The authors discuss the use of cardioplegic solution as well as its composition. The immediate stop of the heart beats can be obtained with cardioplegic solutions whether they are crystalloid or blood-cardioplegia, oxygen-enriched or not, either in association or alone; hypotermia also can be used or not. The agents to stop the heart can be potassium, magnesium, procaine or calcium blockers. Caution is needed in regard to hypotermia since low temperature itself is not enough to protect myocardium for long periods. Substrates like glucose and oxygen must be supplied during the aortic clamping period, to provide some aerobic metabolism. The addition of other substrates like aspartate, glutamate and lactate as well as ATP and/or phosphate creatine, Krebs cicle intermediates can improve the myocardium salvage. The cell membrane, with all its structural, selective and secretory functions, is the most sensible region to ischemic injure. The retrograde cardioplegy allows a better difusion of the solutions. We believe that it should be part of any cardiac surgery, although we must be aware of its limitations. Perfusion is the most important step of the myocardium salvage when the delivery of free radicals occurs, so the use of scavengers can improve the results of reperfusion. The normotermic blood oxygenated cardioplegy in enriched with substrates was used initially in extremely severe cases of muscle dysfunction, in severe myocardium ischemia or for lack of adequate protection during ischemia and/or reperfusion, and now has been extended to all cases. It is advisable to have the heart chambers always drained, avoiding any increase of tension on the walls which would lead to a higher oxygen consumption. The authors describe the technique and the solution for cardioplegy used in the Cardiac Service of IMC and the results achieved with its use. They conclude that the use of blood modified normotermic cardioplegy aminoacid-enriched and asystolic reperfusion are satisfactory in myocardium salvage and for reverting the ischemic injures.
myocardial protection; calcium blockers; free radicals