Cyanosis or necrosis of the fingers is a subclavian artery blood-stealing syndrome, in which ischemic symptoms of the upper extremities are commonly seen in the order of intermittent dyskinesia, upper extremity weakness, pain, and sensory abnormalities, and rarely cause cyanosis or necrosis of the fingers. What are the diseases that can cause cyanosis or necrosis of fingers? 1, atherosclerotic subclavian or head and arm trunk atherosclerosis: often at the same time in the extracranial neck of other blood vessels also have the same damage. As confirmed by angiography, 80% have concurrent damage to the common carotid, internal carotid, external carotid or vertebral arteries. At the same time there are other neck blood vessel damage, and the internal carotid artery is the most common, this is due to atherosclerosis is a systemic vascular damage. 2, congenital subclavian artery blood theft: that is, if this syndrome occurs in the left position of the aortic arch or the aortic arch has a narrowing, there is more than one arterial catheterization and ventricular septal defect at the same time; such as for the right position of the aortic arch, there is often Fallot’s tetralogy of Fallot. If the aortic arch is right-sided, a normal aortic arch with limited hypoplasia, atresia, or isolation of the subclavian arteries may also be seen. Rarely, there are reports of bilateral subclavian artery hypoplasia in the proximal segment of the subclavian artery, and at the same time, there is aortic constriction and bilateral blood stealing. 3.Medical origin of subclavian artery blood theft: In addition, because the right subclavian artery originates from the aorta and runs parallel to the back of the esophagus, it can also cause this syndrome when vascular surgery is performed to correct the malformed dysphagia. 4, traumatic subclavian artery blood theft: car accidents make chest injuries, in the subclavian artery, the vertebral artery at the beginning of the proximal side of the proximal side of the contusion thrombosis, which leads to this syndrome. 5.Other factors: such as rheumatic heart disease complicated by embolization of the first segment of the left subclavian artery, pulselessness, metastatic cancerous embolism and giant cell arteritis. Subclavian artery steal syndrome refers to partial or complete occlusive damage in the subclavian artery or the proximal segment of the vertebral artery of the head and arm trunk at the beginning of the proximal segment of the subclavian artery, due to siphoning, causing the blood flow in the vertebral artery of the affected side of the retrograde into the distal end of the subclavian artery of the affected side, resulting in vertebral-basilar ischemic episodes and ischemic syndrome of the affected side of the upper limb. It can have symptoms of cerebral ischemia or upper extremity ischemia.