PJ3-060 Association of Instability in Myocardial Repolarization with Shunt Size in Pediatric Patients with Ventricular Septal Defect

Objective: This study was designed to investigate the transmural dispersion of repolarization (TDR) for the estimation of the shunt size in children with ventricular septal defect (VSD), and to determine the relationship between shunt ratios and left ventricular mass indexes. Subjects and Methods: The subjects were 30 VSD children. The mean age was 4.3±2.4 years old and the mean body weight was 17.5±6.6 kg. The ECG (CM 5 lead) was measured simultaneously, and the QT time and the time from T peak to T end (Tp-e, Tp-e/QT) were estimated by analysis software (Biopac Acknowledge). The shunt ratio (Qp/Qs) was measured by Doppler echocardiography, and the left ventricular mass index (LVMI) was calculated using the Penn convention to evaluate the correlation with Tp-e and Tp-e/QT, respectively. Results: There was a significant correlation was found between Qp/Qs and Tp-e/QT ratio (r=0.515, p=0.01). A powerful correlation was found between LVMI and Tp-e/QT ratio (r=0.539, p=0.03). No significant correlation was found between Qp/Qs and LVMI. Discussion: This study showed that the instability of myocardial repolarization increased with the shunt flow. However, no significant correlation was found between Qp/Qs and LVMI. These findings suggest that Qp/Qs has a higher correlation with Tp-e/QT than LVMI and that compensatory left ventricular hypertrophy might be detected by TDR.