Ischemia Health Article

Definition

Ischemia is an insufficient supply of oxygenated blood to an organ, usually due to a blocked artery.

Description

Myocardial ischemia is an intermediate condition in coronary artery disease during which the heart tissue is slowly or suddenly starved of oxygen and other nutrients. Eventually, the affected heart tissue will die. When blood flow is completely blocked to the heart, ischemia can lead to a heart attack. Ischemia can be silent or symptomatic. According to the American Heart Association, up to four million Americans may have silent ischemia and be at high risk of having a heart attack with no warning.

Symptomatic ischemia is characterized by chest pain called angina pectoris. The American Heart Association estimates that nearly seven million Americans have angina pectoris, usually called angina. Angina occurs more frequently in women than in men, and more often in African-Americans and Hispanics than in Caucasians. It also occurs more frequently as people age—25% of women over the age of 85 and 27% of men between 80 and 84 years of age have angina.

People with angina are at risk of having a heart attack. Stable angina occurs during exertion, can be quickly relieved by resting or taking nitroglycerine, and lasts from three to 20 minutes. Unstable angina, which increases the risk of a heart attack, occurs more frequently, lasts longer, is more severe, and may cause discomfort during rest or light exertion.

Ischemia also can occur in the arteries of the brain, where blockages can lead to a stroke. About 80–85% of all strokes are ischemic. Most blockages in the cerebral arteries are due to a blood clot, often in an artery narrowed by plaque. Sometimes, a blood clot in the heart or aorta travels to a cerebral artery. A transient ischemic attack (TIA) is a "mini-stroke" caused by a temporary deficiency of blood supply to the brain, or by a blood clot briefly blocking a cerebral artery. It occurs suddenly, lasts a few minutes to a few hours, and is a strong warning sign of an impending stroke. Ischemia can also affect intestines, legs, feet, and kidneys. Pain, malfunctions, and damage in those areas may result.