title: Evaluation of a fluid-controlled artificial heart.
abstract: The Zurich A. H. is a pneumatic drive biventricular cardiac prosthesis with tubular silicone rubber membrane, tilting discvalves, and fluid control system. Membrane position is monitored throughout the cardiac cycle to prevent systolic membrane collapse or insufficient diastolic filling. This A. H. was implanted in 25 dogs weighing 23-50 kg. In five animals, the A. H. performed satisfactorily for more than 24 hr. At an average flow rate of 60-90 ml/min per kg, the aortic pressure ranged from 80 to 100 mm Hg, and both left and right atrial pressures were within normal range. The animals were awake, and they breathed spontaneously after 24 hr; average plasma hemoglobin  levels averaged 91 mg/100 ml, and platelet counts decreased to 65,000 cu mm. In three animals subjected to the A. H. pump for 24 hr, the A. H. was removed and replaced with a transplant. Adequate transplant function was obtained, but there were no long-term survivors. Adequate hemostasis, sepsis, and complex organ dysfunctions associated with prolonged pumping are currently the main biologic problems.
mesh_terms: D000818:Animals; D004285:Dogs; D005069:Evaluation Studies as Topic; D006354:Heart, Artificial; D006439:Hemodynamics