Surgery – Miscellaneous – Methods
Reexamination Certificate
2000-01-12
2001-12-04
Isabella, David J. (Department: 3738)
Surgery
Miscellaneous
Methods
Reexamination Certificate
active
06325067
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to thoracoscopic methods for performing cardiac procedures. More particularly, the present invention relates to thoracoscopic methods for performing procedures externally on or internally within the heart while the patient s chest is unopened, the patient's heart is stopped, and the patient is supported by cardiopulmonary bypass.
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow resulting in the discomfort and risks of angina and ischemia. In severe cases, acute blockage of coronary blood flow can result in myocardial infarction, leading to immediate death or damage to the myocardial tissue.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to treat the symptoms with pharmaceuticals and lifestyle modification to lessen the underlying causes of disease. In more severe cases, the coronary blockage(s) can often be treated endovascularly using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, hot tip probes, and the like.
In cases where pharmaceutical treatment and/or endovascular approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure using open surgical techniques. Such techniques require that the patient's sternum be opened and the chest be spread apart to provide access to the heart. A source of artenal blood is then connected to a coronary artery downstream from an occlusion while the patient is maintained under cardioplegia and is supported by cardiopulmonary bypass. The source of blood is often the left or right internal mammary artery, and the target coronary artery can be the left anterior descending artery or any other coronary artery which might be narrowed or occluded.
While very effective in many cases, the use of open surgery to perform coronary artery bypass grafting is highly traumatic to the patient. The procedure requires immediate postoperative care in an intensive care unit, a total period of hospitalization of seven to ten days, and a recovery period that can be as long as six to eight weeks.
It would therefore be desirable to provide other, less traumatic methods and techniques for performing coronary artery bypass grafting. It would be particularly desirable if such techniques did not require opening of the patient's sternum, and might be even more desirable it such techniques could be performed using thoracoscopic methods. Such thoracoscopic methods could decrease morbidity and mortality, cost, and recovery time when compared to conventional open surgical coronary bypass procedures. In addition, such methods could be even more efficacious than open-surgical bypass procedures.
2. Description of the Background Art
Conventional thoracoscopic techniques are described in Landreneau et al. (1992) Ann. Thorac. Surg. 54: 800-807. Conventional open surgical procedures for performing coronary artery bypass grafting are described in Kirklin and Barratt Boyes,
Cardiac Surgery
, John Wiley & Sons. Inc. New York 1993 (2nd Ed.). Copending applications Ser. No. 07/730.559, filed Jul. 16, 1991, and Ser. No. 07/991,188, tiled Dec. 15, 1992 now abandoned. Which are assigned to the assignee of the present application, describe catheters that are insertable into a patient's arterial system and include a distal balloon which can be expanded to occlude the ascending aorta. The coronary ostia, the heart, and the proximal ascending aorta may thus be isolated from the remainder of the arterial system while the patient is on cardiopulmonary bypass. Such catheters are particularly intended to be used in heart valve replacement procedures.
SUMMARY OF THE INVENTION
According to the present invention, a method for closed-chest cardiac surgical intervention relies on viewing the region of the heart through a percutaneously positioned viewing scope, such as a thoracoscope, or directly through a small opening between two ribs in the chest. The patient's arterial system will be partitioned during such interventional procedures at a location within the ascending aorta between the brachiocephalic artery and the coronary ostia. In a preferred embodiment, such partitioning is achieved by endovascularly advancing the distal end of a catheter to the desired location with the ascending aorta and expanding a blocking element on the catheter at said location to inhibit the flow of blood and other fluids past said location. Such partitioning facilitates isolation of the heart, and in particular permits the heart to be stopped while the patient is supported by cardiopulmonary bypass. Once the patient's heart is stopped, a variety of surgical procedures can be performed using percutaneously introduced instruments in a minimally invasive fashion. Thus, the present invention contemplates, at least in its preferred embodiments, the possibility of effective ascending aortic occlusion, cardiopiegia, venting, right heart deflation and topical cooling in association with extracorporeal cardiopulmonary by-pass all without necessitating a median sternotomy or other thoracic incision.
In a first aspect the present invention consists in a method for inducing cardioplegic arrest of a heart in situ in a patient's body, comprising the steps of
(a) maintaining systemic circulation with peripheral cardiopulmonary by-pass;
(b) occluding the ascending aorta through a percutaneously placed arterial balloon catheter:
(c) introducing a cardioplegic agent into the coronary circulation; and
(d) venting the left side of the heart.
The method according to the present invention 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 according to the invention enables a percutaneous by-pass system to be associated with cardioplegia, venting and cooling of the heart which subverts the need for median sternotomy. This may, in turn, reduce the complications of the surgery.
The maintenance of the systemic circulation involves establishing a cardiopulmonary by-pass. The blood may be drawn into the by-pass merely by positioning a percutaneous catheter into the right atrium and/or into one or both of the vena cavae through which venous blood may be drawn from the heart into an extracorporeal pump oxygenator. In more preferred embodiments of the invention a single catheter with two inflatable cuffs, or two separate catheters, each with an inflatable cuff are introduced into the vena cavae to occlude them adjacent to their right atrial inlets. This allows isolation of the right atrium and allows blood to be drawn from the vena cavae into the by-pass system. There is also preferably provision for percutaneous communication via one catheter with the right atrium to allow infusion of saline into the night atrium. This infusion has the advantage that it allows the heart to be cooled and improves visual acuity within the right heart allowing direct cardioscopic examination and/or intervention.
The catheter used to decompress the right atrium and to draw blood into the by-pass is preferably introduced through the femoral vein by percutaneous puncture or direct cut down. If other than simple venous drainage is required catheters with inflatable cuffs, as described above, are placed preferably such that in inflatable cuff of the cannula is positioned within each of the inferior tsuprahepatic) and superior vena cavae. There is preferably a lumen in the cannula acting as a common blood outlet from the vena cavae leading to the pump oxygenator. A separate lumen is preferably used to infuse saline between the two inflated cuffs into the right atrium. If, alternatively, separate catheters are used to
Curtis Patricia E.
MacHold Timothy R.
Peters William S.
Siegel Lawrence C.
Sterman Wesley D.
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