This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Which of the following statement is true regarding subclavian steal syndrome \nSelect and explain. \nA. Reversal of blood flow in the ipsilateral vertebral artery, B. Reversal of blood flow in the contralateral carotid artery, C. Reversal of blood flow in the contralateral vertebral artery, D. Bilateral reversal of blood flow in the vertebral arteries.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Subclavian steal syndrome -\n\nis a condition in which there is atherosclerotic occlusion in the first part of the subclavian artery.\nReduction of blood flow in the subclavian artery beyond the stenosis leads to diminished blood flow to of arm vessels.\nThis leads -to the formation of the collateral vessel from the vertebral artery which serves as a source of blood flow to the arm.\nThere will be a reversal in the direction of blood flow in the vertebral artery, as the pressure in the vessels of the arm is low.', 'role': 'assistant'}]