Thrombus is the general term for all blood clots, including appendage thrombosis, venous thrombosis, and arterial thrombosis. A wall thrombus is a blood clot attached to the wall of a blood vessel, which is easily dislodged if it does not take long to form, and once dislodged can lead to thromboembolism. Wall thrombus is generally most common in the venous vessels or atria of the heart, the arterial system generally does not see wall thrombus, because the arterial blood flow is more rapid, high pressure, the blood vessels have periodic contraction, wall thrombus is not easy to adhere to the blood vessels. In contrast, venous blood is prone to wall thrombosis because of the slow flow and the presence of a venous valve. If the wall thrombosis occurs in the veins of the lower extremities, it is called lower extremity vein thrombosis, and the lower extremity vein thrombosis can easily block the pulmonary vessels. If the thrombosis occurs in the arteries of the heart, it is called coronary heart disease, and if the thrombosis occurs in the cerebral arteries, it is called cerebral embolism.