Long-term circulatory maintenance with a left-sided single artificial heart.

The purpose of this study is to examine the feasibility of long-term circulatory maintenance with only a left-sided single artificial heart that is inserted between the left atrium and the aorta to assist a nonfunctioning heart. The basic hemodynamics were determined in short-term experiments in goats (n = 4), and feasibility studies of long-term circulatory maintenance with a single artificial heart during cardiac arrest were performed in long-term experiments (n = 12). When pulmonary vascular resistance was less than 15,000 dynes .sec.cm-5.kg, which was twice the normal value, the circulation was well maintained with the single artificial heart alone, so long as the right atrial pressure was kept at 14 to 16 mm Hg. Under such conditions the flow yielded by the single artificial heart fluctuated between 80 and 140 ml/kg/min depending on the animal's demand, while the mean arterial pressure was kept above 80 mm Hg. The goats behaved normally, although retention of pleural effusion was a serious problem in maintaining normal circulation over a long-term. Maintaining the plasma total protein level above 6.0 gm/dl delayed the onset of retention or even prevented pooling of pleural effusion. The longest survival period to date has been 38 days. We conclude that when the pulmonary vascular resistance is less than twice the normal value and the total protein level is above 6.0 gm/dl, a left-sided single artificial heart alone can maintain normal circulation and provide time for patients with a nonfunctioning heart to undergo a further treatment, such as heart transplantation.