Arrhythmias

Specialties > General practice

Background knowledge 🧠

Definition

Arrhythmias are abnormalities in the rate, rhythm, or sequence of cardiac electrical activity.
They can be classified based on their origin (e.g., atrial, ventricular) and the speed of the heart rate (e.g., tachyarrhythmia, bradyarrhythmia).
Clinical significance varies from benign to life-threatening conditions.

Epidemiology

Arrhythmias are common, affecting millions worldwide.
Prevalence increases with age, particularly after 60.
Atrial fibrillation (AF) is the most common arrhythmia.
Higher prevalence in patients with cardiovascular diseases.
Men are more frequently affected than women.

Aetiology and Pathophysiology

Coronary artery disease, myocardial infarction.
Electrolyte imbalances (e.g., hypokalemia, hyperkalemia).
Structural heart disease (e.g., cardiomyopathy).
Medication side effects (e.g., digoxin, beta-blockers).
Congenital heart defects.
Autonomic nervous system influences.

Types

Supraventricular arrhythmias: Atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT).
Ventricular arrhythmias: Ventricular tachycardia, ventricular fibrillation.
Bradyarrhythmias: Sinus bradycardia, AV block.
Pre-excitation syndromes: Wolff-Parkinson-White (WPW) syndrome.
Others: Long QT syndrome, Torsades de Pointes.

Clinical Features 🌡️

Symptoms

Palpitations: Sensation of rapid, irregular, or forceful heartbeats.
Dizziness or lightheadedness.
Syncope or near-syncope.
Fatigue or weakness.
Dyspnoea, especially on exertion.
Chest discomfort or pain.
Asymptomatic in some cases, especially in bradyarrhythmias.

Signs

Irregular pulse, often irregularly irregular in AF.
Tachycardia or bradycardia on examination.
Hypotension, especially in severe cases.
Heart sounds may reveal a variable S1 or absence of a P wave.
Signs of underlying conditions (e.g., heart failure, myocardial infarction).

Investigations 🧪

Tests

ECG: First-line test to diagnose arrhythmias.
Holter monitor: 24-48 hour ECG monitoring for intermittent arrhythmias.
Echocardiogram: Assess structural heart disease.
Blood tests: U&Es, thyroid function, troponin.
Electrophysiological studies (EPS): For complex arrhythmias or pre-ablation.
Tilt-table test: Assess vasovagal syncope or autonomic dysfunction.

Management 🥼

Management

Pharmacological: Beta-blockers, calcium channel blockers, antiarrhythmics (e.g., amiodarone).
Non-pharmacological: Cardioversion, catheter ablation, pacemaker insertion.
Lifestyle modification: Address risk factors (e.g., smoking cessation, weight loss).
Anticoagulation: For stroke prevention in AF (e.g., warfarin, DOACs).
Management of underlying conditions (e.g., coronary artery disease).

Complications

Stroke, particularly in AF.
Heart failure, especially with persistent tachyarrhythmias.
Sudden cardiac death in severe ventricular arrhythmias.
Thromboembolism.
Medication side effects (e.g., bradycardia, hypotension).
Psychological impact (e.g., anxiety, depression).

Prognosis

Prognosis varies widely depending on the type and underlying cause.
AF: Increased mortality, particularly due to stroke and heart failure.
Ventricular arrhythmias: High risk of sudden cardiac death.
Bradyarrhythmias: Generally good with appropriate pacing.
Close monitoring and regular follow-up are essential.

Key Points

Arrhythmias are common and range from benign to life-threatening.
Timely diagnosis and management are crucial to prevent complications.
ECG is the cornerstone of diagnosis.
Management often requires a combination of pharmacological and non-pharmacological strategies.
Regular follow-up and risk factor management are key to improving outcomes.

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