ECG of the Week – 22rd January 2018 – Interpretation

The following ECG is from a 78 yr old female who presented to the Emergency Department with a history of progressively worsening dysponea and peripheral oedema. Her past medical history includes ischaemic heart disease and hypertension.


Click to enlarge



Things to think about

  • What are the key ECG abnormalities ?
  • How could you improve the quality of the patient’s ECG ?


Rate:

  • 60 bpm

Rhythm:

  • Regular
  • Sinus rhythm

Axis:

  • Normal

Intervals:

  • PR – Normal (~200ms)
  • QRS – Prolonged (120ms)

Additional:

  • RBBB Pattern
  • Baseline wander in limb leads ? U waves
  • Significant high frequency artefact obscuring majority of details in precordial leads

Interpretation:

  • Sinus rhythm with RBBB
  • Significant artefact obscuring rest of ECG interpretation

Troubleshooting artefact

There are multiple factors that can generate artefact during the ECG recording / printing process including:

  • 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
    • Habitus – very thin or obese patients, paediatric patients
    • Poor pad contact due to hair
    • Poor pad contact due to moisture – sweating, immersion etc.
  • Lead factors
    • Poor pad contact
    • Pad misplacement
    • Damaged lead or lead connection
  • ECG Machine Factors
    • Inappropriate settings of gain or filtering modes
    • Electrical artifact from power supply
  • Printing factors
    • Low ink
    • Print head tracking
    • Paper alignment
  • External factors
    • Interference from surrounding electronic devices. Relatively rare using newer ECG machines and environmental interference is usually compounded by incorrect machine filter settings.
An awareness of these factors and a systemic approach to addressing each point in the recording process, from patient to printer, is important in addressing recording problems such as artifact and lead mal-positioning.


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.

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