ECG of the Week - 8th October 2018 - Interpretation

This ECG is from a 50 yr old female who presented complaining of palpitations for the last few hours. She has no past medical history and takes no regular medications.





Click to enlarge

Rate:

• 156 bpm

Rhythm:

• Regular
• Atrial activity very difficult to see
• Potential P wave visible in lead I just after T wave
• Very low voltage
• Not always appreciable

Axis:

• Normal

Intervals:

• QRS - Normal 

Additional:

• Inferior ST depression
• T waves broad in leads II, III, aVF, V3-6

Interpretation:
Challenging ECG in terms of the rhythm, three possible DDx:

• Sinus tachycardia
• Atrial tachycardia
• Atrial flutter 2:1 block

Below is the rhythm strip with some of the possible atrial complexes highlights with a red square.




Click to enlarge

A few helpful strategies would be to:

• Alter paper speed, gain and rhythm strip lead
• Use a Lewis lead configuration
• Treat the patient - Sx treatment, seek and treat potential causes, consider adenosine

Lewis Lead

The Lewis lead configuration was first described in 1931 and uses a modified lead placement to assist in the identification of atrial activity. 

You can read more about the Lewis lead and how to perform it in the links below:

• Bakker AL, Nijkerk G, Groenemeijer BE, Waalewijn RA, Koomen EM, Braam RL, Wellens HJ.The Lewis lead: making recognition of P waves easy during wide QRS complex tachycardia.Circulation. 2009 Jun 23;119(24):e592-3.
• EMCritWee - The Lewis Lead
• Dr Smith's ECG Blog - Wide Complex Tachycardia: Lewis Leads Do Not Differentiate VT from SVT with Aberrancy

References / Further Reading

Life in the Fast Lane

• Atrial tachycardia
• Atrial flutter 

Textbook

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