The primary cause of embolism is deep vein thrombosis, a condition in which blood clots form in the large veins of the lower extremities, such as in the thigh or lower leg. If the blood clot breaks free from the wall of the vein, it can travel through the bloodstream and cause an embolism by blocking an artery.

How is an embolus formed?

A common source for an embolus is from areas of hardening (atherosclerosis) in the aorta and other large blood vessels. These clots can break loose and flow down to the legs and feet.

What causes an embolism in the heart?

When plaque or another substance, such as a blood clot, travels through the blood stream and becomes wedged in a blood vessel because the diameter of the vessel is too small for it to pass, it is called an embolism. A cardiac embolism is an obstruction that travels from the heart to lodge in a blood vessel.