Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
1999-05-04
2001-10-23
Gilbert, Samuel G. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
Reexamination Certificate
active
06306074
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the delivery of treating elements by a catheter to a selected location within the intraluminal passageways, either vascular or non-vascular, of a patient. Intraluminal passageways are defined herein as all lumens, passageways, conduits, ducts, channels, canals, vessels, and cavities within the human body. More particularly, the present invention relates to method and apparatus for the delivery of a treating element, such as a radiation source, through a catheter to a desired site, such as a coronary artery, for inhibiting wound healing response, such as restenosis following balloon angioplasty, and also for inhibiting other occurrences of cell migration, proliferation, and enlargement, including that of cancerous cells, which may not result from wound healing response.
BACKGROUND OF THE INVENTION
It is known that the human body's healing response to wounds typically includes the formation of what is commonly called scar tissue. This response also occurs within the vascular system of a person following injury to a blood vessel. An injury that provokes the formation of scar tissue may occur in various locations within the vascular system, such as in the carotid artery or in coronary bypasses, or in various ways, such as trauma from surgical or diagnostic procedures.
Just as with lumens within the vascular system, non-vascular intraluminal passageways within a human patient can experience stenosis. Procedures, such as those described below, are performed for eliminating the areas of narrowing in non-vascular body lumens, and the walls of the treated lumens most likely are injured during the process. As a result of the injury, the human body begins its healing response and an overgrowth of tissue due to increased cell proliferation renarrows the lumens.
One area of the vascular system of particular concern with respect to such injuries is coronary arteries that are subjected to procedures for removing or reducing blockages due to plaque within the arteries. Partial and even complete blockage of coronary arteries by the formation of an atherosclerotic plaque is a well known and frequent medical problem. Such blockages may be treated using atherectomy devices, which mechanically remove the plaque; hot or cold lasers, which vaporize the plaque; stents, which hold the artery open; and other devices and procedures which have the objective of allowing increased blood flow through the artery. The most common such procedure is the percutaneous transluminal coronary angioplasty (PTCA) procedures—more commonly referred to as balloon angioplasty. In this procedure, a catheter having an inflatable balloon at its distal end is introduced into the coronary artery, the uninflated balloon is positioned at the stenotic site and the balloon is inflated. Inflation of the balloon disrupts and flattens the plaque against the arterial wall, and stretches the arterial wall, resulting in enlargement of the intraluminal passageway and increased blood flow. After such expansion, the balloon is deflated and the balloon catheter removed.
PTCA is a widely used procedure and has an initial success rate of between 90 and 95 percent. However, long term success of PTCA (as well as the other artery-opening procedures referred to above) is much more limited, due largely to restenosis, or reclosing of the intraluminal passageway through the artery. Restenosis, wherein the vessel passageway narrows to approximately 50% or less of the size of the native vessel, is experienced in approximately 30 to 50 percent of the patients within six months after PTCA. Restenosis may occur for various reasons, but it is now believed that restenosis is, in significant part, a natural healing response to the vessel injury caused by inflation of the angioplasty balloon.
Vessel injury may occur in several ways during PTCA, including: denudation (stripping) of the endothelium (the layer of flat cells that line the blood vessels); cracking, splitting and/or disruption of the atherosclerotic plaque and intima (innermost lining of the blood vessel); dehiscence (bursting) of the intima and the plaque from the underlying media; stretching and tearing of the media and adventitia (outside covering of the artery) which may result in aneurysmal expansion; and injury to the vessel smooth muscle. Such injury to the vessel typically initiates the body's own natural repair and healing process. During this healing process, fibrin and platelets rapidly accumulate in the endothelium, and vascular smooth muscle cells proliferate and migrate into the intima. The formation of scar tissue by smooth muscle proliferation, also known as intimal hyperplasia, is believed to be a major contributor to restenosis following balloon angioplasty of the coronary artery.
Prior attempts to inhibit restenosis of coronary arteries have included, among other things, the use of various light therapies, chemotherapeutic agents, stents, atherectomy devices, hot and cold lasers, as well as exposure of the stenotic site to radiation. These therapies have had varying degrees of success, and certain disadvantages are associated with each of these therapies. Although radiation therapy has shown promise, particularly in inhibiting intimal hyperplasia, the devices available for delivery of radiation sources to a stenotic site have been limited and have tended to suffer from drawbacks which limit their usefulness. Typical of the devices using radiation to treat restenosis are those shown or described in U.S. Pat. Nos. 5,059,166 to Fischell; 5,213,561 to Weinstein; 5,302,168 to Hess, 5,199,939 to Dake; 5,084,002 to Liprie; and 3,324,847 to Zoumboulis.
SUMMARY OF THE INVENTION
The present invention is directed to apparatus and methods for delivering one or more treating elements, such as a radiation source, through a catheter to a desired location within the intraluminal passageways, either vascular or non-vascular, of a human patient and to retrieving the treating element(s) through the catheter, if so desired. The treating elements may be used to treat the intraluminal passageway through which they are delivered or may be used to treat a surrounding area of the body located within a maximum radius of the intraluminal passageway through which they are delivered. The present invention is particularly applicable, but not limited, to the treatment of coronary arteries that have been or will be subjected to PTCA or other artery-opening procedures, in order to inhibit intimal hyperplasia and reduce the risk of restenosis. Other areas of the vascular system in which the present invention is also useful include the carotid, renal, iliac, and subclavian arteries, peripheral arteries, vessels leading to and from the brain, anastomotic sites, vein grafts, and internal mammary grafts. Bypass grafts may be treated with radiation either before or after they are implanted for bypass surgery. Non-vascular areas which the present invention is also useful include the brain ventricles, esophagus, trachea, bronchi, ureteral and urethral structures and other urological areas, vagina, uterus, and other gynecological areas, prostate gland and other male structures, biliary ducts, hepatic ducts, pancreatic ducts, and thoracic ducts. The present invention is also useful in areas of the body where endoscopic procedures are performed, and in the placement of shunts, such as dialysis shunts and transjugular intrahepatic portalsystemic shunts. Non-luminal areas of the body, including the brain, lungs, liver, gall bladder, pancreas, ovaries, cervix, endometrium, and prostate, may be treated through the delivery of treating elements via the catheter to a nearby intraluminal body passageway.
More specifically, as set forth in the appended claims, the present invention comprises an elongated flexible catheter tube having a proximal end portion adapted to remain outside the patient's body, a distal end portion adapted to be positioned at a selected location within the vascular system of the patient and a lumen extending therebetween, wit
Bonnoitt, Jr. George K.
Crocker Ian R.
Halpern David S.
Hillstead Richard A.
Larsen Charles E.
Cook Alex McFarron Manzo Cummings & Mehler, Ltd.
Gilbert Samuel G.
Novoste Corporation
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