ECG Practical Content and Preparation 3

Question 1

A QRS complex that is wider than 0.12 seconds most likely indicates:

Accepted Answer

Ventricular conduction abnormality or bundle branch block

Answer

A QRS duration ≥0.12 seconds indicates delayed intraventricular conduction, typical of bundle branch blocks or ventricular rhythms.

Question 2

Which precordial lead is positioned at the fourth intercostal space, right sternal border?

Accepted Answer

V1

Answer

V1 is placed at the fourth intercostal space along the right sternal border, directly over the right ventricle.

Question 3

In a patient with atrial fibrillation, which ECG feature is characteristically absent?

Accepted Answer

Distinct P waves

Answer

Atrial fibrillation produces chaotic atrial activity with no discernible P waves, replaced by irregular fibrillatory baseline.

Question 4

When measuring QT interval, the measurement should end at:

Accepted Answer

The point where the T wave returns to the isoelectric baseline

Answer

The QT interval is measured from the start of the QRS to the point where the T wave returns to baseline, not its peak.

Question 5

Which of the following rhythms would show a 'sawtooth' flutter wave pattern at approximately 300 bpm?

Accepted Answer

Atrial flutter

Answer

Atrial flutter produces regular sawtooth flutter waves (F waves) typically at 250–350 bpm, best seen in leads II, III, and aVF.

ECG Certification Practice Test