A 15-Year-Old Male With Wide Complex Tachyarrhythmia.

A 15-year-old male presented with exertional syncope and was found to be in an unstable regular wide complex tachyarrhythmia (WCT). After a trial of antiarrhythmic medication, his clinical condition declined, necessitating synchronized cardioversion. Although he noted symptomatic improvement after cardioversion, he was found to be in third-degree heart block. The patient was transported by rotor wing aircraft to a pediatric cardiac intensive care unit where he was ultimately diagnosed with Lyme disease. He was treated with a course of intravenous antibiotics, his heart block resolved, and he was discharged home with a good neurologic outcome.