The thinning of blood vessels is divided into arteries and veins, and the most likely cause of thinning of veins is from venous valve insufficiency in the lower limbs, when the valve reflux cannot be completely closed, resulting in regurgitation of some blood in the return flow of the heart, causing a significant increase in fluid pressure in the veins and leading to vascular expansion, and the expansion of blood vessels will cause the thinning of the walls of the corresponding segments, while the main cause of thinning of arteries is due to atherosclerosis time. The main reason for the thinning of arteries is the thickening of intima and intima, which can lead to calcification, bleeding and plaque formation in severe cases. The plaque has no ability to resist arterial pressure, and when the arterial pressure is too high, the plaque will rupture and cause the dilatation of the outer membrane under the plaque, and the lumen of the vessel will become thinner, and this dilatation is very dangerous and often ruptures with the increase of arterial pulsation.