Sustained torsades de pointes
The same patient and the same start, but the run does not stop. Without a pulse it is a cardiac arrest: defibrillate.
On the trace
- Measure the QT on the sinus beats. The same as in the non-sustained form: QTc about 670 ms.
- Find the start. The same short-long-short sequence, about five seconds into the recording, and a premature beat at a coupling interval of about 490 ms.
- Watch the run. It twists as before, at about 260 per minute, and does not stop: the finished sheet is all torsades.
Telling it apart
| Non-sustained | Sustained | |
|---|---|---|
| QT before it | QTc about 670 ms | The same |
| Start | Short-long-short | The same |
| Run | Stops after about 4 s | Does not stop |
| Patient | Palpitations, syncope | Cardiac arrest without a pulse |
What it means
A run of torsades that does not stop, without a pulse, is a cardiac arrest: give an unsynchronised shock. A run can also degenerate into ventricular fibrillation. After the shock, prevent the next run: magnesium, potassium to the high-normal range, stop the QT-prolonging drug, and pacing for pauses.
Full articleTorsades de PointesHow to recognise it, why it happens, what it means and what to do.