If the venous return cannula is inserted too far into the superior vena cava during CPB, which venous structure is most likely obstructed?

If the venous return cannula is inserted too far into the superior vena cava during CPB, which venous structure is most likely obstructed?

• A. Superior vena cava
• B. Right innominate vein
• C. Left brachiocephalic vein
• D. Internal jugular vein

Answer: (B)

When placing a venous return cannula for CPB, the goal is to allow smooth drainage from the major upper-body veins into the cannula. If the tip is advanced too far into the SVC, it can occlude the opening where the right innominate vein drains into the SVC. Blocking that junction prevents drainage from the right upper extremity and the right-sided head and neck, making the right innominate vein the structure most likely to be obstructed. The other veins either drain into the SVC at a different location or would be less impacted by a cannula that is simply too deep within the SVC.

When placing a venous return cannula for CPB, the goal is to allow smooth drainage from the major upper-body veins into the cannula. If the tip is advanced too far into the SVC, it can occlude the opening where the right innominate vein drains into the SVC. Blocking that junction prevents drainage from the right upper extremity and the right-sided head and neck, making the right innominate vein the structure most likely to be obstructed. The other veins either drain into the SVC at a different location or would be less impacted by a cannula that is simply too deep within the SVC.