WO1999004706A1

WO1999004706A1 - Reduction of restenosis

Info

Publication number: WO1999004706A1
Application number: PCT/IL1998/000048
Authority: WO
Inventors: Uri Oron
Original assignee: Biosense Inc.
Priority date: 1997-07-28
Filing date: 1998-02-02
Publication date: 1999-02-04
Also published as: AU5778698A

Abstract

A method of treating a blood vessel (50) which includes irradiating an area in the blood vessel with biostimulative radiation from a radiation source (30) so as to reduce restenosis after the treatment. Preferably, the biostimulative radiation palliates tissue inflammation and substantially does not cause damage to human cells. The radiation preferably includes infrared radiation.

Description

REDUCTION OF RESTENOSIS

RELATED APPLICATIONS

This patent application claims priority from PCT/TL97/00257, and is related to PCT application PCT/IL97/00010, both of which are assigned to the assignee of the present application. These related applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to methods and apparatus for cardiac treatment, and particularly to methods and apparatus for reduction of restenosis phenomena following angioplasty. BACKGROUND OF THE INVENTION

Heart disease or heart failure following myocardial infarction is still a major cause of death in the western world. One of the major problems which causes heart failure is occlusion of blood vessels, also referred to as a stenosis, especially of coronary arteries, which causes ischemia in the heart. One common procedure performed to open occluded arteries, is balloon angioplasty (PTCA), described for example in (A.R. Gnientzig et al. Long-term follow-up after percutaneous transmural coronary angioplasty, N. Engl. J. Med. 316: 1127-32, 1987) and in U.S. patents 4,643,186 and 5,669,880, which are incorporated herein by reference.

Another common treatment of arterial occlusion involves the use of a stent to mechanically support collapsed and occluded blood vessels in the heart. This method is commonly performed together with balloon angioplasty and is described, for example, in U.S. patents 4,848,343 and 5,662,703, which are incorporated herein by reference. An additional treatment includes ablation of the occlusion. For such treatment, a catheter as described, for example, in U.S. patents 5,423,805, 5,624,433 and 4,878,492, which are incorporated herein by reference, may be employed. However, in a significant percentage of the patients, between 10% and 40%, restenosis of the treated coronary arteries occurs with time. There are many explanations of the phenomenon of restenosis. The main cause is believed to be the initial damage to the endothelial cells, i.e., the cells that occupy the inner layer of the arteries, from the occlusion opening treatment. The damage may include, for example, mechanical damage from the balloon or stent or radiation-induced damage. It is assumed that the damage to the endothelial and smooth muscle cells causes an inflammatory response in the inner layer of the blood vessels and growth or proliferation of smooth muscle that finally results in the restenosis of the blood vessel.

Various methods have been suggested in order to minimize the occurrence of restenosis. Several drugs, including heparin and psoralen have been suggested for use during angioplasty, in order to prevent restenosis. U.S. patent 5,514,707, which is incorporated herein by reference, suggests administering psoralen to the patient and irradiating with visible light in order to activate the psoralen, and thereby inhibit growth of smooth muscle cells that cause restenosis. Another method of treatment is suggested in U.S. patents 5,213,561, 5,503,613 and 5,540659, which are incorporated herein by reference, and suggest inserting a radioactive element into the artery so as to irradiate the treated artery. This method, like the other methods described above, is meant to damage or destroy cells surrounding the stenosis and thus to prevent the cells from proliferating and forming the stenosis once again.

Another method for destroying surrounding smooth cells is suggested in U.S. patents 5,053,033 and 5,607,419 which are incorporated herein by reference. U.S. patent 5,053,033 describes cytotoxic irradiation of smooth muscle cells with UV radiation, which kills the cells and thus reduces restenosis caused by their proliferation. Tests cited in this patent show that only UV radiation is suitable for destruction of the cells. Similarly, U.S. patent 5,417,653 suggests irradiating a preselected portion of a blood vessel with visible light, which is believed to inhibit restenosis by deactivating or killing certain smooth muscle cells and to have an anti-spasmodic effect on the luminal wall.

In recent studies it has been shown that low-power laser irradiation has dramatically reduced inflammation post cold injury to skeletal muscle tissue. One such study is described by A. Bibikova et al. (1993), in an article entitled, "Promotion of muscle regeneration following cold injury to the toad gastrocnemious muscle by low energy laser irradiation," Anat. Rec. 235: P. 374-380.

Low power radiation therapy of live tissue is described, for example in U.S. patent 4,646,743, which is incorporated herein by reference. SUMMARY OF THE INVENTION

The present invention seeks to provide methods and apparatus for prevention of restenosis following treatment for opening of an occluded artery.

It is an object of some aspects of the present invention to provide methods and apparatus for prevention of restenosis which have substantially no side effects.

The above-mentioned PCT patent application IL97/00257 describes the use of low power irradiation in heart therapy. In this PCT application it was shown that low power radiation has a beneficial effect in preservation of the mitochondria in heart cells of an infarcted zone. In accordance with preferred embodiments of the present invention, low-power irradiation is administered to endothelial cells of an occluded artery or other blood vessel, before, during and/or after artery-opening treatment is administered to the occluded artery. Preferably, the radiation is administered immediately before and/or immediately after the treatment, so as to mitigate detrimental effects that the treatment may have on the endothelial cells. The artery- opening treatment may include one or more of balloon angioplasty, stent implant, high power laser irradiation and/or any other method known in the art. The low-power irradiation provides biostimulation of the endothelium, which is believed to reduce or eliminate restenosis of the artery in at least a substantial fraction of cases^' treated.

Preferably, the biostimulatory low-power irradiation in accordance with the principles of the present invention is limited to power levels below a threshold at which harmful effects may be caused to human tissue. Intravascular biostimulation is distinguished from methods of intra- arterial irradiation known in the art, such as laser angioplasty or methods of destroying or deactivating smooth muscle cells as described in the above-mentioned U.S. patents 5,053,033, 5,607,419 and 5,417,653, in that biostimulation is not directed toward destruction of cells, but rather toward stimulating cell healing. Therefore, the power level of the biostimulatory radiation incident on the endothelium is not sufficient to ablate intra-arterial plaque or tissue, and preferably is not sufficient to cause any harm to the cells. Rather, the power level is such that it produces biostimulatory effects, which reduce restenosis. Preferably, the power level is between about 5 and 200 milliwatts or about 0.3-10 joules total energy. Although there is no definite explanation of the mechanism of biostimulation, it is believed that the low-power radiation protects cells from degeneration and/or damage in unfavorable conditions such as lack of oxygen. Thus, no injury will occur and inflammatory cells will not fill the "injured" zone in an attempt to replace the "injured" cells. Although it is believed that radiation over a wide span of wavelengths in the infrared (IR), visible and ultraviolet (UV) range may have biostimulatory effects, the radiation administered in accordance with preferred embodiments of the present invention, is preferably in a range of wavelengths having comparatively large biostimulation effects, and low harmful effects, to human cells. Such wavelengths have been found by the inventor to be most preferably, in the infrared range. The choice of the particular wavelength and power level is preferably made in accordance with the patient's needs. In some preferred embodiments of the present invention, a wavelength of between 850-950 nanometers is used for biostimulation.

In preferred embodiments of the present invention, the radiation is produced by a radiation source outside the body of a patient, and is coupled to the interior of the artery by a waveguide contained within a suitable intravascular catheter. Preferably, the radiation is coherent, such as radiation provided by a diode laser. Preferably, the diode laser has a power output in the range of 5 mW to 5W and a wavelength in the range of 250 to 940 nm. The diode laser may comprise, for example, a gallium arsenide diode which operates at a wavelength of 904 nanometers. Alternatively, the radiation comprises non-coherent light, preferably, from a high intensity xenon lamp. Preferably, the xenon lamp has a power flux of 30 to 500 mW/cm^.

In some preferred embodiments of the present invention, the radiation is administered in one or more sessions. Preferably, each session has a duration of between about 2-10 minutes, most preferably between 5-10 minutes. Alternatively or additionally, when the radiation is administered from a catheter within the occluded artery, the radiation is administered during the angioplasty treatment whenever possible, so as to minimize the time in which the catheter is within the artery.

In some preferred embodiments of the present invention, irradiation of the endothelial cells surrounding a stenosis is performed using a catheter which is inserted to perform the artery opening treatment, as well. The catheter includes, in addition to the apparatus ordinarily used for the artery opening, the waveguide which is coupled to the external radiation source. When the catheter is inserted, for example, for balloon angioplasty, the radiation source is operated prior to expansion of the balloon. The radiation is directed toward the endothelial cells against which the balloon is to be expanded and is administered for a suitable period. After the radiation has been applied for a sufficient period, the balloon is inflated and the treatment is performed.

Preferably, the balloon and waveguide are arranged on the catheter in a manner which allows the source to irradiate the treated artery while the balloon is being expanded. After the balloon is deflated and possibly removed the radiation source is preferably operated again for a post- treatment radiation session.

In some preferred embodiments of the present invention, a balloon angioplasty catheter comprises a balloon which is at least partially radiation-transparent at the radiation wavelengths of the biostimulation, and at least one waveguide which irradiates the endothelium from within the balloon. Preferably, a distal end of the waveguide which emits the irradiation is situated within the balloon and directs the radiation toward the endothelial cells. Thus, it is possible to irradiate endothelial cells in the vicinity of the stenosis while the balloon is inflated. Additionally, the radiation path is substantially within the balloon and is therefore controlled by a surgeon, and is free from radiation absorbent materials, such as blood. Thus, the irradiation is not absorbed by blood or other substances within the artery which normally are in the radiation path between the waveguide and the endothelial cells.

In some preferred embodiment of the present invention, the waveguide comprises a fiberoptic bundle. Preferably, the fiberoptics are attached to the balloon in a uniform distribution around its surface, such that when the balloon is inflated, the radiation from the fiberoptics is directed at the endothelial cells in proximity to the balloon. Preferably, the irradiation may also be applied when the balloon is in a deflated state. Preferably, the fiberoptics are within the balloon. Alternatively or additionally, the fiberoptics are attached to the outer surface of the balloon. In other preferred embodiments of the present invention, an additional catheter is inserted into the patient's artery to administer the radiation treatment, separate from the catheter used for angioplasty. Thus, it is possible to adjust the position and orientation of the distal end of the waveguide independent of the position and orientation of the catheter which is used in the balloon angioplasty procedure. In other preferred embodiments of the present invention, a single separable catheter is used to carry the balloon and the waveguide to the treated artery. At the site of the occlusion in the artery, the catheter is separated so that the balloon catheter and the waveguide may be positioned independently of each other. In a preferred embodiment of the present invention, the separable catheter comprises a large catheter with an inner lumen, and a smaller catheter which passes through the lumen. Preferably, the large catheter comprises an angioplasty treatment catheter while the smaller catheter comprises an irradiation catheter.

In other preferred embodiments, in which angioplasty is performed using high power irradiation, a single catheter carrying the waveguide is inserted to the artery. The waveguide is first coupled at its proximal end to a low power laser source for biostimulative irradiation of the endothelial cells prior to the treatment. The proximal end of the waveguide is then coupled to a high power laser for ablation. Preferably, after the artery treatment, the waveguide is coupled once again to the low power laser source for post-treatment irradiation. Preferably, the catheter comprises optics at its distal end which spread the biostimulative radiation and concentrate the ablative radiation, which are most preferably in different wavelength ranges.

In other preferred embodiments of the present invention, a single catheter carries at least two waveguides. One of the waveguides is coupled to a low power laser source while the other waveguide is coupled to a high power laser. Preferably, each of the waveguides is accommodated to its specific purpose. The accommodation preferably includes a suitable choice of optics at the distal end of the waveguide, and/or specific design of the waveguide itself. For example, a waveguide and optics for ablation are preferably designed to concentrate the radiation, while the biostimulative waveguide are preferably designed to spread the radiation. In addition, the use of more than one waveguide allows the low power irradiation to be administered during the artery opening treatment. Preferably, both waveguides are directed together so that placement of the waveguides is simple. Alternatively or additionally, the orientation of the waveguides may be adjusted relative to each other, allowing fine direction of the radiation.

In an alternative embodiment of the present invention, biostimulative irradiation of the arteries may be non-invasive both to the body and to the heart, for example, by placing a radiation source against the skin of the patient and irradiating the occluded artery therefrom. Use of non-invasive procedures is especially desired in periods before and after the artery treatment, in which repeated invasive procedures are undesired. Non-invasive irradiation may be performed as described, for example, in PCT publication WO97/29699, PCT application IL97/00257, U.S. patent 5,590,657 and U.S. patent 5,078, 144, which are incorporated herein by reference.

In another alternative embodiment, a biostimulative radiation source is partially inserted transcutaneously into the chest cavity of a patient, in order to minimize the amount of muscle tissue which the radiation must penetrate on its way to the heart, thus attaining a higher, more optimal radiative power on the treated artery. Preferably, the radiation source is inserted in a minimally invasive procedure so as to incur minimal injury to the patient's tissue.

In some preferred embodiments of the present invention, the angioplasty treatment is controlled using a tracking system of any type known in the art. Such tracking system may include an imaging system, such as X-ray or ultrasonic imaging systems. Preferably, a position sensor, for example a magnetic position sensor, as is known in the art, is attached to the angioplasty catheter to enable navigation and location of the catheter Preferably, signals from the position sensor are used to direct biostimulative radiation toward the occluded area in the artery. In a preferred embodiment of the present invention, a wireless position sensor, preferably attached to a stent, is implanted at the site of the occlusion in the artery such that post -treatment irradiation administered after the catheter is removed from the body may be easily directed toward the site.

In accordance with a preferred embodiment of the present invention, the irradiation directed at the occluded artery is detected and measured in order to accurately control the irradiation procedure Preferably, the irradiation is monitored for its intensity, direction, and/or other parameters The orientation and/or intensity of the radiation is adjusted according to these observations Alternatively or additionally, the duration of the irradiation is determined according to these observations

Preferably a fiberoptic light guide, for monitoring of the irradiation is mounted on the catheter and is connected at its distal end to a light sensor Alternatively, an additional waveguide is mounted on the catheter to detect the parameters of the radiation After the irradiation is accordingly adjusted, the observation waveguide may be used for further irradiation or for the artery treatment.

In an alternative embodiment of the present invention, the catheter comprises a radiometric sensor, which measures the local instant radiation power level incident on the tissue and the total irradiative energy supplied to the tissue during an irradiation session Preferably, the radiometric sensor comprises an implantable sensor which is implanted near the occluded artery The power and the energy level readings may be employed for modulation of the radiation source output power level and for determination of a session's duration Optionally, the readings may serve to ascertain successful transmission of the radiation from the source to the designated occluded artery area.

There is therefore provided in accordance with a preferred embodiment of the present invention, a method of treating a blood vessel, including irradiating an area in the blood vessel with biostimulative radiation so as to reduce restenosis thereof after treatment. Preferably, the method includes opening an occlusion in the blood vessel

Opening the occlusion may include inflating an angioplasty balloon, implanting a stent and/or ablating a stenosis Preferably, inflating the balloon includes inflating a balloon which is at least partially radiation reflective so as to aid in distribution of the radiation on the artery.

Preferably, irradiating includes irradiating before, during and/or after opening of the occlusion. Preferably, irradiating with biostimulative radiation includes irradiating with radiation which substantially does not cause damage to human cells.

Further preferably, irradiating with biostimulative radiation palliates tissue inflammation.

Preferably, irradiating includes inserting a catheter into the blood vessel and irradiating therefrom. Preferably, the method includes inserting a sensor into the artery and monitoring the irradiation responsive to signals from the sensor.

Alternatively or additionally, irradiating includes irradiating from a source external to the artery.

Preferably, irradiating includes irradiating with infrared radiation. Preferably, irradiating includes irradiating at a power less than or about 200 milliwatts.

Preferably, irradiating includes irradiating with laser radiation.

Preferably, irradiating includes uniformly irradiating substantially the entire radial inner surface of the artery.

There is further provided in accordance with a preferred embodiment of the present invention, a catheter for treatment of a blood vessel, including apparatus for opening an occlusion in the blood vessel, and a waveguide for irradiating the blood vessel with biostimulative radiation.

Preferably, the apparatus includes an angioplasty balloon.

Preferably, the balloon is connected to the catheter along a radial periphery of the catheter.

Alternatively or additionally, the balloon covers the distal end of the catheter.

Preferably, the waveguide has a distal end which emits the radiation and the distal end is situated within the balloon.

Preferably, at least part of the balloon includes a radiation transparent material. Alternatively or additionally, at least part of the balloon includes a radiation reflective material.

Preferably, the waveguide is movable within the catheter. Further preferably, the waveguide includes a fiberoptic bundle.

Preferably, optical fibers from the fiberoptic bundle are connected to the balloon.

Preferably, the fibers are fixed to an inner or outer surface of the balloon.

Preferably, the fibers are connected to the balloon in a manner such that the fibers emit radiation in an outward, generally radial direction relative to an outer surface of the balloon surface.

Preferably, the fibers are fixed to the balloon in a substantially uniform distribution over at least a portion of the surface of the balloon.

Preferably, the waveguide includes an optic, a wide-angle lens or a fisheye lens. Preferably, the optic includes a dichroic optic, which spreads the biostimulative radiation while concentrating radiation which is passed through the waveguide to ablate an occlusion in the artery.

Preferably, the waveguide includes a fiberoptic having a substantially uncladded portion along its length through which the radiation is emitted. Preferably, the uncladded portion allows emission of the radiation in a substantially uniform radial pattern.

Alternatively or additionally, the uncladded portion allows emission of substantially only biostimulative radiation.

Preferably, the uncladded portion allows emission of substantially only infrared radiation. In a preferred embodiment of the present invention, the apparatus includes a stent.

Preferably, the stent includes a position indicator.

Preferably, the position indicator includes a fiducial mark.

Alternatively or additionally, the position indicator includes a position-sensing coil.

Preferably, the apparatus includes a waveguide to convey radiation to the blood vessel for ablating the occlusion.

There is further provided in accordance with a preferred embodiment of the present invention, apparatus for prevention of restenosis in an artery including a radiation source which generates biostimulative radiation, and a waveguide which directs the radiation to the artery.

The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic illustration of an angioplasty and biostimulation catheter, in accordance with a preferred embodiment of the present invention;

Fig. 2A is a schematic illustration of the catheter of Fig. 1 in a closed state within an artery;

Fig. 2B is a schematic illustration of the catheter of Fig. 1 in an open state within the artery;

Figs. 3A and 3B are schematic illustrations of a balloon dilation and biostimulation catheter, in accordance with a preferred embodiment of the present invention; Fig. 4A is a schematic illustration of a balloon dilation and biostimulation catheter, in accordance with another preferred embodiment of the present invention;

Fig. 4B is a schematic illustration of a balloon dilation and biostimulation catheter, in accordance with still another preferred embodiment of the present invention;

Fig. 5A is a schematic side view of a balloon dilation and biostimulation catheter, in accordance with another preferred embodiment of the present invention;

Figs. 5B is a schematic cross-sectional view of the catheter of Fig. 5A;

Fig. 6 is a schematic cross-sectional view of a balloon dilation and biostimulation catheter, in accordance with still another preferred embodiment of the present invention;

Fig. 7 is a schematic illustration of a balloon dilation and biostimulation catheter within an occluded artery, in accordance with still another preferred embodiment of the present invention;

Fig. 8 is a schematic illustration of a stent implanting and biostimulation catheter, in accordance with a preferred embodiment of the present invention;

Fig. 9 is a schematic illustration of an irradiation catheter within an artery, in accordance with a preferred embodiment of the present invention;

Fig. 10A is a schematic illustration of a biostimulation catheter, in accordance with another preferred embodiment of the present invention; and

Fig. 1 OB is a simplified pictorial illustration of a console for controlling the catheter of Fig. 10A, in accordance with another preferred embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 illustrates a catheter 22 for balloon angioplasty and biostimulation inside an artery of a patient, in accordance with a preferred embodiment of the present invention. Catheter 22 comprises a balloon 24 which is mounted at a distal end 25 of the catheter. A fluid channel 26 connects between balloon 24 and the proximal end of catheter 22, allowing a surgeon to inflate the balloon. Catheter 22 further comprises a waveguide 28 which conveys radiation along the catheter. A lens 32 at the distal end of catheter 22 directs the irradiation from waveguide 28. Alternatively or additionally, a longitudinally-disposed radiation-emitting element, for example, a window or lens, for delivering radiation in a radial direction is situated along the length of the catheter adjacent distal end 25. At its proximal end, waveguide 28 is coupled to a radiation source 30, which preferably comprises a laser, such as an infrared diode laser. Alternatively or additionally, source 30 comprises a non-coherent radiation source such as a xenon lamp.

Preferably, catheter 22 includes a position sensor 36 which generates signals indicative of the position and orientation of the catheter. Preferably, position sensor 36 comprises one or more coils 38, preferably an assembly of three orthogonal coils, which generate the signals responsive to magnetic fields, as described, for example, in U.S. patent 5,319,991, PCT publication WO96/05768 or U.S. provisional patent application 60/061,269, which is assigned to the assignee of the present application, all of which are incorporated herein by reference. The signals are passed via wires 39 to signal processing circuitry 40 which determines the position and /or orientation of catheter 22.

Lens 32 preferably comprises a wide angle lens, for example, a fish-eye lens, as is known in the art, so as to widen the irradiation beam over a short focal distance and thus to reduce the number of different points at which the catheter must be repositioned in order to irradiate completely a designated area within the artery. In other preferred embodiments, lens 32 may be replaced by specially-designed beam output optics, so as to increase the irradiated area still further and/or to give a desired output radiation profile.

Figs. 2A and 2B illustrate the use of catheter 22, in accordance with a preferred embodiment of the present invention. As shown in Fig. 2A, catheter 22 is inserted into an occluded artery 50. Catheter 22 is directed toward a stenosis 52 using any suitable method, such as X-ray imaging, ultrasound imaging, etc. Preferably, position sensor 36 aids in bringing catheter 22 into proximity with stenosis 52. When catheter 22 is properly positioned, radiation source 30 is operated for a pre-angioplasty biostimulation period, suitable for stimulation of endothelial cells 54 of artery 50. Preferably, catheter 22 is moved along the length of artery 50 in proximity to stenosis 52 and/or is rotated about its axis during the pre-angioplasty irradiation period so as to substantially uniformly deliver the radiation to cells 54.

After endothelial cells 54 are irradiated, catheter 22 is suitably positioned for balloon expansion, and balloon 24 is enlarged as shown in Fig. 2B. In a preferred embodiment of the present invention, irradiation is administered during the opening of balloon 24, as well.

Preferably, balloon 24 comprises at least partially a reflective coating, such as a suitable metallic or dielectric coating, which aids in distribution of the radiation on endothelial cells 54.

After balloon 24 is collapsed, a post angioplasty irradiation session is preferably performed in a manner similar to the irradiation administration before the angioplasty treatment. The biostimulatory irradiation administered before, during and/or after angioplasty reduces later restenosis.

Figs. 3A and 3B are schematic illustrations of a balloon dilation and biostimulation catheter 90, in accordance with another preferred embodiment of the present invention. Catheter 90 comprises a central shaft 92 forming a catheter core around which a concentric balloon 94 is positioned. Preferably, balloon 94 is bonded distally and/or proximally to shaft 92 close to a distal end 95 of the shaft. Preferably, a channel 98 coaxial with shaft 92 leads to balloon 94 and allows infusion of air or a radiopaque contrast liquid into the balloon in order to inflate it. Alternatively, channel 98 runs along a side of shaft 92 or within the shaft.

Central shaft 92 is preferably an open ended shaft which carries within it a waveguide 100, preferably a fiberoptic bundle, as shown in Fig. 3 A, which conveys irradiation from source 30 to the stenosis area. Other apparatus may be included within shaft 92, such as a position sensor, as described above. In a preferred embodiment of the present invention, waveguide 100 is fixed within shaft 92. Alternatively, waveguide 100 may be removably fitted into shaft 92, so that when the waveguide is removed, other apparatus may be passed through the shaft. Thus, after an irradiation session, waveguide 100 may be removed from shaft 92, as shown in Fig. 3B, and the shaft may be used, for example, for infusion of liquids, drugs and/or contrast media. Preferably, waveguide 100 is reinserted later on for another irradiation session.

In a preferred embodiment of the present invention, catheter 90 is inserted into an artery along a guide wire, as described, for example, in U.S. patents 4,757,827 and 4,815,478, which are incorporated herein by reference. After the guide wire is positioned in the artery, shaft 92 is loaded onto the guide wire and is passed to the occluded portion of the artery. Thereafter, the guide wire is removed from the artery, and waveguide 100 is inserted along shaft 92. Alternatively, if shaft 92 is wide enough, waveguide 100 may be inserted along shaft 92 while the guide wire is within the shaft. Further alternatively or additionally, the guide wire comprises a waveguide within it.

Fig. 4A is a schematic illustration of a balloon dilation and biostimulation catheter 110, in accordance with another preferred embodiment of the present invention. Catheter 110 comprises a balloon 102 which is at least partially transmissive to biostimulative irradiation and covers a distal end 112 of catheter 1 10. Preferably, balloon 102 is transmissive to biostimulative radiation in both deflated and inflated states. A waveguide 1 14 runs along catheter 1 10 and conveys biostimulative irradiation from radiation source 30 to the inner side of balloon 102, through which the radiation passes to the endothelial cells in the occluded artery. The volume of catheter 110 which is not occupied by waveguide 1 14 includes channel 98 for inflating and deflating the balloon. Alternatively or additionally, channel 98 and waveguide 1 14 are in separately defined lumens, and interior walls separate the lumens along the length of the catheter. Thus, it is easier to inflate balloon 94 with a liquid without danger to other apparatus within the catheter.

Preferably, optics 106 are situated at the distal end of waveguide 1 14 and convey the irradiation beam from the waveguide to the endothelial cells. Preferably, optics 106 spread the irradiation beam to cover a larger area than the cross-section of the catheter, preferably to cover substantially the entire surface of balloon 102. In a preferred embodiment of the present invention, optics 106 includes a wide angle lens, for example, a fish-eye lens, as is known in the art. Preferably, balloon 102 comprises a radiation-reflecting surface, such as a parabolic or multifaceted reflector, a scattering membrane, a layered polarizer membrane, translucent membrane or any other suitable optical membrane known in the art, to spread and/or diffuse the radiation emitted by the waveguide. In a preferred embodiment of the present invention, a portion 104 of balloon 102 comprises a partially or entirely reflecting material while the rest of the balloon is transparent. It will be appreciated that other configurations of balloon 102 may also be employed to enhance the efficiency of the radiation distribution on the endothelial cells.

When catheter 1 10 is inserted into the occluded artery, balloon 102 is in a deflated state surrounding distal end 1 12 in a manner which does not impede insertion of the catheter into the artery. Preferably, balloon 102 comprises an elastic and flexible membrane which, when it is in a deflated state, has a predetermined shape suitable for insertion of the catheter. Preferably, balloon 102 in the deflated state protects distal end 112 and optics 106 from damage from blood clots and collisions during insertion. Preferably, the deflated state of balloon 102 is designed so as to enhance the radiation delivery from optics 106 to the endothelial cells. Fig. 4B is a schematic illustration of a balloon dilation catheter 1 16, in accordance with another preferred embodiment of the present invention. Catheter 1 16 comprises a fiberoptic bundle 117, including a plurality of optical fibers 119, which runs along the catheter, and a balloon 1 15. Catheter 1 16 is similar to catheter 110 of Fig. 4 A, except that in catheter 110, waveguide 114 terminates at optics 106, whereas in catheter 1 16, the optical fibers continue into balloon 115. Preferably, while catheter 1 16 is inserted into the artery, bundle 1 17 is situated within the catheter so as not to impede the advancement of the catheter in the artery. When catheter 116 is situated in place for an irradiation session, bundle 1 17 is extended distally from the catheter to enlarge the irradiation area of the bundle. In a preferred embodiment of the present invention, fibers 1 19 from bundle 1 17 are attached to balloon 1 15 all around the inner surface of the. balloon. When balloon 1 15 is inflated, it presses on the stenosis and on endothelial tissue in proximity thereto. Thus, having fibers 119 connected to the balloon brings the fiberoptics into close proximity with the stenosis.

A further advantage of administering the biostimulatory irradiation from within balloon 102 or 115 is that there is a generally unobstructed radiation path from waveguide 1 14 or bundle 117 to the endothelial cells. When administering the irradiation, balloon 102 or 1 15 is preferably placed directly against the cells, so that blood and other radiation-absorbing substances do not get into the radiation path.

Figs. 5A and 5B are schematic side view and cross-sectional illustrations, respectively of a balloon dilation and biostimulation catheter 120, in accordance with another preferred embodiment of the present invention. Catheter 120 comprises a first lumen 122 which is used to apply irradiation and/or perform other tasks such as direct the catheter into the artery along a guide wire or introduce drugs or medicine to the area of the stenosis. A second lumen 124 terminates in a balloon 126 which is inflated and deflated through the second lumen. Catheter 120 may be generally as described, for example, in U.S. patent 5,669,880. Preferably, one or more waveguides are permanently situated within first lumen 122. Further preferably, a lens as described above in reference to Fig. 1 is situated at the distal end of first lumen 122.

Fig. 6 is a schematic, cross-sectional illustration of a balloon dilation and biostimulation catheter 130, in accordance with still another preferred embodiment of the present invention. Catheter 130 comprises three coaxially extending lumens. A first lumen 132 is used for applying irradiation to the stenosis in any of the various methods described above, a second lumen 134 is used for inflating and deflating a balloon, and a third lumen 136 serves for other tasks as described above. Fig. 7 is a schematic illustration of a balloon dilation and biostimulation catheter 150 within occluded artery 50, in accordance with still another preferred embodiment of the present invention. Catheter 150 includes a balloon 151, generally as described above, and a through channel 152 with two exits 154 and 156. Channel 152 is suited for passing a waveguide 155 to either of exits 154 and 156. Preferably, waveguide 155 is steerable, so that a surgeon can direct the waveguide to substantially any point from which it may be desired to irradiate endothelial cells 152. During the angioplasty treatment, waveguide 155 may be positioned in a first configuration 160 and may then be moved to a different configuration 162, without moving the catheter. Fig. 8 is a schematic illustration of a combined irradiation and stent implanting catheter

170, in accordance with a preferred embodiment of the present invention. Catheter 170 is adapted for implanting a stent 172 as described, for example, in U.S. patents 5,662,703 and 4,848,343. Stent 172 is situated at the distal end of catheter 170, and is detached from the catheter when the surgeon has confirmed that the stent is at a desired point along the artery. A waveguide 173, substantially as described above, is incorporated within catheter 170.

Preferably, a position sensor 174 is embedded within stent 172. During insertion of catheter 170 into the artery, sensor 174 may be used to direct the catheter to the stenosis. After implantation of stent 172, sensor 174 is used to easily locate the stenosis and direct thereto post- treatment bio-stimulative radiation. The post-treatment radiation may be non-invasive, as described in PCT/IL97/00257.

Preferably, position sensor 174 comprises at least one miniature coil which generates signals indicative of its position responsive to magnetic fields. In a preferred embodiment of the present invention, sensor 174 comprises a single coil which requires minimal space, preferably a lithographic coil. Preferably, the sensor is a wireless sensor as described, for example, in PCT publication IL97/00308 which is incorporated herein by reference. Alternatively, sensor 174 comprises an assembly of three orthogonal coils, as described above. Alternatively or additionally, other position indicators may be used, such as fiducial marks and ultrasound transponders.

Fig. 9 is a schematic illustration of an irradiation catheter 180 within an artery 50, in accordance with a preferred embodiment of the present invention. Catheter 180 comprises a fiber optic 182 which directs the radiation to the stenosis area. Preferably, along most of its length, fiber optic 182 is covered by a cladding material 184, which does not allow radiation to escape the fiber optic. A portion 186 of fiberoptic 182, preferably a distal end thereof, is not cladded and emits the radiation radially through 360°, as indicated by arrows 188. Alternatively or additionally, portion 186 is covered by a filtering material which is transparent substantially only to biostimulative wavelengths, such as selected infrared wavelengths. Fiberoptic 182 provides uniform, low-power irradiation of relatively large areas and can irradiate substantially the total inner surface of artery 50 in the vicinity of stent 172, as shown in Fig. 9. It is noted that fiberoptic 182 may be inserted through a larger catheter, for example, instead of waveguide 155 shown in Fig. 7 or may be positioned within an angioplasty balloon.

Fig. 10A illustrates a catheter 200 for laser ablation of a stenosis and biostimulation, in accordance with a preferred embodiment of the present invention. Catheter 200 comprises a waveguide 202 which directs radiation to the stenosis area through an optic 232, as described hereinbelow. Preferably, waveguide 202 is suitable for directing radiation of a wide span of wavelengths and energy levels, for example, a quartz waveguide. Preferably, catheter 200 comprises near its distal end 25 a sensor 204 for supplying signals used for control of the irradiation. Sensor 204 may comprise a contact sensor, which assures that the tip of catheter 200 is close enough to endothelial cells 54, or an electrode which supplies signals indicative of the electrical activity in the vicinity of the distal end of catheter 200. Alternatively or additionally, sensor 204 may comprise a light sensor, a radiometric sensor, or another physiological sensor for determining viability or non-viability. Preferably, catheter 200 includes position sensor 36 as described above. Fig. 10B illustrates a console 210 used together with catheter 200, in accordance with a preferred embodiment of the present invention. Console 210 comprises signal processing circuitry 40 for processing signals received from position sensor 36 and sensor 204. A low- power laser source 30, such as a HeNe laser, emitting red light suitable for biostimulation of the artery cells, is included in console 210. A second, high-power laser source 212, such as an ultraviolet excimer laser, provides high-power radiation suitable for intra-arterial ablation, as is known in the art, is also included in console 210. The proximal end of waveguide 202 is easily connectable to both low power source 30 and high power source 212. Preferably, waveguide 202 comprises a quick-connect fitting 216 which fits into sockets 218 of laser sources 30 and 212. Alternatively, waveguide 202 is coupled to the laser sources via a switch box which allows changing the radiation source by moving a switch. Further alternatively, waveguide 202 is coupled to both laser sources simultaneously, via a dichroic beam splitter, for example, as is known in the art. Before the ablation treatment, catheter 200 is brought to the vicinity of the stenosis for biostimulative irradiation. Waveguide 212 is coupled to low power source 30, and source 30 is operated so that endothelial cells 54 are irradiated with suitable radiation. Waveguide 202 is then coupled to high power laser source 212, and source 212 is operated so as to ablate the occlusion in the artery. Preferably, after the ablation, source 30 is again operated for post-ablation biostimulative treatment.

Preferably, optic 232 comprises a dichroic optic, which concentrate the ablation radiation from high-power source 212, while spreading the biostimulatory radiation from low-power source 30. For example, optic 232 may comprise a diffractive focusing element, as is known in the art, which is preferably made of quartz and is designed to focus ultraviolet or blue radiation and spread red or infrared radiation. In this way, the high-power radiation is concentrated in order to ablate the occlusion, while the biostimulatory radiation is delivered over a wide area at relatively low intensity, to provide optimal anti-restenosis effect.

In an alternative preferred embodiment of the present invention, not shown in the figures, separate catheters are used for the artery treatment and for irradiation. In such embodiments the irradiation catheter may be as described, for example, in PCT/IL97/00257.

It will be appreciated that the preferred embodiments described above are cited by way of example, and the full scope of the invention is- limited only by the claims.

Claims

1. A method of treating a blood vessel, comprising irradiating an area in the blood vessel with biostimulative radiation so as to reduce restenosis thereof after treatment.

2. A method in accordance with claim 1, and comprising opening an occlusion in the blood vessel.

3. A method in accordance with claim 2, wherein opening the occlusion comprises inflating an angioplasty balloon.

4. A method in accordance with claim 3, wherein inflating the balloon comprises inflating a balloon which is at least partially radiation reflective so as to aid in distribution of the radiation on the artery.

5. A method in accordance with claim 2, wherein opening the occlusion comprises implanting a stent.

6. A method in accordance with claim 2, wherein opening the occlusion comprises ablating a stenosis.

7. A method in accordance with claim 2, wherein irradiating comprises irradiating before opening of the occlusion.

8. A method in accordance with claim 2, wherein irradiating comprises irradiating during opening of the occlusion.

9. A method in accordance with claim 2, wherein irradiating comprises irradiating after opening the occlusion.

10. A method in accordance with claim 1 , wherein irradiating with biostimulative radiation comprises irradiating with radiation which substantially does not cause damage to human cells.

11. A method in accordance with claim 1 , wherein irradiating with biostimulative radiation palliates tissue inflammation.

12. A method in accordance with claim 1, wherein irradiating comprises inserting a catheter into the blood vessel and irradiating therefrom.

13. A method in accordance with claim 1 , and comprising inserting a sensor into the artery and monitoring the irradiation responsive to signals from the sensor.

14. A method in accordance with claim 1 , wherein irradiating comprises irradiating from a source external to the artery.

15. A method in accordance with any of claims 1-14, wherein irradiating comprises irradiating with infrared radiation.

16. A method in accordance with claim 1, wherein irradiating comprises irradiating at a power less than or about 200 milliwatts.

17. A method in accordance with claim 1, wherein irradiating comprises irradiating with laser radiation.

18. A method in accordance with claim 1, wherein irradiating comprises uniformly irradiating substantially the entire radial inner surface of the artery.

19. A catheter for treatment of a blood vessel, comprising: apparatus for opening an occlusion in the blood vessel ; and a waveguide for irradiating the blood vessel with biostimulative radiation.

20. A catheter in accordance with claim 19, wherein the apparatus comprises an angioplasty balloon.

21. A catheter in accordance with claim 20, wherein the balloon is connected to the catheter along a radial periphery of the catheter.

22. A catheter in accordance with claim 21 , wherein the balloon covers the distal end of the catheter.

23. A catheter in accordance with claim 21 or 22, wherein the waveguide has a distal end which emits the radiation and the distal end is situated within the balloon.

24. A catheter in accordance with claim 23, wherein at least part of the balloon comprises a radiation transparent material.

25. A catheter in accordance with claim 23, wherein at least part of the balloon comprises a radiation reflective material.

26 A catheter in accordance with claim 19, wherein the waveguide is movable within the catheter.

27. A catheter in accordance with claim 19, wherein the waveguide comprises a fiberoptic bundle.

28. A catheter in accordance with claim 20, wherein the waveguide comprises a fiberoptic bundle.

29. A catheter in accordance with claim 28, wherein optical fibers from the fiberoptic bundle are connected to the balloon.

30. A catheter in accordance with claim 29, wherein the fibers are fixed to an inner surface of the balloon.

31. A catheter in accordance with claim 29, wherein the fibers are fixed to an outer surface of the balloon.

32. A catheter in accordance with claim 29, wherein the fibers are connected to the balloon in a manner such that the fibers emit radiation in an outward, generally radial direction relative to an outer surface of the balloon surface.

33. A catheter in accordance with claim 29, wherein the fibers are fixed to the balloon in a substantially uniform distribution over at least a portion of the surface of the balloon.

34. A catheter in accordance with claim 19, wherein the waveguide comprises an optic.

35. A catheter in accordance with claim 34, wherein the optic comprises a wide-angle lens.

36. A catheter in accordance with claim 35, wherein the lens comprises a fisheye lens.

37. A catheter in accordance with claim 34, wherein the optic comprises a dichroic optic, which spreads the biostimulative radiation while concentrating radiation which is passed through the waveguide to ablate an occlusion in the artery.

38. A catheter in accordance with claim 19, wherein the waveguide comprises a fiberoptic having a substantially uncladded portion along its length through which the radiation is emitted.

39. A catheter in accordance with claim 38, wherein the uncladded portion allows emission of the radiation in a substantially uniform radial pattern.

40. A catheter in accordance with claim 38, wherein the uncladded portion allows emission of substantially only biostimulative radiation.

41. A catheter in accordance with claim 38, wherein the uncladded portion allows emission of substantially only infrared radiation.

42. A catheter in accordance with claim 19, wherein the apparatus comprises a stent.

43. A catheter in accordance with claim 42, wherein the stent comprises a position indicator.

44. A catheter in accordance with claim 43, wherein the position indicator comprises a fiducial mark.

45. A catheter in accordance with claim 43, wherein the position indicator comprises a position-sensing coil.

46. A catheter in accordance with claim 19, wherein the apparatus comprises a waveguide to convey radiation to the blood vessel for ablating the occlusion.

47. Apparatus for prevention of restenosis in an artery comprising: a radiation source which generates biostimulative radiation; and a waveguide which directs the radiation to the artery.