Impact of Microaxial Flow Pump on Coronary Flow Dynamics in Normal Hearts: An Experimental Evaluation

The effects of microaxial flow pump (mAFP) support on coronary flow (CF) are well characterized in failing hearts, but its impact on CF in normal hearts under different levels of left ventricular (LV) unloading remains unclear. Seven anesthetized Saanen goats underwent left thoracotomy, and an Impella 5.5 device was implanted via the left common carotid artery and operated at incremental support levels: Control (P1-2), Partial (P4-6), and Total (P7-9). Coronary perfusion pressure (CPP), coronary vascular resistance (CVR), myocardial oxygen consumption (MVO₂), and diastolic LV wall stress were calculated at each level. With increasing mAFP support, CPP increased whereas CF decreased by 32.1% from Control to Total support (69.6 ± 19.8 vs. 48.4 ± 21.1 mL/min), and CVR increased 260% (0.5 ± 0.2 vs. 1.8 ± 1.3 mmHg·min/mL). In normal hearts, mAFP elevates CPP but paradoxically reduces CF due to increased CVR associated with LV unloading.