Phasic coronary blood flow pattern during a continuous flow left ventricular assist support

Objective: Continuous flow left ventricular assist devices (LVADs) have been introduced and tested as a bridge to heart transplantation, bridge to recovery, and destination therapy, and several studies have been conducted to assess the physiologic effects of continuous flow LVADs. However, the effect of reduced pulsatility on the phasic coronary blood flow pattern is unknown. The aim of this study was to investigate the phasic coronary blood flow patterns during continuous flow LVAD support. Methods: Phasic coronary blood flow patterns and hemodynamic data were analyzed using three flow probes placed around the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and the right coronary artery (RCA) in 16 pigs before and after initiating the LVAD support with or without creating LAD stenosis. Results: The total coronary blood flow (TCBF, 112.8 ± 31.4 mL/min) gradually decreased when the continuous flow LVAD support increased to 2.0 L/min (110.7 ± 29.0 mL/min, P = 0.571), 2.5 L/min (103.7 ± 26.1 mL/min, P = 0.079), and 3.0 L/min (101.5 ± 27.2 mL/min, P = 0.027) because of decreases in LAD flow and LCX flow. LVAD support caused decrease in systolic and peak systolic LAD flow, LCX flow, and RCA flow, whereas diastolic RCA flow increased. In the presence of LAD stenosis, the TCBF (97.7 ± 36.1 mL/min) decreased when the continuous flow LVAD support increased to 2.0 L/min (83.9 ± 22.1 mL/min, P = 0.029), 2.5 L/min (83.2 ± 25.2 mL/min, P = 0.012), and 3.0 L/min (87.6 ± 23.4 mL/min, P = 0.005) because of decreases in LCX flow. Conclusion: Use of a continuous flow LVAD decreased TCBF, LAD flow, and LCX flow secondary to reduced systolic LAD flow and LCX flow, and decreased TCBF and LCX flow in the presence of LAD stenosis. These findings are potentially relevant to understanding the physiology of myocardial blood perfusion during continuous flow LVAD support especially in patients with coronary artery disease.