Practical Content and Preparation Flashcards

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

Answer: Ventricular conduction abnormality or bundle branch block

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

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

Answer: V1

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

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

Answer: Distinct P waves

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

When measuring QT interval, the measurement should end at:

Answer: The point where the T wave returns to the isoelectric baseline

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

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

Answer: Atrial flutter

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

A technician notices 60-Hz electrical interference on the ECG tracing. The most appropriate first step is to:

Answer: Check and improve electrode-skin contact and grounding

60-Hz artifact usually results from poor electrode contact or nearby electrical interference; improving skin prep and contact is the first corrective step.

Delta waves on an ECG are associated with which pre-excitation syndrome?

Answer: Wolff-Parkinson-White syndrome

Wolff-Parkinson-White syndrome causes delta waves due to early ventricular activation via an accessory pathway (Bundle of Kent).