Atrial flutter, 1:1 conduction
Every flutter wave conducts. Here a slower flutter in large atria, and sympathetic drive that speeds the AV node, give a ventricular rate of about 200. It is an emergency.
On the trace
- Measure the ventricular rate. About 200 per minute, regular, R-R 301 ms.
- Count the flutter waves for each QRS. One. Every wave conducts, so the sawtooth is hidden in the QRS and T.
- Measure the flutter cycle. 301 ms: about 200 per minute, slower than typical flutter. Large, fibrosed atria give the wave a longer circuit and slow it.
- Measure the QRS. 96 ms, narrow. At 1:1 the QRS can widen, and the rhythm then looks like VT.
Telling it apart
| 2:1 | 1:1 | |
|---|---|---|
| Flutter rate | 300 | About 200 |
| Ventricular rate | 150 | About 200 |
| Flutter waves for each QRS | Two | One |
| Sawtooth | One wave visible between beats | Hidden in the QRS and T |
What it means
The AV node follows every flutter wave. It needs a slower flutter (from large atria or a class IC drug) and a node that recovers quickly (sympathetic drive, from exertion or illness). The rate can cause collapse. Do synchronised cardioversion if the patient is unstable. Otherwise give an AV nodal blocker.
Full articleAtrial FlutterHow to recognise it, why it happens, what it means and what to do.