Anomalous muscle bundles causing double-chambered right ventricle in adults

Double-chambered right ventricle (DCRV) causing right ventricular outflow tract (RVOT) obstruction, is an uncommon cardiac disease especially when first diagnosed in adults. Diagnosis can be challenging when it is asymptomatic. We report a 40-year-old man who was referred to cardiology for work-up of a heart murmur that was found on a routine physical examination prior to obtaining a pilot's license. A transesophageal echocardiogram (TEE) revealed a DCRV and a small perimembranous ventricular septal defect (VSD) with left-to-right shunt and severe RVOT obstruction. Right heart catheterization showed an estimated gradient of 135 mm Hg across the two chambers due to subpulmonary stenosis. The pressure in the proximal right ventricular chamber was 160/25 mm Hg and 25/17 mm Hg in the distal chamber. Surgical correction was successfully performed. A postoperative TEE showed no residual gradients across the RVOT. DCRV has been reported as a rare disease in adults. It is difficult to diagnose DCRV using the transthoracic echocardiogram in adults. However, subcostal windows can offer better visualization of subpulmonary outflow tract compared to the parasternal and apical windows. TEE remains the main non-invasive modality for diagnosing DCRV in adults. Cardiac magnetic resonance imaging and invasive testing can provide further information to confirm the diagnosis and guide therapeutic decisions.