ECG of the Week - 3rd June 2013 - Interpretation

This ECG is from a male presenting with chest pain, I don't know his age so let's say mid-fifties.

Click to enlarge

Rate:

• ~60

Rhythm:

• Regular
• Ectopic Atrial Rhythm
• Abnormal p wave axis

Axis

• LAD (-55 deg)

Intervals:

• PR - Normal (~12-140ms)
• QRS - Normal (100ms)
• QT - 400ms (QTc Bazette ~ 400 ms)

Segments:

• ST elevation lead V1 (1mm)
• Up-sloping ST segment lead V2

Additional:

• T wave inversion leads II, III, aVF
• P wave inverted leads II, III, aVF, V1-2
• Notched p wave lead V3
• Positive p wave aVR
• Voltage criteria for LVH
• aVL >11mm

Interpretation:

• Ectopic Atrial Rhythm
• LAFB
• Inferior T Wave Inversion

But....

• Normal p wave morphology in lateral leads
• Inferior leads show inversion of not only p wave but also QRS complex and T wave
• This looks really odd

What happened ?

As many of our comment's noted this ECG is suspicious for limb lead misplacement.

On review of the patient the limb electrodes had been misplaced with RA-RL and LA-LL reversal !

This reversal pattern is described as having a flat lead I which is not seen in this ECG. This is likely due to this ECG being recorded using a modified Mason-Likar system; the limb electrodes being placed on the shoulders and abdominal wall, rather than on the ankles and wrists.

The leads were reapplied in the correct configuration and the ECG was repeated which looked liked this:

Click to enlarge

Note the resolution of the inferior T wave abnormalities with a normal p wave axis.
The p wave in leads V1 and V2 have also changed, this may be due to replacement of the precordial electrodes when the lead misplacement was corrected or due to change in pt position. There is concavity of the inferior ST segments with ST elevation in V1, now <1mm.

I know the patient was placed on the cardiac chest pain pathway with serial ECG's and troponin testing, but unfortunately I don't know the ultimate outcome of these tests.

VAQ Corner

A 53 year old male presents to your Emergency Department with two hours of chest pain.
Vital signs are normal.

a) Describe and interpret his ECG (100%)

References / Further Reading

Life in the Fast Lane

• Left Axis Deviation here
• Left Anterior Fasicular Block here
• Ectopic atrial rhythm here
• Lead Reversal here
• P Wave Morphology here

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.