The hardening of the veins of endovascular fistula may be related to dietary factors, ageing and diseases. 1. Dietary factors: patients who do not arrange their diets properly, often eat fried, greasy and spicy food, such as fries, chili peppers, etc., can lead to lipid deposition in the vein wall and fibrous hyperplasia, which may lead to the hardening of the endocaval veins. 2. Ageing: as the patient grows older, the brittleness of blood vessels increases in middle-aged and old age, which can easily lead to the hardening of the endocaval vein. 3. Disease: patients suffering from hypertension, diabetes, atherosclerosis, phlebitis and other diseases, not timely treatment, may also lead to endovascular stenosis. Endovascular stiffness is caused by a variety of reasons, if you want to clarify the specific causes, it is recommended to go to the hospital through the examination to identify.