Heart rhythm problems, from palpitations to pacing and ablation.

• Family 1 · Supraventricular

  Rhythms starting above the ventricles

  The commonest is atrial fibrillation, an irregular rhythm that raises stroke risk. Others include atrial flutter, AVNRT, AVRT (including Wolff-Parkinson-White) and focal atrial tachycardia. Many are curable with catheter ablation.

• Family 2 · Ventricular

  Rhythms starting in the ventricles

  Ventricular tachycardia and ventricular fibrillation are the most dangerous arrhythmias and the usual mechanism of cardiac arrest. Frequent ventricular ectopy is common and usually benign but occasionally warrants investigation.

• Family 3 · Bradycardia

  Rhythms that are too slow

  Sinus bradycardia, sinus node disease and heart block at first, second or third degree. Symptomatic bradycardia and complete heart block are usually treated with a pacemaker.

• Family 4 · Inherited electrical

  Genetic arrhythmia syndromes

  Long QT syndrome, Brugada syndrome, catecholaminergic polymorphic VT (CPVT) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Managed in specialist commissioned inherited cardiac conditions clinics with genetic testing and family screening.

• Family 5 · Sudden cardiac death risk

  People with a high risk of a life-threatening arrhythmia

  Not a separate diagnosis but a risk category running across the other families. Survivors of cardiac arrest, people with severe heart failure and those with inherited high-risk conditions are considered for an implantable defibrillator - transvenous or subcutaneous - and detailed family screening.

• Palpitations

  A conscious awareness of the heartbeat - fluttering, pounding, skipped or racing. See our dedicated guide on heart palpitations for detail.

• Dizziness and pre-syncope

  Light-headedness on standing or during exertion often reflects an inadequate cardiac output from a fast or slow rhythm.

• Syncope

  A sudden loss of consciousness, especially without warning or during exercise, is a red flag for a serious arrhythmia. See our fainting guide.

• Breathlessness

  Dyspnoea at rest or on exertion can be the dominant symptom in AF and in tachycardia-mediated cardiomyopathy.

• Chest pain or tightness

  Palpitations with chest pain need urgent assessment to exclude ischaemia and dangerous ventricular rhythms.

• Fatigue and exercise intolerance

  Bradycardia and persistent AF often present as tiredness or a drop in usual exercise capacity, not as a racing heart.

• Cardiac arrest

  The most extreme presentation - see our cardiac arrest guide. Survivors are worked up for inherited and structural causes.

• Red flag - exertional syncope

  Fainting during exercise, a family history of sudden death, or syncope after a loud noise deserves urgent specialist referral.

For a symptom-focused view, see our patient guides to heart palpitations and fainting (syncope).

• Exertional or unwarned syncope

  Fainting during exercise, or with no warning, can be the first sign of a life-threatening ventricular arrhythmia. Urgent cardiology referral.

• Family history of sudden death

  Sudden cardiac death in a first-degree relative under 40 warrants specialist inherited cardiac conditions review and family screening.

• Wide-complex tachycardia

  Any broad-complex tachycardia on ECG is treated as ventricular tachycardia until proven otherwise. Emergency admission.

• Palpitations with chest pain

  Palpitations combined with ischaemic-sounding chest pain need same-day assessment to exclude acute coronary syndrome and unstable VT.

• Complete heart block

  Third-degree AV block with bradycardia, syncope or haemodynamic compromise usually needs urgent pacing.

• New atrial fibrillation

  Any newly detected AF should be assessed for stroke risk and started on anticoagulation where indicated - a stroke is the first presentation for many.

• Prolonged QT on ECG

  A QTc above 500 ms - or a shorter one on a QT-prolonging drug - raises the risk of torsades de pointes. Review medication and refer.

• Cardiac arrest survivor

  Any survivor of an out-of-hospital cardiac arrest needs a full electrical and structural work-up before discharge.

• Brugada or ARVC pattern

  Characteristic ECG patterns even without symptoms deserve specialist review and family screening.