Fluorocarbon cardioplegia and myocardial protection

This study compares myocardial protection using nonoxygenated clear cardioplegia with oxygen-carrying solutions of blood (PO2, 100 mm Hg) and fluorocarbon (FC-47 perfluorotributylamine, PO2, 500 mm Hg), all containing 25 mEq/L of potassium chloride. Three groups of dogs, each consisting of 5 animals, were placed on cardiopulmonary bypass, and the aorta of each dog was cross-clamped for 45 minutes. Hemodynamic and biochemical variables were measured at baseline and during recovery. Levels of the myocardial isoenzyme of creatine phosphokinase (CPK-MB) in the coronary sinus were significantly lower in the fluorocarbon cardioplegia group at 15 minutes of aortic cross-clamping (p less than 0.01), while both the fluorocarbon and blood cardioplegia groups demonstrated lower CPK-MB levels at 45 minutes (p less than 0.001 and p less than 0.05, respectively), compared with the clear cardioplegia group. The blood and fluorocarbon groups had improved mean aortic blood pressure (p less than 0.02 and p less than 0.05, respectively) and left ventricular pressure. At 45 minutes of reperfusion and recovery, all hemodynamic and enzymatic variables were similar in each group. We conclude that oxygenated solutions better protect the myocardial cell, but that further work is needed to determine the most effective oxygen level for maximum protection with cardioplegia.