Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
1999-09-16
2001-09-04
Lacyk, John P. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
Reexamination Certificate
active
06283911
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to radiation delivery devices, and to methods of making such devices. The invention is particularly useful in coronary revasculization therapy to remove vascular obstructions, and therefore is described below with respect to such an application, but it will be appreciated that the invention could also be used in other applications.
Coronary vascular obstructions generally require coronary bypass surgery, but frequently such an obstruction may be removed or reduced by Percutaneous Coronary Revascularization (PCR), such as by “balloon angioplasty”. However, such a PCR treatment frequently results in a renarrowing of the vessel, called “restenosis”, triggered by the injury to the vessel wall. Thus, the injury itself may trigger a healing response in the form of growth of a new inner lining within the vessel to heal the injured area (“intimal hyperplasia”).
Restenosis is commonly treated today by stenting. It has been found, however, that the provision of a stent may actually increase hyperplasia and thereby aggrevate restenosis, rather than reduce it. Moreover, restenosis following stenting is particularly difficult to treat.
Another technique now being investigated for preventing renarrowing of the vessel caused by hyperplasia is by the use of drugs, but this approach introduces other problems relating to the drug used.
At the present time, the application of radiation appears to be the most promising treatment now being examined for the prevention of restenosis following PCR. Radiation has been found to work particularly well in inhibiting new growth as has been shown for years in cancer management. External beam radiation, administered in relatively high doses, has a damaging effect on the patient's body, and therefore this approach does not appear to be suitable for reducing restenosis. However, using low-dosage radioactive sources, such as seeds temporarily implanted or inserted into the patient's body (endovascular brachytherapy), appears to be a promising treatment for the prevention of restenosis following PCR.
U.S. Pat. No. 5,683,345, which issued Nov. 4, 1997, discloses a technique for utilizing a catheter to deliver a radiation source to a desired site in the vascular system. The radiation source is in the form of a plurality of individually sealed seeds which emit beta radiation. These seeds are stored in a hand-held device and are hydraulically moved through a sterile catheter, inserted into the patient's vascular system, to the site in the vascular system to be treated. However, precisely locating radiation elements when moved in this manner is particularly difficult especially when they are to be located at a plurality of different sites. Also, this technique does not permit shielding those body parts which are not to be irradiated during the passage of the radiation-producing elements to the treatment site.
OBJECTS AND BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide another device for delivering radiation to one or more preselected sites in a vascular system of a patient. Another object of the invention is to provide a method of producing such a device.
According to one aspect of the present invention, there is provided a device for delivering radiation to at least one preselected site in a vascular system of a patient, comprising: an elongated flexible catheter tube of a diameter for insertion into the patient's vascular system; a flexible guide wire within the catheter tube and movable along its length, the guide wire including a proximal end to be located externally of the patient's vascular system for moving the guide wire within the catheter tube, and a rounded distal tip at the opposite end of the guide wire to facilitate its movement through the catheter tube; and at least one radiation-producing element fixed to the guide wire at an intermediate location thereof spaced from the rounded distal tip. The radiation-producing element is formed with a slot extending radially from an outer edge to its central region for receiving the flexible guide wire, and for fixing the radiation-producing element to the flexible guide wire.
According to further features in the described preferred embodiments, there are a plurality of the radiation-producing elements positioned along the length of the guide wire for delivering radiation to a plurality of preselected sites along the length of the guide wire.
According to another aspect of the present invention, there is provided a device for delivering radiation to a plurality of preselected sites in a vascular system of a patient, comprising: an elongated flexible catheter tube of a diameter for insertion into the patient's vascular system; a flexible guide wire within the catheter tube and movable along its length, the guide wire including a proximal end to be located externally of the patient's vascular system for moving the guide wire within the catheter tube; and a plurality of radiation-producing elements fixed to the guide wire at the distal end thereof. The device further includes a plurality of non-radiation producing spacer elements fixed to the guide wire between at least some of the radiation-producing elements for spacing the latter elements from each other along the guide wire.
According to a still further aspect of the present invention, there is provided a device for delivering radiation to a plurality of preselected sites in a vascular system of a patient, comprising: an elongated flexible catheter tube of a diameter for insertion into the patient's vascular system; a flexible guide wire within the catheter tube and movable along its length, the guide wire including a proximal end to be located externally of the patient's vascular system for moving the guide wire within the catheter tube; and a plurality of radiation-producing elements fixed to the guide wire at the distal end thereof; each of the radiation-producing elements being of a modular bead-like configuration including a socket section at one end, and a plug section at the opposite end configured to be received with a snap-fit into the socket section of another like radiation-producing element to form a string of such radiation-producing elements; the distal end of the guide wire being formed with a ball received in the socket section of the radiation-producing elements at one end of said string.
As will be described more particularly below, a device constructed in accordance with the foregoing features may be used for accurately delivering radiation to one or more preselected sites in a vascular system for any desired time interval, and may be conveniently removed for reuse after that time interval has expired. In addition, the flexible guide wire may further be provided with a tubular shield normally enclosing each radiation-producing element on the guide wire so as to protect the tissues not to be irradiated. Such shield would be movable longitudinally of the guide wire to uncover and expose selected radiation-producing elements during the treatment process.
Further, at least some of the radiation-producing elements may be separated by dummy elements fixed to the guide wire. Such dummy elements may be of the same configuration as the radial producing elements but not producing radiation. The provision of such dummy elements permits the device to have more uniformity in the construction and manipulatability of the device, but at the same time permits selectivity as to the site or sites in the vascular system to be radiated.
Further features and advantages of the invention will be apparent from the description below.
REFERENCES:
patent: 5213561 (1993-05-01), Weinstein et al.
patent: 5302168 (1994-04-01), Hess
patent: 5728042 (1998-03-01), Schwager
patent: 6056686 (2000-05-01), Mawad
patent: 6071227 (2000-06-01), Popowski et al.
patent: 6080099 (2000-06-01), Slater et al.
Cadugan Joseph A
Lacyk John P.
Medirad I.R.T. Ltd.
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