Heart rate variability is impaired in adults after closure of ventricular septal defect in childhood: A novel finding associated with right bundle branch block

Abstract

BackgroundVentricular septal defects (VSDs) generally have benign long-term prognoses, but recent studies have indicated increased pulmonary vascular resistance. A potential tool for monitoring pulmonary artery pressure is heart rate variability, and therefore, the aim of this study was to assess heart rate variability in adults with a surgically repaired or unrepaired VSD. MethodsIn a long-term, follow-up study, three groups were included; VSD-patients operated in early childhood, patients with an open VSD, and controls. For each patient, 24-hour Holter monitoring was performed and heart rate variability was assessed. ResultsIn total, 30 participants with a surgically closed VSD, 30 participants with an unrepaired VSD, and 36 controls were included. In the closed VSD group, there was a higher proportion of participants, who had low sNN50 (p = 0.005) and low sNN6% (p = 0.017) than in the other two groups. Similar differences were found when sNN50 was divided into increases and decreases (p = 0.007 and p = 0.005, respectively) as well as sNN6% (p = 0.014 and p = 0.014, respectively). Lastly, there was a higher proportion of patients in the closed VSD group with low rMSSD than in the other two groups (p = 0.005). For the closed VSD group, the proportion of participants with low total sNN50 (p = 0.046) and low total sNN6% (p = 0.046) were higher among participants with a complete right bundle branch block (RBBB) than among participants with no or an incomplete RBBB. ConclusionsAdults who had surgical VSD closure in early childhood had impaired heart rate variability and, particularly, participants with complete RBBB had lower heart rate variability.