Overview

Atrial flutter (AFL) is a type of re-entrant supraventricular tachycardia characterised by a rapid atrial rate of around 300 bpm and a ventricular rate that may be fixed or variable. AFL is the second most common arrhythmia after atrial fibrillation.

Pathophysiology

The atrial rate is generally around 300 bpm and the ventricular rate may be around 150 bpm. This is because the atrioventricular (AV) node ‘blocks’ atrial impulses which results in slower ventricular rates. This is generally an atrial rate:ventricular rate ratio of 2:1 (e.g. 300 bpm atrial rate results in a 150 bpm ventricular rate), however, this depends on the refractory period of the AV node.

Some people with accessory pathways e.g. Wolff-Parkinson-White syndrome may allow the re-entrant signal to bypass the AV node leading to a 1:1 flutter – where the ventricular rate is 300bpm as well, which may progress to ventricular fibrillation (VF).

Presentation

Some patients may present with haemodynamic instability. These patients need urgent emergency care:

  • Acute heart failure:
  • Cardiogenic shock:
    • Tachycardia (>150 bpm) and hypotension (systolic blood pressure <90 mmHg)
  • Syncope/pre-syncope
  • Cardiac chest pain and shortness of breath

Investigations

Overview

  • ECG:
    • Diagnoses AFL and shows flutter waves which are a sawtooth pattern most prominent in leads II, III, and aVF
  • Holter (ambulatory ECG) monitoring:
    • If the ECG fails to show AFL

Figure 1: An ECG showing atrial flutter

Management

Overview

Management is essentially the same as atrial fibrillation including rate control, rhythm control, and reduction of stroke risk. AFL is generally more sensitive to cardioversion and radiofrequency ablation may be curable for many patients.

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