Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-07-13
2001-06-26
Kennedy, Sharon (Department: 3734)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C606S194000
Reexamination Certificate
active
06251093
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to apparatus and methods for reducing migration of occlusion members. A specific application of the invention is described in conjunction with devices and methods for temporarily inducing cardioplegic arrest in the heart of a patient and for establishing cardiopulmonary bypass in order to facilitate surgical procedures on the heart and blood vessels.
BACKGROUND OF THE INVENTION
Various cardiovascular, neurosurgical, pulmonary and other interventional procedures, including repair or replacement of aortic, mitral and other heart valves, repair of septal defects, congenital defect repairs, pulmonary thrombectomy, coronary artery bypass grafting, angioplasty, atherectomy, treatment of aneurysms, electrophysiological mapping and ablation, and neurovascular procedures, may require general anesthesia, cardiopulmonary bypass, and arrest of cardiac function. In such procedures, the heart and coronary blood vessels are isolated from the remainder of the circulatory system. This serves several purposes. First, such isolation facilitates infusion of cardioplegic fluid into the coronary arteries to perfuse the myocardium and arrest cardiac function without allowing the cardioplegic fluid to be distributed elsewhere in the patient's circulatory system. Second, such isolation facilitates use of a cardiopulmonary bypass system to maintain circulation of oxygenated blood throughout the circulatory system without allowing such blood to reach the coronary arteries and resuscitate the heart. Third, in cardiac procedures, such isolation creates a working space into which the flow of blood and other fluids can be controlled or prevented so as to create an optimum surgical environment.
One medical procedure of particular interest to the present invention is the treatment of heart valve disease. Co-owned, copending patent application Ser. No. 08/281,962 and Ser. No. 08/486,216, which are incorporated herein by reference, describe methods of performing closed-chest or thoracoscopic heart valve replacement surgery. Isolating the heart from the systemic blood circulation, inducing cardioplegic arrest and establishing cardiopulmonary bypass are important steps in the performance of the heart valve replacement procedure.
The endovascular system includes an elongated aortic partitioning catheter having an occluding member on a distal portion of the catheter adapted to occlude a patient's ascending aorta. The catheter preferably has an inner lumen extending within the catheter to a port in the distal end of the catheter. The catheter is adapted to be inserted into the patient's arterial system (e.g. through the femoral or brachial arteries) and advanced to the ascending aorta where the occluding member is expanded to occlude the aorta. The occluding member separates the left ventricle of the heart and an upstream portion of the ascending aorta from the rest of the patient's arterial system. Thus, the catheter provides an endovascularly inserted, internal vascular clamp, similar in function to the external “cross-clamp” used in open cardiac surgical procedures. The internal clamp is less traumatic to the clamped vessel and provides a lumen or working channel through which instruments or fluids may be passed into or withdrawn from the area upstream of the distal end of the clamp.
Also included with the system is a cardiopulmonary bypass system which withdraws blood from the patient's venous system, e.g. the femoral or jugular vein, removes CO
2
and adds oxygen to the withdrawn blood, and returns the oxygenated blood to the patient's arterial system, e.g. the femoral or brachial artery. The system is also provided with a device for infusing fluid containing cardioplegic material (e.g. an aqueous solution of KCl and/or magnesium procaine and the like) through the coronary arteries so as to temporarily paralyze the myocardium.
A preferred method for inducing cardioplegic arrest of a heart in situ in a patient's body, includes the steps of:
(a) maintaining systemic circulation with peripheral cardiopulmonary bypass;
(b) partitioning the coronary arteries from the ascending aorta by, e.g., occluding the ascending aorta through a percutaneously placed arterial balloon catheter;
(c) introducing a cardioplegic agent into the coronary circulation; and
(d) venting the heart.
The method may be carried out on humans or other mammalian animals. The method is of particular applicability in humans as it allows an alternative approach to open heart surgery and the development of closed cardioscopic surgery. The method enables a percutaneous bypass system to be associated with cardioplegia, venting and cooling of the heart which overcomes the need for a median sternotomy.
In a preferred embodiment, the occluding member is an inflatable cuff or balloon of sufficient size to occlude the ascending aorta. The length of the balloon should preferably not be so long as to impede the flow of blood or other solution to the coronary arteries or to the brachiocephalic, left carotid or left subclavian arteries. A balloon length of about 20-40 mm and diameter of about 35 mm is suitable in humans. The balloon may be cylindrical, spherical, ellipsoidal or any other appropriate shape to fully and evenly accommodate the lumen of the ascending aorta. This maximizes the surface area contact with the aorta, and allows for even distribution of occlusive pressure.
The balloon is preferably inflated with a saline solution mixed with a radiopaque contrast agent to avoid introducing an air embolism if the balloon ruptures. The balloon should be inflated to a pressure sufficient to prevent regurgitation of blood into the aortic root and to prevent migration of the balloon into the root whilst not being so high as to damage the aorta. An intermediate pressure of about 350 mm Hg, for example, is preferred.
The aortic partitioning catheter is preferably introduced under fluoroscopic guidance over a guidewire. Transoesophageal echocardiography can also be used for positioning the aortic catheter. The catheter may serve a number of separate functions and the number of lumina in the catheter will depend upon how many of those functions the catheter is to serve. The catheter can be used to introduce the cardioplegic agent, normally in solution, into the aortic root via one lumen. The luminal diameter will preferably be such that a flow of the order of 100-500 ml/min of cardioplegic solution, and more preferably 250-500 ml/min, can be introduced into the aortic root under positive pressure to perfuse the heart by way of the coronary arteries. The same lumen can, by applying negative pressure to the lumen from an outside source, effectively vent the left heart of blood or other solutions. The cardioplegic agent may be any known cardioplegic agent. The agent is preferably infused as a solution into the aortic root through one of the lumina of the aortic catheter.
It may also be desirable to introduce medical instruments and/or a cardioscope into the heart through another lumen in the catheter. The lumen should be of a diameter suitable to pass a fiberoptic light camera of no greater than 3 mm diameter. It is, however, preferable that the diameter and cross-section of the internal lumina are such that the external diameter of the catheter is small enough for introduction into the adult femoral artery by either percutaneous puncture or direct cutdown.
The oxygenated blood returning to the body from the bypass system is conveyed into the aorta from another lumen in the cannula carrying the balloon. In this case, the returning blood is preferably discarded from the catheter in the external iliac artery. In another embodiment of the invention, and in order to reduce the diameter of the catheter carrying the balloon, a separate arterial catheter of known type may be used to return blood to the patient from the bypass system. In this case a short catheter is positioned in the other femoral artery to provide systemic arterial blood from the bypass system. The control end of th
Fan Sylvia W.
Mueller, Jr. Richard L.
Snow David W.
Valley Kirsten L.
Heartport Inc.
Hoekendijk Jens E.
Kennedy Sharon
Rodriguez Cris L.
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