Contribution of each ventricular wall to ventricular interdependence.

The influences of pressure and volume changes in one ventricle on the other ventricle may be determined from the relative compliances of the ventricular free walls and the interventricular septum. If this is correct, then disease states which alter regional compliances should influence the diastolic mechanical coupling between the ventricles. To examine this hypothesis, the hearts of 15 canine dogs were removed and placed in cool cardioplegic solution. Balloons were inserted into each ventricle and the right and left ventricular pressure (delta Pr, delta Pl) and volume (delta Vr, delta Vl) changes caused by changing the pressure and volume of the other ventricle were recorded. Acute changes in right ventricular free wall (N = 5), septal (N = 5), and left ventricular free wall (N = 5) compliances were induced by glutaraldehyde injections. After injecting glutaraldehyde into the right coronary artery, delta Pl/delta Vr, delta Vl/delta Vr, delta Pr/delta Pl, and delta Pr/delta Vl increased significantly (P less than 0.05). After septal artery injection, pressure and volume transfer between the ventricles was significantly depressed. After left coronary artery injection, delta Pl/delta Pr, delta Pl/delta Vr, delta Pr/delta Vl, and delta Vr/delta Vl increased significantly (P less than 0.05). Thus, selective alterations in the mechanical coupling between the ventricles occurred following changes in right ventricular, septal, and left ventricular free wall compliances. Such changes may be important in diseases which primarily affect one side of the heart.