Form of supraventricular tachycardia characterised by a succession of rapid atrial depolarisation waves

Aetiology

• More likely to occur with pulmonary disease e.g. COPD, obstructive sleep apnoea, PE, pulmonary hypertension
• Other causes include: ischaemic heart disease, cardiomyopathy, thyroxytosis, sepsis, alcohol

Pathophysiology

• Usually paroxysmal
• Aberrant macro re-entry circuit within the right atrium which cycles at 300bpm
• Not all P waves make it to the ventricles so the atria ‘flutter’

Clinical features

• Mostly asymptomatic
• Less commonly symptoms of arrhythmias → palpitations, dizziness, chest pain

Investigations

ECG

• Rhythm: regular, may be variable
  • Variable block makes the rhythm appear irregular and can be hard to distinguish from AF
• P wave: saw tooth ‘F’ wave
• QRS: narrow
• Rate: atrial 300 bmp, ventricular rate depends on the level of AV block (150 bmp in 2:1 AV block - most common)

Management

Management in haemodynamically unstable patients