CONTRIBUTION OF THE INTERVENTRICULAR SEPTUM TO MAXIMAL RIGHT-VENTRICULAR FUNCTION

Objective: Maximal right ventricular (RV) function is influenced by le ft heart hemodynamics, possibly mediated by the interventricular septu m (IVS). We examined the potential contribution of the IVS function to right heart function. Methods: In 12 canine isovolumic right heart pr eparations, 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 consta nt 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, re spectively, P < 0.001), and RV dP/dt (inactivated vs. working NS: 720 +/- 220 vs. 1350 +/- 190 mmHg/s, respectively, P < 0.001). Conclusions : These results suggest that the functional status of the IVS is a maj or determinant of maximal RV function. At constant LV conditions and a rterial pressure, an inactivated IVS leads to a significant decrease i n maximal RVDP and RV dP/dt under the conditions of this study. (C) 19 98 Elsevier Science B.V. All rights reserved.