ECG Clinical Applications 4

Question 1

A 45-year-old woman has an ECG showing delta waves and a short PR interval. She is asymptomatic. What is the appropriate management?

Accepted Answer

Electrophysiology study referral for risk stratification

Answer

Asymptomatic WPW requires electrophysiology study to assess the refractory period of the accessory pathway and risk of sudden death.

Question 2

Which ECG finding suggests left ventricular hypertrophy using the Sokolow-Lyon criteria?

Accepted Answer

S in V1 + R in V5 or V6 ≥35 mm

Answer

Sokolow-Lyon criteria for LVH: S wave in V1 plus the tallest R wave in V5 or V6 ≥35 mm.

Question 3

A patient develops wide complex tachycardia at 160 bpm. Which finding favors ventricular tachycardia over SVT with aberrancy?

Accepted Answer

AV dissociation on the ECG

Answer

AV dissociation (P waves marching independently of QRS) is a hallmark of ventricular tachycardia and rules out SVT.

Question 4

An ECG shows no P waves, a ventricular rate of 35 bpm, and wide QRS complexes. What rhythm is this?

Accepted Answer

Third-degree (complete) AV block with ventricular escape

Answer

Complete AV block with ventricular escape produces slow wide-complex rhythm independent of P waves (which may be present but dissociated).

Question 5

Which ECG pattern is seen in posterior MI and how is it diagnosed on a standard 12-lead ECG?

Accepted Answer

Tall R wave and ST depression in V1-V2 (mirror image)

Answer

Posterior MI appears as tall R waves with ST depression and upright T waves in V1-V2, representing the mirror image of the true posterior injury.

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