Regulation of coronary circulation during left ventricular assist

Regulatory mechanisms of coronary circulation during left ventricular assist (LVA) were studied in chronic experiments using adult goats. In normal heart studies (n = 3), circumflex coronary artery flow (CxF) and endocardial blood flow (MBF) decreased in proportion to decrease of tension time index (TTI). Mean CxF/TTI was constant at 0.22, whether the LVA functioned or not. In the left anterior descending branch ligation model (AMI) study (n = 2), CxF decreased according to decrease of TTI throughout the experiment, if the bypass ratio was kept within a normal range of systemic pressure. Mean CxF/TTI was maintained at approximately 0.21 by LVA, fell to 0.16 when LVA was turned off during the early stages. Coronary circulation during LVA was regulated by oxygen demand if systemic circulation was maintained, and LVA improved oxygen demand-supply balance in failing hearts.