Surgery – Instruments – Surgical mesh – connector – clip – clamp or band
Reexamination Certificate
2000-05-03
2003-02-11
Chaudhuri, Olik (Department: 2814)
Surgery
Instruments
Surgical mesh, connector, clip, clamp or band
C606S108000, C606S200000
Reexamination Certificate
active
06517559
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to devices for the treatment vascular disease and, more particularly, the invention relates to a filter device for placement within a blood vessel that is operable to catch and retain embolic material dislodged during the treatment of atherosclerotic disease.
2. Description of the Related Technology
Atherosclerotic disease in the coronary and carotid vasculature is one of the leading causes of morbidity and mortality in the United States. Atherosclerotic disease can cause insufficient circulation of oxygenated blood due to luminal narrowing caused by formation of atherosclerotic plaque. In addition, atherosclerotic disease can cause thromboembolism.
Atherosclerosis is a progressive, degenerative arterial disease that leads to occlusion of affected blood vessels, thereby reducing vessel patency, and hence, blood flow through them. During the course of this vascular disease, plaques develop on the inner lining of the arteries narrowing the lumen of the blood vessels. Sometimes these plaques become hardened by calcium deposits, resulting in a form of atherosclerosis called arteriosclerosis or “hardening of the arteries.” Atherosclerosis attacks arteries throughout the body, but the most serious consequences involve damage to the vessels of the brain and heart. In the brain, atherosclerosis is the primary cause of strokes, whereas in the heart, when total blockage of an artery occurs, portions of heart muscle can die and disrupt the electrical impulses that make the heart beat.
The internal carotid artery is an artery often affected by atherosclerosis. When atherosclerosis is detected in the carotid artery, physicians need to remove the plaque, thereby restoring circulation to the brain and preventing a cerebral vascular accident.
Treatment for atherosclerosis ranges from preventive measures such as lowering fat intake and medication to endarterectomy, balloon angioplasty or atherectomy. In endarterectomy, the affected artery is surgically opened and plaque deposits are removed from the lining of the arterial wall. Occasionally during endarterectomy, large pieces of plaque break away from the arterial walls and enter the blood stream. Additionally, thrombotic material may develop if damage to the arterial wall occurs from the removal of plaque. Dislodged plaque deposits and thrombotic material, causing a condition called thromboembolism, may occlude smaller vessels downstream resulting in a vascular problems and potentially death. Thus, it is common practice by one skilled in the art to capture dislodged plaque, or any thrombotic material, by using a vacuuming procedure throughout the duration of the endarterectomy procedure. Although a significant percentage of plaque and thrombotic material is captured by this vacuuming procedure, pieces of plaque as well as thrombotic material inevitably escape.
Balloon angioplasty is a another method of treating atherosclerosis. In balloon angioplasty, a balloon-tipped catheter is inserted through the skin into the vessel and maneuvered to the lesion in the artery. The balloon tipped catheter is threaded through the lesion and inflated, increasing the vessel lumen to improve blood flow at the site. After deflating the balloon, stents are often inserted to keep the lumen of the vessel open, maintain blood flow and provide a scaffolding for tissue growth. Although balloon angioplasty and stenting are alternative methods of treatment, recent studies have documented adverse side effects associated with carotid stenting and, therefore, such procedures may not be as desirable as endarterectomy.
An additional method of treatment, atherectomy, is a procedure during which the plaque in coronary arteries is ground into minuscule particles that the body can clean from the bloodstream. Occasionally, during such procedures, large pieces of plaque break away from the arterial walls and enter the blood stream. As described above, this plaque debris can not be processed by the body and, therefore, must be vacuumed from the bloodstream to prevent the plaque from clogging arteries in the brain or elsewhere.
The primary use of blood filters historically has been to prevent pulmonary embolism. Blood filters are implanted within a vein, typically the inferior vena cava, and are intended to trap large blood clots while allowing blood to pass freely through the filter around the clot. In most cases trapped blood clots will normally dissolve over time.
Most often, blood filters are implanted within the inferior vena cava from a variety of peripheral vein access sites, for example, the jugular or femoral veins. An early example of such a filter was the Mobin-Uddin (MU) umbrella filter, which was developed and made available by American Edwards Laboratories in Santa Monica, Calif. in the 1970s. The Mobin-Uddin umbrella was composed of six flat ELGILOY spokes radiating from a hub and partially covered by a web designed to capture blood clots. MU filters were introduced into the body via a cutdown of the jugular or femoral vein and subsequent passing of a catheter through the access site to the filter implant site in the infrarenal inferior vena cava. While this method was an improvement over previous methods, the MU filter was associated with a high incidence of occlusion of the inferior vena cava, in which blood flow through the vena cava was completely obstructed.
In the mid-1970's, the Kimray-Greenfield (KG) vena cava filter was introduced. The original KG filter is conical in shape and is composed of six stainless steel wires equally spaced with its apex cephalad. Although the filter was originally placed using a local cutdown of the jugular or femoral vein, it was later adapted to be inserted percutaneously. The KG filter is designed to capture clots 7 mm or greater in diameter, holding the clots in the infrarenal vena cava until the body's own lytic system dissolves the clot. The principal drawbacks of the KG filter are the possibility of tilting and filter migration, often related to a failure to open, or untimely ejection of the filter from the introducer.
Subsequent versions of the so-called Greenfield filter were developed to reduce the size of the introducer catheter to facilitate percutaneous introduction. Other vena cava filters were introduced in the United States in the late 1980s, including the Vena Tech—LGM vena cava filter, the Bird's Nest vena cava filter, and the Simon-Nitinol vena cava filter. The Vena Tech—LGM filter is a conical filter made from the PHYNOX alloy, with longitudinal stabilizing legs in addition to the intraluminal cone. The Bird's Nest filter is a “nest” of stainless steel wire which is wound into the vena cava, while the Simon Nitinol filter is a two-stage filter made from nickel-titanium alloy with a conical lower section and a petal-shaped upper section. All of these devices are permanent implants which cannot be removed from the body without a major surgical intervention.
Among numerous vena cava filters introduced in Europe but never brought to the United States was the optimal central trapping (OPCETRA) filter. The OPCETRA filter has two main parts: a main basket with ten, long stainless steel wire arms and a distal basket with five, short stainless steel wire arms. This design gives the filter an hourglass shape which provides a self-orienting structure for the filter within the lumen of a blood vessel. The OPCETRA filter was also a permanently implanted vena cava filter.
All of the above-identified vena cava filters are inserted into the body by passing the filter through a catheter to the site of deployment in the infrarenal inferior vena cava. After ejection from the catheter, these filters open or are manually deployed until the filter anchoring elements engage the vessel wall. These filters often have hooks or some other means by which the filter becomes fixed permanently to the vessel wall.
For an important subset of patients, in particular young trauma patients and patients undergoing total hip or knee replacement
Marshall Gerstein & Borun
Trinh (Vikki) Hoa B.
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