Atrial Fibrillation (RVR)
Atrial Fibrillation (RVR)
Atrial fibrillation with a rapid ventricular response: irregularly irregular, ventricular rate over 100 bpm.
On the trace
The atrial picture is that of any AFib: no P waves, a restless fibrillatory baseline, a narrow QRS. What the rapid rate changes is the one thing that gives the diagnosis away.
- The ventricular rate is over 100.
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152 bpm here, commonly 110 to 170. The AV node is conducting freely, so far more impulses reach the ventricles than in controlled AFib. - The irregularity gets harder to see the faster it goes.
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Here consecutive R-R intervals differ by 83 ms on average, against 380 ms in controlled AFib. Same rhythm, but at speed the differences shrink until it can look almost regular, which is how rapid AFib gets mislabelled as an SVT. - March out several intervals before you commit.
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They still run from 308 to 788 ms, and they still never settle into a repeating pattern.
How to recognise it
| Feature | Value | Notes |
|---|---|---|
| Rhythm | Irregularly irregular | Still the defining feature, but subtle at speed. If it looks regular, measure before you commit. |
| P waves | Absent | Fibrillatory baseline, unchanged from controlled AFib. |
| Ventricular rate | Over 100 bpm | 152 here, commonly 110 to 170. The only thing that separates it from controlled AFib. |
| QRS | Narrow (under 120 ms) | A wide, fast, irregular rhythm is pre-excited AF: a different and more dangerous problem. |
The strip
Management
Unstable: cardiovert
Hypotension, ischaemic chest pain, acute heart failure or altered mental state: synchronised cardioversion now. The rate is what is decompensating the patient, so the rate is what you fix first.
Stable: rate control
An AV-nodal blocker to slow conduction: a beta-blocker or a non-dihydropyridine calcium-channel blocker (diltiazem, verapamil); digoxin where those are poorly tolerated. Never block the node in pre-excited AF, because it pushes conduction down the accessory pathway.
Rate control treats the symptom the speed is causing; it does nothing for the stroke risk, which is decided separately and is unchanged from any other AFib.