Comparison of three methods of myocardial protection.

Ischemic arrest (45 minutes), injection cardioplegia (2-3 ml/kg body weight within 1 minute) using Cardioplegin (magnesium-aspartate-procaine-sorbitol) according to Kirsch (90 minutes), and infusion cardioplegia (30 ml/kg body weight within 5 to 7 minutes) employing solution LK 352 (sodium-potassium-magnesium-aspartate-sorbitol) according to Bretschneider (90 minutes) were investigated in dogs in order to evaluate their efficacy of protection during myocardial ischemia and their effects on post-ischemic cardiac function. Parameters studied were myocardial tissue levels of adenine nucleotides, creatine phosphate, total creatine and glycogen as well as heart rate, systemic pressure, cardiac output, LVEDP, left ventricular pressure-volume-work, dp/dtmax, t-dp/dtmax, (dp/dtmax)/IP, and Vpm. According to biochemical data corrected for differences in myocardial temperature during arrest, myocardial protection during aortic cross-clamping at a core temperature of 30 degrees C was increased 1.8-fold by Cardioplegin and 3.4-fold by LK 352 administration respectively when compared to ischemic arrest. Functional recovery was poor after ischemic arrest and better after Cardiplegin arrest. Infusion cardioplegia with LK 352 did not result in a post-arrest depression of functional parameters.