Resolution of Abnormal Body Surface Maps in Children with Atrial Septal Defect after Intracardiac Repair

Varied onset of heart ventricular depolarization in different age groups of healthy volunteers

Group mean isopotential maps of initial parts of ventricular depolarization (QRS complex) in 4 age groups (10, 14, 19 and 22 years) of young healthy subjects, females and males, were analyzed using different increments between isopotential lines. It was found that the increment 0.1 mV masks some features of the maps, which are seen only by smaller increment (0.02 mV): the time of appearance of maximum and minimum on the anterior chest, smaller voltage values of the extrema as usually published, minimum dominating over maximum in the youngest groups. Therefore, the often applied criterion for the QRS onset – the increasing maximum on the anterior chest – should be reconsidered at least when it concerns the isopotential maps of children.

Prolonged repolarization in atrial septal defect: An example of mechanoelectrical feedback due to right ventricular volume overload

BACKGROUND

Prolonged corrected QT (QTc) intervals are frequently observed in children before atrial septal defect (ASD) closure in our department.

OBJECTIVE

The aim of the study was to assess the effect of long-term right ventricular volume overload on repolarization.

METHODS

QRS, QT, and JT intervals were measured manually in leads II and V5 of a standard 12-lead electrocardiogram in 45 children with an isolated ASD a day before and at least 6 months after ASD closure. QT intervals were corrected for heart rate using the Bazett, Fridericia, Framingham, and Hodges formulas. Each QTc interval calculated using the Bazett formula was compared to sex- and age-matched normal values.

RESULTS

Individual QTc intervals shortened significantly (P < .001) using all correction formulas, whereas the QRS duration did not change. The prevalence of prolonged QTc interval decreased from 22.2% to 2.2% after shunt closure (P = .007).

CONCLUSION

The QTc interval shortens significantly after the closure of a hemodynamically relevant ASD in childhood. This phenomenon is independent of the used QT correction formula and may reflect a mechanoelectrical feedback associated with right ventricular volume overload.