RETROGRADE CARDIOPLEGIA PRESERVES MYOCARDIAL-FUNCTION AFTER INDUCED CORONARY AIR-EMBOLISM

Coronary air embolism is a potential complication of cardiopulmonary b ypass. We compared left ventricular function before and after the admi nistration of antegrade or retrograde cardioplegic solution in a porci ne model of coronary air embolism. Nineteen pigs were placed on cardio pulmonary bypass support and cooled to 32 degrees C. The heart was ini tially arrested with antegrade cold blood cardioplegic solution. The a ortic crossclamp was released at 30 minutes and 0.02 cc/kg body weight of air was injected into the left anterior descending artery distal t o the first diagonal branch. After 5 minutes the aorta was reclamped a nd the animals treated with 15 ml/kg body weight of 1:4 blood cardiopl egic solution delivered by the antegrade (n = 6) or retrograde (n = 7) method. Control animals (n = 6) were not treated. Changes in regional preload recruitable stroke work were used to assess left ventricular performance before and after cardiopulmonary bypass. Two control anima ls could not be weaned from cardiopulmonary bypass. Left ventricular f unction was best preserved after treatment of induced coronary air emb olism with retrograde cardioplegia (90% of baseline). Coronary air emb olism treatment with antegrade cardioplegia resulted in diminished lef t ventricular performance (68% of baseline). In control animals left v entricular contractility was significantly impaired (39% of baseline). We conclude that administration of retrograde cardioplegic solution m ay be an effective method of treating coronary air embolism. The favor able outcome seen with cardioplegia may be in part because of its abil ity to protect the ischemic myocardium while the solution mechanically dislodges air from the vascular bed.