The causes of carotid artery dilation are carotid artery sclerosis, hyperthyroidism and aortic valve closure insufficiency diseases. With carotid atherosclerosis, the walls of the arteries thicken and harden, blood circulation is poor, and plaques are formed. Carotid arteries can become physiologically dilated under high pressure, and the diameter of the arteries can increase significantly, producing physiological congestion as a sign of a compensatory response. Hyperthyroidism can present with significant changes in carotid blood flow, poor vascular elasticity, and vasodilation. Aortic valve closure insufficiency can occur when the force of the aorta is higher than the pressure of the left ventricle, and closed vessels and vascular elasticity produce diastolic pressure. Aortic closure insufficiency causes the left ventricle to drain blood into the aorta during systole and blood to flow backwards into the left ventricle during diastole, so that the carotid artery will pulsate abnormally, leading to a rapid increase in blood flow in the carotid vessels, resulting in carotid dilation.