Progressive Subvalvular Right Ventricular Outflow Tract Obstruction With a Single Coronary Artery in an Adult.

CASE SUMMARY: A 57-year-old man with a history of ventricular septal defect and prior infective endocarditis presented with progressive exertional dyspnea. Multimodality imaging demonstrated severe subvalvular right ventricular outflow tract (RVOT) obstruction with a marked intraventricular pressure gradient (190 mm Hg proximal right ventricle vs 15 mm Hg pulmonary artery). Coronary angiography revealed a single coronary artery arising from the left coronary sinus (Lipton type L1), with a branch crossing anterior to the RVOT.

DISCUSSION: Progression of obstruction suggested evolving double-chambered right ventricular physiology and/or superimposed infection-related remodeling. The anomalous coronary course had important procedural implications.

TAKE-HOME MESSAGES: Progressive subvalvular RVOT obstruction in adults warrants consideration of both congenital mechanisms, such as double-chambered right ventricle, and acquired causes including prior infective endocarditis. Comprehensive multimodality imaging is essential to define coronary anatomy and hemodynamic severity before considering intervention.