Concomitant T-Wave Alternans and Pulsus Alternans in a Child With Long-QT Syndrome

A13-month-old girl was hospitalized for cardiogenic shock and convulsions after a few days of fever and malaise. She was known to have long-QT syndrome and titers for adenovirus. Her myocardial function was poor, and myocarditis was suspected. ECG monitoring showed extremely long QT and QTc with T-wave alternans. A simultaneous arterial pressure curve showed pulsus alternans (Figure 1). The occurrence of concomitant electrical alternans and mechanical alternans is extremely rare; the former is related to action potential duration changes and is a marker for electrical instability, and the latter is explained by hemodynamic alterations. Gradually, a pseudo 2:1 AV block developed (extreme prolongation of ventricular refractoriness), with bradycardia and hypotension (Figure 2). After 10 days of ventilation and massive inotropic support, she was extubated and recovered slowly. Before leaving the hospital, the patient had a pacemaker-defibrillator with epipericardial patch surgically implanted (Figure 3), and β-blockade reinstalled.