Electrocardiography Flashcards

Which ECG finding is characteristic of left bundle branch block (LBBB)?

Answer: Wide QRS (≥0.12 s) with broad monophasic R wave in V5–V6 and deep S in V1

LBBB shows a broad, notched R wave in lateral leads (I, aVL, V5–V6) and a deep QS or rS in V1, with QRS duration ≥0.12 seconds.

A 45-year-old athlete's resting ECG shows sinus bradycardia at 48 bpm with no symptoms. What is the most appropriate action?

Answer: Consider it a normal training adaptation and document it

Sinus bradycardia in well-trained athletes is a common physiologic adaptation due to increased vagal tone and does not require intervention if asymptomatic.

What ECG change is associated with hyperkalemia?

Answer: Peaked (tall, narrow) T waves followed by widening QRS

Hyperkalemia classically produces tall peaked T waves early, followed by PR prolongation, QRS widening, and eventually a sine-wave pattern as potassium rises.

During an exercise test, the exercise physiologist observes three consecutive wide-complex beats at >100 bpm. This finding is best described as:

Answer: Non-sustained ventricular tachycardia

Three or more consecutive wide-complex beats at a rate >100 bpm lasting <30 seconds defines non-sustained ventricular tachycardia.

Which ECG lead is placed at the fourth intercostal space, right sternal border?

Answer: V1

V1 is positioned at the fourth intercostal space to the right of the sternum, directly opposite V2 on the left sternal border.

A delta wave on an ECG is pathognomonic of which condition?

Answer: Wolff-Parkinson-White (WPW) syndrome

A delta wave (slurred upstroke of the QRS) results from ventricular pre-excitation via an accessory pathway, which is the hallmark of WPW syndrome.

In ECG interpretation, what does the term 'axis deviation' refer to?

Answer: The mean direction of ventricular depolarization in the frontal plane

Cardiac axis describes the mean vector of ventricular depolarization; left axis deviation (+100°) can indicate specific pathological conditions.