Reviewed by Dr. A M Thirugnanam, MD, MSICP, FSCAI, Ph.D. — Senior Interventional Cardiologist
Almost everyone notices their heartbeat at some point — a thud, a flutter, a sensation that the heart has turned over in the chest. Most of these are harmless. A few are not. The difficulty is that the harmless and the dangerous can feel identical, so the distinction is made not by how it feels but by what accompanies it and what an ECG shows.
What an arrhythmia is
Your heart has its own electrical system. A natural pacemaker in the right atrium fires roughly sixty to a hundred times a minute, and the impulse travels along defined pathways to make the chambers contract in sequence. An arrhythmia is any disturbance of that sequence — too fast, too slow, or disordered.
The common ones
Ectopic beats — the flutter most people feel
An extra beat arrives early, and the following pause allows the heart to fill more than usual. The next beat is therefore forceful, and it is that thud you feel — not the extra beat itself. Ectopics are extremely common, increase with caffeine, alcohol, poor sleep and stress, and in a structurally normal heart are generally harmless. They often become more noticeable when lying down at night simply because there is less to distract you.
Atrial fibrillation
The upper chambers quiver instead of contracting, producing a completely irregular pulse. This is the arrhythmia that matters most, because blood pools in the quivering atrium, can clot, and that clot can travel to the brain. Atrial fibrillation multiplies stroke risk roughly fivefold — and a large proportion of strokes in people over sixty-five are caused by it.
It may cause palpitations, breathlessness, fatigue or reduced exercise tolerance. It may equally cause nothing at all, and be discovered incidentally — sometimes only after a stroke has already occurred.
The critical point: treatment is not primarily about the palpitations. It is about preventing stroke with an anticoagulant, if your risk score warrants one. Aspirin is not adequate protection for atrial fibrillation, though it is still wrongly prescribed for this purpose.
Supraventricular tachycardia
A sudden, regular, very fast heartbeat — often 150 to 200 a minute — that starts and stops abruptly, like a switch. Common in younger people and rarely dangerous, but distressing. It can often be cured permanently by a catheter ablation.
Ventricular arrhythmias
Arising from the lower chambers, these are the serious ones. They usually occur in a heart already damaged by a previous heart attack or by a weakened muscle. They may cause collapse or cardiac arrest. Any palpitation associated with fainting demands urgent assessment.
Bradycardia — too slow
A rate persistently below fifty may be entirely normal in a trained athlete. In an older person with dizziness, fatigue or blackouts, it may reflect conduction disease and sometimes needs a pacemaker.
Red flags — when palpitations need urgent attention
Seek same-day medical assessment for palpitations accompanied by:
- Fainting or near-fainting
- Chest pain or pressure
- Severe breathlessness
- A completely irregular pulse that does not settle
- Palpitations in someone with known heart disease or a weakened heart muscle
- A family history of sudden unexplained death below the age of fifty
By contrast, brief flutters in an otherwise healthy person with a normal ECG, occurring after coffee or a poor night’s sleep, can reasonably be discussed at a routine appointment.
How it is investigated
The central difficulty is capturing the rhythm while it is happening. A normal ECG in the clinic does not exclude an arrhythmia that occurs twice a month.
- ECG — a snapshot; useful if symptoms are present at the time
- Holter monitor — continuous recording for 24 to 72 hours
- Event or patch monitor — worn for one to four weeks, better for infrequent episodes
- Echocardiogram — to determine whether the heart is structurally normal, which largely determines how worried to be
- Blood tests — thyroid function, haemoglobin, potassium and magnesium, all of which can provoke arrhythmia
- Smartwatch recordings — increasingly useful. If your watch flags an irregular rhythm, save the tracing and take it to your doctor rather than dismissing it.
What you can do
- Reduce caffeine — including strong tea — and alcohol. Alcohol is a well-recognised trigger for atrial fibrillation.
- Protect your sleep. Sleep deprivation and untreated sleep apnoea are major and reversible drivers.
- Treat blood pressure. Long-standing hypertension stretches the atrium and is the commonest route into atrial fibrillation.
- Check for thyroid overactivity and anaemia — both are easily missed and easily corrected.
- Review stimulants: some decongestants, asthma inhalers, weight-loss preparations and unregulated supplements provoke palpitations.
- Keep a simple diary — time, duration, what preceded it, and whether the pulse was regular or irregular. Feel your own pulse during an episode; that single observation is often more useful than a description.
What to ask your doctor
- Is my heart structurally normal on an echocardiogram?
- Have my thyroid, haemoglobin, potassium and magnesium been checked?
- If I have atrial fibrillation, what is my stroke risk score, and should I be on an anticoagulant rather than aspirin?
- Would a longer-duration monitor be more likely to capture my episodes?
- Is my arrhythmia one that could be cured by ablation?
Emergency: call 108 or go to the nearest hospital. Do not use this website.
This guide is educational and does not replace a consultation with your own doctor.
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