Right heart function during prosthetic left ventricular assistance in a porcine model of congestive heart failure

A left ventricular assist device was used to produce a 90% reduction in peak systolic left ventricular pressure in pigs with congestive heart failure, and the resultant effects on right ventricular function were determined. Initially, eight farm pigs underwent rapid ventricular pacing at 230 beats/min for 7 days to produce congestive heart failure. When compared with an independent series of normal pigs, cardiac output in the paced animals was 33.3% less (2.2 +/- 0.2 versus 3.3 +/- 0.5 L/min; p less than 0.05), left ventricular end-diastolic pressure was elevated (13.8 +/- 3.5 versus 6.6 +/- 1.8 mm Hg; p less than 0.05), and the slope of the right ventricular global stroke work curve was significantly depressed (0.004 +/- 0.001 versus 0.033 +/- 0.003 joules/mm Hg; p less than 0.05). Next, the left ventricular assist device was connected between left ventricular apex and ascending aorta and left ventricular pressure was reduced from 92.0 +/- 3.8 to 10.5 +/- 2.2 mm Hg, while systemic arterial pressure was maintained constant. This led to a further impairment in cardiac output (-14%), mean arterial pressure (-15%), and the slope of the right ventricular global stroke work curve (-50%). Under each condition, right ventricular preload recruitable stroke work and end-systolic pressure-dimension relationships were studied in three different regions on the right ventricle during both steady-state and transient inferior vena caval occlusion. In the right ventricular septal-free wall dimension, left ventricular pressure unloading resulted in a 47.5% +/- 5.4% (p less than 0.05) reduction in the slope and 20.1% +/- 4.8% (p less than 0.05) increase in the dimension intercept of the preload recruitable stroke work relationship. There was also a 44.6% +/- 4.8% (p less than 0.05) reduction in the slope and 15.6% +/- 2.8% (p less than 0.05) increase in the dimension intercept of the end-systolic pressure-dimension relation. These slope changes plus reductions in cardiac output and in global stroke work, which are indicative of impaired right ventricular function during left ventricular pressure unloading in the congestive heart failure pigs, are not seen in normal hearts, whereas the intercept changes associated with leftward septal shift are present in both. These results suggest that anatomic ventricular interactions have a more significant role in heart failure than in the normal heart in determining overall right ventricular function during left ventricular assist device support.