20-year-old male presenting with seizures. BP 80/50. 

TOP 100 ECG QUIZ LITFL 004

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

TOP 100 ECG SERIES


Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

2 Comments

  1. It looks to me more like a 2:1 AVB rather than a 1st degree. There are several leads but very clear in Lead II where it looks like a P wave right after the QRS morphology.

  2. True, it resembles 2:1 block, though the PP interval varies.
    My concern is different. Sinus rythm should have positive p waves in leads II, III, aVF and negative in aVR and this ECG in my opinion shows exactly the opposite. Could it be some ectopic atrial rythm than?

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