Effects of mechanical left ventricular support on right ventricular diastolic function

Background: Previous studies have shown that left ventricular (LV) unloading alters right ventricular (RV) systolic mechanics, but the effects of LV assist device (LVAD) support on RV diastolic function have not been examined in intact subjects. Methods: Seven closed-chest, sedated dogs were studied after placement of a LVAD and 27 myocardial markers; in four animals, a right coronary artery occluder was placed to induce acute RV free wall ischemia. Data were recorded with the LVAD off and LVAD on before (control) and during RV ischemia. Assessment of RV diastolic function included RV myocardial relaxation (time constant of isovolumic pressure decay [τ]), RV chamber stiffness (slope of the end-diastolic pressure-volume relation), and RV filling dynamics (peak filling rate and mean filling rate during early diastole). Results: During control, full LVAD support did not alter RV τ (104 ± 67 msec LVAD) off versus 109 ± 49 msec LVAD on, p > 0.50), RV diastolic stiffness (0.56 ± 0.31 versus 0.51 ± 0.25 mm Hg/ml, p > 0.20), peak filling rate(107 ± 51 versus 119 ± 82 ml/sec, p > 0.35) or mean filling rate during early diastole (32 ± 28 versus 27 ± 18 ml/sec, p > 0.40). With right coronary artery occlusion, RV τ rose to 136 ± 33 msec (p < 0.001), and RV diastolic stiffness fell to 0.29 ± 0.13 mm Hg/ml (p < 0.005), but there was no change in RV filling rates (p > 0.20). With mechanical LV support during acute RV ischemia, there was no additional change in RV τ, diastolic stiffness, or filling dynamics (p > 0.20). Conclusions: In intact animals, RV ischemia impaired RV relaxation and decreased chamber stiffness, but there was no change in RV filling rates. Mechanical LV support, during the control state and with RV ischemia, did not affect RV diastolic performance.