New pluronic-free perfluorocarbon cardioplegia improves myocardial oxygenation

Cardioplegic protection with oxygenated lecithin-emulsified methyl adamantane, a perfluorocarbon with high oxygen solubility, was compared with oxygenated crystalloid cardioplegic solution in an ischemic rabbit heart model. The cardioplegic solutions had identical salt compositions with a potassium concentration of 15 meq/l. Eighteen isolated rabbit hearts underwent 180 minutes of global ischemia at 30°C, followed by a 45-minute period of reperfusion at 37°C. During the ischemic period, cardioplegic solution was infused every 30 minutes, and myocardial oxygen extraction was calculated. Left ventricular function was assessed before and after ischemia by measuring left ventricular isovolumic developed pressure and the first derivative of pressure (dP/dt). Cardioplegia oxygen extraction for the methyl adamantane hearts was 230 ± 11 ml of O₂/100 g heart wt and 150 ± 25 ml O₂/100 g heart wt for the crystalloid hearts (p < 0.05). Recovery of dP/dt at 30 minutes of reperfusion, expressed as a percentage of preischemic control, was 80% ± 3% for the methyl adamantane hearts and 61% ± 3% for the crytalloid hearts (p < 0.05). The developed pressure for the methyl adamantane hearts was 73% ± 3% and for the crystalloid hearts, 62% ± 2% (p < 0.05). In this global ischemia model, perfluorocarbon emulsified with egg-yolk phospholipid improved oxygen delivery and postischemic myocardial performance compared with an oxygenated crystalloid cardioplegic solution.