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Sudden death is a possible occurrence for newborns younger than 1 year with severe aortic coarctation (CoA) before surgical correction. Basic research and animal experiments have shown electrophysiologic changes during mechanical ventricular pressure overload. The current study aimed to evaluate the effect of severe CoA on the heterogeneity of ventricular repolarization by examining corrected QT and JT interval dispersion (respectively, QTc-D and JTc-D) and electrocardiographic parameters of spatial heterogeneity of ventricular repolarization in newborns with no associated congenital cardiac malformations. The study enrolled 30 isolated severe CoA neonates (age, 45 ± 15 days; 17 males) with normal size and wall thickness of the left ventricle before surgical correction and 30 age- and sex-matched healthy newborns used as control subjects. Heart rate, QRS duration, maximum and minimum QT and JT intervals, and QTc-D and JTc-D measurements were performed. The healthy control group did not significantly differ from the CoA group in terms of heart rate, weight, height, and echocardiographic parameters. Compared with the healthy control group, the CoA group presented significantly increased values of QTc-D (109.7 ± 43.4 vs. 23 ± 15 ms; P = 0.03) and JTc-D (99.1 ± 43.3 vs. 65.8 ± 24.1 ms; P = 0.04). A statistically significant correlation was found between the Doppler peak pressure gradient across the coarctation site and the values of QTc-D ( r = 0.48; P = 0.03) and JTc-D ( r = 0.42; P = 0.04). Our study showed significantly increased QTc-D and JTc-D in isolated CoA newborns with normal left ventricular geometry. [ABSTRACT FROM AUTHOR]

In adults, increased QT dispersion has been shown to predict arrhythmic risk as well as risk of sudden death in several clinical settings. It is controversial whether QT and JT dispersion are increased in children with ventricular ectopy and a structurally normal heart. We studied two groups of children: 25 patients with ventricular ectopy and 25 healthy children as controls. Standard electrocardiograms were reviewed and dispersions of both corrected QT (QTc) and JT (JTc) intervals were compared. We conclude that QTc and JTc dispersions are significantly increased in children with ventricular ectopy compared to control subjects. [ABSTRACT FROM AUTHOR]

Sudden cardiac death in myotonic dystrophy type I (DM1) patients can be attributed to atrioventricular blocks as far as to the development of life-threatening arrhythmias which occur even in hearts with normal left ventricular systolic and diastolic function. Heterogeneity of ventricular repolarization is considered to provide an electrophysiological substrate for malignant arrhythmias. QTc dispersion (QTc-D), JTc dispersion (JTc-D) and transmural dispersion of repolarization (TDR) could reflect the physiological variability of regional and transmural ventricular repolarization. Aim of the present study was to investigate the heterogeneity of ventricular repolarization in patients with DM1 and preserved diastolic and systolic cardiac function. The study enrolled 50 DM1 patients (mean age 44 ± 5 years; M:F: 29:21) with preserved systolic and diastolic function of left ventricle among 247 DM1 patients followed at Cardiomyology and Medical Genetics of Second University of Naples, and 50 sexand age-matched healthy controls. The electrocardiographic parameters investigated were the following: Heart Rate, QRS duration, maximum and minimum QT and JT intervals, QTc- D, JTc-D and TDR. Compared to the controls, the DM1 group presented increased values of QTc-D (86.7 ± 40.1 vs 52.3 ± 11.9 ms; p = 0.03), JTc-D (78.6 ± 31.3 vs 61.3 ± 10.2 ms; p = 0.001) and TDR (101.6 ± 18.06 vs 90.1 ± 14.3 ms; p = 0.004) suggesting a significant increase in regional and transmural heterogeneity of the ventricular repolarization in these patients, despite a preserved systolic and diastolic cardiac function.