EMS Registry Ready

Multifocal atrial tachycardia on an ECG strip

Irregular, over 100/min, with three or more different P-wave shapes and a PR that varies.

What to look for

A fast, irregularly irregular rhythm over 100/min. Look for at least three different P-wave shapes in the same lead, varying P-P, PR and R-R intervals, and a flat baseline between the P waves (no flutter waves). No single atrial pacemaker is in charge. You'll usually see it in very sick patients, often with COPD.

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 1 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
140/min14 QRS complexes in 6 seconds × 10 = 140/min
Rhythm
Irregularly irregular
P waves
Three or more shapes in II, changing from beat to beat
P to QRS
1:1, each P conducted, each with its own PR
PR
Changes beat to beat, 0.14 s to 0.20 s
QRS
0.09 s, narrow
Example 2 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
134/min13 QRS complexes in 6 seconds × 10 = 130/min
Rhythm
Irregularly irregular
P waves
Three or more shapes in II, changing from beat to beat
P to QRS
1:1, each P conducted, each with its own PR
PR
Changes beat to beat, 0.12 s to 0.18 s
QRS
0.08 s, narrow
Example 3 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
128/min12 QRS complexes in 6 seconds × 10 = 120/min
Rhythm
Irregularly irregular
P waves
Three or more shapes in II, changing from beat to beat
P to QRS
1:1, each P conducted, each with its own PR
PR
Changes beat to beat, 0.14 s to 0.20 s
QRS
0.08 s, narrow

Don't confuse it with

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 Drill

Where the criteria come from

Others in the Atrial group