The use of a safe and effective artificial heart can be lifesaving for those patients with end stage cardiac disease refractory to inotropic support or intra aortic balloon counterpulsation.
The current status of worldwide total artificial heart (TAR) development programs is reviewed in this paper. A comparison is made of the clinical results from the 33 cases utilizing TAH implantation and the first 30 cardiac transplantation cases. Initial results from former group further encouraged the use of the TAH: five cases represent the first human TAH implants and 28 cases used TAH as a bridge to transplant.
These results suggest that the following conditions must be met for clinically acceptable TAH systems: durable components with good biocompatibility and minimal hemolysis; easy control modes having simple and reliable sensors; smaller component size with good anatomical fit; and totally implantable systems offering patients a good quality of life.
The second major topic discussed pertains to the current status of the TAH development programs at major centers worldwide. The pump designs and materials used at several centers are summarized including the Cleveland Clinic's Biolized pump.
Progress with various types of actuation and TAH control modes were also outlined. The Cleveland Clinic's variable rate mode used with the pusher plate type pumps is described. An adaptation hypothesis relative to TAH implantation, which divided into three stages, includes the confusion stage, the fighting stage and the live together stage, is presented with experimental results.
In conclusion, all the major centers achieved equally feasible results with regard to clinical application of their TAR devices.
Future programs for totally implantable TAR systems, including the Cleveland Clinic's version of an electrohydraulic one piece TAH, are also summarized.

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Extracorporeal membrane oxygenation (ECMO) was used in the treatment of 120 newborn infants with respiratory failure in three phase: Phase I (50 moribund patients to determine safety, efficacy, and risks); Phase 11 (30 high risk patients to compare ECMO to conventional ventilation); and Phase III (40 moderate to high risk patients, the current protocol). Ninety one patients survived including 54% in Phase I, 90% in Phase II, 92% in Phase III. The major complication was intracranial bleeding which occurred in 89% of premature infants (<35 weeks) and 15% of full-term infants. Best survival results were in persistent fetal circulation (14, 14 survived), followed by congenital diaphramatic hernia (13, 10 survived), meconium aspiration (51, 44 survived), respiratory distress syndrome (27, 14 survived), and sepsis (12, 7 survived). There were seven late deaths; in follow up 63% are normal or near normal, 17% had moderate to severe CNS dysfunction and 8% had severe pulmonary dysfunction. ECMO is now used in several neonatal centers as the treatment of choice for full-term infants with respiratory failure which is unresponsive to conventional management. The success of this technique establishes prolonged extracorporeal circulation as a definitive means of treatment in reversible vital organ failure.

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Primary amine, tertiary amine or quaternary ammonium were covalently bonded to polystyrene fiber and were examined for antibacterial activity. The antibacterial activity of quaternary ammonium covalently bonded to a polystyrene fiber was optimal for derivatives having an alkyl chain of C:6 or C:8. Tertiary amine covalently bonded to polystyrene fiber as well as quaternary ammonium covalently bonded to polystyrene fiber showed a high antimicrobial activity against E. coli, though primary amine covalently bonded to polystyrene fiber had a lower one. The tertiary amine covalently bonded to polystyrene exhibited an antibacterial activity against gram-negative bacteria. This activity was accentuated by deoxycholate or actinomycin D, to which E. coli is normally insusceptible. On the other hand, the antimicrobial activity was inhibited by Mg²⁺ or by lowering pH conditions. Scanning electron microscopy showed no E. coli on the fiber. But on fiber which had contact with E. coli (10⁹ CFU/ml) only for 10 s, E. coli was observed and there were many projections on the cell surface. Taken together, these results imply the functional and structural damage of the bacterial outer membrane by tertiary amine covalently bonded to a polystyrene fiber.

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The hydrodynamic effect on clot growth and erythrocyte destruction was investigated quantitatively in vitro. Constant velocity gradient from 30 to 1, 500s^-1 were applied to a canine blood sample contained in a cone and plate (made of polymethyl methacrylate) viscometer for 120min at 24°C. Evaluation of clot growth was derived from the clotting ratio (the volumetric fraction of clot in the whole blood), which was experimentally determined from the rate of increase of frictional torque between the rotating cone and the stationary plate. Evaluation of erythrocyte destruction was derived from the hemolysis ratio (plasma hemoglobin count per whole blood hemoglobin count). The results show that both the clotting ratio and the hemolysis ratio are maintained in small values (<0.3 and <0.01, respectively) for the velocity applying time of <120min at a velocity gradient from 400 to 1, 000s^-1.

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We have developed a new compliant suture (CS), made of segmented polyester, to improve the patency of small caliber arterial anastomosis. We evaluated its mechanical properties and usefulness by in vitro and in vivo experiments. In vitro experiments, 1) CS was a monofilament and had proper elasticity; 2) its pattern of stress-strain curve, markedly different from those of such sutures as polypropylene (PP), PDS and nylon, was similar to that of natural arteries; 3) CS was much stronger than PP; 4) durability of CS was much better than that of PP. In vivo experiments, 5) preserving rate of anastomotic compliance with CS, 92.2±6.6%, was significantly higher than that with PP, 62.7±9.1%; 6) in light and electron microscopy, CS had almost no foreign body reaction or tissue reaction, and CS showed no intimal hyperplasia 6 months after anastomosis. Therefore, it was concluded that CS was very useful to small caliber arterial anastomosis.

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Long term heart preservation is one of the most important problems for clinical heart transplantation. We use the continuous hypothermic coronary perfusion method for experimental trial. In this experiment two kinds of perfusates were examined for 24h heart preservation. One is modified Collins' (MC) solution (group A) and the other is perfluorochemicals (PFC) added MC solution (group B). The change in heart weight was less in group B than in group A. Perfusion flow was very unstable in group A. Left ventricular passive compliance was markedly depressed in group A than in group B. The concentration of CPK, LDH in perfusate was higher in group A than in group B. These data indicate that group B is preserved in better conditions than group A and perfluorochemicals has good effects for long term heart preservation.

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The influence of hypothermia during extracorporeal circulation with core cooling on enzymes and metabolic changes was studied in one hundred and six patients. The enzymes and metabolic changes were suppressed by hypothermia. The critical point of body temperature during and after extracorporeal circulation with core cooling was decided on enzymes and metabolic changes by stepwise discriminant analysis. Results were summarized as follows: 1) The critical body temperature was twenty eight centigrade and sixty minutes after initiation of perfusion and core cooling, although the lowest body temperature was brought at thirty minutes after initiation of perfusion. 2) The carbohydrate and lactic acid metabolism were significant coefficient factors of ciritical body temperature during extracorporeal circulation with core cooling. 3) The ciritical body temperature was twenty four centigrade and next morning after surgery, although, the body temperature was normal at the end of perfusion. 4) The enzyme changes were significant coefficient factors of critical body temperature after extracorporeal circulation with core cooling.

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