To: Bill Rogers who wrote (189 ) 3/16/1998 10:18:00 PM From: Ray Tarke Respond to of 2887
One out of 5 Americans, Over 65 million Americans suffer from some form of coronary or peripheral vascular disease. The most noted of these diseases is cardiovascular. This disease is progressive and degenerative, and is characterized by a buildup of fatty materials ("plaque") within the lining of the arterial blood vessels. The buildup of plaque results in an obstruction (stenosis) that reduces blood flow through the arteries and may eventually lead to total blockage causing tissue damage and death. The plaque forms at varying degrees of hardness, eccentrically or concentrically within the artery, reducing the elastic nature of the vessel and thereby compromising the vessel's ability to efficiently pump blood to vital organs. Despite significant advances in product technologies, the disease continues to be the leading cause of mortality in the U.S. today. Degenerative atherosclerotic narrowing of the arteries that feed the heart ("coronary arteries"), known as coronary heart disease, afflicts over six million persons in the U.S. alone. It is largely responsible for approximately 1.5 million "heart attacks" each year in the U.S., of which approximately 500,000 result in death. Atherosclerosis also affects arteries in the kidneys ("renal arteries") and in the abdomen, groin and legs ("peripheral arteries") and is a leading cause of strokes, reno-vascular hypertension (a type of high blood pressure) and peripheral vascular disease. Prior to the late 1960's, pharmaceuticals represented the most common form of treatment for coronary heart disease and other forms of atherosclerosis. While often effective in alleviating many symptoms, pharmaceuticals did not address the underlying problems of narrowed arteries and reduced blood flow. During the late 1960's, cardiovascular surgeons pioneered a new type of open heart surgery that grafted a blood vessel from the patient's leg to the diseased coronary artery to bypass the blockage, thereby providing a longer-term treatment, but one that was highly invasive, costly and required a lengthy hospital stay. Today, bypass graft surgeries of the coronary arteries and of other peripheral vessels account for over 600,000 procedures annually in the United States. Bypass surgery generally is performed when the patient displays extensive deposits. atherosclerotic plaque throughout the length of one or more vessels thereby rendering impractical the attempted opening ("dilating") of the blocked ("occluded") arteries due to the procedural time required, the critical location of the occlusion, or the inability to safely access the blockage. In the late 1970's, cardiologists developed a less-invasive method of treating atherosclerosis, the method known as balloon angioplasty. In its simplest form, balloon angioplasty involves threading a small balloon-tipped catheter through the arterial system to the site of the blockage. The balloon is inflated, dilating the vessel and thereby displacing the plaque by pressing it against the artery wall. The arterial opening is thereby enlarged, restoring blood flow. There are inherent risks in balloon angioplasty, including vessel dissection, acute closure due to overstretching of the vessel, and the potential that small pieces of plaque will break off and move downstream to block critical parts of the blood vessel. The blood supply to critical heart tissue is temporarily cut off while the balloon is inflated, increasing the risk of a heart attack during the procedure. The balloon-dilated artery may spasm during and/or immediately after the procedure and cut off the blood supply to critical tissues. Balloon angioplasty is generally not considered suitable for patients with extensive atherosclerosis nor for patients who suffer from very severe blockages of arteries that supply large areas of the heart with blood. Additionally, since the atherosclerotic plaque is not removed during the balloon procedure and because certain damage to the inner lining of the arteries can occur when the balloon is inflated, there is a high rate of re-blockage or "restenosis" of the treated artery(ies). The limitations inherent in balloon angioplasty have created a significant opportunity for alternative types of angioplasty devices, including stents and atherectomy devices. A third method, lasers, has been shown to be damaging to the arterial walls and now is used only for narrowly defined clinical indications. Laser systems are expensive and require special facilities and maintenance. Stents and atherectomy devices are rapidly becoming the growth products in atherosclerotic procedures. The number of angioplasty (including atherectomy) procedures performed and the market for coronary and peripheral angioplasty devices and accessories have grown at a rapid rate as a result of a number of factors, including the general aging of the world's population. Industry sources project the stent and atherectomy device market to grow at a rate of 50% and 30% per annum, respectively(1). Based upon such projections, stents would become a $750 million business by 1998, while the sale of Atherectomy devices would grow to $350 million in sales by 1998(1). Delivery catheters for coatings of the treated stenosis is projected to be over $100 million by 1998. Regards, R.T