ECG Practical Content and Preparation 2

Question 1

A patient's ECG shows a PR interval of 0.28 seconds with no dropped beats. Which condition does this represent?

Accepted Answer

First-degree AV block

Answer

First-degree AV block is defined by a PR interval >0.20 seconds with every P wave conducted to the ventricles.

Question 2

Which electrode placement error would most likely cause an artificially inverted P wave in lead II?

Accepted Answer

Reversing the right arm and left arm electrodes

Answer

Swapping the right arm (RA) and left arm (LA) electrodes inverts leads I and aVL and reverses the polarity of lead II, causing an inverted P wave.

Question 3

When preparing a patient for a 12-lead ECG, the technician should instruct the patient to:

Accepted Answer

Remain still and avoid talking

Answer

Patient movement and speech introduce artifact, so the patient must remain still and quiet during the recording.

Question 4

On standard ECG paper running at 25 mm/sec, one large box (5 mm) represents which time interval?

Accepted Answer

0.20 seconds

Answer

At 25 mm/sec, each large box (5 mm) equals 0.20 seconds; each small box (1 mm) equals 0.04 seconds.

Question 5

Which finding on a rhythm strip most reliably confirms sinus rhythm?

Accepted Answer

Positive P wave in lead II preceding each QRS

Answer

Sinus rhythm requires that the SA node drive the heart, confirmed by an upright P wave in lead II before every QRS complex.

ECG Certification Practice Test