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Polymorphic ventricular tachycardia on an ECG strip

A wide-complex tachycardia whose complexes change shape from beat to beat.

What to look for

A wide-complex tachycardia where the QRS keeps changing: its size, direction and width differ from one complex to the next. The QT before the run is normal. The most common cause is ischemia or infarction. On this strip, a PVC on the T wave of the last sinus beat (R on T) starts it.

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
184/min during the run16 QRS complexes in 6 seconds × 10 = 160/min
Rhythm
Irregular
P waves
Upright in II before the run; not seen during it
P to QRS
1:1 before the run; none during it
PR
0.13 s
QRS
0.09 s, narrowThe beats before the run
Example 2 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
178/min during the run16 QRS complexes in 6 seconds × 10 = 160/min
Rhythm
Irregular
P waves
Upright in II before the run; not seen during it
P to QRS
1:1 before the run; none during it
PR
0.15 s
QRS
0.10 s, narrowThe beats before the run
Example 3 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
168/min during the run17 QRS complexes in 6 seconds × 10 = 170/min
Rhythm
Irregular
P waves
Upright in II before the run; not seen during it
P to QRS
1:1 before the run; none during it
PR
0.13 s
QRS
0.10 s, narrowThe beats before the run

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 Ventricular group