ECG of the Week - 22nd April 2013 - Interpretation

This ECG is from a 78 yr old male who presented with a 2 day history of lethargy and dizziness

He has a history of ischaemic heart disease, type 2 DM, hypertension, and chronic renal failure. 
Medications include calcium-channel blocker, beta-blocker, and ACE-inhibitor.

Conscious with systolic BP of 70 !

Click to enlarge

Rate:

• ~42

Rhythm:

• Regularly irregular 
• Complexes occurring in paired group
• Flat baseline without atrial activity

Axis:

• 1st Complex in pair
• Normal (70 deg)
• 2nd Complex in pair
• LAD(-45 deg)

Intervals:

• 1st Complex in pair
• QRS - Normal (80ms)
• QT - 520ms
• 2nd Complex in pair
• QRS - Normal in limb leads, Prolonged V1-3 (80-120ms)
• QT - 440ms

Segments:

• 1st Complex in pair
• ST Depression leads II, aVF
• 2nd Complex in pair
• Minimal ST elevation lead aVR

Additional:

• 1st Complex in pair
• T wave inversion II, III, aVF
• Biphasic T lead V3
• 2nd Complex in pair
• RsR' Morphology V1-3
• Inverted notching terminal portion QRS II, III, aVF also positive notching aVL
• ? Retrograde P waves ? Secondary to conduction delay

Interpretation:

• Escape bigeminy
• In setting of sinus arrest / sinus exit block
• Non-specific ST / T wave changes

Differential of causes:

• Ischaemia
• Electrolyte disturbance
• Acid-base disturbance
• Cardiotoxic drugs
• Sinus node dysfunction
• Hypothermia
• Multifactorial combination of above

What happened ?

Bloods showed:

• Acute on chronic renal failure
• Metabolic acidosis - pH 7.0 Bicarb 7.0
• K 6.0

Tx with isoprenaline, sodium bicarb, cessation of cardiotoxic medication, and dialysis.

Following acute episode found to have sinus pauses on telemetry necessitating pacemaker insertion.

References / Further Reading

Life in the Fast Lane

• Sinus Arrest here
• Sinoatrial exit block here

Textbook

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