Wednesday, 9 December 2015

ECG of the Week - 7th December 2015 - Interpretation

This ECG series is from a 35 yr old male who presented complaining of feeling generally unwell for the preceding 24 hours.



Click to enlarge
Patient's initial ECG
Rate:
  • 90 bpm
Rhythm:
  • Sinus arrhythmia
Axis:
  • Normal (~25 deg)
Intervals:
  • PR - Normal (~130ms)
  • QRS - Normal (100ms)
  • QT - 320ms (QTc Bazette ~390 ms)
Additional:
  • Partial RBBB 
    • rSr' in lead V1
  • Baseline artifact in left precordial and inferior leads
Interpretation:
  • Essentially normal ECG without concerning features

Click to enlarge
2nd ECG ~60 mins following 1st ECG
Rate:
  • 78 bpm
Rhythm:
  • Regular
  • Ventricular rhythm
  • Sinus activity difficult to see given poor rhythm strip
    • Possible p waves seen in ST / T junction in lead III and V3
Axis:
  • Inferior / subtle right axis deviation
    • aVF clearly positive but lead I either isoelectric (= inferior axis ~90 deg) or slight negative (= minor RAD)
Intervals:
  • QRS - Prolonged (120-160 ms)
Additional:
  • Appropriate ST segment and T wave discordant change
    • Expected given ventricular origin of rhythm
  • Extensive baseline artifact in leads I, II, aVR, aVL and rhythm strip
  • Not typical LBBB morphology
    • Clear R wave in leads V1-2
    • Lack of R wave in leads I, aVL
  • Nil capture or fusion beat
Interpretation:
  • Accelerated idioventricular rhythm
  • Given the Inferior access and some LBBB features a concern of RVOT (Right ventricular outflow tract tachycardia) was raised although the rate is <100 bpm

Click to enlarge
3rd ECG ~5 mins after 2nd ECG
Rate:
  • Mean ventricular rate 90 bpm
Rhythm:
  • Initial sinus rhythm with sinus arrhythmia
  • Complex #13 fusion beat
  • Complex #14 and #15 (partially captured) ventricular in origin with morphology similar to 2nd ECG
Additional:
  • Majority of the ECG is same and the patient's 1st ECG with a rhythm change in the last few complexes. 
  • Sinus --> Fusion --> Ventricular rhythm
Interpretation:
  • Transition captured between features seen in both 1st and 2nd ECG
  • Patient noted associated palpitations 
What happened ?

The patient was admitted under the cardiology team for investigation of episodic broad complex rhythm with associated palpitations. He had a normal transthoracic echo. negative stress test, normal coronary angiography and a caradiac MRI which showed no evidence of infiltrative disease or RV wall  / outflow tract abnormality. 

Following electrophysiology consultation the episodes were considered non-malignant episodes of an idioventricular rhythm with preserved chronotrophic competence. Nil further management was required and the patient is able to perform all activities without limitation.

References / Further Reading

Life in the Fast Lane

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