Levophase of left coronary angiogram showing the coronary sinus and its tributaries. Levophase of the angiogram is obtained when you continue the cine recording till the contrast passes from the arterial tree through the capillaries to the venous system. Levophase angiogram gives an outline of the coronary sinus and its major tributaries. But it will not be enough for an excellent visualisation of the venous anatomy for left ventricular lead placement for cardiac resynchronization therapy (CRT). While planning to locate a good vein for CRT, coronary sinus angiography is directly performed by retrograde cannulation of the coronary sinus ostium from the right atrium. Care is needed to avoid dissection of the coronary sinus or its tributaries which are thin walled structures compared to the coronary arteries. Since the flow in the venous system is against the direction of contrast injection, proximal balloon occlusion is needed for good visualisation of the tributaries of the coronary sinus. The tributaries seen here are the middle cardiac vein (Middle cardiac V) and the lateral marginal vein (Lateral marginal V). The catheter tip of left Judkins catheter introduced via the transfemoral route is engaging the ostium of the left main coronary artery (LMCA).