Blood clots are clumps of hardened blood that have coagulated, transforming from a liquid to a solid form. While some blood clots dissolve back into the bloodstream and cause no problems, others may lodge themselves within a blood vessel or artery, blocking blood flow and leading to potentially serious or life-threatening side effects.
Embolism
An embolus is a thrombus (a blood clot that forms inside a blood vessel or artery and remains there) that has migrated from a blood vessel or the heart to another location in the body. This migration can lead to a disorder called an embolism, in which the embolus partially or fully blocks blood flow to a part of the body, leading to potentially life-threatening consequences. For example, a pulmonary embolism occurs when an embolus blocks one or more arteries in the lungs, causing unexplained shortness of breath, coughing up bloody sputum and chest pain, according to the Mayo Clinic. Deep venous thrombosis (DVT) is a condition in which a blood clot forms in the legs and breaks off and moves to the heart, lungs or brain where it can cause a pulmonary embolism, heart attack or stroke.
Ischemia
Blood clots can cause ischemia, or a blockage of blood flow and oxygen to tissue. Cardiac ischemia occurs when blood flow to the heart muscle becomes partially or fully blocked, causing shortness of breath, fainting, cardiac arrhythmia or even death. Acute intestinal ischemia is typically caused by a blood clot that forms in the heart and travels to an intestinal artery. According to the Mayo Clinic, in other cases, a primary blood clot may form in a vein that leads away from the intestines. Intestinal ischemia prevents food and nutrients from being absorbed and, if left untreated, can lead to bloody diarrhea, gangrene, infection or death.
Heart and Brain Effects
Blood clots can cause life-threatening effects on the heart and brain. According to the American Heart Association, blood clots can partially block or constrict arteries and reduce blood flow to the heart muscle. This can lead to the development of unstable angina--a condition characterized by unexpected chest pain that usually occurs while at rest. Unstable angina differs from typical or "stable" angina in that chest discomfort is more severe and prolonged. The AHA advises that anyone with new chest pain or unstable angina should immediately go to the emergency room for evaluation, as he is at heightened risk for a heart attack, severe heart arrhythmias and fibrillation. The person is also at risk of having a cardiac arrest that causes sudden death.
Blood clots may also interrupt the flow of blood to the brain, leading to an ischemic stroke. An ischemic stroke can occur when a blood clot fully blocks a narrow artery in the brain (thrombic stroke) or when a clot breaks off from somewhere else in the body and travels to block a small artery in the brain (embolic stroke). In some cases, blood clots that form in the heart can travel to and get stuck in the brain's narrow arteries (cerebral stroke). If a blood clot stops the flow of blood for more than a few seconds, it deprives the brain of necessary oxygen, causes a stroke, and leads to permanent brain cell death in and around the affected area, according to the NIH.
