Differences in the recovery of right and left ventricular function after ischaemic arrest and cardioplegia

Abstract

Differential susceptibility of right (RV) and left (LV) ventricles toplain ischaemia and the contribution of cardioplegia in reducing theischaemic damage was evaluated in a sheep model of cardiopulmonary bypass.Sheep (n = 16) were equally divided for the two protocols of the study.Each sheep served as its own control. RV and LV functions were studied andcompared by plotting ventricular function curves (Starling and Sarnoff).The mathematical centre of mass (COM) for each curve was computed by apolynomial regression program. The COM values of the contractility indices[stroke volume (SV), stroke work (SW)] represented ventricular heterometricreserve. RV and LV heterometric reserve was significantly (P less than0.01) reduced after 1 h plain ischaemia, and quantitatively this change wasmore for RV than for LV (P less than 0.05). As compared to LV, asignificantly greater reduction in RVSW was brought about by asignificantly (P less than 0.01) greater reduction in RVSV, because therewere no significant differences between the post-ischaemic recovery in theRV and LV afterloads. Cardioplegic protection nearly normalized fillingpressure and contractility (SV, SW) of both ventricles, but majordifferences were observed in the recovery of compliance. Recovery in the RVcompliance exceeded the control values, and quantitatively the recovery inRVSW was slightly more than in LVSW. The results of this study indicatethat the RV suffers more damage from plain ischaemic arrest and hencebenefits more from the cardioplegic protection.