Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-09-22
2003-05-27
Nerbun, Peter (Department: 3765)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C606S200000
Reexamination Certificate
active
06569147
ABSTRACT:
BACKGROUND OF THE INVENTION
This application relates generally to medical systems and procedures and more particularly to systems and procedures for treating targeted tissues, e.g., cardiac tissue, of a living being and to medical instruments and methods of use to remove occlusive material from a vessel, duct or lumen within the body of a living being.
Cardiovascular disease is the leading cause of death in the industrial world today. During the disease process, atherosclerotic plaques develop at various locations within the arterial system of those affected. These plaques restrict the flow of blood through the affected vessels. Of particular concern is when these plaques develop within the blood vessels that feed the muscles and other tissues of the heart. In healthy hearts, cardiac blood perfusion results from the two coronary arterial vessels, the left and right coronary arteries that perfuse the myocardium from the epicardial surface inward towards the endocardium. The blood flows through the capillary system into the coronary veins and into the right atrium via the coronary sinus. When atherosclerosis occurs within the arteries of the heart it leads to myocardial infarctions, or heart attacks, and ischemia due to reduced blood flow to the heart tissues. Over the past few years numerous devices and methods have been evaluated for treating cardiovascular disease, and for treating the resulting detrimental effects that the disease has upon the myocardium and the other heart tissues. They are: traditional surgical methods (e.g. open heart surgery), minimally invasive surgery, traditional interventional cardiology (e.g. angioplasty, atherectomy, stents), and advanced interventional cardiology (e.g. catheter based drug delivery). Other recent advances in cardiovascular disease treatment involve transmyocardial revascularization (TMR), and growth factor and gene delivery.
Traditional methods for treating cardiovascular disease utilize open surgical procedures to access the heart and bypass blockages in the coronary blood vessels. These procedures require an incision in the skin extending from the supra-sternal notch to the zyphoid process, the sawing of the sternum longitudinally in half, and the spreading of the rib-cage to surgically expose the patient's heart. Based upon the degree of coronary artery disease, a single, double, triple, or even greater number of vessels are bypassed. Each bypass is typically performed by creating a separate conduit from the aorta to a stenosed coronary artery at a location distal to the occluded site. In general, the conduits are either synthetic or natural bypass grafts. Grafting with the internal thoracic (internal mammary) artery directly to the blocked coronary site has been particularly successful with superior long-term patency results. During conventional cardiac surgery, the heart is stopped using cardioplegia solutions and the patient is put on cardiopulmonary bypass. The bypass procedure uses a heart-lung machine to maintain circulation throughout the body during the surgical procedure. A state of hypothermia may be induced in the heart tissue during the bypass procedure to preserve the tissue from necrosis. Once the procedure is complete, the heart is resuscitated and the patient is removed from bypass.
There are great risks associated with these traditional surgical procedures such as significant pain, extended rehabilitation time and high risk of mortality for the patient. The procedure is time-consuming and costly to perform. Traditional cardiac surgery also requires that the patient have both adequate lung and kidney function in order to tolerate the circulatory bypass associated with the procedure and a number of patients which are medically unstable are thus not a candidate for bypass surgery. As a result, over the past few years, minimally invasive techniques for performing bypass surgery have been developed and in some instances the need for cardiopulmonary bypass and extended recovery times are avoided. A number of companies, e.g., Heartport, Inc. of Redwood City, Calif. and Cardiothoracic Systems, Inc. of Cupertino, Calif., have developed devices that allow for cardiac surgical procedures that do not require a grossly invasive median sternotomy or traditional cardiopulmonary bypass equipment. The procedures result in a significant reduction in pain and rehabilitation time.
In addition, as an alternative to surgical methods, traditional interventional cardiology methods (e.g. angioplasty, atherectomy, and stents) non-surgical procedures, such as percutaneous transluminal coronary angioplasty (PTCA), rotational atherectomy, and stenting have been successfully used to treat this disease in a less invasive non-surgical fashion. In balloon angioplasty a long, thin catheter having a tiny inflatable balloon at its distal end is threaded through the cardiovascular system until the balloon is located at the location of the narrowed blood vessel. The balloon is then inflated to separate and expand the obstructing plaque and expand the arterial wall, thereby restoring or improving the flow of blood to the local and distal tissues. Stenting utilizes a balloon tipped catheter to expand a small coil-spring-like scaffold at the site of the blockage to hold the blood vessel open. Rotational atherectomy utilizes a similarly long and thin catheter, but with a rotational cutting tip at its distal end for cutting through the occluding material.
Catheter instruments have been suggested or disclosed in the patent literature for effecting non-invasive or minimally invasive revascularization of occluded arteries. For example, in U.S. Pat. No. 4,445,509 there is disclosed a recanalization catheter designed specifically for cutting away hard, abnormal deposits, such as atherosclerotic plaque, from the inside of an artery, while supposedly preserving the soft arterial tissue. That recanalizing catheter includes a sharp-edged, multi-fluted, rotating cutting tip mounted at the distal end of the catheter and arranged to be rotated by a flexible drive shaft extending down the center of the catheter. The rotation of the cutting head is stated as producing a “differential cutting” effect, whereupon relatively hard deposits are cut away from relatively soft tissue. Suction ports are provided to pull the hard particles produced by the cutting action into the catheter for removal at the proximal end thereof so that such particles do not flow distally of the catheter where they could have an adverse effect on the patients' body.
In U.S. Pat. No. 4,700,705, which is assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein, there are disclosed and claimed catheters and methods of use for effecting the opening of a vessel, duct or lumen, such as the opening of a atherosclerotic restriction (partial or total occlusion) in an artery. These catheters are elongated flexible members of sufficient flexibility to enable them to be readily passed through the body of the patient to the situs of the atherosclerotic plaque in the artery to be opened. A working head is mounted at the distal end of the catheter and is arranged for high-speed rotation about the longitudinal axis of the catheter. In some embodiments the catheter may eject fluid at the working head to expedite the restriction-opening procedure.
In U.S. Pat. No. 4,747,821, which is also assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein, there is disclosed and claimed other catheters particularly suited for revascularization of arteries. Each of those catheters includes a rotary working head having at least one non-sharp impacting surface to effect material removal without cutting. Moreover, those catheters are arranged to eject fluid adjacent the working head to expedite the revascularization procedure. In particular, the rotation of the working head produces a powerful, toroidal shaped vortex contiguous with the working head which has the effect of recirculating any particles that may have been broke
Evans Douglas G.
Nash John E.
Caesar Rivise Bernstein Cohen & Pokotilow Ltd.
Kensey Nash Corporation
Nerbun Peter
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