Palpitations in a Fontan patient: what now?

A 32-year-old male presented to our emergency department with palpitations. His blood pressure was 95/65 mmHg, heart rate 150 beats per minute, oxygen saturation 87% on room air, and body temperature 36°C. The electrocardiogram (EKG) showed paroxysmal supraventricular tachycardia (PSVT). He reported a history of heart surgery – Fontan procedure – during childhood for a complex congenital heart disease (CHD) characterized by a single atrium, a single ventricle, and a single atrioventricular valve. A focused cardiac ultrasound confirmed a single atrium, a single ventricle, no pericardial effusion, and an estimated ejection fraction of 50% (Videos 1 and 2). His current medication regimen included sotalol 80 mg, losartan 12.5 mg, dapagliflozin 10 mg, furosemide 25 mg, and warfarin.