pat. No. 3,858,577, issued Jan. 7, 1975, Bass, et al., and U.S. Pat. 
No. 4,146,019, issued Mar.27, 1979, Bass, et al. The disclosures in these 
two patents are hereby incorporated by reference. 
Laser 34 has to deliver to the target area sufficient power at the 
predetermined wavelength to destroy, vaporize or soften plaque material 
92. The laser beam should be conducted through optical fiber 26 with as 
little power loss as feasible. Additionally, the laser should interact 
with the plaque material rather than with the surrounding normal tissue of 
the artery or any infrared liquid that may be present. Several types of 
lasers can be used, for example, argon-ion, carbon dioxide, and Neodynium 
YAG lasers. Lasers having a wavelength capable of destroying or softening 
plaque but without adverse effect on blood cells or tissue are preferred. 
For lasers of certain wavelengths, for instance, carbon dioxide lasers, 
some laser-transmitting guide other than an optical fiber might have to be 
used. 
To achieve the high intensities required for destruction of plaque material 
92, the laser is focused by a short-focal length lens 28. Lens 28 is 
either spaced from the end of optical fiber 26, or, as shown, affixed to 
the end of optical fiber 26. Lens 28 may comprise a plurality of lenses. 
The laser will destroy blood cells present and may produce blood clotting 
in the area of the targeted occlusion. Clotting in the occluded coronary 
artery would further compromise blood flow to the heart. Thus, laser 
surgery in the coronary artery requires that blood flow to the targeted 
occlusion be stopped. Catheter assembly 10 includes an inflatable or 
expandable balloon 16 for temporarily stopping the flow of blood into the 
area in front of the distal end of catheter 14. Blood flow in the coronary 
artery, however, cannot be interrupted for more than 12 to 15 seconds 
without endangering the patient's life. By temporarily interrupting the 
flow of blood, blood can be excluded from the region, the obstructed or 
constricted area can be viewed, and the obstruction can be successfully 
removed. The region in front of the distal end of catheter 14 can also be 
flushed with a solution, such as Ringer's or saline, to dilute any blood 
present in that region. Perhaps, a gas such as carbon dioxide could also 
be injected into this region to expand the artery, and to clear blood from 
the ends of the optical fibers. 
Inflatable balloon 16 is circumferentially affixed about the exterior 
surface of catheter 14, and is located near the distal end of catheter 14. 
Prior to opening shutter 38, balloon 16 is inflated to sealingly engage 
the interior walls of coronary artery 90, thereby stopping the flow of 
blood into the area of targeted occlusion 92, see FIG. 1C. The laser will 
vaporize the occlusion within a time period of less than one second 
depending upon the type and power of laser used. Afterwards, balloon 16 
may be deflated to permit blood flow through the coronary artery, or if 
time permits, catheter 14 may be extended further to remove or soften an 
additional section of plaque before the flow of blood is restored. 
As balloon 16 only has to stop the flow of blood and not expand the artery, 
the balloon can be inflated by lower pressures and be constructed of less 
rigid materials than a "Gruntzig"-type balloon. Alternatively, balloon 16 
may be constructed to stop blood flow as well as to expand soft plaque or 
any other deformable construction in an artery. 
In an alternate embodiment, as illustrated in FIG. 8, catheter assembly 10 
may have inflatable means 16 circumferentially affixed about the exterior 
surface of catheter 12 near the distal end 12a thereof. This embodiment is 
particularly useful in the removal of plaque or clot 102 found in a 
peripheral vessel 100, such as the iliar and femoral arteries. 
A pair of channels 18, see FIG. 2, extend through catheter 14 and are 
connected to the interior of balloon 16 by means of a flexible tubing 18a. 
A gas, such as carbon dioxide, or a liquid, such as saline, is passed 
through channels 18 from a source, which is not illustrated, to expand 
balloon 16. To deflate the balloon, the gas or fluid may be withdrawn from 
the balloon by means of these channels. Channels 18 may also be built into 
the wall of catheter 14. 
A cable pulley arrangement is provided to position catheter 14 which 
carries the laser, illumination, and viewing fiber optics. As shown in 
FIG. 2, the cables are attached at appropriate points 80 to a sheath 82 
which is disposed circumferentially about optical fibers 22, viewing 
bundle 20, and laser fiber 26. Sheath 82 may extend the length of the 
optical fibers back to proximal end 14b of catheter 14. Sheath 82 defines 
a grouping 30 of fiber optics within the central section of catheter 14. 
The grouping includes viewing bundle 20, laser optical fiber 26, and 
illumination optical fibers 22. As in gastroendoscopy, the cable pulley 
arrangement can be operated to tilt grouping 30 or to cause it to move 
transversely relative to the central axis of the catheter assembly. This 
permits viewing and laser irradiation of sites in the artery which are not 
centrally located with respect to catheter 14. Alternatively, as shown in 
FIG. 8, cables 81 of the cable pulley arrangement may be attached at 
appropriate points 80 to the outside surface of catheter 14 at the distal 
end thereof. The illumination fiber optics of catheter 10 have been 
described as comprising a plurality of individual optical fibers 22 
disposed within catheter 14. It is to be understood, however, that a fiber 
optical bundle, like bundle 20, could be fashioned to include both 
illumination and viewing optical fibers. Such an approach is described 
below. 
An alternative embodiment of the catheter assembly of the present invention 
is illustrated in FIGS. 4 through 7. In that embodiment, catheter assembly 
120 includes two fiber optical bundles 42 and 44 to provide binocular 
vision, and thus depth perception of the target area. Each bundle 42 and 
44 in turn includes an illumination bundle portion connected to an intense 
light source for illuminating the area in front of distal end 14a, and a 
viewing bundle portion connected to an eyepiece for viewing the area in 
front of distal end 14a. 
Bundles 42 and 44 are located on either side of the central axis of 
catheter 14, and they collect light through their own respective tilted 
lenses 33 and 35. The lenses are suitably tilted to allow observation of 
the central portion of the artery as well as the surrounding area. This 
stereoscopic binocular approach permits perception of depth within the 
artery. As in the embodiment described above, bundles 42 and 44 permit 
observation of a wide area of the coronary artery, as well as the 
.obstruction and laser focal spot. 
The embodiment illustrated in FIG. 7 also includes an intense coherent 
light source 60 which is located between laser 34 and laser fiber optic 
26. Light source 60 is slightly offset from the laser propagation axis. 
Light source 60 permits viewing of the precise region of the laser focus 
as well as the exact size of the focused laser beam. An optical filter 61 
and a beam splitter 62 are located between light source 60 and laser fiber 
optic 26 to help distinguish the laser focal region from the region of 
general illumination. Light source 60 serves as an aiming beam or target 
light when lasers having an invisible wavelength are used. 
Catheter assembly 120 further includes a flushing tube 70 and a suction 
tube 72. Both of these tubes extend within catheter 14 from its proximal 
end 14b to a point inwardly of distal end 14a, see FIGS. 4 through 6. 
Flushing tube 70 is provided for injecting a flushing fluid, such as saline 
or Ringer's solution, into the area between the distal end of catheter 14 
and the occlusion. The flushing fluid can be injected to dilute and/or 
remove any trapped blood, after blood flow to the occlusion is stopped by 
balloon 16. A radio-opaque dye may also be injected into this area through 
flushing tube 70 so that the dye may be viewed on a fluoroscope to 
determine the site of the obstruction. A gas such as carbon dioxide could 
also be injected through flushing tube 70. Suction tube 72, which is 
connected to an appropriate filtering system outside of catheter 14, is 
designed to remove the aforesaid diluted blood and flushing fluid, dye, or 
any products that may form after the plaque material has been vapored or 
otherwise removed by the laser. 
Grouping 30 of catheter assembly 120 includes laser-transmitting fiber 
optic 26, and fiber optic bundles 42 and 44. Grouping 30 also includes 
flushing and suction tubes 70 and 72. To position grouping 30, a series of 
positioning balloons 50 are disposed circumferentially about the grouping. 
Inflatable balloons 50 are each operably connected to independent pressure 
sources, which are not illustrated, via tubes, also not illustrated, 
extending from the proximal end of catheter 14. As with the cable pulley 
arrangement, inflatable balloons 50 permit grouping 30 to move 
transversely and tilt relative to the central axis of the catheter 
assembly. The positioning-balloon system permits viewing and laser 
irradiation of sites that are not centrally located relative to the 
central axis of catheter 14. 
As shown in FIGS. 5 and 6, where reference numeral 39 represents the 
central axis of grouping 30, by inflating some balloons and deflating 
others, grouping 30 can be appropriately positioned relative to the target 
area. FIG. 5 shows an arrangement where grouping 30 has been moved 
transversely with respect to the central axis of the catheter assembly. 
FIG. 6 shows an arrangement in which grouping 30 has been moved 
transversely and tilted. 
In other embodiments, the catheter assembly of the present invention could 
employ more than one laser. 
The laser-transmitting fiber could also be offset from the central axis of 
the inner catheter and could use a tilted or nonsymmetrical lens. 
Different configurations of the viewing and illuminating optical fibers 
are also possible. 
Although certain specific embodiments of the invention have been described 
herein in detail, the invention is not to be limited to only such 
embodiments, but rather only by the appendant claims.