Electrocardiogram
Medically reviewed by: Dr. Theodoros Barlogiannis, CardiologistLast updated: 26 July 2026
An electrocardiogram (ECG) is a painless, non-invasive test that records the electrical activity of the heart. It shows the heart's rhythm and rate and can reveal arrhythmias, ischemia or signs of a previous heart attack. The test takes only a few minutes and requires no preparation.
What is an Electrocardiogram (ECG)?
An Electrocardiogram (ECG) is a painless, non-invasive test that provides critical information about the electrical activity of the heart. It is performed by placing electrodes at specific spots on the body, which detect and measure the electrical impulses generated by each cardiac contraction. The test results offer diagnostic information regarding the heart's rhythm, pulses, and overall function.
When should an Electrocardiogram be conducted?
An Electrocardiogram is a fundamental tool for diagnosing and monitoring various heart conditions. It can be conducted in many situations, including:
- Routine Check-ups: ECGs may be part of regular check-ups, especially for individuals with risk factors for heart disease or a family history of cardiovascular issues.
- Chest Discomfort or Pain: When an individual experiences pain, discomfort, or other symptoms indicative of a heart problem, an ECG can quickly provide valuable information, especially if performed during the episode.
- Cardiac Issues: For individuals with cardiovascular problems, such as arrhythmias, coronary artery disease, or heart failure, regular ECGs are essential for monitoring the condition and adjusting treatment.
- Preoperative Evaluation: Before most surgeries, an ECG is conducted to assess the heart's condition.
What does an Electrocardiogram show?
An Electrocardiogram provides valuable information about various aspects of cardiac health, such as:
- Detection of Abnormal Heartbeats and Rhythm: The ECG can identify irregularities in heartbeats and rhythm associated with common cardiac conditions.
- Cardiac Structure: Changes in the size of heart chambers or walls can be detected, serving as a warning for potential pathological conditions.
- Ischemia or Infarction: An ECG can reveal areas with reduced blood flow or damage to the myocardium, indicating conditions like angina or a previous heart attack.
How is an Electrocardiogram conducted?
During an ECG, electrodes are placed on the chest, upper, and lower limbs of the patient. These electrodes are connected to an electrocardiograph, a device that records the heart's electrical activity. The examination is painless, non-invasive, and typically completed within a few minutes.
Frequently Asked Questions
How long does an electrocardiogram take?
The whole visit takes about 5 to 10 minutes. The recording itself lasts only a few seconds; the rest of the time is spent placing the electrodes on the chest, arms and legs. You can return to your normal activities immediately afterwards.
Do I need to prepare for an ECG?
No special preparation is needed. You do not need to fast and you can take your regular medication as usual. It helps to avoid oily body lotion on the chest on the day of the test, so the electrodes adhere properly to the skin.
What does an electrocardiogram show?
An ECG records the heart's rhythm and rate. It can reveal arrhythmias, conduction disorders, signs of ischemia or a previous heart attack, and evidence of ventricular hypertrophy. It is often the first test in a cardiac work-up and guides any further testing.
When is an ECG needed?
An ECG is recommended when symptoms such as palpitations, dizziness, shortness of breath or chest pain are present, and also preventively as part of a routine cardiac check-up, pre-participation sports screening or pre-operative assessment. For your individual case, consult your cardiologist.
Is an ECG painful or dangerous?
No. An electrocardiogram is completely painless and harmless. The electrodes simply record the electrical activity produced by the heart itself — they do not deliver any current to the body. It can be repeated as often as needed, at any age.
The information above is educational and does not replace medical advice.