Surgery – Instruments – Light application
Utility Patent
1997-12-16
2001-01-02
Nasser, Robert L. (Department: 3736)
Surgery
Instruments
Light application
C606S016000, C606S002000, C606S007000
Utility Patent
active
06168591
ABSTRACT:
BACKGROUND OF THE INVENTION
The technical field of this invention is phototherapy and, in particular, instruments employing optical fibers or other flexible light waveguides to deliver radiation to a targeted biological site.
Fiber optic phototherapy is an increasingly popular modality for the diagnosis and/or treatment of a wide variety of diseases. For example, in surgery, infrared laser radiation will often be delivered to a surgical site via an optically transmissive fiber in order to coagulate blood vessels or cauterize tissue. Similar fiber optic delivery systems have been proposed for endoscopic or catheter-based instruments to deliver therapeutic radiation to a body lumen or cavity. U.S. Pat. No. 4, 336,809 (Clark) and U.S. Reissue Pat. No. RE 34,544 (Spears) disclose that hematoporphyrin dyes and the like selectively accumulate in tumorous tissue and such accumulations can be detected by a characteristic fluorescence under irradiation with blue light. These patents further teach that cancerous tissue that has taken up the dye can be preferentially destroyed by radiation (typically by high intensity red light).
Others have proposed the use of fiber-delivered radiation to treat artherosclerotic disease. For example, U.S. Pat. No. 4,878,492 (Sinofsky et al.) discloses the use of infrared radiation to heat blood vessel walls during balloon angioplasty in order to fuse the endothelial lining of the blood vessel and seal the surface. Another application of fiber-delivered radiation is disclosed in U.S. Pat. No. 5,053,033 (Clarke) which teaches that restenosis following angioplasty can be inhibited by application of UV radiation to the angioplasty site to kill smooth muscle cells which would otherwise proliferate in response to angioplasty-induced injuries to blood vessel walls.
In yet another application, phototherapeutic instruments are employed to treat electrical arrhythmia of the heart. In such applications, a catheter having a fiber optic component is fed via a major artery into a patient's heart. Once inside the heart, a catheter senses electrical impulses with electrical contacts on its outer sheath or other catheter elements in order to locate the source of arrhythmia. Once located, the phototherapeutic component is activated to “ablate” a portion of the inner heart wall. The likelihood that the patient's heart will continue to experience arrhythmia is reduced by coagulating heart tissue in the vicinity of the arrhythmia source.
In other applications, laser radiation can be used in conjunction with a similar catheter instrument inside a patient's heart to increase blood flow to oxygen starved regions of the heart muscle. In such procedures, the laser radiation is used to form small holes in the heart muscle so that the oxygen-depleted tissue is bathed with blood from the ventricular cavity.
In all of these applications, if the light-emitting catheter instrument is too rigid, there is the potential for damage to a patient's artery or other blood vessel, especially the aorta. Furthermore, a rigid catheter instrument is difficult to steer to a desired location.
Accordingly, there exists a need for better apparatus for fiber-optic phototherapy. In particular, a phototherapeutic instrument that can “guide” an optical fiber with a light-emitting tip along a torturous lumen to the location of target tissue and then can penetrate the target tissue with the light-emitting tip would meet a particularly important need in the field of minimally-invasive phototherapeutic surgery.
SUMMARY OF THE INVENTION
Phototherapeutic instruments are disclosed having a light transmitting optical fiber with a flexible portion which facilitates passage of the instrument through a tortuous lumen within a patient, and an outer support sheath slidably disposed around the optical fiber. In one preferred embodiment, the instrument can further include a rigid light-emitting tip. The support sheath is configured to protect the more delicate optical fiber and provide support for the flexible portion of the optical fiber during penetration of the light-emitting tip into a patient's tissue. During insertion of the instrument into a tortuous lumen, the distal end of the optical fiber is covered by the support sheath. In a preferred embodiment the tip of the sheath articulates, i.e., the tip is steerable. The flexible portion of the fiber and the steerable tip of the sheath allow the distal end of the optical fiber-sheath apparatus to deflect as it travels along a tortuous lumen. When the fiber is retracted in the support sheath, the flexible region coincides with the articulated region of the steerable catheter.
When the distal end or tip of the optical fiber arrives at the site of the target tissue, the tip is advanced to the target tissue region (e.g., the heart wall). While the sheath is held still, the fiber element carried within the sheath is then mechanically advanced by itself, forcing the light-emitting tip to penetrate the target tissue. The flexible portion of the fiber element fits snugly in the sheath so that when an operator pushes on the fiber element from a remote location, the sheath-fiber element configuration transmits enough force on the proximal end of the light-emitting tip to advance the tip to penetrate the target tissue. Preferably, the clearance between the flexible portion of the fiber element and the rigid sheath is about 100 micrometers to about 500 micrometers.
A phototherapeutic instrument according to one embodiment of the invention includes a light transmitting optical fiber, and a support sheath slidably mounted about the fiber. The fiber has a proximal and a distal end. The proximal end is adapted for coupling to a source of phototherapeutic radiation. The distal end has an element for directing radiation into biological tissue. The fiber includes a first, stiff portion, a second, flexible portion connected to the distal end of the first stiff portion, and a third, stiff portion connected to the distal end of the second, flexible portion and forming the distal end of the fiber. Thus, the fiber's distal end can be covered by the support sheath as the fiber's distal end is advanced to a target site and then once the fiber's distal end has been positioned at the target site, a selected portion of the fiber's distal end can be extended outside the support sheath for insertion into the tissue. In other words, a phototherapeutic instrument according to one embodiment of the invention is configured to provide the instrument with gradient stiffness or a gradient flex property, e.g., an instrument with a sequence of stiff-floppy-stiff portions.
The invention is particularly useful in assisting an optically-transmissive fiber element's insertion along a tortuous lumen and in facilitating the penetration of the light-emitting tip of the fiber element into target tissue, thereby, reducing the possibility of fiber damage and/or perforation of a body lumen or organ. The invention is useful in placing an ablative laser radiation device into the ventricle of the heart when performing arrhythmia-correcting laser ablative procedures or when revascularizing the heart percutaneously. In these types of procedures, the surgeon seeks to pass the phototherapeutic instrument over the aortic arch and to partially penetrate the heart muscle. The instrument configurations of the present invention allow passage of a light-emitting tip of a phototherapeutic through a torturous lumen while providing stability to the fiber element during insertion and operation of the light-emitting tip of the fiber element.
The invention will next be described in connection with certain preferred embodiments. However, it should be clear that various changes and modifications can be made by those skilled in the art without departing from the spirit or scope of the invention.
REFERENCES:
patent: 5163935 (1992-11-01), Black et al.
patent: 5169395 (1992-12-01), Narciso, Jr.
patent: 5196005 (1993-03-01), Doiron
patent: 5415653 (1995-05-01), Wardle et al.
patent: 5441497
CardioFocus, Inc.
Engellenner Thomas J.
Nasser Robert L.
Nutter & McClennen & Fish LLP
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