Electrocardiogram (ECG) and Excercise Stress Test

The electrocardiogram (ECG) represents the electrical activity of the heart recorded on the surface of the body. Just as a stone thrown into a body of water creates a series of concentric circles traveling in an outward direction, the heart’s pacemaker (a small area of specialized heart tissue located in the upper right area of the heart), generates a small charge of electricity (at rest, 60 to 70 times per minute) that spreads over the upper chambers of the heart and triggers the passage of electrical current throughout the lower chambers of the heart.

At rest or during exercise, this electrical signal, the ECG, can be detected on the surface of the body. The ECG test at rest and during exercise may be used to:

1. Uncover “silent” coronary heart disease;
2. Help in differentiating the causes of chest pain;
3. Determine the safety of beginning a vigorous exercise program (especially if a person has risk factors for coronary heart disease)
4. Determine a person’s current fitness level
5. Serve as a basis for an exercise prescription.

Exercise ECG Test:

To begin the exercise ECG test, sometimes referred to as an “exercise stress test,” a technician will place several electrodes (small sticky patches with conductive gel in the center) on your chest and abdomen area. The electrodes will then be connected to small wires that lead to the ECG machine on which the ECG signal will be monitored and periodically printed for interpretation.

You will then be asked to exercise on a motor- driven treadmill or stationary bicycle. The speed and grade of the treadmill (or the resistance of the bike) will be increased intermittently until you are unable to continue exercise. Because the physician or exercise technician will be continuously monitoring the ECG and periodically taking your blood pressure, you should feel confident exercising to your maximal effort.

If potential threatening ECG or blood pressure changes develop or you feel symptoms such as chest discomfort, severe shortness of breath, or severe fatigue, your physician or exercise technician will discontinue the test.

After you complete the exercise portion of the test, the ECG and blood pressure will be monitored during recovery (a period of five to ten minutes). Following the test, your physician will interpret the results.

The role of exercise treadmill testing in predicting future heart problems in people without symptoms for heart disease continues to be explored. Because exercise testing of individuals who are without symptoms for CAD can result in false-positive results (the test incorrectly identifies a person with CAD),it is not recommended to do  exercise testing in healthy individuals who don’t have symptoms for CAD.

Ambulatory Electrocardiographic Monitoring:

Another form of ECG is ambulatory electrocardiographic monitoring, also referred to as Holter monitoring. In this test, the ECG electrodes are connected from the patient to a portable ECG machine that contains a tape recorder. The patient’s ECG is monitored while the patient is performing normal daily activities over a day or two. This is usually done when arrhythmias or blackout spells have occurred or are suspected.

Patients are allowed to go home and asked to keep a record of their normal activities during the monitoring period. If a patient has an abnormal event, such as a sensation that the heart rate has sped up or the feeling that an abnormal heart rhythm is occurring, he or she presses a button on the ECG recorder to mark the exact time of the symptoms.The ECG can also be checked over the telephone.

Telephone checks can be helpful in patients with pacemakers because pacemaker activity can be monitored without the need to travel to the doctor’s office. To do this, an electronic device with an electrode is attached to the skin and then connected to the telephone. The physician at the other end has to have the necessary equipment so the ECG can be transmitted and printed out.