Study on the establishment of a therapeutic system for severe cardiac failure by means of artificial heart as a bridge to heart transplantation

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1. Left ventricular assist device composed of electrohydraulic linear actuator and diaphram type blood pump has been investigated in this institute together with Aisin Seiki LTD.In this study series, the control system of this VAD was designed and examined. From the pressure volume curve obtained in the blood pump Ea/Ees was calculated. It was possible to get Ea/Ees as near to 1 as possible by controling stroke volume, rate, upper duty, lower duty and % systole of the VAD using multiple regression analysis in this control system.2. In order to speculate the effect of coagulation and fibrinolysis during artificial circulation including VAD on the implanted donor heart and recipient, changes of coagulation and fibrinolysis were examined during and after Cardiopulmonary bypass(CPB) : thrombocytes, beta-TG, ATIII, FPA, PLG, D-dimer, alpha_2PI etc. Both coagulation and fibrinolysis were activated during CPB.Nafamostat Mesilate(NM), however, inhibited these activities. It is considered that … More NM administration might prevent thromboembolic and hemorrhagic episodes during ventricular assist.3. In order to study whether cell mediated immunity responses would be suppressed or activated by the effect of CPB or ventricular assist, peripheral blood lymphocyte subsets and antibody dependent cell mediated cytotoxicity were investigated during artificial circulation. The total lymmphocyte (OKT 3 and OKT 11+) number did not change significantly. Suppressor/cytotoxic T cell(OKT8+) and NK cell (Leu 7+ and Leu 11+) numbers remarkably increased. But helper/inducer T cell(OKT 4+) and B cell(Leu 12+) numbers decreased. Mixed lymphocyte reaction and NK cytotoxicity were also activated during this study. It may be concluded that open heart surgery using CPB is associated with the activation of cytotoxic cell mediated immunity.4. Inthe recipient of heart transplanation who undergoes VAD as a bridge, blood coagulation, fibrinolysis and cytotoxic cell mediated immunity would be activated and therefore the incidence of thromboembolic episode and acute rejection might increase compared with simple heart transplantation. Less