Impact of Left Ventricular Unloading Under Circulatory Support with Venoarterial ECMO in Heart Failure Animal Model

Abstract

<h3>Purpose</h3> An additional left ventricular (LV) unloading device could be effective for LV distension caused by V-A ECMO. However, the appropriate flow proportion between V-A ECMO and LV unloading devices has still been controversial. The purpose of this study was to evaluate the effect of flow proportion between V-A ECMO and LV unloading. <h3>Methods</h3> Microsphere was injected to the left anterior descending artery of 12 adult sheep to induce myocardial ischemia, aiming at the criteria of cardiac output to be less than 50% of that before the microsphere injection. V-A ECMO was established between the right atrium and the abdominal aorta. LV unloading was performed by venting blood from LV apex to the abdominal aorta using a centrifugal pump. V-A ECMO support and LV unloading were maintained for 6 hours with a total systemic flow to be 80-100ml/kg/min. We categorized into 3 groups based on different mechanical circulatory configurations and flow proportion: No LV unloading group (V-A ECMO without LV unloading), Low LV unloading group (LV unloading with V-A ECMO, ECMO: LV venting=3:1), and High LV unloading group (LV unloading with V-A ECMO, ECMO: LV venting=1:1). The LV and right ventricle (RV) functions of these 3 groups were investigated by analyzing hemodynamic parameters as well as the evaluation of LV pressure-volume loops and echocardiography. <h3>Results</h3> During the V-A ECMO support, LVEDP and potential energy of Low and High LV unloading groups were significantly lower than that of No LV unloading group (Figure1A). The RVDd/ LVDd ratio on echocardiography of High LV unloading group was higher than that of Low LV unloading group, while RVFAC of High LV unloading group was lower than that of Low LV unloading group (Figure 1B), suggesting that high LV unloading could be related to RV dysfunction. <h3>Conclusion</h3> LV unloading is mandatory for V-A ECMO in avoiding LV dysfunction, whereas excessive LV unloading has the possibility to cause RV dysfunction.