EARLY CHANGES IN CIRCULATING BLOOD-VOLUME AND VOLUME REGULATING HUMORAL-FACTORS AFTER IMPLANTATION OF AN ELECTROHYDRAULIC TOTAL ARTIFICIAL-HEART

The early changes in circulating blood volume (CBV) and volume regulat ing humoral factors after implantation of an electrohydraulic total ar tificial heart (EH-TAH) were investigated in a calf and compared with results in a sham operated control calf. CBV was measured by the dye d ilution method using indocyanine green. CBV and humoral factors were p eriodically investigated. In the EH-TAH implanted calf, the cardiac ou tput was estimated at 6-7 L/min (94-109 ml/kg/min), and the aortic pre ssure and aerobic metabolic condition were favorable. Nevertheless, th e CBV was increased to 132 and 168% of the pre-operative value (range in the control calf, 83-103%) on post operative days 4 and 8, respecti vely. The atrial natriuretic peptide level on days 2, 5, and 7 was 23, 170, and 240 (in the control calf, 19-61) pg/ml, respectively, and th e antidiuretic hormone level was 7.3, 2.0, and 1.3 (0.5-1.3) pg/ml, re spectively. The plasma renin activity was 3.2, 3.7, and 3.1 (0.5-0.3) ng/ml/hr, respectively. The angiotensin-I and angiotensin-II levels we re also increased in the EH-TAH implanted calf. It is concluded that s ignificant water retention occurs even at sufficient cardiac output ea rly after EH-TAH implantation. The changes in humoral factors are sugg ested to arise secondary to the increased CBV or other unknown factors .