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The Apico Aortic Blood Pump (AABP) is a centrifugal continuous flow left ventricular assist device (LVAD) with ceramic bearings. The device is in the initial development phase and is being designed to be attached directly to the left ventricular apex by introducing an inlet cannula. This paper reports results from in vitro experiments. In order to evaluate implantation procedures and device dimensioning, in vitro experiments included an anatomic positioning study for the analysis of surgical implantation procedure and device dimensions and positioning that was performed using the body of a pig. The results revealed no damage caused by the device, and the surgical implantation procedure was considered feasible. Hydrodynamic performance curves were obtained to verify the applicability of the device as an LVAD, showing adequate performance. Mechanical blood trauma was analyzed through 6-h hemolysis tests, with total pressure head of 100 mm Hg and flow of 5 L/min. Mean normalized index of hemolysis was 0.009 g/100 L (±0.002 g/100 L). Studies using a hybrid cardiovascular simulator were conducted for three types of circulatory conditions: normal healthy conditions, concentric hypertrophic heart failure (CHHF), and CHHF with AABP assistance. Analysis of cardiovascular parameters under those three conditions demonstrated that when the AABP was assisting the system, parameters under CHHF conditions went back to normal healthy values, indicating the AABP's effectiveness as CHHF therapy. Our preliminary results indicate that it is feasible to use the AABP as a LVAD. The next steps include long-term in vivo experiments.

Dynamic cardiomyoplasty has been performed to reinforce the myocardium in the treatment of patients with severe cardiomyopathies. At the Heart Institute of Sao Paulo University Medical School, 36 patients were submitted to cardiomyoplasty between May 1988 and December 1993. The indications were idiopathic dilated cardiomyopathy in 31, ischemic cardiomyopathy in 3, and Chagas' disease cardiomyopathy in 2 patients. Twenty-eight patients were categorized in New York Heart Association (NYHA) Class III and 8 in Class IV despite the use of maximal medical therapy. There were no hospital deaths, and patients were followed up from 2 to 70 months (mean, 24 months). Besides the improvement of NYHA functional class from 3.2 +/- 0.6 to 1.6 +/- 0.9 at 6 months of follow-up, patients also presented significant changes in the left ventricular systolic and diastolic functions. Nevertheless, 16 patients died, and 2 patients were submitted to heart transplantation during late follow-up. Actuarial survival rates were 82.3% at 1 year, 61.5% at 2 years, and 38.8% at 5 years of follow-up. Otherwise, the analysis of factors influencing the outcome showed that long-term survival was significantly affected by preoperative functional class and by pulmonary vascular resistance. The 26 patients operated in NYHA functional Class III and with pulmonary vascular resistance below 4 Wood units presented survival rates of 72.7% at 2 years and of 63% at 5 years of follow-up. In conclusion dynamic cardiomyoplasty improves functional class and left ventricular function in patients with severe cardiomyopathies. However, the long-term survival after this surgical procedure may be limited by the patients' condition before the operation.

This paper describes the design of a ventricular assist device (VAD), its manufacturing, and testing. The VAD presented is pulsatile, with a free-floating membrane, smooth internal surfaces, and pericardial valves. It comprehends also a pneumatic driving unit capable of operating in the "full to empty," EKG synchronized or asynchronous modes. In vitro tests were performed to assess its mechanical durability, hydrodynamic performance, and hemolysis. To optimize cannulas and implant techniques, we performed in vivo tests in 22 sheep and 8 calves. In these tests, we also evaluated hemolysis and the device's capacity to normalize hemodynamic parameters during induced cardiac failure. The VAD worked for 4,000 h without failure in a mock circulatory loop. In full to empty mode, it displayed a rate-mediated "Starling-like" performance. Optimum output was achieved with a systole duration of 40% of the cycle. The in vitro hemolysis index (IH) was 6.7 +/- 2.1. Hemolysis in animal experiments was clinically nonsignificant. In calves with induced cardiac failure, the VAD was able to normalize hemodynamic parameters within 120 min.