Preserved right ventricular systolic performance in right ventricular failure due to chronic pulmonary stenosis in the conscious dog
Adaptations of right ventricular (RV) systolic performance to chronic pulmonary stenosis (PS) in clinical RV failure are poorly understood. Therefore, 7 dogs underwent chronic implantation of pneumatic pulmonary artery occluders, and epicardial dimension transducers. RV volumes (RVV) were calculated using a shell subtraction model (RW = biventricular epicardial volume-LV epicardial volumeRV wall volume). Micromanometers measured ventricular pressures. Dogs were studied in the control state and in clinical RV failure induced by PS (mean increase in RV mean-ejection pressure of 42±21mmHg). At an average of 2.3 weeks, all animals demonstrated ascites and pleura! effusions. RV systolic performance was characterized by the slopes and x-intercepts of the stroke work (SW) vs enddiastolic volume (EDV) relationship (mpRSw.xPRSW) and the end-systolic pressure(ESP)-volume relationship (mESPVR,ESPVR) These regression constants were then used to calculate SW at a constant EDV (SWCV), and ESP at a constant end-systolic volume(ESPCV). Data are mean±S.D.p<0 05 vs control. mPRSW, xPRSW SWCV mESPVR xESPVR ESPCV J/m1×10-3ml J mmHg/ml ml mmHg Control 2.4±0.5 48±21 0.13±0.06 0.83±0.13 27±22 58±16 Failure 2.9±0.564±260.11±0.04 2.3±1.040±16104±31These data demonstrate that chronic PS significantly increases the slopes and x-intercepts of both relationships. SWCV was not significantly altered by RV failure, and ESPCV actually increased (p= 009). These data clearly demonstrate the adaptation of the RV to markedly increased aftcrload despite severe clinical failure.
Lilly, RE; Silvestry, SC; Marathe, US; Davis, JW; Glower, DD
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