1, thrombo-occlusive vasculitis: thrombo-occlusive vasculitis is a chronic occlusive disease involving vascular segments, inflammatory and periodic episodes. It mainly involves small and medium-sized arteries and veins of the extremities, especially the lower extremity vessels. Most of the patients are young and middle-aged men. The main clinical features include coldness, hypothermia, pale or cyanotic skin, abnormal sensation, intermittent claudication or resting pain, diminished or absent distal arterial pulsation, ischemic ulceration or gangrene at the end of the affected limb, and wandering superficial phlebitis. Arteriography shows segmental occlusion of arteries with smooth vessel walls on the proximal and distal sides of the lesion. 2, arteriosclerosis occlusive disease: mostly seen in the elderly, mostly occurring in the large and medium-sized arteries throughout the body, with the distal abdominal aorta and the iliac, femoral and N arteries being the most common. Early symptoms are intermittent claudication, weakening or disappearance of distal arterial pulsation, skin atrophy and thinning, shiny, muscle atrophy, hair loss, thickening and deformation of toenails when the limb is chronically ischemic. Later, resting pain, cyanosis with decreased skin temperature, gangrene and ulceration of the distal limb appear. Arteriography shows extensive irregular stenosis and segmental occlusion, wall calcification, dilatation and distortion of sclerotic arteries. 3, arterial embolism: rapid onset, obvious symptoms, rapid progression, the main clinical manifestations of the 5 “P” syndrome: pain (Pain); pallor (Pallor); pulselessness (Pulselessness); abnormal sensation (Paresthesia); paralysis (Paralysis). 4, multiple aortitis: also known as pulselessness, Takayasu disease. It is a chronic, multiple non-specific inflammation of the aorta and its branches, resulting in arterial stenosis or occlusion, causing ischemic clinical manifestations of the diseased arterial blood supply tissue. The disease is usually seen in young women, with early onset of hypothermia, malaise, muscle or joint pain, followed by gradual onset of weakness in one or both upper limbs, weakened or absent pulsations in the brachial and radial arteries, reduced or undetectable blood pressure in the upper limbs, and normal blood pressure and arterial pulsations in the lower limbs; or weak or absent pulsations in one or both carotid arteries, accompanied by symptoms of transient cerebral ischemia, and audible vascular murmurs in the carotid artery, or femoral artery and its The arterial pulsation of the femoral artery and its distal side is weakened, and a vascular murmur is heard in the upper abdomen, or persistent hypertension, and a vascular murmur is heard in the upper abdomen or back. 5, Raynaud’s syndrome: small artery spasm, the affected area appears pale and chilly, bruising and pain, flushing after recovery of the typical symptoms, mostly seen in young women, cold stimulation or emotional onset, most often in the fingers, often bilateral, no other symptoms in the interval except for finger skin temperature decreased, the radial artery or dorsalis pedis artery pulsation is normal.