Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
1999-05-06
2001-02-06
Hindenburg, Max (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
Reexamination Certificate
active
06183410
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a device which may be inserted into blood vessels, body cavities, etc. for radiating selectable areas in the vessels or cavities, for therapeutic or other purposes. More particularly, the present invention relates to an expandable catheter for placing in direct contact with a selected area in a blood vessel, body cavity or the like, which allows both radial and longitudinal control of radiation dosage.
2. State of the Art
Catheters have long been used for threading into blood vessels or other body orifices for such purposes as delivering emboli to target locations, delivering therapeutic drugs to such locations, sensing conditions in the vessel or cavity by sensors inserted into the catheter, etc. Typically, a guide wire is first threaded into the vessel or cavity until the distal end of the guide wire reaches a target location, and then the catheter which is placed about the guide wire is moved to the target location as guided by the guide wire. Then, depending upon the treatment, the guide wire may be withdrawn or left in place and the treatment commenced, such as by injecting drugs through the catheter to the target location.
There are some diseases, such as restenosis, which become sited in blood vessels or body cavities which cannot be effectively treated by drugs, but instead respond to appropriate doses of radiation from a radioactive source. Effective treatment of such diseases requires exposure of diseased tissues to levels of radiation within a therapeutic range. This presents a problem if the diseased areas are not readily accessible but can only be reached by a pathway which extends past healthy tissue to the diseased area. It would thus be desirable to have an apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source which may be threaded into a patient's anatomy such as by means of a catheter.
However, it is desirable to provide the radiation dose to the diseased area without exposing surrounding healthy tissue to such radiation. Thus, it is desirable to place the radiation source in as close a proximity to the diseased area as possible in order to produce a desired benefit, while also keeping the radiation source as far away from healthy tissue as possible. It would thus be desirable to provide an apparatus and method for selectively exposing areas of blood vessels, body cavities and the like to radiation in which healthy tissue in such vessels and cavities are protected from such radiation during insertion of the device and treatment therewith. It would thus also be desirable to have an apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source wherein the radiation dose may be both radially and longitudinally controlled relative to the patient's anatomy.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a method and apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source inside.
It is another object of the invention to provide such an apparatus which allows sufficient flow of bodily fluids around or through the apparatus during insertion and treatment.
It is still another object of the invention to provide an apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source wherein the radiation dose may be both radially and longitudinally controlled relative to the patient's anatomy.
It is also an object of the invention to provide such an apparatus and method in which healthy tissue in such vessels and cavities are protected from radiation during treatment.
It is yet another object of the invention to provide such an apparatus and method which allows for the safe handling and insertion of the radiation source into blood vessels, body cavities and the like.
It is a further object of the invention, in accordance with one aspect thereof, to provide such a method and apparatus which allows for selectively placing a radiation source in close proximity to a target area, but removed from adjacent areas.
The above and other objects of the invention are realized in a specific illustrative embodiment of apparatus for selectively irradiating blood vessels, body cavities and the like. Such apparatus includes a catheter having a distal end for threading into a blood vessel or body cavity, and having at least one lumen. Also included is a wire for threading into the lumen of the catheter, the wire having a proximal end and a distal end, and a radiation source disposed near the distal end for irradiating tissue adjacent to the radiation source.
In accordance with one aspect of the invention, the catheter includes a section which absorbs radiation from the radiation source so that when the radiation source is positioned within the section, radiation is substantially blocked or reduced from reaching adjacent tissue.
In accordance with another aspect of the invention, a portion of the catheter near the distal end is formed to spread apart when positioned in a blood vessel or cavity, and move into close proximity or contact with the vessel or cavity walls where a diseased area is located. Then, the radiation source on the wire may be moved in the catheter to a position adjacent the diseased area, for irradiating the diseased area.
In use, the wire would be threaded into the lumen of the catheter until the radiation source is positioned within the section which is absorbent of radiation, and then the catheter and wire would be threaded either directly into the blood vessel or cavity, or through another larger catheter to the target area in the vessel or cavity. All the time during the movement of the catheter to the target location, the radiation source would be maintained within the absorbent section of the catheter to reduce the chance of radiation damage to healthy tissue past which the radiation source is moved.
After the end portion of the catheter has moved to the target location, the wire is manipulated so that the radiation source is moved out of the absorbent section of the catheter into the portion of the catheter adjacent the diseased area to enable irradiating the diseased area. After completing the irradiation for the desired time, the radiation source may be moved back to within the absorbent section, or, more preferably, the wire is further retracted so that the radiation source becomes contained within another radiation absorbent section disposed proximally from the coiled distal end. The catheter and wire may then be withdrawn from the vessel or cavity. Alternatively, the entire catheter and wire may be drawn into a second, larger catheter, and withdrawn through or with the second catheter.
REFERENCES:
patent: 4957476 (1990-09-01), Cano
patent: 5976106 (1999-11-01), Verin et al.
patent: 6053900 (2000-04-01), Brown et al.
Backman Kent
Davis Clark C.
Jacobsen Stephen C.
Lippert John
Hindenburg Max
Precision Vascular Systems, Inc.
Szmal Brian
Thorpe North & Western LLP
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