Electrocardiogram

The electrocardiogram (ECG) is a graphic recording of the heart’s electrical activity.
 
Electrodes connected to the arms, legs, and attached to the chest (via flat paddles) monitor the electrical activity generated by the heart.
 
To be considered normal, this electrical activity should have a characteristic pattern. From the electrocardiogram, the physician can tell a great deal about the heart:
 

•	Rate (speed)
•	Rhythm (how “regular” is the heart beat)
•	Signs of Cardiac Enlargement (seen with some forms of heart disease)
•	Signs of Heart Injury (or “heart attack”)
•	Miscellaneous Changes (e.g. electrolyte abnormality, pulmonary embolism, drug toxicity, and drug side effects)

 
In some cases, an ECG can be performed after a period of exercise. This is known as a stress test and is frequently a good predictor for the presence of coronary artery disease.
 
This extremely useful test has become a standard part of yearly physical exams for most patients over the age of 40, and those with any outstanding cardiac risk factors ( e.g. smokers, high blood pressure, prior heart attack, diabetics,high cholesterol, or family history for heart attack). Patients with potential cardiac symptoms (chest pain) will receive an ECG as part of their evaluation.
 

•	There are no risks associated with an ECG.
•	Some medications (e.g. digoxin) can alter your ECG, therefore, make sure your doctor knows what medication you are taking.
•	Electrolyte imbalance (low or high potassium, low calcium) can alter your ECG.
•	An ECG is painless.

 
Although most physicians have training which qualifies them to interpret the ECG, the Cardiologist is the expert in this area.
 
In most cases, an ECG can correctly diagnose an active heart attack. An ECG cannot accurately predict the presence of blockages in the blood vessels (coronary arteries), which result in chest pains (angina). For this reason, the stress test or cardiac catheterization can be required.

RETURN TO ENCYCLOPEDIA