948-50 Dissociation Between Changes of Plasma Volume and its Neurohumoral Determinants Post-HeartMate Implantation in Heart Failure Patients

Abstract

Congestive heart failure is associated with blood volume expansion which by itself increases the burden on the heart. High PV with congestive heart failure has been attributed to stimulation of the renin-aldersterone system and AVP. The use of left ventricular assist devices as bridges to heart transplantation has increased the survival of these patients during this critical period. We hypothesized that improvement of cardiac mechanical function by HeartMate (left ventricular assist device) is associated with a normalization of volume load secondary to normalization of neurohumoral determinants of plasma volume. To assess this hypothesis, we studied 15 patients (13 M: 2 F; age 50 ± 9 yrs) with end stage heart failure who were cardiac transplant candidates, before and after HeartMate 1000 (HM) implantation. We measured plasma volume (pV, RISA). and plasma levels of atrial natiuretic hormone (ANFI. aldosterone (PA), renin (PRA), and arginine vasopressin (AVP). sequentially at pre HM, and post HM (weeks 2, 4 and 8). Pre HM W2 W4 W8 PV 117 ± 22 123 ± 17 119 ± 19 111 ± 12 ANF 276 ± 199 199 ± 62 180 ± 110 141 ± 66 PA 53 ± 52 16 ± 9 17 ± 18 14 ± 9 * PRA 46 ± 25 7 ± 3 * 8 ± 7 * 11 ± 18 * AVP 5.2 ± 5 0.8 ± 1 0.6 ± 0.7 * 1.1 ± 1 * x ± SD, P(paired t) * < 005 vs pre HM The reduction of PV, PRA, PA and AVP occurs earlier than the reduction of plasma volume and ANF after HeartMate, possibly due to decreased pulmonary congestion and improved renal perfusion. The reduction of ANF cannot be responsible for lack of adequate decrease of plasma volume; its reduction can be taken as a marker of improved cardiac pump function and decreased atrial stretch.