ECG of the Week - 19th December 2016 - Interpretation

The following ECG is from a 63 yr old female who presented complaining of palpitations. She has a history of prior episodes of palpitations.

Click to enlarge

Rate:

• ~200 bpm

Rhythm:

• Regular

Axis:

• Normal 

Intervals:

• QRS - Normal (50ms)

Segments:

• ST Depression leads I, II, V2-6

Additional:

• Notching terminal QRS best seen leads I & aVR
• Negative QRS lead III 
• Associated T wave inversion on sinus ECG below
• Possible LA / LL reversal 
• Results in negative III
• Leads I and II switch places 
• Leads aVL and aVF switch places

Interpretation:

• Narrow complex regular tachycardia
• ? LA / LL lead reversal

General differentials for a regular narrow complex tachycardia are:

• Sinus tachycardia
• AVNRT
• AVRT
• Atrial tachycardia
• Atrial flutter
• Sinus node re-entry tachycardia
• Junctional tachycardia

What happened ?

The patient had a prior ablation for recurrent AVNRT several years prior and remained symptom free till this episode. Following administration of 6mg iv adenosine she reverted to sinus rhythm, ECG below.

Post cardioversion
Click to enlarge

She was then discharged for out-patient follow-up with her regular cardiologist.

References / Further Reading

Life in the Fast Lane

• SVT / AVNRT

Textbook

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