Isorhythmic atrioventricular dissociation in an adult with levo-transposition of the great arteries.

A 36-year-old woman with levo-transposition of the great arteries presented for a programmed visit. She was asymptomatic and the clinical examination showed no signs of decompensated heart failure. Standard 12-lead ECG showed isorhythmic atrioventricular dissociation. A 24-hour ambulatory recording demonstrated sinus rhythm with intermittent periods of isorhythmic dissociation. This case highlights the association between two rare conditions.