Heart rate variability in patients undergoing univentricular heart repair.

Objective: Altered cardiac autonomic control may play a role in the long-term outcome of patients undergoing univentricular heart repair. This study was undertaken to compare bidirectional superior cavopulmonary anastomosis with preserved antegrade pulmonary blood flow and total cavopulmonary connection, with regard to their effects on cardiac autonomic activity, as measured by heart rate variability indices, prior to and early after surgery.
Methods: This prospective study included 46 patients (27 with bidirectional superior cavopulmonary anastomosis and 19 with total cavopulmonary connection. Heart rate variability was measured preoperatively and at 2 and 9 months postoperatively. The heart rate variability was measured by a 900-s electrocardiogram recording. Comparisons were drawn between and within groups, using standard statistical methods.
Results: All heart rate variability parameters were comparable in the 2 groups preoperatively. At the first follow-up, all heart rate variability parameters had decreased in both groups, but the decreases were not statistically significant. Between-group comparisons showed significantly higher parasympathetic and lower sympathetic tone in the bidirectional superior cavopulmonary anastomosis group. At the second follow-up, the bidirectional superior cavopulmonary anastomosis group had a significant increase in overall cardiac autonomic tone, and the total cavopulmonary connection group had a significant increase in parasympathetic tone, compared to the first follow-up. Between-group comparisons showed higher cardiac autonomic tone in the bidirectional superior cavopulmonary anastomosis group.
Conclusion: Total cavopulmonary connection leads to a significant reduction in overall cardiac autonomic tone, compared to bidirectional superior cavopulmonary anastomosis with antegrade pulmonary blood flow.