Pulsus alternans in a child with dilated cardiomyopathy.

A previously healthy 21-month-old presented with new-onset dilated cardiomyopathy. Evaluation noted pulsus alternans, with beat-to-beat alternations in aortic pulse wave amplitude, both clinically and on diagnostic studies. Pulsus alternans is an infrequent, complex pathophysiologic sign often associated with severe heart failure. The mechanisms are incompletely understood, but theorised aetiologies include beat-to-beat changes in left ventricular loading conditions, variations in myocardial oxygen supply/demand, and alternations in myocardial contractility. Recognition of pulsus alternans is important as it provides significant clinical information, may suggest suboptimal medical management, and may be the first warning sign of severe cardiac dysfunction.