Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1998-07-23
2001-06-19
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Internal pressure applicator
Reexamination Certificate
active
06248121
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to occlusion devices and methods of use thereof. More specifically, the present invention relates to balloon occlusion devices for performing cardiac bypass or other vascular procedures.
2. Brief Description of the Related Art
Coronary artery diseases are often caused by atherosclerosis or narrowing of the small arteries between the aorta and the heart muscles. There are several ways to provide blood blow around occluded segments of arteries or veins, however, the known methods commonly cause a large amount of trauma to the patient. One method is to perform an “open heart surgery,” which involves cracking open the chest and exposing the heart and treating the vessel directly. However, the large incision and surgically cut sternum take a long time to heal.
In the bypass operation, a section of the saphenous vein, or a suitable substitute, is grafted, usually between the ascending aorta just above the heart and one or more of the coronary arteries beyond the points of blockage. The bypass operation is performed with the patient connected to a heart-lung machine and the heart is stopped. Because the heart is stopped, the heart-lung bypass can damage blood cells. Additionally, the patient's internal body temperature is reduced while on a heart-lung bypass to reduce basil metabolism and then the body temperature is increased to normal when the procedure is over. This thermal change to a person's body can cause damage to the intestinal track as well as causing additional stress to the patient.
If the patient is not placed on a heart-lung bypass, the aorta is typically partially clamped along its axis to create an area of blood stasis and a small channel for blood flow. However, clamping the aorta can cause injury to the aorta and can also cause plaque formations to break off into the blood stream and cause severe disorders such as strokes and emboli.
Sometimes, occlusion balloons are inserted through the femoral artery up to the blood vessel to be occluded. Both clamps and existing occlusion devices commonly cause damage to the internal blood vessel walls and they introduce plaque into the patient's blood stream. Existing balloons are also likely to move longitudinally along the catheter while in the blood vessel, and thus are likely to move into the heart or interfere with blood flow.
SUMMARY OF THE INVENTION
The present invention relates to a direct-access device with a balloon for occluding blood vessels, and methods of use thereof. The invention also relates generally to the design and manufacturing of this occlusion device. The occlusion device is ideally suited for occluding a patient's aorta during stopped-heart cardiac procedures.
A preferred embodiment of the present device comprises a flexible balloon member which is attached to the exterior of a tubular member to form an inflatable balloon. The tubular member includes an inflation lumen which can be used to inflate and deflate the thin-profile balloon. Together, the balloon member and tubular member occlude a blood vessel. The balloon member is preferably attached near the distal end of the tubular member. The width of the outer peripheral contact area of the balloon member, which comes in contact with the inner wall of the blood vessel, is substantially narrower than the balloon member's diameter. The contact area between the balloon member and the inner blood vessel wall is thus reduced over prior designs.
The balloon member is preferably made of a low compliance material, which limits the expansion of the balloon member to expanding 1% to 40% radially and 1% to 50% longitudinally after the balloon member is initially inflated under ambient pressure to its normal, unstretched shape. In one embodiment, the low compliance material limits the expansion of the balloon member to expanding 10% to 33% radially and 10% to 40% longitudinally. In one embodiment, the low compliance material comprises polyurethane.
In addition to the inflation lumen, the tubular member preferably comprises a blood flow lumen which carries blood between the patient and an external medical device, such as a heart-lung machine. The tubular member preferably has other lumens to measure blood pressure and introduce a cardioplegia solution and/or drugs. In one embodiment, the tubular member is bent near the distal end to allow the balloon member to conveniently be directly introduced into and positioned within the blood vessel.
A significant advantage of the present device is that the inflated balloon member has a thin profile at its periphery. In a preferred embodiment, the balloon member produces a longitudinal contact distance which is less than 50% of (and preferably 20-30% of) the inner diameter of the blood vessel. Thus, the thin-profile balloon member contacts only a narrow segment of the blood vessel when the balloon member is inflated. Because the surface area of contact is reduced, the potential damage to the blood vessel commonly caused by such contact is also reduced. Another benefit of using a thin-profile balloon member is that the balloon member is less likely to move longitudinally along the catheter while in the blood vessel, and thus less likely to move into the heart or interfere with the device's blood flow port.
Another substantial advantage of the present device is that it can be used to occlude the aorta without the need for clamps, and thus reduces the likelihood of plaque being introduced into the blood stream.
Another important advantage results from the limited compliance of the balloon member. The limited compliance of the balloon member reduces longitudinal stretching and maintains a small peripheral surface area which comes in contact with the internal blood vessel wall. This prevents the balloon member from blocking the distal end of the tubular member or the opening of a branching blood vessel, such as the innominate artery. The limited compliance also limits radial stretching, and thus reduces potential damage to the blood vessel wall. In addition, the limited compliance reduces the likelihood of dissections and breakoffs of the inflatable balloon member, and reduces the risk of the balloon bursting.
If the balloon is inserted in the aorta, another advantage of the thin-profile of the balloon is that it allows the physician to move the balloon closer to the innominate artery (brachiocephalic artery). This creates more working space in the aorta for anastomosis.
In one embodiment, the balloon member comprises at least one pair of internal ribs which support the structure of the balloon member (maintain its thin profile) and prevent the balloon member from expanding by more than 1% to 50% after the balloon member is initially inflated. In one embodiment, the internal ribs limit the longitudinal expansion of the balloon member even further than the limited compliance material. These internal ribs interconnect the proximal and distal walls of the balloon member. In one configuration of balloon member, the ribs overlap one another and are bonded together. The balloon member with internal ribs may be formed by dipping a mandrel, with grooves or channels formed therein, a number of times into liquid polyethylene, polyurethane or other material with similar properties. In other embodiments of the invention, the internal ribs feature may be used to limit or control the expansion of other types of occlusion balloons, such as angioplasty balloons.
In another configuration, the balloon member comprises at least one indent or bump along the peripheral edge of the balloon member. These indents or bumps help to maintain the position of the balloon member within the blood vessel, prevent the balloon member from slipping, and reduce the contact area between the balloon and the internal wall of the blood vessel.
REFERENCES:
patent: Re. 35352 (1996-10-01), Peters
patent: 2473742 (1949-06-01), Auzin
patent: 3292627 (1966-12-01), Harautuneian
patent: 3394705 (1968-07-01), Abramson
patent: 4119100 (1978-10-01), Rickett
Cardio Medical Solutions, Inc.
Knobbe Martens Olson & Bear LLP
Robert Eduardo C.
Smith Jeffrey A.
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