Wednesday, 24 January 2018

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.