Summary
Using an isolated rat heart preparation as a model of cardiopulmonary bypass and ischemic
arrest, the effects of the addition of the calcium antagonist, diltiazem, to St. Thomas'
cardioplegic Solution were investigated. Under conditions of normothermic ischemic
arrest (37 ° C, 35 min), the addition of diltiazem improved the protective properties
of the St. Thomas' cardioplegic Solution. Moreover, studies with varying concentrations
produced a bell-shaped dose-response curve for diltiazem with its optimal concentration
at 0.5 μmoles/Iiter (0.21 mg/liter) when postischemic recovery of aortic flow was
improved from 53.2 ± 4.3% to 79.2 ± 4.4% (p<0.01) and postischemic creatine kinase
leakage was reduced by approximately 40%. Despite this marked additional protection
when ischemic arrest was normothermic, diltiazem afforded no improvement in protection
under conditions of hypothermic (20 °C, 180 min) ischemic arrest.
Key words
Calcium antagonists - Diltiazem - Cardioplegia - Myocardial protection - Hypothermie
