EMS Registry ReadyExample 1 · 12-lead · 10 seconds
- Rate
- 63/min
- Rhythm
- RegularSinus: upright in II, biphasic in V1, one before every QRS
- PR
- 0.19 s
- QRS
- 0.09 s, narrow
- Axis
- -82°, left axis deviation
- QTc
- 0.42 s
- ST up
- None
- ST down
- None
- T inverted
- III, aVF
Left axis deviation on a 12-lead ECG
A QRS axis more negative than -30°: lead I positive, lead II and aVF mostly negative.
What to look for
The frontal QRS axis is beyond -30° (LITFL: less than -30°). For a quick check, look for lead I positive and lead II negative. Causes include left anterior fascicular block (the most common), inferior infarction, LVH, paced rhythms and WPW.
Examples
Each is a standard 12-lead: 2.5 seconds of each lead in four columns, with 10 seconds of lead II along the bottom, drawn to scale (25 mm a second, 10 mm a millivolt). The measurements are under each one.
Example 2 · 12-lead · 10 seconds
- Rate
- 65/min
- Rhythm
- RegularSinus: upright in II, biphasic in V1, one before every QRS
- PR
- 0.18 s
- QRS
- 0.10 s, narrow
- Axis
- -37°, left axis deviation
- QTc
- 0.40 s
- ST up
- None
- ST down
- None
- T inverted
- III
Don't confuse it with
- Left anterior fascicular block
Left axis deviation (-45° to -90°) with qR in I and aVL, rS in II, III and aVF, and a QRS under 0.12 s.
- Extreme axis deviation
A QRS axis between -90° and 180° (the 'northwest'): lead I and aVF both negative, aVR positive.
- Normal 12-lead ECG
Sinus rhythm, a normal axis, normal intervals, R waves growing from V1 to V5, and no ST elevation or depression.
The ECG tool in the app gives you a new 12-lead every time and walks you through reading it: rate, QRS, axis, then where the ST is up and down. It's part of the Paramedic level, and you can try 5 ECGs a day free.
Try the 12-lead drill