Electrocardiogram

Overview

An electrocardiogram — usually called an ECG or EKG — is a simple, painless test that records the electrical signals that make your heart beat. Each heartbeat starts with a tiny electrical signal. Sticky pads placed on your chest, arms and legs pick up those signals and a machine draws them as wavy lines on paper or a screen. Your doctor looks at the pattern of the waves to see how fast your heart is beating, whether the beat is steady, and whether the different parts of your heart are working together in the normal order. An ECG takes only a few minutes and does not hurt. It sends no electricity into your body — it only listens.

Very common. An ECG is one of the most frequently used heart tests in the world. It is done in GP surgeries, hospitals, emergency departments and ambulances, and sometimes as part of a routine health check.

Anyone can have an ECG — newborn babies, athletes, pregnant women and people in their nineties. It is most often done in adults who have chest pain, a fluttering heartbeat, dizziness or breathlessness, or who have a known heart condition or a family history of one.

Symptoms

Common symptoms

• An ECG is a test, not an illness, so it has no symptoms of its own. These are the symptoms that most often lead a doctor to order one:
• Chest pain, tightness, heaviness or pressure
• A heartbeat that feels fast, pounding, fluttering or skipping beats (palpitations)
• Feeling dizzy, lightheaded or like you might faint
• Actually fainting or blacking out
• Shortness of breath, especially with activity or when lying flat
• Swelling in the ankles or legs
• Feeling very tired or unable to manage your usual activity
• A slow pulse, or a pulse that feels irregular when you check it

Symptoms in children

• ECGs are safe for babies and children and are done quite often. In children, a doctor may suggest one for:
• Fainting during exercise or while excited
• A heartbeat that races suddenly, or a pulse that feels irregular
• Blue or grey lips or skin during feeding or crying
• Poor feeding, sweating or tiredness in a baby
• A known heart condition, or a family history of sudden cardiac death or an inherited heart rhythm problem
• Before starting a medicine that can affect the heart, or as part of checking a heart murmur
• Children may be upset by the sticky pads. It helps to explain that the test is quiet and painless, and to stay close and hold their hand.

Symptoms in older adults

• ECGs are very commonly done in older adults, sometimes as part of a routine review and sometimes because of new symptoms.
• Dizziness or falls, which may be caused by a slow or irregular heartbeat
• Breathlessness or tiredness that has come on gradually
• A known heart condition, high blood pressure or diabetes being monitored
• Before an operation, or while taking medicines that can affect heart rhythm
• Confusion or a sudden change in how someone is, which can sometimes be linked to the heart
• Older adults often have more than one health condition, so an ECG is read alongside the whole picture, not on its own.

Causes

Main causes

• Reasons a doctor may ask for an ECG include:
• Chest pain or suspected heart attack
• An irregular, fast or slow heartbeat (arrhythmia)
• Fainting, blackouts or dizziness
• Breathlessness or swelling that might come from the heart
• Checking a known heart condition, or how well a treatment is working
• Before surgery or a procedure, as part of fitness checks
• Monitoring the effect of medicines that can change heart rhythm
• Looking for signs of heart strain, an enlarged heart, or changes in the heart muscle
• Investigating a family history of inherited heart conditions
• Sometimes as part of a routine health check or insurance or work medical

Risk factors

• Things that make a heart rhythm problem or heart strain more likely — and so make an ECG more likely to be needed — include:
• Getting older
• High blood pressure
• Existing heart disease, or a previous heart attack
• Diabetes
• A close family member with a heart rhythm problem or sudden cardiac death at a young age
• Smoking
• Being very overweight
• Sleep apnoea (loud snoring with pauses in breathing at night)
• An overactive or underactive thyroid
• Low or high levels of salts in the blood, such as potassium or calcium
• Heavy alcohol use or a lot of caffeine or energy drinks
• Some medicines, including certain cold remedies and herbal products
• Severe stress, fever or dehydration
• None of these means you will definitely have a heart problem. They simply raise the chance and help your doctor decide what to check.

When to see a doctor

See a doctor urgently if:

• Chest pain or pressure, particularly with sweating, sickness or breathlessness — call your local emergency number
• Fainting, or a blackout, especially during exercise or while lying down
• A racing heartbeat that will not settle, or comes with dizziness or chest pain
• A pulse that is very slow (under about 50 beats a minute) with dizziness or tiredness
• Sudden severe breathlessness, or breathlessness that wakes you at night
• Swelling in the legs that has come on quickly, with weight gain over a few days

Book a routine appointment if:

• Palpitations that come and go but are becoming more frequent
• Occasional dizziness or lightheadedness
• A slow or irregular pulse you have noticed but feel otherwise well
• Tiredness or reduced exercise tolerance that is new and unexplained
• A family history of inherited heart conditions — ask whether screening is right for you
• You have been advised to have an ECG as part of a health check, pre-surgery review or medicine monitoring
• Taking a medicine and wondering whether it could affect your heart

Diagnosis

An ECG is the test itself, so there is nothing to diagnose beforehand. Here is how it usually goes: you lie on a couch, sometimes with your chest bare. Small sticky pads are placed on your chest, wrists and ankles, and soft wires connect them to the machine. You lie still and breathe normally, and the machine records for a few seconds. Sometimes you are asked to hold your breath briefly. The whole thing takes about 10 minutes. There is no needle, no radiation and no pain — you may only feel the pads as slightly cold or sticky. Your doctor then reads the tracing, sometimes with a specialist, and explains what it shows and whether more tests are needed.

Tests that may be done

• Resting ECG — the standard 10-minute recording
• Ambulatory ECG (Holter monitor) — a small portable recorder worn for 24 to 48 hours, useful when symptoms come and go
• Event recorder or patch monitor — worn for days or weeks, and pressed or triggered when symptoms happen
• Exercise or stress ECG — recorded while walking on a treadmill or cycling, to see how the heart behaves when working hard
• Blood tests — to check for heart muscle strain, salts, thyroid and other causes
• Echocardiogram — an ultrasound scan that shows the heart's shape and how well it pumps
• Chest X-ray — to look at heart size and the lungs
• Blood pressure checks, and sometimes a heart monitor you wear at home
• Your doctor may also ask about your symptoms, medicines, family history and lifestyle — this matters as much as the tracing itself

What to expect at your appointment

You can eat and drink normally before a resting ECG, and you can take your usual medicines. Wear loose clothing that is easy to remove at the top, or you may be given a gown. You may need to remove a hairy patch of skin for the pads to stick, and you should avoid body lotion on the chest that day. For a monitor you wear at home, you will be shown how to use it and asked to keep a diary of symptoms and what you were doing at the time. Results of a resting ECG are usually available quickly — often the same day. Do not be alarmed if you are told it needs a specialist to look at it; that is normal and does not mean something is wrong.

Treatment

An ECG is not a treatment and does not change your body. Its job is to guide your care. If the tracing is normal and your symptoms settle, you may need nothing more than reassurance and a review if things change. If something shows up, the next step is to work out the cause and treat that — not just the tracing. Always talk to a qualified healthcare professional before making any decisions about your care, and ask them to explain anything you do not understand.

Self-care at home

• Keep a short symptom diary: what you felt, when, how long it lasted and what you were doing
• Note your pulse when symptoms happen, if you can — many phones and watches can help
• Bring a list of all your medicines, including over-the-counter remedies and herbal products
• Cut back on caffeine, energy drinks and alcohol if palpitations are a problem
• Stay hydrated, and avoid getting over-tired
• Keep moving — regular gentle activity is good for the heart
• Attend follow-up appointments and any repeat tests
• Ask your pharmacist before starting any new medicine or supplement
• Do not stop a prescribed medicine on your own — speak to your doctor first

Medical treatments

What happens next depends entirely on what the ECG shows and what is causing your symptoms. Often nothing is needed beyond monitoring. When treatment is needed, it usually means treating the underlying problem — for example, bringing high blood pressure under control, correcting a thyroid or salt imbalance, or reviewing medicines that may be affecting the heart. Where the heart rhythm itself is the issue, doctors may use medicines to steady or slow the heartbeat, or medicines to reduce the risk of clots. Some people are offered a small implanted device, such as a pacemaker to keep the heartbeat from going too slow, or a device that corrects a dangerous rhythm. Your doctor will explain the options, the benefits and the drawbacks, and the choice is yours to make with their support.

When is surgery considered?

Most people who have an ECG never need surgery. Sometimes a procedure is helpful — for example, a catheter ablation, where a thin tube is guided to the heart to switch off the tiny patch of tissue causing an abnormal rhythm, or fitting a pacemaker or similar device under the skin of the chest. These are usually day-case or short-stay procedures. Your heart team will only suggest one if the expected benefit clearly outweighs the risks, and they will talk it through with you first.

Living with this condition

For most people, having an ECG changes very little day to day. You have the test, you get the result, and you carry on. If you are given a monitor to wear at home, it can feel a bit awkward for a day or two, but you can usually wash, sleep and go about normal life — just follow the instructions you are given about showering and about keeping the device dry. If your ECG leads to a diagnosis, you may have appointments to come, and possibly medicines to take. Many people find that understanding what is going on helps them feel calmer and more in control.

Lifestyle tips

• Stay active — build up gradually if you have not exercised for a while
• Keep to a healthy weight
• Do not smoke, and get help if you want to stop
• Keep alcohol within low-risk levels
• Go easy on caffeine and energy drinks if they trigger palpitations
• Get enough sleep, and ask about snoring or breathing pauses at night
• Manage stress — breathing exercises, hobbies, time outdoors, talking to someone
• Take medicines as prescribed and use a pill box or phone reminder if it helps
• Go to your routine reviews, even when you feel well

Diet and exercise

A heart-friendly way of eating means plenty of vegetables, fruit, beans, wholegrains, nuts and oily fish, with less salt, sugar and processed food. Aim for movement most days — a brisk walk counts. If you have a heart condition, ask your doctor or a cardiac team what level of activity is right for you; most people are encouraged to keep exercising, sometimes with a supervised programme. If exercise brings on chest pain, breathlessness or dizziness, stop and get medical advice.

Mental health and emotional wellbeing

Being sent for a heart test can be worrying, and waiting for results can be an anxious time. Palpitations themselves can make anxiety worse, and anxiety can make palpitations more noticeable — a loop that is very common and very human. Talk to your doctor if you feel low, panicky or unable to switch off. Support such as talking therapies, relaxation practice or a cardiac rehabilitation group can help a great deal. If at any point you feel you might harm yourself, contact your local emergency number or a crisis support line in your country straight away, or reach out to someone you trust and stay with them until help arrives.

Prevention

You cannot prevent needing an ECG — it is simply a test, and anyone may need one at some point. What you can do is look after your heart so that rhythm problems and heart disease are less likely in the first place. That means keeping blood pressure and cholesterol in a healthy range, not smoking, staying active, eating well, limiting alcohol and keeping to a healthy weight. If you have a strong family history of heart rhythm problems, tell your doctor — early advice can make a real difference.

Vaccines

If you have a heart condition, your doctor may recommend certain vaccinations, such as the yearly flu vaccine, because infections can put extra strain on the heart. Ask your GP or pharmacist which ones are advised for you.

Screening programmes

There is no routine ECG screening for everyone. Some people are offered one because of their age, a health check, a family history or a medicine they take. A blood pressure check is a quick and useful heart health measure and is available at most GP surgeries and many pharmacies. If heart disease runs in your family, ask your doctor whether extra checks are right for you.

Complications

If left untreated

• An ECG itself has no complications — it is a recording, and it is safe.
• The complications that matter are from whatever the ECG is looking for, if that problem is left unchecked:
• An untreated irregular heartbeat can cause fainting, falls or injury
• Some rhythms raise the risk of a stroke, which is why doctors sometimes prescribe clot-reducing medicine
• A heart that is working under strain can gradually weaken, leading to heart failure
• A heart attack that is not treated quickly can cause lasting damage to the heart muscle
• This is exactly why the test is done — finding a problem early usually means it can be managed well

Long-term outlook

For most people an ECG brings reassurance and nothing more. When something is found, modern heart care is very good at managing it — many rhythm problems are controlled with medicines, lifestyle changes or a small device, and most people go on living full, active lives. A test result is a starting point for a conversation, not a verdict. Ask your doctor to explain what your result means for you specifically, and what the next step is.

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