Cardiac arrest after induction of anesthesia in a 2-month-old infant with undiagnosed Williams syndrome.

A 2-month-old male infant presented for elective repair of inguinal hernias. His preoperative medical history and physical examination were unremarkable. During induction of anesthesia, the infant sustained an adverse cardiac event. The event was characterized by tachycardia, hypotension, and massive ST-segment elevation. Despite vigorous resuscitation, spontaneous hemodynamic stability could not be achieved and extracorporeal membrane oxygenation was required. A transthoracic echocardiogram revealed severe hypoplasia of the ascending aorta. As effective cardiac function did not recover and there was evidence of diffuse ischemic brain injury, life support was withdrawn. Genetic testing performed postoperatively was definitive for Williams syndrome.