WO1999042168A2

WO1999042168A2 - Method of intravascular electromagnetic radiation treatment

Info

Publication number: WO1999042168A2
Application number: PCT/US1999/003947
Authority: WO
Inventors: Ziv Karni; Baruch Ben-Dor
Original assignee: Esc Medical Systems Ltd.; Friedman, Mark, M.
Priority date: 1998-02-24
Filing date: 1999-02-24
Publication date: 1999-08-26
Also published as: AU3309299A; WO1999042168A3

Abstract

This invention is a method of narrowing or occluding a blood vessel. The method includes the steps of obtaining an apparatus including a radiation source (14) for generating electromagnetic radiation output falling within a spectral range; at least one optical fiber (18) having a proximal end, and a distal end; the proximal end of the optical fiber (18) being optically coupled to the radiation source; inserting the distal end into the blood vessel; and internally irradiating the blood vessel with the electromagnetic radiation in an energy sufficient for causing blood coagulation within or wall shrinkage of the vessel.

Description

METHOD OF LNTRA VASCULAR ELECTROMAGNETIC RADIATION

TREATMENT

FIELD AND BACKGROUND OF THE INVENTION The present invention relates generally to the art of therapeutic electromagnetic treatments. More particularly, the present invention relates to a method of intravascular electromagnetic radiation treatment.

The method of the present invention serves for effecting blood coagulation within and/or shrinkage of blood vessels, such as veins, arteries and valves, in conditions such as, but not limited to, dilated veins, aneurysms, vascular malformations and arteriovenous fistulas, which are, as so far, treated surgically.

It is known in the prior art to use electromagnetic radiation in medical applications for therapeutic uses. External application of electromagnetic radiation is most effective in treating external and surficial conditions, such as, but not limited to, skin blood vessel disorders (e.g., port wine stains, etc.).

However, external application of electromagnetic radiation is much less effective in treating blood vessel disorders residing deeper within the body, since the radiation cannot penetrate the required depth and/or damages healthy tissue present along its path to the treatment site.

There are known medical conditions in which shrinking or coagulating blood vessels is required. As used herein term "shrinking" refers to narrowing or occluding. These conditions include, for example, dilated veins, aneurysms, vascular malformations and arteriovenous fistulas. Shrinking blood vessels is currently effected by surgical techniques such as ligation or ligation followed by stripping. Ligation is effected by making a small incision above the vein and ligation of the vein through this incision using, for example, a string. Stripping is effected by transmitting a wire in a vein and thereby stripping its inside. Being surgical, these methods suffer disadvantages as compared with minimal invasive methods. Additional disadvantages include longer recovery time and, in many cases, ugly cosmetic appearance.

U.S. Pat. Nos. 5,100,429; 5,330,490; and 5,620,439 teach minimal invasive laser techniques and systems for removing obstructions formed within blood vessels. These systems utilize catheters and optical fibers which bring in laser radiation having energy sufficient for drilling a hole in the obstruction, thereby removing the obstruction.

U.S. Pat. No. 4,735,201 to O'Reilly teaches a method for blocking blood vessels which employs a metallic tip insertable into a treated blood vessel, which is heated by electromagnetic radiation arriving via an optical fiber, and is left in the vessel to block blood flow therein.

In sharp contrast with the prior art, a method for directly intra-heating a vessel's wall or blood which flows therein to effect wall shrinkage or blood coagulation, respectively, and thereby narrowing or completely occluding the vessel is disclosed herein.

SUMMARY OF THE INVENTION

According to the present invention there is provided a method for effecting blood coagulation within, and/or shrinkage of, blood vessels, such as veins, arteries and valves.

According to further features in preferred embodiments of the invention described below, provided is a method of narrowing or occluding a blood vessel, the method comprising the steps of (a) obtaining an apparatus including (i) a radiation source for generating electromagnetic radiation output falling within a spectral range; and (ii) at least one optical fiber having a proximal end and a distal end, the proximal end of the optical fiber being optically coupled to the radiation source; (b) inserting the distal end into the blood vessel; and (c) internally irradiating the blood vessel with the electromagnetic radiation in an energy sufficient for causing blood coagulation within or wall shrinkage of the vessel. According to still further features in the described preferred embodiments the spectral range is between 0.6 μm and 2.5 μm.

According to still further features in the described preferred embodiments the radiation source is a laser. According to still further features in the described preferred embodiments the laser is a Nd:YAG laser operating at 1.064 μm or 1.32 μm.

According to still further features in the described preferred embodiments, the laser is a Diode laser operating in the 0.6-2.5 μm spectral range. According to still further features in the described preferred embodiments the radiation source is a multiband source.

According to still further features in the described preferred embodiments the multiband source is an arc lamp.

According to still further features in the described preferred embodiments the at least one optical fiber includes a distal diffusion region close to its distal end, such that the electromagnetic radiation dissipates through the diffusion region.

According to still further features in the described preferred embodiments the electromagnetic radiation dissipates through the distal end of the optical fiber.

According to still further features in the described preferred embodiments the apparatus further includes a catheter forming a protective sheath around a central lumen, the at least one optical fiber is mounted within the central lumen, whereas the step of inserting the distal end into the blood vessel is effected by inserting the catheter into the blood vessel.

According to still further features in the described preferred embodiments an inflatable balloon is mounted over the catheter, whereas the method further comprising the step of (d) prior to the step of internally irradiating the blood vessel with the electromagnetic radiation, inflating the balloon for blocking blood flow through the vessel, such that the electromagnetic radiation impinges on the walls of the vessel, thereby causing shrinkage of the vessel.

According to still further features in the described preferred embodiments the blood vessel is a neck of an incompetent valve of a dilated vein, and the shrinkage is performed until the competence of the valve is restored.

According to still further features in the described preferred embodiments the catheter is made of a substance which is substantially transparent to the electromagnetic radiation. According to still further features in the described preferred embodiments blood flows in the vessel when the step of internally irradiating the blood vessel is effected, thereby blockage of the vessel is effected by blood coagulation within the vessel.

According to still further features in the described preferred embodiments internally irradiating the blood vessel with the electromagnetic radiation is effected in a plurality of locations along the vessel.

According to still further features in the described preferred embodiments the method further comprising the step of (d) withdrawing the at least one optical fiber from the vessel. According to still further features in the described preferred embodiments the step of internally irradiating the blood vessel with the electromagnetic radiation is effected by pulses of irradiation.

According to still further features in the described preferred embodiments the blood vessel is involved in a condition selected from the group consisting of, dilated veins, aneurysms, vascular malformations and arteriovenous fistulas.

It is an object of the present invention to provide a minimally invasive method for providing precisely positioned intravascular occlusions or for narrowing of blood vessels. It is another object of the present invention to provide a laser catheter device and a method of using same to shrink or to seal off blood vessels, e.g., in cases of dilated veins and aneurysms, by cauterization without excessive tissue damage and without major surgery. Thus, the present invention successfully addresses the shortcomings of the presently known configurations by providing a minimal invasive method for electromagnetically treating blood vessels which are otherwise treated surgically.

Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention herein described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic depiction of an apparatus for effecting the method according to the present invention, the apparatus includes a radiation source optically coupled to a single optical fiber;

FIG. 2 is a schematic depiction of a distal end of a fiber for effecting the method according to the present invention, the fiber is supplemented with a distal diffusion region;

FIG. 3 is a schematic depiction of an apparatus for effecting the method according to the present invention, the apparatus includes a radiation source optically coupled to a single optical fiber which is protected by a catheter supplemented with an inflating balloon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a method of electromagnetically treating blood vessels, which can be used for occluding or narrowing the vessels. Specifically, the present invention can be used for treating conditions, such as, but not limited to, dilated veins, aneurysms, vascular malformations and arteriovenous fistulas, which are, as so far, treated surgically.

The principles and operation of a combined apparatus according to the present invention may be better understood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Thus, according to the present invention there is provided a method of narrowing or occluding a blood vessel. The method includes the following steps.

First an apparatus for effecting the method is obtained. Figures 1-3 provide schematic depictions of few embodiments of suitable apparatuses.

With specific reference to Figure 1, the apparatus, which is generally referred to hereinbelow as apparatus 10, includes a radiation source 12. Radiation source 12 serves for generating electromagnetic radiation output which falls within a desired spectral range, say within the range of 0.6 μm and

2.5 μm.

According to a preferred embodiment of the present invention radiation source 12 generates coherent radiation. Preferably, radiation source 12 is a laser device 14, which is easily capable of generating coherent radiation having high energy.

According to a preferred embodiment laser device 14 is a Nd:YAG laser operating at 1.064 μm or at 1.32 μm. Alternatively, laser device 14 is a Diode laser operating at the 0.8 - 1.0 μm spectral range. According to another preferred embodiment of the present invention radiation source 12 is a multiband radiation source, such as, but not limited to, an arc lamp 16. These radiation sources are well known in the art and therefore require no further description herein. As further shown in Figure 1, apparatus 10 further includes at least one

(one is shown) optical fiber 18. Fiber 18 has a proximal end 20 and a distal end 22. Proximal end 20 of optical fiber 18 is optically coupled to radiation source 12. Coupling an optical fiber or a bundle thereof to a radiation source is well known in the art and requires no further description herein. According to a preferred embodiment of the present invention, and as specifically shown in Figure 2, optical fiber 18 includes a distal diffusion region 24 located close to its distal end 22, such that, as indicated by arrows 26, the electromagnetic radiation laterally dissipates through diffusion region 24, as well as longitudinally from distal end 22, as indicated by arrows 28. Providing a diffusion region in an optical fiber is a well known technology which requires no further description herein. A fiber including a diffusion region in its distal end is distributed by Rare Earth Medical Inc., West Yarmouth, MA, USA. For some applications, it may be desirous to optically block distal end 22 and thereby restrict all of the radiation to leave fiber 18 via diffusion region 24. In other applications, light diffusion may be limiting. In these cases a simple optical fiber is employed, wherein all of the radiation leaves the fiber longitudinally through distal end 22.

In the second step of the method according to the present invention, distal end 22 is inserted into the blood vessel and appropriately located at a region of the vessel to be narrowed or occluded.

Appropriately locating end 22 within the vessel is preferably effected by an imaging method capable of imaging both the vessel and the fiber/catheter or a part thereof. Suitable imaging methods are, for example, ultrasound and X- ray imaging. For X-ray imaging, a metallic marker 36 is preferably included close to, or at, end 22 of fiber 18. Alternatively, appropriately locating end 22 within the vessel is effected by a co-aligned visible laser providing a guiding light beam (e.g., guiding red light), which is visible through the tissue (e.g., skin, vessel's walls) of the patient. In the second step of the method according to the present invention, the blood vessel is internally irradiated with the electromagnetic radiation in an energy sufficient for causing blood coagulation within, or wall shrinkage of, the vessel.

Using a single fiber 18 is advantageous when narrow (e.g., about 1-3 mm in diameter) vessels are treated.

For larger vessels (e.g., about 4-15 mm in diameter), as specifically shown in Figure 3, according to a preferred embodiment of the present invention apparatus 10 further includes a catheter 30 forming a protective sheath 32 around a central lumen 34. Optical fiber 18 is mounted within central lumen 34. Distal end 22 of optical fiber 18 preferably protrudes from catheter 30. In this case, the step of inserting distal end 22 into the blood vessel is effected by inserting catheter 30 into the blood vessel. Inserting catheters into blood vessels is a well established medical procedure.

According to a preferred embodiment of the present invention catheter 30 is made of a substance which is substantially transparent to the electromagnetic radiation (e.g., transparent polyethylene).

Upon irradiation, blood that flows within the vessel coagulates and thereby occludes the vessel. This procedure is preferably executed a in a plurality of locations, say 3 -5 successive locations along the vessel, to ensure complete, prolonged and safe blockage of the vessel.

In this case, rapid heating is required for immediate coagulation and blockage of the vessel, so as to avoid migrating thromboses. Rapid heating can be effected by short high-energy laser pulses, each lasting a millisecond and up to a second. For limited narrowing of the vessel, as further shown in Figure 3, according to another preferred embodiment of the present invention, an inflatable balloon 36 (shown inflated in Figure 3) is mounted over catheter 30.

In this case, the method further includes a step in which balloon 36 is inflated and thereby blocks blood flow through the vessel, such that the electromagnetic radiation impinges on the walls of the vessel, thereby causing the walls to collapse which results in shrinkage (i.e., narrowing or full blockage) of the vessel. Inflatable balloon including catheters are well known in the art and are conventionally used for angiography. In this case, slow heating is sufficient. Slow heating can be effected by long medium-energy laser pulses, or continuous low-energy laser pulse lasting from 5 seconds to five minutes.

This embodiment of the invention is highly suitable for narrowing blood vessels. For example, narrowing a neck of an incompetent valve of a dilated vein, whereas shrinkage is performed as described until the competence_of the valve is restored.

According to all of the embodiments herein described, upon irradiation of the vessel, the irradiated tissue is heated. As a result, blood coagulates, whereas vessel walls collapse and the vessel narrows. Thus, in accordance with the present invention, end 22 of fiber 18 is positioned intravascularly within the neck of the point which is to be narrowed or occluded and laser energy is transmitted in a short and intense pulse through optical fiber 18 to heat the blood and/or the vessel's walls and thereby to narrow or occlude (e.g., shrink or thrombose) the vessel. According to a preferred embodiment the radiation is pulsative.

Radiation sources for generating pulsative radiation are well known in the art.

However, according to another embodiment the radiation continuous. In any case, the vessel is internally irradiated in an energy and for a period of time sufficient either to narrow or to totally occlude the vessel. According to all the embodiments of the present invention, when the treatment is completed the fiber/catheter is withdrawn from the vessel. If a balloon is employed, it is first deflated and the treated tissue is allowed to set for some time, after which catheter 30 is withdrawn from the vessel. The following lists few considerations for wavelength selection.

The first criterion in this respect is that the radiation will be homogeneously absorbed by the walls of the vessel. Medium absorption is preferred for this purpose, such that it will not penetrate too deep into the vessel's tissue and further such that it will not be completely absorbed by the inner superficial layer of the vessel.

A second criterion is that the radiation will penetrate through the remaining blood to the vessel walls (for the slow heating mode). For the rapid heating mode (blood coagulation) the same wavelength is suitable since it will coagulate the blood more uniformly. In the slow heating mode (wall shrinkage) the power applied is a function of the illuminated area, which depends upon the fiber tip geometry. It should be set in such a way that it will heat the vessel wall to between about 70-

80 °C.

In the slow heating mode the energy should be applied slowly in such a way that it will heat the vessel wall to between 70-80 °C. This steady state heating should be applied until the vessel shrinks to a desired diameter. This time is typically between 5 seconds to 5 minutes, depending on the specific application.

In the rapid heating mode the energy should be applied fast enough to create blood coagulation and thrombosis. This time is between milliseconds to several seconds.

In the rapid heating mode there is no importance if the blood is flowing

(if the pulse prolongs less than a second). In the slow heating mode it is important that the blood flow will be stopped (via the inflated balloon) in order to prevent the creation of small migrating thromboses in the blood. Reference is now made to the following example, which together with the above descriptions, illustrate the invention in a non limiting fashion.

EXAMPLE

A single optical fiber having a 1 cm diffusion region close to its distal end, connected to a 100 watts Nd:YAG 1.064 μm laser, was employed to treat veins of several human patients. After each pulse the fiber was withdrawn a little (e.g., about 5 mm to about 5 cm) and another pulse was given. A total of 4-5 pulses were given to each vein treated. One second long pulses of 100 watts were sufficient to completely block a saphena parva (lesser saphenous vein) in several people.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method of narrowing or occluding a blood vessel comprising the steps of:

(a) obtaining an apparatus including:

(i) a radiation source for generating electromagnetic radiation output falling within a spectral range; and

(ii) at least one optical fiber having a proximal end and a distal end, said proximal end of said optical fiber being optically coupled to said radiation source;

(b) inserting said distal end into the blood vessel; and

(c) internally irradiating the blood vessel with said electromagnetic radiation in an energy sufficient for causing blood coagulation within or wall shrinkage of the vessel.

2. The method of claim 1 , wherein said spectral range is between 0.6 ╬╝m and 2.5 ╬╝m

3. The method of claim 1, wherein said radiation source is a laser.

4. The method of claim 3, wherein said laser is a Nd:YAG laser operating at 1.064 ╬╝m or 1.32 ╬╝m.

5. The method of claim 3, wherein, said laser is a Diode laser operating in the 0.6-2.5 ╬╝m spectral range.

6. The method of claim 1, wherein said radiation source is a multiband source.

The method of claim 6, wherein said multiband source is an arc lamp.

8. The method of claim 1, wherein said at least one optical fiber includes a distal diffusion region close to its distal end, such that said electromagnetic radiation dissipates through said diffusion region.

9. The method of claim 1, wherein said electromagnetic radiation dissipates through said distal end of the said optical fiber.

10. The method of claim 1, wherein said apparatus further includes a catheter forming a protective sheath around a central lumen, said at least one optical fiber is mounted within said central lumen, whereas the step of inserting said distal end into the blood vessel is effected by inserting said catheter into the blood vessel.

11. The method of claim 10, wherein an inflatable balloon is mounted over said catheter, whereas the method further comprising the step of:

(d) prior to internally irradiating the blood vessel with said electromagnetic radiation, inflating said balloon for blocking blood flow through the vessel, such that said electromagnetic radiation impinges on the walls of the vessel, thereby causing shrinkage of said vessel.

12. The method of claim 11, wherein the blood vessel is a neck of an incompetent valve of a dilated vein, and said shrinkage is performed until the competence of the valve is restored.

13. The method of claim 10, wherein said catheter is made of a substance which is substantially transparent to said electromagnetic radiation.

14. The method of claim 1, wherein blood flows in the vessel when the step of internally irradiating the blood vessel is effected, thereby blockage of the vessel is effected by blood coagulation within the vessel.

15. The method of claim 1, wherein internally irradiating the blood vessel with said electromagnetic radiation is effected in a plurality of locations along the vessel.

16. The method of claim 1 , further comprising the step of: (d) withdrawing said at least one optical fiber from the vessel.

17. The method of claim 1, wherein the step of internally irradiating the blood vessel with said electromagnetic radiation is effected by pulses of irradiation.

18. The method of claim 1, wherein said blood vessel is involved in a condition selected from the group consisting of dilated veins, aneurysms, vascular malformations and arteriovenous fistulas.