Electrocardiogram (ECG / EKG)

What is an Electrocardiogram?

An electrocardiogram, written ECG or EKG, is a quick painless test that records the electrical activity of your heart. Every heartbeat begins as an electrical signal in the sinoatrial node, the heart's natural pacemaker. From there it spreads through the muscle to make it contract. Ten small sticky electrodes placed on the chest, arms, and legs pick up those signals from the skin surface. A machine translates them into the familiar tracing of peaks and dips. It views the heart from twelve different angles. The pattern shows how fast the heart is beating and whether the rhythm is regular. It also shows whether the electrical signal is traveling normally, and whether any part of the heart muscle is thickened, strained, or short of blood. The recording itself takes about ten seconds, and the whole visit takes only a few minutes. No electricity is sent into your body. The machine only listens, so there is no possibility of a shock.

Why Dr. Nanavati may recommend this

The ECG is the first test in cardiology for good reason. It is fast, inexpensive, harmless, and it can identify an emergency within seconds.

Dr. Nanavati may order an ECG if you have:

• Chest pain, pressure, or tightness, where an ECG helps identify a heart attack quickly.
• Heart palpitations, a racing pulse, or a skipped beat.
• Dizziness, fainting, or near-fainting
• Shortness of breath or unexplained fatigue.
• High blood pressure, diabetes, high cholesterol, or a smoking history.
• A known arrhythmia that needs periodic checking.
• A new medication that can affect heart rhythm.
• An upcoming surgery requiring cardiac clearance.
• A pacemaker or defibrillator, as part of routine follow-up.

The American Heart Association explains how arrhythmias are identified and treated, and the National Heart, Lung, and Blood Institute reviews the arrhythmias an ECG can reveal.

How to prepare

There is essentially nothing to do. That is part of why this test is so useful.

• Eat and drink normally. No fasting is required.
• Take all of your medications as usual, and bring an up-to-date list. Many medications change the tracing.
• Avoid heavy exercise and caffeine right before the test if you can. Both raise heart rate.
• Skip lotion, oil, and powder on your chest, arms, and legs that morning. Electrodes will not stick to slick skin.
• Wear a two piece outfit. You will need to expose your chest. Your ankles and wrists must be reachable.
• Leave off pantyhose and tight compression sleeves, since electrodes go directly on the skin.
• Tell the staff if you have an allergy to adhesives, or if you have a pacemaker or defibrillator.
• Bring copies of any previous ECG tracings. Comparison with an older tracing often matters more than the new one alone.
• Allow about 10 to 15 minutes.

What happens during the procedure

You undress from the waist up and put on a gown. Then you lie flat on your back on an exam table. Your arms rest at your sides.

The technician cleans small areas of skin and may lightly buff them with an abrasive pad. Excess chest hair is sometimes shaved in small patches so the electrodes make firm contact. Ten disposable electrodes are then applied. Six go across the chest in a precise pattern, and one goes on each arm and leg. The exact positions matter, because misplaced electrodes change the tracing.

You are asked to lie still, relax your shoulders, breathe normally, and avoid talking. Muscle movement adds noise to the recording. A few seconds of stillness produces a much cleaner result. If you are shivering or tense, say so.

The machine records for about ten seconds and prints a tracing. Sometimes a second recording is taken if the first is unclear or if an electrode came loose.

The electrodes are then peeled off, which may sting slightly, and you can dress. Some people are asked to stay for a repeat tracing later. Others stay for continuous monitoring if a rhythm problem is suspected.

Recovery and results

There is no recovery. You can drive, work, and exercise immediately.

Results are quick. The machine prints a computer-generated interpretation right away. That automatic reading is not the final word. A physician must review the tracing, because the software often over-calls or misses subtle findings. When an ECG is done in the office, Dr. Nanavati usually reviews it during the same visit and tells you what it shows.

A normal ECG is reassuring but limited. It captures only ten seconds, so an intermittent rhythm problem can easily be missed. A normal tracing also does not exclude coronary artery disease. That is why symptoms that come and go often lead to Holter monitoring or a longer 7 to 10 day ambulatory rhythm monitor.

An abnormal ECG points the way to the next test rather than settling the question by itself. Depending on the finding, that may be an echocardiogram for structure, a stress test for blood flow, or blood tests. Changes suggesting an active heart attack lead to emergency treatment immediately.

Risks and safety

A standard resting ECG has no medical risks. It is entirely passive. The electrodes read electrical signals that your heart already produces. No current passes from the machine into your body. There is no radiation, no needle, no dye, and no medication.

The only real discomforts are minor. The electrode adhesive can cause brief redness or itching. A small number of people develop a mild rash that fades in a day or two. Removing electrodes from hairy skin can sting. Shaving small patches of chest hair leaves temporary stubble. Lying flat can be uncomfortable if you have back pain or trouble breathing when supine. The table can usually be raised slightly.

The meaningful caution is interpretive. A single normal tracing does not rule out heart disease. A mildly abnormal tracing is often a harmless variant, particularly in young athletes. The tracing must be read alongside your symptoms, examination, and history. That is why it belongs in a cardiology visit rather than as an isolated result.

If you have chest pain now, or pain with sweating, nausea, or breathlessness, call 911 rather than waiting for an office appointment.

Related services and conditions

• Holter monitoring for 24 to 48 hours of continuous recording.
• Echocardiogram to look at heart structure and pumping.
• Arrhythmias and heart palpitations
• Cardiology services at our practice.