ECG of the Week – 2nd September 2013 – Interpretation

By | 4 september 2013

This ECG is from a 39 yr old male who presented with 2 hours of chest pain. 
Strong family history of cardiac disease. 
Nil regular meds. BP 134/78. Sats 98% RA
Check out the excellent comments on this ECG in our original case post here.





Click to enlarge

As per Ken’s suggestion, see comments section, I’ve included below a labelled version of the ECG with the complexes numbered from 1 to 13. It may help those who interpret on a computer screen / tablet, and ensures we are all taking about the same bits of the ECG. Thanks Ken 🙂


Click to enlarge

Rate:

  • Mean ventricular rate 78

Rhythm:

  • Complex rhythm
  • Alternating broad & narrow QRS complexes
  • Complexes #4,6,8,10
    • Sinus
    • Narrow Complex ~70ms
  • Complexes #1,3,5,7,9,11,13
    • Premature ventricular complexes (PVC)
    • Broad complexes (~140ms)
  • Complex #2
    • Preceded by abnormal p wave
    • PR interval very short (~70ms)
    • Premature junctional complex (PJC)

Axis:

  • Sinus complexes – Inferior (~90 deg)
  • Ventricular complexes – LAD (-65 deg)

Intervals:

  • Sinus complexes (#4,6,8,10)
    • PR – Normal (~125 ms)
    • QRS – Normal (70-80 ms)
    • QT – 480 ms
  • Ventricular  complexes (#4,6,8,10)
    • QRS – Broad (140 ms)
    • QT – 360 ms
  • Complex # 2
    • PR – Short (~70ms)
    • QRS – Normal (70-80 ms)
    • QT – 380 ms

Segments:

  • ST Elevation – Sinus Complexes
    • Leads V1 (0.5mm) V2 (2.5mm) V3 (6mm) V4 (3mm)
  • ST Depression – Sinus Complexes 
    • Leads II, III
  • Note ST elevation evident in PVC’s in leads aVL,V2, V3

Additional:

  • Variable morphology ventricular complexes
    • #7 & #9 Notching QRS
  • Regular relationship between narrow complex and broad complex
    • R-R interval 500ms
  • Partial RBBB morphology in narrow QRS complexes

Interpretation:

  • Acute Anterior STEMI
  • Regular PVC’s
  • Single PJC

Whilst the rhythm of this ECG has prompted the most comments and discussion the real key feature is the ST elevation which is easy to miss amongst all the PVC’s. This highlights the importance of a systematic interpretation of the ECG and the risks associated with a pattern recognition approach.
I’ve included an edited version of this ECG below with the broad QRS complexes edited out just to highlight the ST changes in the narrow complexes.


Same ECG with broad complexes masked
Click to enlarge

Clinical Outcome

The ST segment changes were immediately recognised and the patient was transferred for urgent angiogram and PCI. 
His angiogram showed:
LM – no stenosis
LAD – occluded mid –>  PCI
Cx – no stenosis
RCA – dominant no stenosis
Left ventriculogram – Ejection fraction 55%

The patient was discharged following a 3 day in-patient stay.

Thrombolysis

I just thought I briefly touch on contraindications for thrombolysis in STEMI as I’m currently reading for the FACEM exam and it comes up occasionally. 
The following list is taken from the Australian Resuscitation Council Guideline 14.3 ‘Acute Coronary Syndromes: Reperfusion Strategy’.


Contraindications to thrombolysis in STEMI
ARC Guideline 14.3
Click to enlarge

VAQ Corner

A 39 year old male presents to your rural Emergency Department with 2 hours of typical chest pain. He is a smoker with a strong family history of cardiac disease. Nil regular meds. BP 134/78. Sats 98% RA

a) Describe & interpret his ECG (50%)
b) Outline indications & contraindications for thrombolysis (50%)


References / Further Reading

Life in the Fast Lane

  • Anterior STEMI here
  • Premature Junctional Complex here
  • Premature Ventricular Complex here

Australian Resuscitation Council

Textbook

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

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