ECG of the Week – 13th June 2016 – Interpretation

The following ECG is from a 52yr old male presenting with dysponea.




Click to enlarge

Rate:
  • 96 bpm
Rhythm:
  • Regular
  • P waves difficult to see but likely present
    • Best appreciated in leads I & II
Axis:
  • RAD
Intervals:
  • PR - Unable to adequately identify P wave morphology to measure, suugestion of pr prolongation in lateral leads
  • QRS - Normal (100ms)
Additional:

  • High frequency artefact in all leads
  • Maximal in precordial leads
  • Relative sparring of leads I & aVL 

Interpretation:

  • Significant artefact obscuring the baseline and majority of ECG segments
  • Likely electrical interference from power supply (50Hz AC)
  • Need to check correct line frequency filter, electrode contact and remove obvious potential interfering devices from patient / area


What are the causes of ECG artefact ?

There are multiple causes of ECG artefact and they may relate to the patient, environment or equipment. They include:

  • Patient Factors
    • Implanted devices
    • PPM - Pacing Spikes
    • Nerve stimulators
    • Movement disorders e.g. Parkinson's, essential tremor
    • Rigors
    • Muscle tremor / activity can be related to pain, hypothermia etc.
    • CPR
    • Transport artefact e.g. vehicle movement
  • Environmental
    • Interference from surrounding electronic devices. Relatively rare using newer ECG machines and environmental interferece if usually compounded by incorrect machine filter settings.
  • Equipment
    • Poor lead contact 
    • Damaged cable / connector
    • Filter settings including monitor vs filter mode and main supply hertz filtering



References / Further Reading

Life in the Fast Lane

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

    ECG of the Week – 6th June 2016 – Interpretation

    The following ECG is from a 70 yr old female who presented following an episode of chest pain at home.


    Click to enlarge
    Rate:
    • 54 bpm
    Rhythm:
    • Sinus arrhythmia
    Axis:
    • Normal
    Intervals:
    • PR - Normal (~160-180ms)
    • QRS - Normal (100ms)
    • QT - 440ms
    Segments:
    • Nil significant change
    Additional:
    • Deep T wave inversion leads V1-3 & aVL
    • Prominent T waves III, aVF, V6 
    Interpretation:
    • Wellen's pattern
      • Deep T wave inversion leads V1-3
      • aVL inversion consistent with ACS

    What happened ?

    The patient had an angiogram which showed:
    • Left main: Normal
    • LAD: 80% mid stenosis
    • Cx: 40% stenosis
    • RCA: 60% proximal & 90% mid stenosis
    The LAD lesion was stented and subsequent echo showed only mild LV systolic dysfunction. Medical therapy was maximised and staged further intervention was planned for the RCA lesion.

    More on Wellen's

    Check out:

    Dr Smith's ECG Blog
    Articles
    • Rhinehardt J, Brady WJ, Perron AD, Mattu A. Electrocardiographic manifestations of Wellens' syndrome. Am J Emerg Med. 2002 Nov;20(7):638-43. PMID: 12442245 Full text here
    • Mead NE, O'Keefe KP. Wellen's syndrome: An ominous EKG pattern. J Emerg Trauma Shock. 2009 Sep-Dec; 2(3): 206–208.  Full text here.
    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.