EMS Registry Ready

SVT with aberrant conduction on an ECG strip

Regular, wide and 150-250/min, in the same bundle branch block shape as the sinus beats before it.

What to look for

A regular wide-complex tachycardia at 150-250/min: an SVT whose QRS is wide because of a bundle branch block. From one lead, you can't tell it from VT with certainty, and LITFL's rule is "if in doubt, treat as VT". What points to SVT here is the sinus beats before it, with a bundle branch block of exactly the same shape, and the PAC that 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
206/min during the run19 QRS complexes in 6 seconds × 10 = 190/min
Rhythm
Regular
P waves
Not visible
P to QRS
No visible P waves (retrograde P buried in the QRS)
PR
0.15 s
QRS
0.13 s, wide
Example 2 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
169/min during the run13 QRS complexes in 6 seconds × 10 = 130/min
Rhythm
Regular
P waves
Not visible
P to QRS
No visible P waves (retrograde P buried in the QRS)
PR
0.13 s
QRS
0.15 s, wide
Example 3 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
240/min during the run22 QRS complexes in 6 seconds × 10 = 220/min
Rhythm
Regular
P waves
Not visible
P to QRS
No visible P waves (retrograde P buried in the QRS)
PR
0.14 s
QRS
0.13 s, wide

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 Junctional group