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Atrial Flutter

caution
Lead II
25 mm/s10 mm/mV
Heart rate
72bpm
RR
833ms
QT
328ms
Conduction Ratio

Ventricular rate: 75 BPM

Atrial Flutter

A macro-re-entrant circuit in the right atrium producing organized atrial depolarization at ~300/min. The AV node typically conducts every 2nd flutter wave, giving a ventricular rate of ~150 bpm.

Recognition· 4
  • Sawtooth flutter waves (F-waves)
  • Regular rhythm (if fixed conduction)
  • Atrial rate ~300/min
  • Ventricular rate often ~150 bpm (2:1 block)
Mechanism

Circular re-entry in right atrium fires at 300/min — AV node blocks some impulses

A macro-re-entrant circuit travels around the tricuspid valve in the right atrium at ~300/min. The AV node cannot conduct this fast, so it blocks some flutter waves. With 2:1 conduction (every 2nd wave conducted), ventricular rate is 150 bpm. Other ratios: 3:1 (100 bpm), 4:1 (75 bpm).

Findings· 3
  • Regular rhythm (if fixed conduction ratio).
  • Sawtooth flutter waves (F-waves) best seen in leads II, III, aVF.
  • Ventricular rate often ~150 bpm (2:1 block).
Clinical Impact
Stroke risk (similar to atrial fibrillation)
↓
Heart failure if prolonged rapid rate
↓
Can degenerate to atrial fibrillationRISK

Similar to A-fib — stroke risk requires anticoagulation

Management· 3
1

Primary Treatment

Rate control or cardioversion (chemical or electrical).

2

Additional Options

Catheter ablation of cavotricuspid isthmus highly effective (>90% cure).

3

Long-term Management

Anticoagulation based on CHA₂DS₂-VASc score.

Differential· 2
Atrial Fibrillation

Both lack discrete P waves. Flutter has organized sawtooth waves vs chaotic fibrillatory baseline.

Sinus Tachycardia

2:1 flutter at ~150 bpm mimics sinus tachy. Adenosine unmasks flutter waves.