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': 'Best Material for below inguinal arterial graft is \nSelect and explain. \nA. Saphenous vein graft (upside-down), B. PTFE,, C. Dacron, D. Teflon', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Critical limb ischemia (CLI) is defined by the presence of ischemic rest pain in the distal foot, ischemic nonhealing ulcerations, or gangrene.\nCLI is the progressive evolution and clinical manifestation of peripheral arterial disease (PAD).\nIt is seen in patients with severe arterial occlusive disease in whom resting blood flow cannot accommodate basal nutritional needs of the tissues.\nPatients will complain of rest pain or a feeling of cold or numbness in the foot and toes.\nFrequently, these symptoms occur at night when the legs are horizontal and improve when the legs are in a dependent position. With severe ischemia, rest pain may be persistent.', 'role': 'assistant'}]