What Is an ECG?

We have seen doctors using Stethoscope to examine patients. By using the stethoscope doctors listen to the internal sounds of the body, especially heart beating, lungs,intestines etc. During each heart beat, small electrical signals are generated along with the sound. These electrical activity of human heart is measured and monitored by using electrocardiogram (ECG). Electrodes are attached to the outer surface of the skin, which detects the signals. These signals are amplified and recorded on ECG paper by ECG machine.

For diagnosis and monitoring of heart and heart diseases different types of ECG is used.

Resting ECG

A Resting Electrocardiogram (ECG) is used to analyze how the heart performs when the person is at rest. This test aids the doctor in evaluating the condition of the heart. It is also used to monitor patients who have undergone an angiogram, angioplasty, cardiac surgery or change in dosage of heart medication. The Resting ECG helps to detect a wide range of heart conditions and takes approximately 15-20 minutes.

Stress Test (Exercise ECG)

The ECG obtained when the heart is working harder due to exercise or medication induced stress is termed exercise ECG, or stress test. This test is useful in detecting problems that may not be detected in a resting ECG. It also shows any abnormal flows of blood to muscle tissue. The stress test is done by trained personnel under a controlled environment.

Stress test is used as a screening tool for people with coronary artery disease. This test can help predicting future heart attacks in people with multiple risk factors even if the person doesn't have any heart disease.

Holter ECG

A Holter monitor is a portable device for continuously monitoring the electrical activity of the cardiovascular system for at least 24 hours. The Holter monitor is named after its inventor, Norman J. Holter. The increased recording period can be useful for detecting arrhythmia, the condition in which the heart can beat too fast, too slow, or with an irregular rhythm. The electrodes are placed over bones to minimize the readings obtained from muscular activity. Most Holter monitors employ between three and eight electrodes. These electrodes are connected to a small piece of equipment that is attached to the patient's belt or hung around the neck. This recorder keeps a log of the electrical activity of the heart.

Holter monitoring is used mainly after a heart attack, to diagnose heart rhythm problems and when starting a new heart medicine.

Monitoring in ICU

Using the continuous measurement of the heart's electrical activity, the ICU staff can monitor if the heart is beating abnormally fast or slow and if the heart is following a normal or abnormal rhythm. The ECG is one of the most common monitoring devices used in the hospital. The variations in the heart rate or rhythm may be the first sign of an adverse or abnormal development, and they help to alert the doctor or nurse. Thus it is a reliable and frequently used method of patient-monitoring in the ICUs.