Roles of the right ventricular free wall and ventricular septum in right ventricular performance and influence of the parietal pericardium during right ventricular failure in dogs.

The roles of the right ventricular (RV) free wall and ventricular septum in RV performance were studied in the canine heart. The parietal pericardium was kept intact. Acute ischemia of the RV free wall from right coronary ligation decreased the RV stroke work index more than did that of the ventricular septum from the septal branch of the left coronary artery ligation (41 and 23%, respectively, p less than 0.01). The response of the RV stroke work index to acute volume loading was also decreased. Left ventricular dysfunction was detected only with ventricular septal ischemia. Combined RV free wall and ventricular septal ischemia produced more severe and predominant RV dysfunction with disproportionate elevation of RV end-diastolic pressure. After combined ischemia, pericardiotomy improved the RV stroke work index as well as the left ventricular stroke work index (40 and 27%, respectively, p less than 0.05), although the increase in RV stroke work index was greater than in left ventricular stroke work index (p less than 0.05). The results of this study suggest that (1) the RV free wall has a more important role than the ventricular septum in RV performance, (2) predominant RV failure can be induced experimentally after combined RV free wall and ventricular septal ischemia, and (3) the pericardium has a restrictive effect on the damaged and dilated right ventricle.