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Despite clinical importance of ventricular repolarisation, it remains difficult to analyse. Conventionally, quantification of the electrocardiographic ventricular repolarization is usually performed with reference to axis of the T wave and QT interval duration. A variety of factors can prolong the QT interval, such as drug effects, electrolyte imbalances, and myocardial ischemia. The biggest risk with prolongation of the QT interval is the development of torsades de pointes. Commonly accepted reference ranges for the electrocardiogram (ECG) have been in use, with little change, for many years. Populations throughout the world present several differences: age, ethnic compositions, and are exposed to different environmental factors. Recent studies have reported reference data for QT interval in healthy population and have evaluated the influence of age, gender, QRS duration and heart rate on this interval. In this review, we address several issues relative to the measurement, and interpretation of QT interval and its adjustment for rate, age, gender and QRS duration.

Background Despite successful repair of aortic coarctation (AoC), changes in the left ventricular (LV) regional myocardial function are reported. The aim of this study was to assess the left ventricular systolic function in patients after the successful repair of aortic coarctation using tissue Doppler imaging (TDI) according to the age of aortic coarctation repair. Methods 31 patients (mean age, 12.0 +/− 4.2 years) followed up after a successful chirurgical repair of aortic coarctation (mean follow up, 8,6 ± 7,6 years) were studied by echocardiography. The study population was divided in two groups: patients repaired at age 2 years (Group 1, n = 17) and patients repaired at age > 2 years (group 2, n = 14). The TDI parameters and the conventional echocardiographic indices of the left ventricular systolic function were analyzed and compared between the two groups. Results Standard echocardiographic studies revealed normal global left ventricular (LV) function. The LV dimensions, LV ejection fraction, LV shortening fraction, indexed LV mass did not differ between the examined groups. Among the studied LV filling parameters, peak early (E wave) transmitral flow velocity, as well as deceleration time DT, was similar between the two groups. The Tei index was also not affected by the age at repair of aortic coarctation. Regarding TDI measures, the early diastolic and the systolic velocities on the lateral side of the mitral annulus were significantly higher in group 1 than in group 2 (Sa: 12,7 ± 2,59 cm/s vs 10,6 ± 1,8 cm/s, p = 0,025; Ea : 20,7 ± 3,4 cm/s vs 17,3 ± 4,7 cm/s, p = 0,03). TDI velocities on the septal side of the mitral annulus and on the right ventricle (RV) free wall side of the tricuspid annulus were not different between early (before 2 years) and late (after 2 years) repair of the aortic coarctation. There were no differences of the TDI or conventional parameters between hypertensive and normotensive patients. Conclusion Left ventricular systolic performance in patients after the surgical repair of aortic coarctation reveals tendency to decrease at follow-up in patients repaired at age > 2 years despite a satisfactory results after surgery.

IntroductionCoarctation of the aorta (CoA) is a stenosis usually located in the isthmus of the descending aorta. Treatment consists of surgical or percutaneous removal of the obstruction and may present excellent immediate results. However, despite immediate good results, significant residual problems often persist. The aim of the study is to describe the presentation, treatment and long-term evolution of a population of 48 unselected consecutive patients with CoA in a single pediatric cardiology center.MethodsThis was a retrospective study of all patients with isolated CoA associated or not to either atrial or ventricular septal defects. RESULTS: The patients (n = 48, 56,3% male) were diagnosed at a mean age of 84 ± 109 months. The clinical presentation differed between patients aged less or more than two years, the former presenting with heart failure and the latter being asymptomatic with evidence of hypertension (p < 0.01). Treatment was surgical in all cases (32 end-to-end anastomosis). The mean age of patients was 94 ± 109 months. There was two late deaths, in a mean follow-up of 8,6 ± 7,7 years. Recoarctation occurred in 12 patients (25%). There are patients who currently have hypertension (17 at rest, 2 with effort), their mean age at diagnosis being older than the others (128 vs. 76 months; p < 0.05). Aortic aneurysms occurred in five patients (10,4%). Aneurysm was associated to bicuspid aortic valve in 3 cases.Conclusionsrepaired CoA has a significant incidence of long-term complications, and should thus no longer be seen as a simple obstruction in the descending aorta, but rather as a complex pathology that requires careful follow-up after treatment.