Arterial thrombosis can be caused by damage to the vascular endothelium, high platelets, slowed blood flow and other reasons. 1. Vascular endothelial damage: the most common is atherosclerosis, vascular endothelial damage in the formation of atherosclerotic plaque on the endothelium. After the plaque is detached, it is embolus, traveling around with the blood flow, and it can be embolized wherever it goes, which is more common, such as cerebral embolism, pulmonary embolism, and heart infarction. 2. High platelets: high blood coagulation can also lead to thrombosis. 3. Slow blood flow: may also lead to thrombosis, such as long-term bedridden patients, sedentary people, will lead to lower limb blood flow slowed down, the formation of lower limb thrombosis. Once the thrombus is dislodged it is easy to develop pulmonary embolism, which is life-threatening. This symptom alone is not enough to diagnose the disease, and may be caused by other factors. It is recommended that the patient consult a doctor in a timely manner to clarify the cause of the disease and give targeted treatment.