Final answer:
Maximizing aortic conduit length during heart valve recovery involves transecting the aortic arch distal to the left subclavian artery, which is the last of three major branches, thus preserving the entire arch.
Step-by-step explanation:
Left subclavian artery.
Transecting the aortic arch distal to the left subclavian artery maximizes aortic conduit length when recovering heart valves. This is because the aortic arch has three major branches: the brachiocephalic artery, the left common carotid artery, and the left subclavian artery.
The order of these branches from proximal to distal in relation to the heart is brachiocephalic, left common carotid, and then left subclavian. To maximize the length of the aortic conduit, the transection should occur after the last branch, which is the left subclavian artery. This allows for the inclusion of the entire aortic arch in the graft material that can be used for transplant, ensuring the maximum amount of tissue to work with.