ECG

Question 1

Middle-aged patient presenting with chest pain and diaphoresis. BP dropped to 80/50 following sublingual nitrates.

Answer 1

Inferior STEMI - RV infarction

General:
* Sinus rhythm, rate 84bpm
* Normal axis
* 1st degree AV block (PR 220ms)

Signs of inferior STEMI:
* STE in inferior leads II, III, aVF
* Reciprocal STD in lateral leads I, aVL, V6

Signs of associated right ventricular infarction:
* STE in III > II
* STE in V1-2

This patient also had STE in V4R, confirming the diagnosis of RV infarction:

• RV infarction complicates 40% of inferior STEMIs
• Suggestive features include:
• ST elevation in V1, the only lead that looks directly at the RV
• ST elevation in III > II, as lead III is more rightward facing
• Diagnosis can be confirmed with right-sided leads
• These patients are preload sensitive and may have an exaggerated hypotensive response to nitrates

Question 2

20-year old female presenting with palpitations and presyncope, BP 75/50

Answer 2

A fib with WPW

Main Abnormalities:
* Irregularly irregular broad complex tachycardia
* Extremely rapid ventricular rates — up to 300 bpm in places (RR intervals as short as 200ms or 1 large square)
* Beat-to-beat variability in the QRS morphology, with subtle variation in QRS width

Explanation of ECG Findings:
* Irregularly irregular rhythm is consistent with atrial fibrillation
* There is a left bundle branch block morphology to the QRS complexes
* However, the ventricular rate is far too rapid for this to be simply AF with LBBB
* The rates of 250-300 bpm and the variability in QRS complex morphology indicate the existence of an accessory pathway between the atria and ventricles