Pericardial closure after cardiac operations. An animal study to assess currently available materials with particular reference to their suitability for use after coronary artery bypass grafting.

An experimental study to assess the performance of currently available pericardial substitutes is described with particular reference to their use after coronary artery bypass grafting. Seventy-two ewes, (six groups of 12 animals) had a 7 x 5 cm portion of the pericardium excised. Each group had either the defect left open, primarily resutured, replaced with coarse Dexon No. 2 mesh (American Cyanamid Co., Danbury, Conn.), replaced with fine Dexon No. 8 mesh, replaced with glutaraldehyde-preserved bovine pericardium, or replaced with polytetrafluoroethylene 0.1 mm surgical membrane. Six animals from each group were assessed at 3 months and the remaining six animals were assessed at 6 months. The open-defect and resutured groups served as control animals. None of the substitutes proved superior to the open-defect group in the prevention of chest wall/lung-to-pericardium adhesions at either 3 or 6 months. The limitations of the animal model in assessing this aspect of substitute performance are discussed. Whereas the bovine pericardium, polytetrafluorethylene, and Dexon No. 8 mesh groups were superior to the resutured group in the prevention of pericardium-to-epithelium adhesions in the area of the patch, this advantage was lost at 6 months when resuturing proved as effective as polytetrafluoroethylene and bovine pericardium. In all groups there was little tendency to produce generalized pericardial adhesions. At 3 months Dexon No. 8 mesh and bovine pericardium produced the least amount of significant epicardial reaction. In two animals in the 3-month polytetrafluoroethylene group and in one animal in the 6-month polytetrafluoroethylene group, a "fibrous peel" was encountered on the inner surface of the patch, which had also become adherent to the epicardium and had obscured the underlying anatomy. At 6 months the open-defect, resutured, and bovine pericardium groups had produced no significant epicardial reaction. In one animal at 6 months the bovine pericardium had become markedly thickened and degenerative. We do not recommend routine closure of the pericardium after coronary artery operations with any of the substitutes investigated in our study.