Ischemia refers to the condition in which the muscles of the heart do not get an adequate supply of oxygen. This mostly happens because of reduced blood flow to the cardiac muscles either due to complete blockages or due to a partial block in the blood vessels that carry blood. This condition, also known as myocardial ischemia, may not persist for a long time in most cases. The heart muscles may have reduced ability to pump blood efficiently. People with ischemia are more affected under stress or physical activity, than during rest, as the oxygen supply may not be enough. Ischemia may happen without any obvious symptoms in some people.
Symptoms, when present, include:
- Angina – This refers to the feeling of pain or discomfort in the chest. This tight feeling often starts under the breast bone and may spread to the shoulders, arm, neck and jaw. In some cases, ischemia may happen without angina, but with all other symptoms.
- Shortness of breath
- Nausea or vomiting
It is often noted in people with chronic conditions, like diabetes. Silent ischemia is more common in older people and women. One should seek medical care immediately if he or she has angina along with any of the other symptoms.
The blockage of blood vessels may occur gradually over a period of time or suddenly. Sometimes the blockage may be such that the blood flow to the heart muscles is decreased considerably at all times, even when the person is at rest. This condition, called chronic ischemia, weakens the heart gradually.
Some of the causes of ischemia include:
- Atherosclerosis – This is one of the most common causes of ischemia and in this condition, cholesterol and other waste products from the cells accumulates on the walls of the blood vessels narrowing it and restricting the flow of blood.
- Blood clot – In some cases, the plaques formed by the build up of cholesterol may break and cause blood clots within the blood vessels. This leads to sudden ischemia that may result in heart attack.
- Spasm of the coronary artery – A temporary contraction of the muscles of the arterial wall narrows the lumen of the blood vessels resulting in reduced blood flow to the heart muscles.
- Certain health conditions – Ischemia may also be caused by certain infections and severe illnesses where the blood pressure falls considerably.
The risk of developing ischemia is increased by factors including:
- High blood pressure
- High levels of cholesterol in blood
- Low physical activity
- Family history of ischemia