Abstract
MUNAKATA, K., SHIRATO, K., ISHIKAWA, K., SAKUMA, M., KANAZAWA, M., HANEDA, T. and TAKISHIMA, T. Significance of the Right Ventricular Free Wall in Dogs with and without Pulmonary Constriction. Tohoku J. Exp. Med., 1995, 177 (2), 93-106-To evaluate the role of the right ventricular (RV) free wall in cardiac function, RV and left ventricular (LV) wall segment lengths were measured by ultrasonic crystals in 10 open chest dogs with the pericardium preserved. Right coronary artery (RCA) was perfused separately by own blood and the flow was reduced stepwise until active shortening (ΔL) of the RV segment disappeared or RCA flow became zero (Ischemia). The experiment was repeated with and without pulmonary stenosis (PS). At Ischemia, RV and LV systolic pressures decreased. RV end-diastolic length increased and RVΔL decreased. LV end- diastolic length and LVΔL were reduced. LV stroke volume concurrently fell. These changes became more prominant with PS. The critical level of RCA flow, at which RVΔL began to change, was higher with PS (5.27±2.85ml/min, mean± S.D.) than without PS (1.44±1.16, p<0.01). Based on the relationships between RVΔL and percent changes in RV developed pressure and stroke volume, the degree of the decreases in RV developed pressure and stroke volume at RVΔL of zero were estimated to be about 20%. These results indicate that the RV free wall partly contributes to maintaining the RV function, especially during RV pressure overload.-critical coronary flow; pressure load; right ventricular function; stroke volume
