Wednesday, 15 February 2017

ECG of the Week - 13th February 2017 - Interpretation

This ECG is from a 91 yr old female who presented to a rural medical center, 260 km (160 miles) from the nearest tertiary hospital, complaining of weakness and difficulty standing. 



ECG on presentation
Click to enlarge
Key features:
  • Bradycardia rate 30 bpm
  • Nil atrial activity visible
  • Normal axis
    • Close to -30 deg with near isoelectric lead II
  • Narrow QRS
    • Similar morphology to old ECG below
  • Late R wave transition
  • T wave inversion leads V2-3
    • New compared with old ECG

ECG from 1 year prior
Click to enlarge

Key features:
  • Sinus rhythm, rate 60 bpm
  • Left axis deviation
  • PR prolongation
  • QRS narrow
  • Voltage criteria for LVH in lead aVL
Interpretation:
  • Junctional bradycardia
    • New T wave changes
    • Nil evidence atrial activity
There are broad causes for the clinical picture and new ECG changes that need to be considered in these cases:

  • ACS
    • New anterior T wave change but nil history of chest pain
    • No significant ST segment changes
  • Structural disease
    • Cardiomyopathy
    • Valvular disease
  • Electrolyte abnormality
    • Hypokalaemia - can cause ECG changes and clinical weakness
    • Hyperkalaemia - can cause almost any ECG abnormality
  • Drug toxicity
    • Consider digoxin, calcium channel blockers, beta blockers
    • Usually chronic toxicity in the elderly but can be acute
    • May be seen with worsening of other co-morbidities especially renal failure / chronic kidney disease
  • Environmental / Endocrine
    • Hypothermia
    • Thyroid Dysfunction - hypo or hyper
  • Inflammatory / Auto-immune
    • Pericarditis
    • Myocarditis
    • Sarcoidosis
    • SLE 
    • Lyme disease
  • Idiopathic / Age Related
  • High vagal tone states
    • Usually transient
    • Vomiting
    • Pain
    • Under anaesthetic

References / Further Reading

Life in the Fast Lane

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