The circulatory system includes the heart, arteries, veins and capillaries. Also known as the cardiovascular system, this network carries oxygen and nutrients to the body. It also transports waste products to the kidneys, liver and lungs for elimination. Cells, hormones and other important chemicals are delivered from one location to another via the circulatory system. Heart and other circulatory problems are major causes of disability and death. Cardiovascular disease is the leading cause of death in the United States, according to the Centers for Disease Control and Prevention (CDC).
High Blood Pressure
High blood pressure, or hypertension, is the most common circulatory system disorder among Americans. Approximately 1 out of 3 adults in the U.S. have hypertension, reports CDC. Most people with high blood pressure have primary hypertension, meaning it is not caused by another disease. Although high blood pressure typically causes no symptoms, untreated hypertension can contribute to a heart attack, heart failure, kidney failure and stroke. The risk for hypertension increases with age. Other risk factors include overweight and obesity, a high-salt diet, lack of regular physical activity, drinking too much alcohol, and a family history of high blood pressure.
Atherosclerosis, or hardening of the arteries, develops when deposits called plaques form along the inner walls of medium to large arteries. Plaques consist of inflammatory cells, connective tissue, calcium, certain fats and other components. Left untreated, atherosclerotic plaques grow over time without causing symptoms until blood flow and oxygen delivery to the affected areas is critically reduced. Atherosclerosis is responsible for the overwhelming majority of heart attacks and strokes. Abnormal blood fat levels, smoking, high blood pressure and diabetes are leading risk factors for the development of atherosclerosis.
Weakening of the blood vessel wall causes a ballooning bulge called an aneurysm. Most aneurysms develop in arteries, as these blood vessels are under high pressure. Large or fast-growing aneurysms can rupture, causing rapid blood loss and depriving organs of a life-sustaining blood supply. Unfortunately, aneurysms typically do not cause symptoms until a rupture occurs. The aorta -- the largest artery of the body -- is a common site for aneurysm formation. Most aortic aneurysms occur in the abdomen, but some occur in the chest. A ruptured aortic aneurysm is a life-threatening medical emergency. The brain is another frequent site for aneurysms, known as cerebral aneurysms. A ruptured cerebral aneurysm typically leads to a stroke, which can be fatal. Smoking and high blood pressure are major risk factors for aneurysms.
Although blood clot formation, or thrombosis, can be life-saving when an injury occurs, spontaneous clot development is a common circulatory system disorder. The greatest danger with a spontaneous clot is loss of blood supply to a vital organ. Blood clots can form in any blood vessel, but some sites are more frequently involved than others. For example, deep vein thrombosis (DVT) most commonly occurs in the deep veins of the calf or thigh. DVT can be life-threatening if a piece of the clot breaks off and travels to the lungs, a condition called pulmonary embolism. The brain is another common site for blood clots. Brain blood clots account for 87 percent of strokes, according to the American Heart Association. Formation of a blood clot in one of the arteries supplying the heart is often the triggering event for a heart attack. Risk factors for thrombotic disorders include smoking, atherosclerosis and lack of mobility.
A congenital cardiovascular defect describes an abnormality in the formation of one or more parts of the circulatory system. These abnormalities are relatively common affecting roughly 1 out of every 125 live births, according to the American Heart Association. Some of the more common abnormalities are minor and often require no treatment. For example, a small hole in the wall that separates the heart chambers -- known as an atrial or ventricular septal defect -- often closes on its own. Major congenital heart defects, however, typically require surgical correction early in life. An arteriovenous malformation, or AVM, is another type of congenital circulatory system defect. An AVM is a tangle of blood vessels that involves abnormal connections between the arterial and venous circulation. AVMs that form in the brain or spinal cord can result in severe problems and even death. Some genetic disorders increase the risk for congenital heart defects, such as Down syndrome. However, these malformations often occur spontaneously without any identifiable genetic or environmental cause.
Reviewed by: Tina M. St. John, M.D.