Clinical assessment of prolonged myocardial preservation for patients with a severely dilated heart.

Background: The purpose of this study was to compare the myocardial protective effect of histidine-tryptophan-potassium and glucose-insulin-potassium cardioplegic solutions in patients with a dilated heart (left ventricular diastolic diameter > 55 mm, left ventricular systolic diameter > 45 mm) associated with prolonged cross-clamp time (longer than 200 minutes).
Methods: We selected 20 patients with dilated hearts due to severe aortic regurgitation. Glucose-insulin-potassium cardioplegia was used in 11 patients and histidine-tryptophan-potassium cardioplegia was used in 9 patients.
Results: After operation, the cardiac index was significantly increased in the histidine-tryptophan-potassium group (p < 0.05). Postoperative percent fractional shortening was 13.4% +/- 3.1% in the glucose-insulin-potassium group and 23.6% +/- 2.6% in the histidine-tryptophan-potassium group (p < 0.05). Creatine kinase levels were significantly lower in the histidine-tryptophan-potassium group than that in the glucose-insulin-potassium group (p < 0.05). The incidence of ventricular arrhythmia (higher than Lown's grade 2) was lower in the histidine-tryptophan-potassium group.
Conclusions: These data support the superiority of the histidine-tryptophan-potassium method over the glucose-insulin-potassium method for protection of the dilated heart during prolonged ischemia in open heart operations.