Where is it that cannulae is placed in order for cardiopulmonary bypass to be accomplished?

Aorta and R atrium: To keep surgical field - heart, in this instance, - " dry" , the blood has to be diverted. So one or two canulas are usually inserted via right atrium into major vein(s) to bring the blood to the oxygenator, that works as artificial lungs. From there blood is pumped to the canula inserted usually in the ascending aorta. Surgical clamp prevents blood from flowing back into the heart.