EMS Registry ReadyExample 1 · lead V1 · 6 seconds
- Rate
- 93/min9 QRS complexes in 6 seconds × 10 = 90/min
- Rhythm
- Regular
- P waves
- Sinus: upright in II, biphasic in V1, one before every QRS
- P to QRS
- 1:1, a P before every QRS
- PR
- 0.16 s
- QRS
- 0.14 s, wide
Sinus rhythm with right bundle branch block on an ECG strip
A QRS of 0.12 s or more with rSR' (an 'M') in V1-V3 and a wide, slurred S in I, aVL, V5 and V6.
What to look for
The right bundle is blocked, so the left ventricle activates normally and the right ventricle activates late and slowly, through muscle. That late rightward, forward activation adds an R' at the end of V1-V3 (rSR', the 'M') and a wide, slurred S in I, aVL, V5 and V6. The ST and T in V1-V3 go the other way (depressed ST, inverted T). That's expected, and it isn't a sign of ischemia. The axis stays normal unless a fascicle is blocked too.
Examples
Each strip is 6 seconds of lead V1, 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 V1 · 6 seconds
- Rate
- 95/min9 QRS complexes in 6 seconds × 10 = 90/min
- Rhythm
- Regular
- P waves
- Sinus: upright in II, biphasic in V1, one before every QRS
- P to QRS
- 1:1, a P before every QRS
- PR
- 0.20 s
- QRS
- 0.16 s, wide
Example 3 · lead V1 · 6 seconds
- Rate
- 86/min9 QRS complexes in 6 seconds × 10 = 90/min
- Rhythm
- Regular
- P waves
- Sinus: upright in II, biphasic in V1, one before every QRS
- P to QRS
- 1:1, a P before every QRS
- PR
- 0.13 s
- QRS
- 0.16 s, wide
Don't confuse it with
- Sinus rhythm with left bundle branch block
A QRS of 0.12 s or more with a deep, broad S (QS or rS) in V1 and a broad R with no Q wave in I, aVL, V5 and V6.
- Brugada pattern, type 1 (coved)
In V1-V2, the ST rises over 2 mm at the J point and falls in a coved, convex curve straight into an inverted T wave.
- Sinus rhythm with WPW (pre-excitation)
A short PR (under 0.12 s), a slurred upstroke at the start of the QRS (the delta wave) and a QRS over 0.11 s.
- Normal sinus rhythm
Regular at 60-100/min, an upright P before every QRS, a PR of 0.12-0.20 s and a narrow 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 Drill