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Pharmacy Links

THE CARDIOLOGY UNIT: THE STRESS TEST AND THE HOLTER MONITOR

April 2, 2009

A stress test is done on a treadmill or stationary bike. The treadmill is a moving walkway, the speed and incline of which can be altered. The faster it moves and the steeper the incline, the more work it forces your heart to do. While you walk on the treadmill, your heart is monitored by EKG, which will show when the demand for oxygen by the heart is beginning to outstrip the supply through the coronary arteries. This is usually well before you feel any pain.

The EKG can show how much of the heart is affected, and which part of the heart. This helps to pinpoint which coronary artery is affected, and roughly where. It is a start on the road to defining what exactly your problem is, but it is too inaccurate to use as the sole basis of treatment.

As a rough rule of thumb, if angina or ischemic changes on the EKG start within two minutes of beginning the treadmill exercise, there is enough coronary disease for serious note to be taken. If you can go ten minutes without pain, and there is no silent ischemia on the EKG, there is little to worry about. However, many people fall in between these limits.

The Holter monitor is a portable computerized EKG machine that can be strapped to your chest for twenty-four or forty-eight hours. You wear it as you perform your everyday tasks and even when you sleep (some angina may occur when you sleep).

The Holter monitor records a continuous trace of your heartbeats throughout the whole time you are wearing it, and is programmed to pick up every abnormality during that time, from episodes of ischemia to bursts of abnormal rhythm, to the odd missed beat. It can compare the episodes of ischemia with your count of episodes of pain. The difference gives the numbers of attacks of silent ischemia, and gives an idea of the whole burden of ischemia your heart is carrying, day and night.

Treadmill testing and Holter monitoring can detect people who are at relatively high risk of a serious heart attack. Cardiologists now recommend that everyone with angina under the age of sixty-five years, regardless of whether their symptoms are mild or severe (remember they often bear no relationship to the severity of your blockage), should be offered these tests. For those aged over sixty-five, the decision to put them to such discomfort depends on their general fitness and on how much their angina is interfering with their quality of life.