Contribution of each ventricular wall to ventricular interdependence

The influences of presure 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 (ΔP_r, ΔP_l) and volume (ΔV_r, ΔV_l) 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, ΔP_l/ΔV_r, ΔV_l/ΔV_r, ΔP_r/ΔP_l, and ΔP_r/ΔV_l increased significantly (P<0.05). After septal artery injection, pressure and volume transfer between the ventricles was significantly depressed. After left coronary artery injection, ΔP_l/ΔP_r, ΔP_l/ΔV_r, ΔP_r/ΔV_l, and ΔV_r/ΔV_l increased significantly (P<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.