ECG of the Week - 18th April 2016 - Interpretation

The following ECG is from an 84 yr old male who presented with chest pain and dizziness. He had a dual chamber pacemaker in-situ inserted for symptomatic bradycardia.

 

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Rate:

• Mean ventricular rate 78 bpm

Rhythm:

• Nil p waves visible
• Bigemny
• V-paced complex followed by premature ventricular complex

V-Paced Complexes (#2,4,6,8,10,12)

Axis:

• LAD

Intervals:

• QRS - Prolonged (150ms)

Segments:

• Appropriate discordant ST segment change
• Note ST depression in V2 as mentioned in comments but this is discordant to positive QRS (not typical LBBB morphology) and as such should be considered Sgarbossa negative

Premature Ventricular Complexes (#1,3,5,7,9,11,13)

Axis:

• Normal

Intervals:

• QRS - Prolonged (130ms)

Segments:

• Discordant ST / T wave changes

Interpretation:

• V-paced rhythm with bigemny
• Underlying sinus node dysfunction - nil native p waves

What happened ?

Despite a mean ventricular rate the patient's pulse rate was only ~40 bpm, i.e. the PVC's were not resulting in 'mechanical' capture. 
The patient had minor electrolyte abnormalities corrected and rate modulating drugs were reduced with resultant decrease in PVC frequency and increased mechanical pulse rate.
Pacemaker interrogation revealed no setting issues and serial troponins were negative.
The patient was discharged with ongoing cardiology follow-up.

References / Further Reading

Life in the Fast Lane

• Pacemaker - normal function
• Sgarbossa Criteria

Textbook

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