EMS Registry ReadyExample 1 · lead II · 6 seconds
- Rate
- 121/min12 QRS complexes in 6 seconds × 10 = 120/min
- Rhythm
- Regular
- P waves
- Inverted in II, just after each QRS
- P to QRS
- Each inverted P comes just after its QRS
- PR
- None to measure
- QRS
- 0.09 s, narrow
Junctional tachycardia on an ECG strip
A regular narrow-complex rhythm over 100/min from the AV junction: no sinus P waves, and the P that is there is inverted in II with a PR under 0.12 s, or comes just after the QRS.
What to look for
The junction is firing faster than 100/min. That's past an escape rhythm (40-60) and past accelerated junctional (60-100). The QRS is narrow, the rhythm regular, and there's no upright sinus P. The P you do see is inverted in II, either just before the QRS with a PR under 0.12 s or just after it. Vagal maneuvers and adenosine don't convert it the way they convert AVNRT, so look for the cause: catecholamines, digoxin, ischemia.
Examples
Each strip is 6 seconds of lead II, drawn to scale (25 mm a second, 10 mm a millivolt), so you can count boxes the way you would on paper. Each one is a different example, measured below it.
Example 2 · lead II · 6 seconds
- Rate
- 112/min11 QRS complexes in 6 seconds × 10 = 110/min
- Rhythm
- Regular
- P waves
- Inverted in II, just after each QRS
- P to QRS
- Each inverted P comes just after its QRS
- PR
- None to measure
- QRS
- 0.09 s, narrow
Example 3 · lead II · 6 seconds
- Rate
- 113/min12 QRS complexes in 6 seconds × 10 = 120/min
- Rhythm
- Regular
- P waves
- Inverted in II, just before each QRS
- P to QRS
- Each inverted P comes just before its QRS, too close to have conducted it (PR under 0.12 s)
- PR
- None to measure
- QRS
- 0.10 s, narrow
Don't confuse it with
- Supraventricular tachycardia (AVNRT)
Regular, narrow and 150-250/min, with no visible P waves.
- Focal atrial tachycardia
A regular narrow tachycardia over 100/min whose P waves aren't sinus: one abnormal shape (here inverted in II), every P alike, each with a PR of 0.12 s or more and a flat baseline between.
- Accelerated junctional rhythm
A regular narrow-complex rhythm at 60-100/min with no upright P waves: the junction firing faster than an escape would.
- Sinus tachycardia
Sinus rhythm over 100/min: regular, with an upright P before every QRS.
Want a new strip every time? The ECG Drill in the app draws a fresh, measured example on every try and steers you toward the rhythms you miss. It's part of the Paramedic level, and you can try 5 strips a day free.
Try the ECG DrillWhere the criteria come from
- LITFL: Accelerated junctional rhythm ajr
- LITFL: Junctional escape rhythm
- LITFL: Premature junctional complex (PJC)