Atriopulmonary Fontan Spontaneous Echo Contrast Improved after Cardioversion

Atriopulmonary Fontan Spontaneous Echo Contrast Improved after CardioversionA 21-year-old woman with tricuspid atresia who had undergone an atriopulmonary Fontan operation at 3 years of age presented with intra-atrial reentrant tachycardia and tachycardia-induced cardiomyopathy.She had done well on no medications, and systolic function was normal on echocardiograms 3 months before this presentation.Since then, she had experienced exertional palpitations, increasing abdominal girth, loose bowel movements, vague abdominal pain, fatigue, and decreased appetite.Examination revealed a blood pressure of 120/70 mmHg, a regular tachycardic pulse, clear lungs, a pulse oximetry saturation of 97%, and a distended abdomen with ascites and hepatomegaly.Laboratory tests showed elevated alanine transaminase of 115 IU/L, brain natriuretic peptide of 556 pg/mL, an international normalized ratio of 1.4, negative stool antitrypsin (no protein-losing enteropathy), and normal renal function, lactate, and cardiac enzyme levels.An electrocardiogram showed flutter waves and 2:1 atrioventricular conduction (ventricular rate, 122 beats/min) (Fig. 1).A transthoracic echocardiogram revealed a dilated left ventricle with severely depressed systolic function, an ejection fraction of 0.25, and spontaneous echo contrast in the dilated inferior vena cava.A transesophageal echocardiogram showed no left atrial appendage thrombus; however, dense contrast was present in the dilated right atrium of the Fontan circuit (Fig. 2).We presumed that tachycardia-induced cardiomyopathy was exacerbating the patient's Fontan circuit stasis, so we recommended terminating the tachycardia.Cardio