Atrial Flutter

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Patient Advice

Definition

Atrial Flutter is an abnormal heart rhythm (arrhythmia) originating in the upper chambers of the heart (atria). It is characterised by a rapid and regular atrial rate, typically around 250–350 beats per minute, leading to an irregular or fast pulse.

Aetiology

Common causes of atrial flutter include:

• Heart Conditions: E.g., ischaemic heart disease, heart failure, or valvular heart disease.
• Hypertension: Long-standing high blood pressure.
• Thyroid Disorders: Particularly hyperthyroidism.
• Lung Diseases: Chronic obstructive pulmonary disease (COPD) or pulmonary embolism.
• Post-Surgery: Common after cardiac surgery.
• Alcohol Consumption: Particularly binge drinking ("holiday heart syndrome").

Pathophysiology

Atrial flutter occurs due to abnormal electrical activity in the atria:

• Re-entry Circuit: A continuous electrical loop within the atria causes rapid and repetitive atrial contractions.
• Ventricular Response: The atrioventricular (AV) node limits how many atrial signals reach the ventricles, often resulting in a 2:1 conduction ratio (e.g., atrial rate of 300 bpm with a ventricular rate of 150 bpm).
• This inefficient pumping reduces cardiac output and may lead to blood pooling in the atria, increasing the risk of clots.

Risk Factors

Risk factors include:

• Ageing, as atrial flutter is more common in older adults.
• Existing heart conditions, such as heart failure or coronary artery disease.
• High blood pressure.
• Thyroid disorders, particularly overactive thyroid (hyperthyroidism).
• Lung diseases like COPD or pulmonary embolism.
• Alcohol consumption or binge drinking.

Signs and Symptoms

Symptoms of atrial flutter include:

• Palpitations: Feeling of a fast or irregular heartbeat.
• Fatigue: Due to reduced cardiac output.
• Shortness of Breath: Especially on exertion.
• Dizziness or Lightheadedness: Due to reduced blood flow to the brain.
• Chest Discomfort: Rarely, this may mimic angina.
• Stroke Symptoms: Sudden weakness or difficulty speaking, if clots form and embolise.

Investigations

Key investigations include:

• Electrocardiogram (ECG):
  • Shows a "sawtooth" pattern of flutter waves, especially in leads II, III, and aVF.
  • May show a regular or irregular ventricular rhythm, depending on AV node conduction.
• Blood Tests:
  • Thyroid Function Tests: To rule out hyperthyroidism.
  • Electrolytes: To detect abnormalities like low potassium or magnesium.
• Echocardiography: To assess heart structure and rule out underlying valvular or structural abnormalities.
• 24-hour Holter Monitoring: To capture intermittent episodes of atrial flutter.

Management

1. Rate Control

• Beta-blockers: E.g., bisoprolol to slow the heart rate.
• Calcium Channel Blockers: E.g., diltiazem, particularly if beta-blockers are not suitable.

2. Rhythm Control

• Electrical Cardioversion: A controlled shock delivered to restore normal rhythm, particularly in unstable patients.
• Antiarrhythmic Drugs: E.g., amiodarone, used under specialist guidance to maintain sinus rhythm.

3. Anticoagulation

• Anticoagulants (e.g., apixaban, rivaroxaban) to reduce the risk of stroke in patients with a CHA₂DS₂-VASc score ≥2.

4. Specialist Referral

• Referral for catheter ablation, which targets and disrupts the re-entry circuit, may be considered for recurrent or symptomatic atrial flutter.

Patient Advice

Key advice includes:

• Take prescribed medications consistently to manage symptoms and reduce complications.
• Adopt a heart-healthy lifestyle, including a balanced diet and regular exercise.
• Avoid excessive alcohol consumption, which can trigger atrial flutter.
• Seek urgent medical attention if symptoms such as severe breathlessness or chest pain occur.