CET 12-Lead ECG Interpretation 3

Question 1

Reciprocal ST depression in leads I and aVL, along with ST elevation in leads II, III, and aVF, suggests occlusion of which artery?

Accepted Answer

Right coronary artery

Answer

Inferior STEMI (II, III, aVF) is most commonly caused by right coronary artery occlusion, with reciprocal changes in lateral leads.

Question 2

A 12-lead ECG shows a QTc of 520 ms. Which of the following is the most serious risk?

Accepted Answer

Torsades de pointes

Answer

A markedly prolonged QTc (>500 ms) greatly increases the risk of torsades de pointes, a potentially fatal polymorphic ventricular tachycardia.

Question 3

On a 12-lead ECG, which leads are considered the lateral leads?

Accepted Answer

I, aVL, V5, V6

Answer

Leads I, aVL, V5, and V6 view the lateral wall of the left ventricle, supplied by the left circumflex artery.

Question 4

Tall, peaked, narrow (tented) T waves on a 12-lead ECG are a classic early sign of:

Accepted Answer

Hyperkalemia

Answer

Early hyperkalemia causes tall, narrow, peaked (tent-shaped) T waves before progressing to wider QRS and sine wave pattern.

Question 5

What ECG finding best differentiates left ventricular hypertrophy (LVH) from anterior STEMI?

Accepted Answer

LVH shows ST elevation in V1–V3 with deep S waves and large R waves elsewhere

Answer

LVH produces a strain pattern with ST-T changes in V1–V3 (repolarization abnormality) accompanied by voltage criteria—deep S in V1 and tall R in V5/V6—unlike STEMI's acute injury pattern.

(CET) Certified Electrocardiogram Technician Practice Test

(CET) Certified Electrocardiogram Technician Practice Test

CET 12-Lead ECG Interpretation 3