Partial Support with a Centrifugal Left Ventricular Assist Device Reduces Myocardial Oxygen Consumption in Chronic, Ischemic Heart Failure

Abstract

Background Left ventricular assist devices (LVAD) are increasingly used for heart failure (CHF); however, the level of optimal support has not been elucidated. We hypothesize that partial LVAD support in an ovine model of microinfarction-induced CHF significantly reduces left ventricular myocardial oxygen consumption (LVVO 2). Methods and Results Microembolization of the circumflex coronary artery was used to induce CHF in 5 sheep (ejection fraction 28 ± 2%). Four months later, animals underwent implantation of a centrifugal LVAD. LVAD flow was incrementally increased from 0% (baseline) to 25%, 50%, and 75% support of the LV. LVVO 2 and stroke work (SW) were calculated at each increment. At baseline, LVVO 2 (μL/100 g LV/beat) measured 43.2 ± 3.4. LVVO 2 decreased to 26.5 ± 8.2, ∗ 20.3 ± 8.9, ∗ and 12.6 ± 6.3 ∗ at 25%, 50%, and 75% support ( ∗ P < .05). SW (mm Hg/mL) measured 1933.0 ± 275.7 at baseline and decreased to 1588.0 ± 204.1, 1181.0 ± 157.2, ∗ and 764.5 ± 171.7 ∗ at 25%, 50%, and 75% support. Cardiac output, heart rate, and left main coronary artery blood flow were unaffected with partial support. Conclusion Complete support with a centrifugal LVAD is not necessary for achieving significant reductions in LVVO 2. Partial support of as little as 25% significantly reduces LVVO 2 in CHF through comparatively minor reductions in cardiac work. This is the first study to examine partial LVAD support in a CHF model.