Retrograde carbon dioxide coronary sinus venography.

It is potentially harmful to perform coronary sinus (CS) angiography in patients with severe contrast allergy or severe renal dysfunction due to the risk of contrast-induced nephropathy (CIN). However, angiography is a well-established method to guide LV-lead position during cardiac resynchronization therapy-implantation. These two case reports describe the first successful applications of carbon dioxide CS angiography in patients requiring cardiac resynchronization therapy.