The mortality of patients with DILV or TA-TGA remains high. The outcomes of these patients are influenced by restriction of pulmonary blood flow, arrhythmia, and pacemaker requirement. Surgical palliation to relieve systemic outflow obstruction is not associated with a poor outcome.

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Objective To compare four heart rate correction formulas for calculation of the rate corrected QT interval (QTc) among infants and young children. Study design R and QT intervals were measured from digital electrocardiograms. QTc were calculated with the Bazett, Fridericia, Hodges, and Framingham formulas. QTc versus RR graphs were plotted, and slopes of the regression lines compared. Slopes of QTc-RR regression lines close to zero indicate consistent QT corrections over the range of heart rates. Results We reviewed electrocardiograms from 702 children, with 233 (33%) <1 year of age and 567 (81%) <2 years. The average heart rate was 122 ±20 bpm (median 121 bpm). The slopes of the QTc-RR regression lines for the four correction formulas were: −0.019 (Bazett); 0.1028 (Fridericia); −0.1241 (Hodges); and 0.2748 (Framingham). With the Bazett formula, a QTc >460 ms was 2 standard deviations above the mean, compared with “prolonged” QTc values of 414, 443, and 353 ms for the Fridericia, Hodges, and Framingham formulas, respectively. Conclusions The Bazett formula calculated the most consistent QTc; 460 msec is the best threshold for prolonged QTc. The study supports continued use of the Bazett formula for infants and children and differs from the use of the Fridericia correction during clinical trials of new medications.

Postoperative arrhythmia is a major cause of morbidity and mortality after cardiac surgery for congenital heart disease. Rhythm disturbances that may be well tolerated in a normal heart often cause hemodynamic instability when they occur in the immediate postoperative period. In the face of pre-existing myocardial dysfunction resulting from preoperative pressure or volume overload, patients with congenital heart conditions are especially vulnerable to rhythm disturbances after cardiac surgery. Cardiopulmonary bypass, intraoperative injury to the conduction system and myocardium, postoperative metabolic abnormalities, electrolyte disturbances, and increased adrenergic tone in response to the stress of the surgery or inotropic agents are also known factors associated with increased risk of arrhythmia in the immediate postoperative period. Surgically related arrhythmia can also present in the late postoperative period, particularly in association with surgical incision sites and surgically induced hemodynamic abnormalities. Early and late postoperative arrhythmias are important risk factors for morbidity and mortality after surgical treatment of many forms of congenital heart disease. This review describes the incidence of the most common forms of arrhythmia and recent advances in their diagnosis and treatment.

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