Whole blood cardioplegia (minicardioplegia) reduces myocardial edema after ischemic injury and cardiopulmonary bypass

Abstract

While blood:crystalloid cardioplegia is the clinical standard for patients undergoing cardiopulmonary bypass (CPB), it has been postulated that whole blood minicardioplegia may benefit the severely injured heart by reducing cardioplegic volume, thereby reducing myocardial edema. To test this hypothesis, we compared the cardioprotection of a popular 4:1 blood:crystalloid cardioplegia to whole blood minicardioplegia (WB) in a porcine model of acute myocardial ischemia. Yorkshire pigs (n = 20) were placed on atriofemoral bypass and subjected to 30 minutes of global normothermic ischemia. Animals were randomized to receive either 4:1 cold cardioplegia (n = 10) or WB cold cardioplegia (n = 10) delivered antegrade continuously for 90 minutes. Baseline (BL) echocardiographic determination of left ventricular mass (LVM) was compared within groups for cardiac edema (%) measured by histologic morphometrics. All (100%) animals receiving WB were successfully weaned off CPB, whereas only 40% of animals receiving 4:1 were successfully weaned off CPB. Cardiac edema percentage (p < .004) and LVM (p < .05) were significantly decreased in the WB group compared with 4:1. WB cardioplegia increases the number of hearts successfully weaned from CPB and decreases cardiac edema in our porcine model of acute myocardial ischemia. This finding implies whole blood cardioplegia may be more protective in a select group of patients undergoing extended CPB time by decreasing myocardial edema.

Figure 1.

Experimental protocol.

Figure 2.

Hearts weaned from CPB and survival at 2 hours.

Figure 3.

Myocardial water content (%).

Figure 4.

LVM, measured in grams. BL, baseline measurement before injury; POST, 15 minutes after weaning from bypass or failure to wean from bypass.

Figure 5.

Representative echocardiograms. Baseline echocardiograms before injury or bypass are designated “Pre,” and echocardiograms of the same heart taken after injury and plegia are designated “Post.”

Figure 6.

Representative histology. Random sections from left ventricle on routine hematoxylin and eosin stain showing differences in myocardial edema.