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Pacemaker failure to pace on an ECG strip

A pause where a pacing spike was due and none came.

What to look for

The pacemaker stops firing. Where spikes and beats are due, you get nothing, just an empty pause, then pacing resumes. Every spike that is delivered captures. The problem isn't capture; there just aren't enough spikes.

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
51/min6 QRS complexes in 6 seconds × 10 = 60/min
Rhythm
Regular, except for the pause
P waves
None: fine fibrillatory baseline
P to QRS
No P waves (atrial fibrillation underneath)
PR
None to measure
QRS
0.18 s, wide
Pacing
VVI at 84/minA 3.02 s gap with no spike at all
Example 2 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
43/min4 QRS complexes in 6 seconds × 10 = 40/min
Rhythm
Regular, except for the pause
P waves
None: fine fibrillatory baseline
P to QRS
No P waves (atrial fibrillation underneath)
PR
None to measure
QRS
0.15 s, wide
Pacing
VVI at 52/minA 1.88 s gap with no spike at all
Example 3 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
46/min5 QRS complexes in 6 seconds × 10 = 50/min
Rhythm
Regular, except for the pause
P waves
None: fine fibrillatory baseline
P to QRS
No P waves (atrial fibrillation underneath)
PR
None to measure
QRS
0.18 s, wide
Pacing
VVI at 63/minA 2.33 s gap with no spike at all

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 Paced group