Development of a pulsatile perfusion apparatus for heart preservation with myocardial impedance monitor

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This study was done to develop a portable perfusion apparatus for heart preservation in which hearts are hypothermically perfused with pulsatile pump for 24 hours and myocardial impedance is continuously measured to assess the myocardial edema. At first we evaluated simple immersion methods for preservation as control with Langendorf using isolated rabbit heart. The left ventricular function after 24 preservation in UW solution was better than in saline and modification at reperfusion, leukocyte depleted terminal cardioplegia, enhanced LV function to sustain the normal circulation after orthotopic heart transplantation in dog. The portable perfusion apparatus with a diaphragm driven by electromagnetic power which derivesd pulsatile flow was made. In vitro test with the apparatus showed 0.05-5ml of stroke volume, 60-120 beat/min, and 15-150 mmHg of perfusion pressure which could be controllable for isolated rabbit heart perfusion. The temperature, however, was difficult to maintain to 10 C during 24 hours perfusion because of the effect of room temperature especially when a "portable" apparatus was desired. Moreover conventional impedance meter should be used at constant temperature and it was proved that the value of tissue impedance at variable temperature was unreliable and worthless.