The effect of the left ventricular assist device on the myocardium during reperfusion after coronary artery occlusion.

The effect of the left ventricular assist device (LVAD) during reperfusion after acute coronary occlusion was evaluated in a canine experimental model. The left circumflex artery was occluded for one hour, then reperfused for six hours immediately after removal of the occluder. Sixteen mongrel dogs were divided into the following two groups; a control group comprised of 7 dogs not given the LVAD support and another group comprised of 9 dogs (the LVAD group) assisted by LVAD for five hours during reperfusion. Throughout the study period, there was no significant difference in heart rate, aortic pressure or PA pressure between the two groups. However, LA pressure was significantly lower, while cardiac output, LV dp/dt, and LVSW were significantly higher in the LVAD group compared to the control group. Regional myocardial blood flow in the LCx area was significantly decreased after LCx occlusion in both groups but in the LVAD group, it recovered to the same level as before LCx occlusion after the beginning of reperfusion, while in the control group it remained significantly low throughout reperfusion. The LVAD group showed a positive myocardial lactate extraction in the early reperfusion period however, there was persistent lactate production in the control group. Thus, the unloading effect of LVAD during reperfusion after acute coronary artery occlusion improved regional myocardial blood flow and myocardial lactate metabolism and consequently, left ventricular function showed better recovery even after weaning from the LVAD support.