Arrhythmias, Palpitations & Syncope
Identify unstable rhythms and distinguish transient loss of consciousness from seizure and other mimics.
Quick revision ↓ Medical Dictionary
01Stability before rhythm detail
Palpitations with hypotension, ongoing ischaemic chest pain, shock or severe heart failure require immediate monitored assessment. Obtain an ECG and involve the emergency team; do not delay treatment of an unstable rhythm to complete a detailed history. For a stable patient, describe rate, regularity, QRS width and the relationship between atrial and ventricular activity before choosing a likely rhythm.
02Atrial fibrillation decisions
An irregularly irregular pulse suggests atrial fibrillation but needs ECG confirmation. Look for infection, thyroid disease, alcohol exposure and structural heart disease. Management considers symptom control, rate or rhythm strategy and stroke prevention. Anticoagulation depends on thromboembolic risk, bleeding considerations, renal function and contraindications rather than symptoms alone. Cardioversion planning must account for duration and thrombus risk when the patient is stable.
03Broad-complex tachycardia
A broad-complex tachycardia can be ventricular tachycardia or a supraventricular rhythm with abnormal conduction. In an uncertain adult presentation, especially with structural heart disease, treat it as potentially ventricular and seek expert help. Some drugs suitable for one rhythm can be dangerous in another. Capture the ECG if feasible without delaying urgent intervention, and review potassium, magnesium, ischaemia and drug effects.
04Evaluate syncope
Syncope is transient loss of consciousness from reduced cerebral perfusion with spontaneous recovery. Ask about posture, exertion, prodrome, palpitations, witness observations and recovery. Exertional or supine episodes, cardiac disease, an abnormal ECG and a family history of sudden death raise concern. Orthostatic measurements and medicine review can reveal contributory hypotension, but a plausible benign trigger does not cancel major cardiac red flags.
05Monitoring and prevention
Intermittent symptoms may need ambulatory rhythm monitoring matched to their frequency. A normal resting ECG cannot exclude every episodic arrhythmia. Review QT-prolonging drugs, electrolytes and reversible triggers. Discuss driving and occupational safety through current local rules and the responsible clinician. Document the next investigation, warning symptoms and follow-up ownership, especially when the cause of collapse remains uncertain.
High-Yield Revision
- Haemodynamic instability determines urgency.
- Confirm atrial fibrillation with an ECG.
- Unexplained exertional syncope needs cardiac assessment.
Common Pitfalls
- Do not assume a normal resting ECG excludes intermittent arrhythmia.
- Do not choose a rate-control drug without considering rhythm type and haemodynamic status.
References & Further Reading
Read the relevant guideline sections alongside these original clinical teaching cases. Local pathways, available services and individual patient factors determine care.
Reference review: 27 September 2026. Consult current local protocols for prescribing, procedures and escalation.