Reduced myocardial blood flow during left ventricular assist device support: a possible cause of premature bypass graft closure.

Our aim was to determine the effect of left ventricular assist device (LVAD) implantation on bypass graft patency and to measure myocardial oxygen consumption (MVO2) and blood flow during LVAD support. Five patients who underwent coronary artery bypass grafting and required LVAD implantation for post-cardiotomy cardiogenic shock had coronary angiography during device support to assess graft patency. Positron emission tomography measurements were made in a separate cohort of LVAD patients with dilated cardiomyopathy to assess the effects of LVAD support on MVO2 and myocardial blood flow. In this small series, LVAD unloading led to a high rate of premature graft occlusion in post-cardiotomy cardiogenic shock patients supported with a device; whereas, positron emission tomography measurements showed significantly reduced MVO2 and myocardial flood flow in dilated cardiomyopathy patients supported with an LVAD, compared with healthy subjects. Reduced myocardial blood flow may be implicated in the premature graft failure observed in post-cardiotomy cardiogenic shock patients and may negatively impact the potential for myocardial recovery and device weaning in this population.