Combined effect of glucose and verapamil in experimental cardioplegia

In this study, we determined whether pre-ischemic enhancement of the ATP level and the addition of verapamil (a calcium blocker) to the cardioplegic solution could improve myocardial protection during cardiac arrest. Using the Langendorff preparation of the isolated rat heart plus different cardioplegic solutions, five groups of normal rat hearts and five groups of hypertrophied rat hearts were subjected to 90-minute ischemic periods at 28 degrees +/- 1 and reperfusion of 30 minutes at 37 degrees C. Group A received no cardioplegic solution; Group B received KCl, 30 mEq/L; Group C received type B perfusion with verapamil; and Group D received 15 minutes of pre-ischemic oxygenated enhancement perfusion containing KCl, 30 mEq/L, and glucose as substrate at 37 degrees C. Group E received the same perfusion as Group D, with the addition of verapamil to the enhancement perfusion. Light and E/M microscopy was performed on representative samples of left ventricular muscle. We found that pre-ischemic enhancement with KCl, glucose, and verapamil was only protective in the normal hearts after 90 minutes of ischemia. In hypertrophied hearts, the addition of verapamil to the enhancement solution was harmful. The use of pre-ischemic enhancement solution without verapamil provided the best myocardial protection after 90 minutes of ischemia in the hypertrophied hearts.