Quick answer
An ECG (electrocardiogram) records the electrical activity of your heart in a few minutes using electrodes on the chest, wrists and ankles. It shows heart rate, rhythm and signs of problems such as irregular heartbeat, a current or past heart attack or a thickened heart muscle. A normal resting heart rate is 60–100 beats per minute. It is painless and needs no fasting.
What does an ECG show?
- Heart rate — too slow (bradycardia) or too fast (tachycardia)
- Heart rhythm — irregular rhythms such as atrial fibrillation
- Signs of a current or past heart attack
- Thickened heart muscle, often from long-standing high blood pressure
- Conduction blocks — delays in the heart’s electrical wiring
- Effects of some medicines and of potassium or calcium imbalance
Typical values on a normal ECG report
Your report will list the machine’s measurements. Typical adult values are below; your doctor reads them together with your symptoms and the ECG tracing itself.
| Measurement | Typical adult value |
|---|---|
| Heart rate | 60–100 beats per minute |
| Rhythm | Sinus rhythm (regular) |
| PR interval | 120–200 ms |
| QRS duration | Under 120 ms |
| QTc | Under about 450 ms (men) and 460 ms (women) |
When do doctors ask for an ECG?
- Chest discomfort, palpitations, breathlessness or dizziness
- Routine check-up for people with diabetes, high blood pressure or high cholesterol
- Before surgery, especially for people over 40
- To monitor heart medicines or a known heart condition
- Before starting some medicines or a new exercise programme
How to prepare
- No fasting needed — eat and take your medicines as usual.
- Wear loose, two-piece clothing.
- Avoid lotion or oil on the chest, wrists and ankles.
- Keep earlier ECG reports to compare.
ECG, 2D echo and TMT — the difference
| Test | What it checks |
|---|---|
| ECG | Electrical activity of the heart at rest |
| 2D echo | Ultrasound of the heart’s structure, valves and pumping |
| TMT (treadmill test) | How the heart copes with exercise |
Frequently asked questions
Can an ECG detect a blocked artery?
An ECG can show signs that the heart muscle is short of blood or has been damaged, but a normal resting ECG does not rule out blocked arteries. Doctors may add a TMT, echo or angiogram.
Is an ECG painful?
No. The electrodes only record signals from the heart; nothing is passed into your body.
How long does an ECG take?
The recording takes a few minutes; with preparation, about 10–15 minutes.
Can I get an ECG at home?
Yes. Live Line offers a 12-lead ECG at home for ₹899 in 20 cities in Andhra Pradesh and Telangana.
Medical disclaimer: This information is for general awareness only and is not a substitute for professional medical advice. Please consult a qualified doctor to interpret your results and before starting or changing any treatment.