ECG of the Week - 1st September 2014 - Interpretation

This ECG is from a 68 yr old male. He was 2  months post pacemaker insertion for sinus node dysfunction and presented following an episode of syncope.

Click to enlarge

Rate:

• Mean ventricular rate 90 bpm

Rhythm:

• Complexes #1-4 & 6-7 A-V sequential paced
• Complexes #5 & 8-15 V-paced

Axis:

• LAD

Intervals:

• QRS - Prolonged (160-180ms)

Segments:

• Appropriate discordant ST segment -T wave change
• Sgarbossa / modified Sgarbossa negative

Additional:

• Abrupt rate change from complex 8 onwards
• Rate increases to ~135 bpm
• Initial rate complexes #1-4 is ~60 bpm
• Notching in baseline after complex #6 best seen in V1-3
• ? Native atrial activity ? artefact

Interpretation:

• Paced rhythm
• Abrupt acceleration in rate

My thoughts were:

• ? Rate modulation
• I don't know how rapid the rate can change as there appears to be no gradual increase in the rate
• ? Sensor induced tachycardia
• ? Pacemaker mediated tachycardia

I don't know the cause of the sudden rate change in this patient I have sent the ECG to our blog electrophysiologists and will update the interpretation once I get their thoughts on this ECG.

Clinical correlation may be helpful regarding presence of symptoms, blood pressure, or driving features for tachycardia e.g. fever. I'd be liaising with the patient's cardiologist for more information on the pacemaker settings and also looking to arrange a pacemaker interrogation to see what's going on.

References / Further Reading

Life in the Fast Lane

• Normal Pacemaker Function
• Pacemaker Malfunctions

Textbook

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