Anatomic interaction between the right and left ventricles during univentricular and biventricular circulatory...

Left heart unloading with a prosthetic ventricle has been shown to result in a leftward shift of the interventricular septum, changing the geometry and possibly the performance of the right heart. The effects of univentricular and biventricular support on septal shifting were compared. In 10 anesthetized pigs Thoratec left (LPV) and right prosthetic ventricles (RPV) were connected from the LV apex to the ascending aorta and the right atrium to the pulmonary artery, respectively. Each heart was instrumented with ultrasonic crystals for LV and RV free wall-to-septum dimensions, RV and LV pressures, and cardiac output (CO). LV and RV end-diastolic pressure and dimensions (EDD), and peak systolic pressures (PSP) and dimensions were analyzed on a computer under control conditions, and during EKG synchronized RPV, LPV, and biventricular (BPV) support. During LPV the septum shifted to the left, and during RPV it shifted to the right, with LVEDD and RVEDD changing in opposite directions under each condition. With BPV septal position changed in the same way as with LPV, although to a smaller degree. The amount of septal movement was linearly related to the change in transseptal gradient produced by the prosthetic ventricles. Each 10 mmHg decrease in left minus right transseptal pressure gradient resulted in a 22% reduction (r = 0.83) in LVEDD and a 27% increase (r = 0.87) in RVEDD at end-diastole, and a 2% reduction (r = 0.87) in LV dimensions and a 2% increase (r = 0.83) in RV dimensions at peak systole.(ABSTRACT TRUNCATED AT 250 WORDS)