Comparison of two cardioplegia solutions using thermodilution cardiac output in neonates and infants

Information from clinical studies is limited regarding the optimal method for myocardial protection in immature hearts, and specifically the benefits of different cardioplegia (CP) formulations. We compared two CP techniques by evaluation of the cardiac index using thermodilution catheters.

The study cohort includes 102 neonates and infants (aged 2 to 269 days) undergoing biventricular repair surgery. A total of 52 patients were managed with commercially available crystalloid CP ("standard CP") and 50 had a custom mix of crystalloid CP with dilute blood ("custom CP"). Repeated-measures analysis of variance was applied to compare the cardiac index every 3 hours during the 24-hour postoperative period between the two groups and stratified by diagnosis. Adjustment for possible confounders was used to more objectively compare the groups.

Standard crystalloid CP provided superior myocardial protection in patients who had transposition of great arteries (p < 0.001), and this advantage held after adjusting for age and cross-clamp time. Shorter ventilatory times and intensive care unit stays were also noted for the standard CP group (p = 0.01). Cardiac index after cardiopulmonary bypass was lower in patients who had transposition of great arteries and intact ventricular septum compared with the group who had transposition of great arteries and ventricular septal defect; and in both subgroups, the standard CP technique was superior to the custom CP solution. Age at operation was inversely correlated with the cardiac index.

Younger patients, particularly neonates, have a significantly higher postoperative cardiac index with standard CP than with custom CP. The advantage is not apparent beyond the neonatal period.