Malignant wide complex tachycardia after adenosine administration to a postoperative pediatric patient with congenital heart disease.

Adenosine has become the treatment of choice for paroxysmal supraventricular tachycardia because of its safety and efficacy. There have been no reports of malignant arrhythmias occurring after adenosine administration. This case report presents the occurrence of a malignant wide complex tachycardia after intravenous adenosine administration in a 10-year-old boy 2 days after a Fontan procedure. Thus the administration of adenosine in a critically ill postoperative patient can have morbidity or potential mortality and must be monitored closely.