Contribution of the interventricular septum to maximal right ventricular function

OBJECTIVE: Maximal right ventricular (RV) function is influenced by left heart hemodynamics, possibly mediated by the interventricular scpturn (IVS). We examined the potential contribution of the IVS function to right heart function. METHODS: In 12 canine isovolumic right heart preparations, incremental volumes were introduced into a high compliance RV balloon until RV failure occurred. Maximal RV developed pressure (RVDP) and maximal positive RV dP/dt were determined with a working IVS at a constant left ventricular (LV) output of 2 l/min and at a constant mean arterial pressure of 80 mmHg. Thereafter the IVS was thermally inactivated, and measurements were repeated using the same protocol. RESULTS: At constant arterial pressure and constant LV output, thermal inactivation of the IVS led to a significant decrease in maximal RVDP (inactivated vs. working IVS: 36.1+/-9.8 vs. 56.8+/-16.2 mmHg, respectively, P < 0.001), and RV dP/dt (inactivated vs. working IVS: 720+/-220 vs. 1350+/-190 mmHg/s, respectively, P < 0.001). CONCLUSIONS: These results suggest that the functional status of the IVS is a major determinant of maximal RV function. At constant LV conditions and arterial pressure, an inactivated IVS leads to a significant decrease in maximal RVDP and RV dP/dt under the conditions of this study.