Mimetic total coronary sinus occlusion due to superselection with the balloon catheter

A 77-year-old man with dilated cardiomyopathy, atrial fibrillation, QRS duration of 140 ms, and NYHA functional class III was referred for cardiac resynchronization therapy device implantation. Coronary sinus (CS) contrast venography by balloon catheter showed no evidence of tributary veins, mimicking total occlusion of the CS. It was found to be due to superselection of a side branch with the balloon catheter.