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Atrial Fibrillation (RVR)

caution
Lead II
25 mm/s10 mm/mV
HR
72
bpm
RR
833
ms
QT
328
ms
Type

Atrial Fibrillation (RVR)

Atrial fibrillation in which the AV node conducts freely, driving a rapid ventricular rate (>100 bpm). The atrial activity is identical to controlled AFib — only the ventricular response is fast.

Recognition· 4
  • Irregularly irregular rhythm
  • No P waves (fibrillatory baseline)
  • Narrow QRS, ventricular rate >100 bpm
  • Irregularity is subtle at fast rates — don't call it SVT
Mechanism

Same chaotic atria — but the AV node lets lots of impulses through

The atria fire chaotically at 350-600/min as in any AFib. Here the AV node conducts freely (sympathetic drive, no rate-control drug), passing many impulses to the ventricles and producing a rapid, irregularly irregular ventricular rate.

Findings· 2
  • Irregularly irregular, no discrete P waves (fibrillatory baseline), narrow QRS, ventricular rate >100 bpm (often 110–170).
  • At fast rates the irregularity can be subtle and is easily mistaken for a regular SVT.
Clinical Impact
Palpitations, dyspnoea, chest pain
↓
Hypotension / demand ischaemia at very fast rates
↓
Stroke risk unchanged from any AFibRISK

Fast + irregular → symptoms → rate control or cardiovert if unstable

Management· 2
1

Unstable

synchronised cardioversion.

2

Stable

AV-nodal rate control (beta-blocker, diltiazem/verapamil); anticoagulation per CHA₂DS₂-VASc.