ECG of the Week - 18th June 2018 - Interpretation

This ECG is from a 42 yr old male with known pre-excitation who presented with a 3 day history of episodic palpitations, dizziness and GI illness.

Click to enlarge

Rate:

• 72 bpm

Rhythm:

• Regular
• Sinus rhythm

Axis:

• Normal

NOTE the rhythm strip on this ECG has not been recorded concurrently with the 12 lead ECG

On the 12 lead ECG (non-rhythm strip recording)

•  PR - Normal (~200ms) 
• QRS - Normal (100ms)
• rSr' pattern lead V1
• T wave inversion leads II, III, aVF
• Prominent T waves leads aVL, V2-4

 

 On the lead II rhythm strip

• Variable conduction
• Complexes #1-3, 8-10 normal PR with same morphology as 12 lead complexes
• Complexes #4-7, 11-13 pr shortening with QRS prolongation and distinctly different QRS morphology

Interpretation:

• Rhythm strip likely reflects intermittent pre-excitation conduction down accessory pathway (AP)
• T wave changes seen on the 12 lead ECG may reflect:
• ACS
• Electrolyte abnormality
• Most likely cardiac T-wave memory secondary to intermittent AP conduction

 What is cardiac T-wave memory ?

'Cardiac T-wave memory' this occurs after a period of abnormal ventricular depolarisation e.g. paced rhythm, VT, SVT with aberrancy and pre-excitation. There is a recent paper by Vakil that is freely available (linked to below) that contains a nice overview of T-wave memory, proposed mechanisms, and a case example. Deep T wave inversion corresponds to the leads in which a negative QRS was seen in the patients pre-excited ECG. Patient's often require work-up to exclude underlying ischaemia or structural disease but cardiac T-wave memory is a benign and self-resolving condition in itself.

•  Vakil K, Gandhi S, Abidi KS, et al. Deep T-Wave Inversions: Cardiac Ischemia or Memory? JCvD 2014;2(2):116-118. Full text here.

We’ve had some cases on the blog before with Cardiac T-wave memory:

• ECG of the Week - 7th July 2014
• ECG of the Week - 1st July 2013

Thanks to Adrian and Jason for sharing more resources and further reading on T-wave memory, links below:

• Lead researches on the topic Chiale PA & Elizari MV.
• "Cardiac Memory" A Struggle Against Forgetting. Folco EJ et al.
• Cardiac Memory Variations in Surface ECG Precordial Mapping. Sadiq Ali F. Baranchuk A.
• ECG Challenge from Jason's Blog.
• Wolff-Parkinson-White Syndrome: Could a Normal PJ Interval Exclude Bundle Branch Block? Chen Y, Xu Z.
• Successful Ablation of Antero-septal Accessory Pathway in the Non-Coronary Cusp in a Child. Kobayashi D, Arya SO, Singh HR.

 What happened ?

The patient had normal electrolytes and cardiac biomarkers. Extended telemetry revealed no episodes of arrhythmia. His echo showed:

• Abnormal septal wall motion secondary to intraventricular conduction delay
• Low normal LV systolic function
• Moderate left atrium dilation
• Normal RV size and function
• Normal valvular function

 He was referred for out-patient electrophysiology follow-up for discussion of management options related to his pre-excitation

References / Further Reading

 

Life in the Fast Lane

• Pre-excitation

Textbook

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