A cause of right ventricular dysfunction after cardiac operations.

We examined the impact of mediastinal healing on right ventricular performance in three groups of five piglets by performing gated blood pool scans in two planes to determine right ventricular ejection fraction. Animals in Group I then had sternotomy and excision of anterior pericardium. Group II animals had a similar operation plus insertion of a silicone rubber sheet as a pericardial substitute. Group III animals (controls) had no operation. Each group was followed up for 60 days, after which gated blood pool scans were repeated in a manner identical to the initial study. Experimental animals in Groups I and II were then put to death and autopsied. Adhesion formation between the right ventricle and sternum was graded on a 0 to 3 scale. Group I animals showed a significant average decline in right ventricular ejection fraction of 19.2% (p less than 0.02). Group II animals demonstrated an average decrease in ejection fraction, although not significant, of 12.2%. Groups I and II combined showed a significant average loss in ejection fraction of 15.7% (p less than 0.01). Severity of adhesions between the right ventricle and sternum correlated well with loss of right ventricular ejection fraction (p less than 0.01). Group III controls demonstrated no significant change in ejection fraction. Mediastinal healing and fibrous attachment of the right ventricle to the sternum may play a significant role in loss of right ventricular ejection fraction after cardiac operations. Variability in loss of right ventricular ejection fraction is related to intensity of the mediastinal healing process.