Volume 3 Supplement 1
Computer simulation of the left ventricular pressure-volume relationship (LVPVR)
© Current Science Ltd 1999
Published: 16 March 2000
The concept of time-varying elastance developed by Suga and Sagawa in the 1970s integrates on the same graph all the components of LV function: contractility (Ees, slope of ESPVR ), preload (Ved),), afterload (slope Ea HR.SVR), matching of LV with arterial system (graphical analysis of SV) and LV efficiency . A computer simulation makes it a remarkable didactic tool.
Input data: volume (V); compliance of capacitive vessels (Cv); venous resistance at the entry of LV(Rv); LV compliance (CLV); (Ecs): zero-volume intercept (Vd); systemic resistances (SVR); heart rate (HR). Output data: Ved = (MSP.CLV)-(MSP.CLV-Ves) × e(t/Rv.CLV) with loading time (t) = (60/HR)-0.2 and mean systemic pressure (MSP)=V/Cv; Ped=e(0.33/CLV)(Ved-Vd)-1; Ea=HR.SVR; Ves=(Ea.Ved+Ees.Vd)/(Ees+Ea); SV=Ved-Ves PES=Ea.SV; LVEF=SV/Ved; CO=HR.SV; Pressure-volume area PVA=EW+PE; external work EW (SV.(Pes-Ptd/2); Potential energy PE=1/2(Ves-Vd).Pes; MVO2=2.5 × APV + 0.3 × Ees+1; 1 mmHg 1.333 × 10-4 J; mechanical efficiency ME=EW/MVO2.
The computer calculates output values according to input data and simultaneously modifies the classic graph on the screen.