Improved left ventricular performance by the transmission of pulse waves through the pulmonary vascular bed

The influence on left ventricular performance of pulsewaves transmitted through the pulmonary vascular bed was studied in a cat lung preparation with the right heart bypassed by a pulsatile blood pump. The pump worked at a frequency slightly different from the intrinsic heart rate; transmitted pulse waves were thereby forced to arrive the left atrium at different phases of the left heart cycle. Slow fluctuations of left atrial pressure, left ventricular systolic pressure and left ventricular dP/dt were observed. Left ventricular systolic pressure and left ventricular dP/dt were maximum when the transmitted pulsewaves arrived left atrium just prior to the atrial contraction. The observed variation in left ventricular systolic pressure was found to be directly dependent on the magnitude of pulsatile hydraulic power transmitted to the left atrium.