Surgery – Instruments – Cyrogenic application
Reexamination Certificate
2001-09-14
2004-09-07
Peffley, Michael (Department: 3739)
Surgery
Instruments
Cyrogenic application
C128S898000
Reexamination Certificate
active
06786900
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical methods and kits. More particularly, the present invention provides methods and kits for cryogenically cooling a blood vessel within a patient's vasculature to treat potential or existing dissections in the blood vessel. The present invention further provides methods and kits for cryogenically cooling a bifurcated blood vessel to treat side branch occlusion. Vessel dissections and side branch occlusion often result from angioplasty or other intravascular procedures for treating atherosclerosis and other diseases of the vasculature.
Atherosclerotic plaque is present to some degree in most adults. Plaques can severely limit the blood flow through a blood vessel by narrowing the open vessel lumen. This narrowing effect or stenosis is often responsible for ischemic heart disease. Fortunately, a number of percutaneous intravascular procedures have been developed for treating atherosclerotic disease in a patient's vasculature. The most successful of these treatments is percutaneous transluminal angioplasty (PTA). PTA employs a catheter having an expansible distal end, usually in the form of an inflatable balloon, to dilate a stenotic region in the vasculature to restore adequate blood flow beyond the stenosis. Other procedures for opening stenotic regions include directional arthrectomy, rotational arthrectomy, laser angioplasty, stents and the like. While these percutaneous intravascular procedures, particularly PTA, have provided significant benefits for treatment of stenosis caused by plaque, they continue to suffer from significant disadvantages. Particularly common disadvantages are the subsequent occurrence of vessel dissection, vessel recoil (acute and delayed), side branch occlusion, restenosis, and other procedure related trauma. Such disadvantages may affect up to 80% of all angioplasty patients to some extent.
During conventional PTA, the inflated balloon tends to create large fissures or tears in the intima of the blood vessel wall, particularly at a junction between the plaque and the vessel wall. Such tears or fissures are referred to as dissections. Vessel dissections compromise the dilated vessel, often constricting or blocking blood flow within the vessel. A number of strategies have been proposed to treat vessel dissections. Previously proposed strategies include prolonged balloon inflation, treatment of the blood vessel with a heated balloon, stenting of the region following balloon angioplasty, and the like. While these proposal have enjoyed varying levels of success, no one of these procedures is proven to be entirely successful. In particular, stenting of the dilated region may address acute problems of intimal dissection and vessel recoil, however stents are believed to actually cause a marked increase in the degree of intimal restenosis or hyperplasia (re-narrowing of the an artery following an initially successful angioplasty). This in turn leads to greater late luminal loss, especially in smaller vessels which are more susceptible to re-closure due to restenosis. Moreover, stents may prove to be an impractical solution when dilating long periphery arteries that may require multiple stent placements. Stents may additionally not always be easily maneuvered to and positioned in dilated regions, especially in the coronary arteries.
Another limitation associated with angioplasty is side branch occlusion in a bifurcated blood vessel during dilatation of a primary vessel lesion. Side branch occlusion can occur by several mechanisms. The “snow plow” effect may be the most common mode of side branch occlusion, in which plaque from a primary vessel is literally “plowed” or “shifted” into the adjacent side vessel during dilatation, narrowing or occluding the side vessel lumen. Known procedures for treating side branch occlusion include the “kissing balloon technique” where two guiding catheters are positioned in the bifurcated vessel, one in the primary vessel and the other in the side branch, and the balloons are inflated simultaneously or sequentially so that they potentially touch or “kiss.” However, such angioplasty techniques alone or in combination with stents, has not been entirely successful in preventing side branch occlusion.
For these reasons, it would be desirable to provide methods and kits for the treatment of dissections in a blood vessel. It would be further desirable to provide methods and kits for the treatment of side branch occlusion in a bifurcated blood vessel. The methods should be suitable for intravascular and intraluminal introduction, preferably via a percutaneous approach. It would be particularly desirable if the new methods were able to deliver the treatment in a very controlled and safe manner with minimum side effects. At least some of these objectives will be met by the invention described herein.
2. Description of the Background Art
Cryoplasty methods and devices are described in U.S. patent application Ser. No. 08/982,824, now U.S. Pat. No. 5,971,979; U.S. patent application Ser. No. 09/203,011 (Attorney Docket No. 018468-000110US) ; U.S. patent application Ser. No. 09/510,903 (Attorney Docket No. 018468-000410US), U.S. patent application Ser. No. 09/619,583 (Attorney Docket No. 018468-000610US), assigned to the assignee of the present application. A cryoplasty device and method are also described in WO 98/38934. Balloon catheters for intravascular cooling or heating a patient are described in U.S. Pat. No. 5,486,208 and WO 91/05528. A cryosurgical probe with an inflatable bladder for performing intrauterine ablation is described in U.S. Pat. No. 5,501,681. Cryosurgical probes relying on Joule-Thomson cooling are described in U.S. Pat. Nos. 5,275,595; 5,190,539; 5,147,355; 5,078,713; and 3,901,241. Catheters with heated balloons for post-angioplasty and other treatments are described in U.S. Pat. Nos. 5,196,024; 5,191,883; 5,151,100; 5,106,360; 5,092,841; 5,041,089; 5,019,075; and 4,754,752. Cryogenic fluid sources are described in U.S. Pat. Nos. 5,644,502; 5,617,739; and 4,336,691. The following U.S. patents may also be relevant to the present invention: 5,458,612; 5,545,195; and 5,733,280.
Side branch occlusion is described by Stephen N. Oesterle in
Angioplasty Techniques for Stenoses Involving Coronary Artery Bifurcations,
Am J Cardiol, vol. 61, pp. 29G-32G (1988); Lefevre et al. in
Stenting of Bifurcation Lesions: Classification. Treaments, and Results,
Catheterization and Cardiovascular Interventions, vol. 49, pp. 274-283 (2000); Chevalier et al. in
Placement of Coronary Stent in Bifurcation Lesions by the “Culotte” Technique,
Am J Cardiol, vol. 82, pp. 943G-949G (1998). Cutting balloons are described at http://www.interventionaltech.com/Products/CuttingBallon.html.
The full disclosures of each of the above references are incorporated herein by reference.
BRIEF SUMMARY OF THE INVENTION
The present invention provides cryotherapy treatment of dissections in a blood vessel of a patient. The present invention further provides cryotherapy treatment of side branch occlusion in a bifurcated blood vessel. The blood vessel may be any blood vessel in the patient's vasculature, including veins, arteries, and particularly coronary arteries. The blood vessel will be at least partially stenosed, typically by eccentric calcified plaque (i.e. the plaque compromises a vessel lumen predominantly from one side) in the coronary and peripheral arteries. In particular, the present invention may limit, reduce, minimize, prevent, mitigate, and/or inhibit potential or existing dissections of a vessel and/or plaque shift from a main branch into a side branch of a bifurcated blood vessel so as to inhibit acute coronary syndrome.
In a first aspect, the present invention provides a method for treating potential or existing dissections in a blood vessel. The method comprises cooling the blood vessel to a temperature and for a time sufficient to remodel the blood vessel such that dissections of the blood vessel are reduced. The coolin
Joye James
Tatsutani Kristine
Barrish, Esq. Mark D.
CryoVascular Systems, Inc.
Peffley Michael
Townsend&Townsend&Crew LLP
Vrettakos Peter
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