ECG ECG Waveform Measurements and Intervals

Question 1

What is the normal duration of the PR interval in adults?

Accepted Answer

0.12–0.20 seconds

Answer

0.04–0.10 seconds

Answer

0.20–0.40 seconds

Answer

0.40–0.60 seconds

Question 2

The QRS complex normally has a duration of:

Accepted Answer

0.06–0.10 seconds

Answer

Less than 0.04 seconds

Answer

0.12–0.20 seconds

Answer

Greater than 0.20 seconds

Question 3

The QT interval represents:

Accepted Answer

Total ventricular depolarization and repolarization

Answer

Atrial depolarization only

Answer

AV nodal conduction time

Answer

Sinoatrial conduction time

Question 4

A corrected QT interval (QTc) is calculated to account for:

Accepted Answer

Heart rate variation

Answer

Patient age

Answer

Lead placement differences

Answer

Blood pressure

Question 5

What does a prolonged QTc interval (>500 ms) indicate clinically?

Accepted Answer

Increased risk of torsades de pointes ventricular tachycardia

Answer

First-degree AV block

Answer

Left ventricular hypertrophy

Answer

Normal variant in athletes

Question 6

The ST segment on the ECG represents:

Accepted Answer

The period between ventricular depolarization and repolarization (plateau phase)

Answer

Atrial repolarization

Answer

P-wave production

Answer

His-Purkinje conduction