ECG of the Week – 27th March 2017 – Interpretation

This ECG is from a 63yr old male who presented with chest pain. He has a 1 month history of exertional chest pain and continuous chest pain for the last 3 hours. He is a hypertensive, ex-smoker with a positive cardiac family history.

Click to enlarge
Rate:
  • 72 bpm
Rhythm:
  • Regular
  • Sinus Rhythm
Axis:
  • Normal
Intervals:
  • PR - Normal (~160ms)
  • QRS - Normal (100ms)
  • QT - 360ms
Segments:

  • ST Elevation leads aVR (1mm) aVL (1mm) V1 (1mm)
  • ST Depression leads II, III, aVF, V4-6

Additional:

  • Prominent  U-wave in antero-septal leads
  • T wave inversion infero-lateral leads
    • Down-up morphology may be due to prominent U waves

Interpretation:

  • Acute ACS
    • Patient with history suspicious of ACS
    • ST / T changes indicative of ACS


What happened ?

The patient was taken for urgent angiography which showed:
  • Right dominant system
  • LM: 50% distal
  • LAD: 90% proximal
  • Cx: 90% mid
  • RCA: 99% distal RCA with 80% ostial - TIMI 3 flow & pain-free patient
  • RCA: Supplying large PDA and 3 PLV branches
  • LH Cath: Inferior akinesis with mild LV impairment
The patient was then transferred to tertiary centre for urgent CABG given severe multi-vessel disease.

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.

Lithium Poisoning

Hello everyone!

Today, we discussed the case of a young man with symptomatic, sinus bradycardia secondary to lithium poisoning. See below for high-yield pearls on lithium intoxication!

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TOP PEARLS

  • Lithium has a narrow therapeutic index; many patients on chronic lithium therapy experience at least one episode of toxicity during the treatment.
  • Differentiate lithium toxicity into 2 phases – acute vs chronic! Cardiac and neurologic manifestations can occur in both acute and chronic poisoning, although renal manifestations preferentially occur in chronic poisoning.
  • Prolonged QTc and sinus bradycardia are the most common cardiac manifestations of lithium poisoning. However, other arrhythmias and cardiomyopathies have been reported to occur!

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Acute Lithium Toxicity

  • GI manifestations: nausea, vomiting diarrhea
  • Cardiac: prolonged QTc and sinus bradycardia are most common manifestations
  • Neurologic : Usually a late manifestation in acute poisoning. Includes ataxia, confusion, agitation, neuromuscular excitability, seizures

Chronic Lithium Toxicity

  • Neurologic: similar to acute manifestations.
  • Cardiac: similar presentation as acute toxicity, but generally with more benign outcomes
  • Renal: Usually specific to chronic poisoning. Nephrogenic diabetes insipidus.

Cardiac Manifestations of Lithium Poisoning!

  • As stated above, most common presentations include prolonged QTc and sinus bradycardia.
  • However, there have been other case reports of cardiac manifestations of lithium poisoning including: diffuse T-wave inversions, acute LV systolic dysfunction, Takotsubo cardiomyopathy, ventricular tachycardia.

Management

  • Lithium levels often do not correlate with signs of toxicity!
  • Hemodialysis is indicated if Li level is >4, regardless of clinical s/sx (this represents a large total body lithium burden), or >2.5 + sxs and/or renal insufficiency and/or IVF is contraindicated (eg decompensated CHF)
  • Management of nephrogenic DI: often becomes irreversible or only partially reversible
    • Discontinue lithium if possible
    • Amiloride: blocks sodium channels in collecting tubules (only helpful if mild/moderate concentrating defect)
    • Thiazide: paradoxically reduces UOP and increases urine osm and urine Na by increasing sodium excretion at distal convoluted tubule and reabsorption of water in proximal tubule, minimizing the effect of ADH at the collecting duct
    • Desmopressin (to attain supraphysiologic level of ADH, as most patients only have partial resistance to ADH)

Filed under: Cardiovascular Medicine, Morning Report