Effects of left ventricular pressure reductions on right ventricular systolic performance.

Reductions in left ventricular pressure (LVP) have been shown to produce a leftward shift of the interventricular septum and to reduce left ventricular contribution to right ventricular performance. To evaluate the magnitude of this contribution in the intact heart, five anesthetized pigs were implanted with a left prosthetic ventricle to gradually decrease LVP while maintaining arterial systemic pressure. Three descriptors of RV global and regional systolic function were studied in the septum to free wall (RVSFW) and anterior to posterior (RVAP) dimensions and in an outflow tract segment length (RVSL), during both steady state and transient inferior vena cava occlusion. LVP gradual reduction from 102 +/- 4 to 11 +/- 3 mmHg (90% decrease in peak systolic pressure) produced no changes in the RV global stroke work curve or in the RVAP and RVSL pressure-dimension relationships. However, the reduction in LVP resulted in parallel shifts in the RVSFW dimension, with 16.6 +/- 6.7% increase in the intercept D(o) of the end-systolic relationship and 16.5 +/- 2.5% increase in D(o) of the dimensional stroke work relationship, with no significant changes in their respective slopes as calculated by linear regression. Therefore, in the normal intact heart, large reductions in left ventricular pressure affect the geometry of the right ventricle because of septal shifting, but there is a negligible net effect of this anatomic ventricular interaction on overall right ventricular performance.