20-year-old male presenting with seizures. BP 80/50.
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
Main Abnormalities
What is the diagnosis?
Reveal answer
In the context of seizures and hypotension, the combination of…
- QRS broadening > 100 ms
- R’ wave in aVR > 3 mm
… is highly suggestive of poisoning with a sodium-channel blocking agent — e.g. tricyclic antidepressant.
The sinus tachycardia may be due to the anticholinergic effects of the TCA.
CLINICAL PEARLS
In the context of sodium channel blockade:
- A QRS duration > 100 ms is predictive of seizures
- A QRS duration > 160 ms is predictive of cardiotoxicity
This patient is already manifesting life-threatening toxicity and needs aggressive resuscitation, including:
- Serum alkalinisation with NaHCO3 to reverse pH-dependent toxicity
- Intubation and hyperventilation aiming for alkaline arterial pH (e.g. 7.45 to 7.55)
- Seizure management with benzodiazepines
- BP management with fluid boluses +/- pressors
Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |