New outlook on pericardial substitution after open heart operations.

The difficulties of reoperation owing to adhesions are well known. Clinical attempts to solve this problem using synthetic materials or glutaraldehyde-fixed pericardial xenograft have been less than satisfactory. Although experimental animal results have been good, they have not considered the influence of cardiopulmonary bypass (CPB) on adhesion formation. This study addressed the influence of CPB on the formation of adhesions and evaluated biodegradable polyglycolic acid as a material to reduce adhesions and as a pericardial substitute. Forty-five weanling sheep received implants of pericardial xenograft and polyglycolic acid with and without CPB. The pericardial xenograft showed no adhesions when implanted without CPB, but severe adhesions formed and a thick fibrinous layer covered the heart when CPB was used, making identification of coronary arteries at reoperation very difficult. The polyglycolic acid mesh implanted without CPB was absorbed and replaced with newly formed host collagen. With CPB, the polyglycolic acid was more rapidly absorbed, and a thinner layer of host collagen formed. Therefore, future animal studies must include CPB. In agreement with reported clinical results, glutaraldehyde-fixed pericardial tissue implanted with CPB resulted in severe epicardial reaction and therefore is not an ideal pericardial substitute.