Arrhythmias: abnormal heart rhythms

Understanding arrhythmias

An arrhythmia is any heartbeat that is not following the heart's normal rhythm — too fast, too slow, or irregular. This page is a starting point: it explains how the heart's electrical system normally works, the main families of rhythm problems, and how Cardiocare approaches them, then links on to a dedicated guide for each specific rhythm.

Each heartbeat begins as a tiny electrical signal from the heart's natural pacemaker (the sinus node, in the right upper chamber), spreads across the two upper chambers (the atria), passes through a relay point (the AV node), and then spreads through the two lower chambers (the ventricles), making them contract and pump blood out to the lungs and body. At rest this normally happens 60 to 100 times a minute, faster with exercise or emotion. An arrhythmia happens when this electrical pathway misfires — a signal starts in the wrong place, travels too fast, is delayed, or does not arrive at all.

The main families of rhythm problem

Arrhythmias are usually grouped by where they start and what they do to the heart rate. Some are common and harmless; others need urgent treatment — the type matters far more than simply "fast" or "slow."

Too fast (tachycardias)

• ●Atrial fibrillation — the most common sustained arrhythmia, where the upper chambers quiver rapidly and irregularly instead of contracting normally, raising stroke risk
• ●Atrial flutter — a fast, organised electrical circuit in the upper chambers, related to atrial fibrillation and carrying similar risks
• ●Supraventricular tachycardia (SVT) — a short-circuit in the upper electrical pathways causing sudden, fast, regular episodes that often start and stop abruptly
• ●Ventricular arrhythmias — an electrical problem starting in the lower chambers; less common, and more likely to need urgent attention because they can affect the heart's pumping directly

Too slow (bradycardias)

The sinus node can fire too slowly, or the signal can be delayed or blocked on its way to the ventricles (a "conduction block"). Some slow rhythms are normal, particularly in fit, young or sleeping people; others cause dizziness, fainting or breathlessness and may need a pacemaker.

Extra or skipped beats (ectopic beats)

An extra heartbeat fires early, is often felt as a "skip" or a thud, and — occurring on their own in an otherwise healthy heart — is usually harmless.

If you already know, or suspect, which type of arrhythmia you have, our dedicated guides go into more depth: read about palpitations if you are trying to describe what you feel, atrial fibrillation for the most common sustained rhythm problem, or pacemakers and ICDs for how slow or dangerous rhythms are treated with a device.

What an arrhythmia may feel like

People experience rhythm problems differently, and some cause no symptoms at all. These are useful clues to discuss with a clinician, not a checklist for diagnosing yourself.

• ●Palpitations — fluttering, racing, pounding or skipping sensations in the chest, throat or neck
• ●A pulse that feels unusually slow, unusually fast, or irregular when you check it
• ●Dizziness, light-headedness, fainting or a near-fainting "about to black out" feeling
• ●Breathlessness, chest discomfort, or fatigue and reduced exercise capacity
• ●No symptoms at all — some arrhythmias, including some episodes of atrial fibrillation, are found only on a routine ECG or device check

What causes arrhythmias

Arrhythmias can start inside the heart's own tissue or be triggered by a problem elsewhere in the body.

• ●Structural heart disease — a prior heart attack, heart failure or valve problem changes the tissue the electrical signal travels through
• ●High blood pressure — over years, strains the heart and alters its electrical behaviour
• ●Thyroid disease — an overactive thyroid speeds up the whole body, including heart rate and rhythm
• ●Electrolyte imbalance — abnormal potassium or magnesium levels disturb the heart's electrical signalling
• ●Stimulants and substances — caffeine, alcohol, nicotine and some stimulant medicines or herbal products
• ●Ageing of the heart's own electrical system, independent of other heart disease

Who is more likely to develop an arrhythmia

• ●High blood pressure — very common in Nigeria and often undiagnosed
• ●Diabetes
• ●Existing structural heart disease, such as a prior heart attack or valve problem
• ●Thyroid disease
• ●Anaemia — common in Nigeria, it forces the heart to work harder
• ●A family history of rhythm problems or sudden cardiac events
• ●Increasing age
• ●Heavy or binge alcohol use

What happens if an arrhythmia goes untreated

The seriousness of an untreated arrhythmia depends heavily on which type it is — this is why an accurate diagnosis, not just "an irregular heartbeat," matters so much.

Stroke. In atrial fibrillation and atrial flutter, blood can pool and clot in the quivering upper chambers; a clot that breaks free can travel to the brain and cause a stroke.

Heart failure. A rhythm that stays abnormally fast for weeks or months, if unrecognised, can gradually weaken the heart's pumping ability.

Fainting and injury. Some rhythm problems briefly reduce blood flow to the brain, risking falls, particularly while driving or working at height.

Cardiac arrest. Rarely, a dangerous ventricular arrhythmia can stop the heart pumping effectively — uncommon, and far more likely with significant underlying heart disease. See our guide to recognising and responding to cardiac arrest.

How Cardiocare investigates an arrhythmia

The exact pathway depends on symptoms, examination, previous results and overall health. It typically draws on some or all of the following:

• 01
  History and examination. When episodes happen, how long they last, what brings them on, plus an examination of your heart, pulse and blood pressure.
• 02
  12-lead ECG. A painless recording of the heart's electrical activity from pads on the chest and limbs, taking minutes.
• 03
  Holter or extended rhythm monitoring. A portable ECG recorder worn for a day or longer, since the test must be worn when the symptom happens to catch it.
• 04
  Echocardiogram. A painless ultrasound scan showing the heart's structure and pumping, to look for an underlying cause.
• 05
  Laboratory tests. Thyroid function, electrolytes and a full blood count help rule out non-cardiac triggers.
• 06
  Electrophysiology (EP) study or device assessment. For selected complex cases, a catheter-based test maps the heart's electrical pathways; for patients with an existing pacemaker or ICD, device interrogation reviews recorded rhythm data directly.

How arrhythmias are treated

Treatment is matched to the specific arrhythmia and its cause — there is no single treatment for "an arrhythmia" as such.

Medicines, by class

Where medicine is used, it is chosen by what it does; your clinician will discuss the right option for your specific rhythm:

• ●Beta blockers — slow and steady the heart rate
• ●Rhythm-control medicines — help keep the heart in, or restore it to, a normal rhythm
• ●Anticoagulants (blood thinners) — prevent the clots that can lead to stroke in atrial fibrillation and atrial flutter

Procedures and devices

Available through Cardiocare's on-site cardiac catheterisation ("cath") laboratory:

• ●Cardioversion — a controlled electrical shock, under sedation, that resets the heart to a normal rhythm
• ●Catheter ablation — while sedated, thin catheters are guided through a vein, usually from the groin, to treat the tissue causing the abnormal rhythm
• ●Pacemakers — for rhythms that are too slow, an implanted device paces the heart to keep it regular
• ●Implantable defibrillators (ICDs) — for selected patients at risk of dangerous fast ventricular rhythms, a device that can detect and treat them automatically

Living with an arrhythmia

• ✓Take anticoagulants or rhythm medicines exactly as prescribed, even when you feel well
• ✓Attend every scheduled device check if you have a pacemaker or ICD — see living with a pacemaker for day-to-day guidance
• ✓Record symptoms and, where possible, your pulse when episodes happen
• ✓Limit caffeine and alcohol if they trigger your symptoms, and protect your sleep
• ✓Ask your clinician which specific symptoms mean you should seek urgent review for your particular rhythm

Preparing for your appointment

What to bring

• ✓A list of all medicines you take, including herbal and over-the-counter preparations
• ✓Any previous ECGs, Holter reports or device-check summaries
• ✓Your HMO card or payment details
• ✓A valid means of identification

What we will ask

When symptoms started, how often they happen, how long episodes last, what triggers them, and any family history of rhythm problems or sudden cardiac events.

Questions worth asking us

• ●Which type of arrhythmia do I have, and what does it mean for me?
• ●Do I need treatment for stroke prevention?
• ●Will I need a device, and what would that involve?
• ●What symptoms mean I should come back urgently?