Inability to cannulate the coronary sinus in patients with supraventricular arrhythmias: congenital and acquired coronary sinus atresia.

We report 4 cases of congenital and acquired coronary sinus ostial atresia incidentally found during electrophysiologic assessment for supraventricular arrhythmias. Congenital variants consisted of coronary sinus drainage predominantly via persistent left superior vena cavae and partial coronary sinus unroofing into the left atrium. The acquired variant was inadvertently produced during surgery for cor triatriatum. A variety of electrophysiologic substrates including right and left-sided accessory pathways and both typical and atypical AV nodal reciprocating tachycardia were identified. Approaches to imaging and accessing the coronary sinus when the os cannot be cannulated are discussed, including a search for right atrial accessory venous collaterals, venography to rule-out a persistent left superior vena cava, and coronary angiography.