Effect of intermittent infusions of glucose-containing crystalloid cardioplegic solution on myocardial tissue lactic acid and recovery of contractility

The objective of this study was to determine the effects of single or intermittent infusions of cardioplegic solution with glucose (5 gm/L) or without glucose on myocardial tissue lactic acid and recovery of myocardial contractility following 80 minutes of total ischemia at 28 degrees C in the isolated, blood-perfused, beating rabbit heart. Ischemia without cardioplegia increased tissue lactic acid (6.79 mg/gm tissue) above the control value (0.9 mg/gm tissue), p less than 0.0025). Lactic acid following single infusions with (4.19 mg/gm tissue) or without glucose (3.67 mg/gm tissue) was significantly greater (p less than 0.0025) than tissue lactic acid following intermittent infusions with (1.06 mg/gm tissue) or without glucose (1.05 mg/gm tissue). Cardioplegic arrest in all cases significantly decreased tissue lactate accumulation when compared to arrest without cardioplegia (p less than 0.01). The decrease in myocardial contractility demonstrated when no cardioplegic protection was employed (86% recovery) was completely eliminated (100% recovery) with a single-bolus infusion of cardioplegic solution containing glucose (p less 0.025). Intermittent infusions of cardioplegic solution containing glucose (92% recovery) and single infusions without glucose (93% recovery) also improved recovery of contractility following ischemia, but the results were not statistically significant.