PLASMA-VOLUME AND ITS REGULATORY FACTORS IN CONGESTIVE-HEART-FAILURE AFTER IMPLANTATION OF LONG-TERM LEFT-VENTRICULAR ASSIST DEVICES

Background Congestive heart failure is associated with blood volume ex pansion caused by stimulation of the renin-aldosterone system and argi nine vasopressin. The use of left ventricular assist devices as bridge s to heart transplantation has improved the survival of patients durin g this critical period. In studying heart failure physiology on suppor t devices, we hypothesized that improvement of cardiac function by a l eft ventricular assist device is associated with normalization of volu me load secondary to normalization of its regulatory substances. Metho ds and Results We studied 15 patients (13 men, 2 women; age, 51+/-8 ye ars) with end-stage heart failure who were cardiac transplant candidat es eligible for HeartMate implantation. We measured plasma volume and plasma levels of atrial natriuretic peptide, aldosterone, renin, and a rginine vasopressin sequentially before HeartMate implantation (baseli ne), after HeartMate implantation (weeks 4 and 8), and after transplan tation. Baseline plasma volume was 123+/-20% of normal; it was 122+/-2 2% at week 4 and decreased to 115+/-14% at week 8. Atrial natriuretic peptide was 359+/-380 pg/mL at baseline, 245+/-175 pg/mL at week 4, an d 151+/-66 pg/mL at week 8. Plasma aldosterone fell from 68+/-59 ng/dL at baseline to 17+/-16 ng/dL at week 4 (P<.05 versus baseline) and wa s 32+/-50 ng/dL at week 8. Plasma renin activity decreased from 80+/-8 8 ng/dL at baseline to 11+/-12 ng/dL at week 4 and was 16+/-38 ng/dL a t week 8 (both P<.05 versus baseline). Arginine vasopressin fell from 5.0+/-4.8 fmol/mL at baseline to 1.1+/-0.7 fmol/mL at week 4 and 1.2+/ -0.8 fmol/mL at week 8 (both P<.05 versus baseline). Conclusions The r eduction of plasma renin activity, plasma aldosterone, and arginine va sopressin occurred earlier than the reduction of plasma volume and atr ial natriuretic peptide after HeartMate implantation, possibly because of decreased pulmonary congestion and improved renal perfusion. The r eduction of atrial natriuretic peptide cannot be responsible for the l ack of adequate decrease of plasma volume; its reduction can be taken as a marker of improved cardiac pump function and decreased atrial str etch.