Related terms: ischemia, restricted blood flow
Ischemia is a condition where the flow of oxygen-rich blood to a part of the body is restricted. Cardiac ischemia refers to lack of blood flow and oxygen to the heart muscle.
Cardiac ischemia happens when an artery becomes narrowed or blocked for a short time, preventing oxygen-rich blood from reaching the heart. If ischemia is severe or lasts too long, it can cause a heart attack (myocardial infarction) and can lead to heart tissue death. In most cases, a temporary blood shortage to the heart causes the pain of angina pectoris. But in other cases, there is no pain. These cases are called silent ischemia.
Silent ischemia may also disturb the heart's rhythm. Abnormal rhythms such as ventricular tachycardia or ventricular fibrillation can interfere with the heart's pumping ability and can cause fainting or even sudden cardiac death.
How common is silent ischemia, and who is at risk?
The American Heart Association estimates that 3 to 4 million Americans have episodes of silent ischemia. People who have had previous heart attacks or those who have diabetes are especially at risk for developing silent ischemia. Heart muscle disease (cardiomyopathy) caused by silent ischemia is among the more common causes of heart failure in the United States.
Major risk factors include
What are the symptoms of silent ischemia?
Silent ischemia has no symptoms. But researchers have found that if you have episodes of noticeable chest pain, you may also have episodes of silent ischemia.
How is silent ischemia diagnosed?
The following tests can be used to diagnose silent ischemia:
- An exercise stress test can show blood flow through your coronary arteries in response to exercise, usually walking on a treadmill.
- Holter monitoring records your heart rate and rhythm over a 24-hour period (or longer). You wear a recording device (the Holter monitor), which is connected to disks on your chest. Doctors can then look at the printout of the recording to find out if you have had episodes of silent ischemia while you were wearing the Holter monitor.
How is ischemia treated?
Treatment for ischemia is similar to that for any form of cardiovascular disease and usually begins with the following lifestyle changes:
- If you smoke, quit.
- Control high blood pressure, cholesterol, and diabetes.
- Limit how much alcohol you drink.
- Adopt healthy eating habits.
- Start an exercise program that has been approved by your doctor.
Medicines and Surgery
The goals of treatment include improving blood flow to your heart and reducing your heart's need for oxygen. Your doctor may give you aspirin, blood-thinning medicines (called anticoagulants), or other blood-thinning agents to prevent blood clots from forming. Oxygen may be given to increase the oxygen content of the blood still flowing through your heart. Painkillers may be used for pain.
Some patients take medicines that slow their heart rate, open and relax their blood vessels, and otherwise reduce the burden on the heart. Most patients respond well to these medicines. Those who do not respond well may need a percutaneous coronary intervention (PCI) such as balloon angioplasty, coronary artery bypass surgery, or a similar procedure.
Updated October 2012