D E Miga1, C L Case, P C Gillette. 1. South Carolina Children's Heart Center, Medical University of South Carolina, Charleston 29425, USA.
Abstract
BACKGROUND: Premature ventricular contractions (PVCs) may occur in 0.3 to 2.2% of routine resting electrocardiograms (ECGs) in children with structurally normal hearts. HYPOTHESIS: This study tests the hypothesis that repolarization abnormalities are present more frequently on the surface ECG in pediatric patients with benign ventricular ectopy. METHODS: A retrospective study was performed examining 32 children with benign ventricular ectopy and structurally normal hearts. The surface ECG was carefully reviewed, concentrating on repolarization abnormalities as evidenced by a prolonged QTc, a prolonged JTc, and/or an abnormal T-wave vector. QTc was calculated using Bazett's formula and considered prolonged if > 440 ms, and the JTc was calculated using a formula analogous to Bazett's formula and considered prolonged if > 340 ms. The T-wave vector was considered normal if between 0 to +90 degrees, concordant with the frontal QRS axis and within 60 degrees of the QRS axis. There were 13 females (41%) and 19 males (59%) with an average age of 9.1 years (range 1-16.1 years). These patients were then compared with age- and gender-matched controls. Fourteen of 32 study patients (44%) and 2 of 32 controls (6%) had evidence of repolarization abnormalities. RESULTS: Using chi 2 analysis, there was a significant difference between groups (p = 0.0005). No patient had an abnormal T-wave vector and there were no other significant ECG abnormalities. There was no significant relationship between repolarization abnormalities and patient gender or age. CONCLUSION: A significant percentage (44%; P = 0.0005) of children with benign ventricular ectopy have associated repolarization abnormalities as evidenced by a prolonged QTc and/or JTc. This finding suggests that children with "benign PVCs" may have repolarization changes indicative of underlying substrate abnormalities.
BACKGROUND:Premature ventricular contractions (PVCs) may occur in 0.3 to 2.2% of routine resting electrocardiograms (ECGs) in children with structurally normal hearts. HYPOTHESIS: This study tests the hypothesis that repolarization abnormalities are present more frequently on the surface ECG in pediatric patients with benign ventricular ectopy. METHODS: A retrospective study was performed examining 32 children with benign ventricular ectopy and structurally normal hearts. The surface ECG was carefully reviewed, concentrating on repolarization abnormalities as evidenced by a prolonged QTc, a prolonged JTc, and/or an abnormal T-wave vector. QTc was calculated using Bazett's formula and considered prolonged if > 440 ms, and the JTc was calculated using a formula analogous to Bazett's formula and considered prolonged if > 340 ms. The T-wave vector was considered normal if between 0 to +90 degrees, concordant with the frontal QRS axis and within 60 degrees of the QRS axis. There were 13 females (41%) and 19 males (59%) with an average age of 9.1 years (range 1-16.1 years). These patients were then compared with age- and gender-matched controls. Fourteen of 32 study patients (44%) and 2 of 32 controls (6%) had evidence of repolarization abnormalities. RESULTS: Using chi 2 analysis, there was a significant difference between groups (p = 0.0005). No patient had an abnormal T-wave vector and there were no other significant ECG abnormalities. There was no significant relationship between repolarization abnormalities and patient gender or age. CONCLUSION: A significant percentage (44%; P = 0.0005) of children with benign ventricular ectopy have associated repolarization abnormalities as evidenced by a prolonged QTc and/or JTc. This finding suggests that children with "benign PVCs" may have repolarization changes indicative of underlying substrate abnormalities.