Surgery – Diagnostic testing – Flexible catheter guide
Reexamination Certificate
2002-02-06
2004-06-08
Truong, Kevin T. (Department: 3731)
Surgery
Diagnostic testing
Flexible catheter guide
Reexamination Certificate
active
06746411
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed vascular medical procedures using catheters and/or guide wires.
BACKGROUND OF THE INVENTION
The state of the art in cardiovascular, and vascular procedures in general, is at the forefront of interventional medicine procedures designed to prolong life and add to the quality of life. Interventional medicine, whether performed by an interventionalist specialist or other practitioner, is an advancing and beneficial science. For many people, a healthy and sustained existence is in constant jeopardy due to clogged, narrowed, sclerosed or damaged vasculature. This is especially true of the cardiovasculature and peripheral vasculature. Interventional medicine is designed to address these and other problems.
Commonly, a vessel may become stenotic, or narrowed. One of the most familiar and common etiologies of this stenosis is atherosclerosis. Atherosclerosis is a thickening and hardening of medium and larger arteries with narrowing of the arterial lumen by atherosclerotic plaques; its cause is multifactorial. See, Andreoli, Carpenter, Plum and Smith,
Cecil, Essentials of Medicine
(W. B. Saunders Co. 1986). Other causes of stenosis include injury, syphilis, polyarteritis nodosa, Takayasu's disease, disseminated lupus erythematous, rheumatoid arthritis and other arteritis. Id. There is also continuing evidence that timely Percutaneous Transluminal Coronary Angioplasty (PTCA) is superior to other treatments in patients with acute myocardial infarction. See, Sutsch, Amamn,
To Stent or Not to Stent,
Schweiz. Med. Wochenchr. 1999;
Blood flow volume through a stenotic vessel is slowed and restricted or “backed up” proximal to the stenosis. This can be further complicated by mechanical, chemical and immunologic injury. The intimal surface of the vessel may ulcerate, thrombose and occlude the lumen of the vessel. This leads to decreased nourishment and oxygenation of the distal tissues and can ultimately lead to necrosis.
Further, and consistent with Bernoulli's law, the velocity of the blood flow is inversely proportional to the pressure exerted by the side of the vessel. In other words, the velocity is greatest and the pressure is lowest at the point of maximum stenosis. This fact has important ramifications as the increased velocity leads to increase turbulence in the flow distal to the stenosis. This, in turn, increases the ability of deposits, i.e. atherosclerotic plaques, to adhere to the vascular intima. In a similar phenomenon, plaques tend to occur at arterial bifurcations, again due to the turbulent flow in the area. The phenomenon is routine at branch sites, i.e. bifurcation and trifurcation of vessels or any multiple branching of a vessel. A common site of bifurcation of vessels is in the coronary vascular anatomy.
It is well known that the coronary arteries are markedly susceptible to atherosclerosis. This is especially true within the first six centimeters of origin of the vessel. Additionally, coronary arteries have multiple bifurcations. For example, the right and left coronary arteries bifurcate and branch as they descend the myocardium. Common sites for stenosis include the left coronary artery bifurcation to the circumflex and anterior interventricular (descending) artery; right coronary artery to the posterior interventricular and right marginal arteries; and bifurcations associated with the crux and marginal arteries. Further, any vessel of the body that suffers the effects of atherosclerosis can stenose and become a candidate for treatment, particularly in the peripheral vessels.
Treatment mechanisms for stenotic vessels have range from and include chemotherapy, radiation, Coronary Artery Bypass Grafting (CABG), angioplasty, rotational cutting devices to remove plaque formation and laser treatments. Each treatment has individual indications and contraindications. Additionally, each treatment modality has its own attendant risks. CABG of blocked or stenotic vessels is the least conservative, most expensive, most painful and is attended by the most serious complications. Surgery also requires the longest convalescence. See, Sutsch, Amamn,
To Stent or Not to Stent,
Schweiz. Med. Wochenchr. 1999; 129:1979-96. Chemotherapy and radiation treatment both have unwanted side effects. Currently, one of the safest and most effective treatments of stenotic vessels is percutaneous angioplasty. A common example of this is PTCA.
In the procedure, considered a non surgical interventional radiological procedure, a balloon catheter is placed in a diseased vessel through a small incision in to a main vessel; the femoral artery, for example. The catheter is tipped with a balloon at the end which can be inflated within the stenotic vessel to make the vessel patent. In order to guide the catheter to the diseased vessel and its stenosed portion, the catheter is placed over a steerable guide wire.
Inflation of the balloon is often all that is needed to make the stenotic vessel patent, but more often a stent is used to maintain patency of the vessel. A stent is a type of intra-vascular medical device used to maintain a bodily orifice or cavity after placement. Usually, a stent is comprised of an interconnected mesh of non-absorbable surgical grade material that, after placement, lies within the lumen of tubular structures and is used to provide support. Very commonly, a stent is used after dilation of an atherosclerotic coronary or peripheral vessel with a balloon catheter.
PTCA, with or without stent deployment, is performed commonly all over the world. Multiple vessels throughout the anatomy are treated. See, Sutsch, Amamn,
To Stent or Not to Stent,
Schweiz. Med. Wochenchr. 1999; 129:1979-96; Tan, Lim,
What you Need to Know—Coronary Stenting—What's New in the Horizon,
Singapore Med. J. 1999; Vol. 40(06). Treatment of bifurcation lesions is also common. See, Holmes et al.,
Coronary Artery Stents,
JACC Vol. 32 No. 5, 1998:1471-82. Treatment of bifurcation lesions is associated with increased early complications including compromise of either the branch vessel (the vessel off the main or parent vessel) or the target lesion (usually the lesion in the parent vessel) and increased potential for restenosis because of inadequate initial results. Stenting has an additional potential problem in that it may impair access to the side branch.
Current practices for improving access to ostial lesions, elongated lesions, bifurcating lesions and other difficult to treat stenoses include multiple guide wires. The use of multiple guide wires can become entangled in the guiding catheter or within the vessel. Many procedures need to be aborted or delayed if the wires become hopelessly entangled; some cases are then moved to open heart surgery due to loss of stents in the coronary vessel or coronary occlusion from dissection. To maintain side branch access, “jailing guide wire technique” has been used in the past where the wire to the side branch artery is pinned between the stent and the vessel wall. If the jailed wire to the side branch artery is not needed, the wire is then removed and the stent further dilated. In addition to jailing the wire, there is also “jailing of the side branch artery access or origin” by the placement of stent across a bifurcating stenosis or a stenosis very close to a side branch artery. However, there is no guide wire in the side branch. But the opening of the side branch is covered with the stent. The side branch opening may be compromised by the struts of the stent, plaque shifting into the side branch or compression. These unwanted effects may acutely close the side branch manifesting as an acute myocardial infarction or later as restenosis from neointimal hyperplasia causing restriction in blood flow or ischemia. Treatment of the side branch next to the stenosis has been recognized as technically challenging for interventionalists as well as to patients. One goal of the current invention is to help eliminate and avoid these challenges.
Given the foregoing, a method and apparatus to avoid entanglement of guid
Perkins Coie LLP
The University of Medicine and Dentistry of New Jersey
Truong Kevin T.
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