If The Patient Is Stable
If the patient is stable, you can ask:
- Is the tachycardia narrow (QRS <120 ms or three small squares on the ECG) or broad complex (QRS >120 ms)?
- Is the tachycardia regular or irregular?
These questions allow you to subdivide the rhythms into four categories (regular narrow complex/ irregular narrow complex/ regular broad complex/ irregular broad complex).
