Extreme pulsus alternans with P wave alternans in a child

Pulsus alternans was observed in a child with left ventricular dysfunction secondary to systemic hypertension. The Echo-Doppler of supravalvular aorta and a simultaneous electrocardiographic trace (ECG) clearly demonstrated the mechanism of an apparent abrupt halving of pulse frequency compared with the ECG, similar to an electromechanical dissociation 2:1. Besides the extreme pulsus alternans, a P wave and a PP cycle length change were also observed. Both mechanical and electrical alternans disappeared with afterload reduction by nitroprusside treatment.