Deck 8: PR Intervals

Question 1

You have determined the heart rate and regularity and examined the P waves and QRS complexes. The next logical step of analyzing an ECG rhythm is to:

A) determine the QT interval.
B) evaluate the PR intervals.
C) examine the T waves.
D) examine the ST segments.

Answer 1

evaluate the PR intervals.

Question 2

The PR interval is the distance from the beginning of the ________ to the beginning of the__________.

A) P wave, Q wave
B) P wave, S wave
C) R wave, T wave.
D) PR segment, Q wave.

Answer 2

P wave, Q wave

Question 3

A normal PR interval:

A) is usually present with all sinus and junctional dysrhythmias.
B) indicates the impulse originated from the AV junction (or close to it) and traveled through the atria and AV node in a regular and unobstructed course.
C) consists of the P wave and a flat line.
D) is seen with wandering atrial pacemaker and multifocal atrial tachycardia.

Answer 3

consists of the P wave and a flat line.

Question 4

The PR interval is normally ____ to ____ seconds in duration.

A) 0.06, 0.12
B) 0.10, 0.12
C) 0.12, 0.16
D) 0.12, 0.20

Question 5

A PR interval of less than 0.12 seconds indicates:

A) an intermittent blocking of the impulse as it passes through the AV node.
B) an increased rate of impulse discharge from the SA node.
C) a pacemaker site which is either in or close to the AV junction.
D) a delay in conduction of the impulse between the SA node and the ventricles.

Question 6

A PR interval of greater than 0.20 seconds indicates:

A) an intermittent blocking of the impulse as it passes through the AV node.
B) an increased rate of impulse discharge from the AV junction.
C) a pacemaker site which is either in or close to the AV junction.
D) a delay in conduction of the impulse between the SA node and the ventricles.

Question 7

PR intervals are considered normal if they are:

A) shorter than 0.12 seconds.
B) consistently the same duration.
C) vary in duration.
D) longer than 0.20 seconds.

Question 8

Shorter than normal PR intervals may be seen in:

A) sinus dysrhythmia.
B) premature atrial complexes that arise in the upper or middle right atrium.
C) junctional escape rhythm.
D) sinus tachycardia.

Question 9

Preexcitation:

A) leads to a delayed depolarization of the ventricles.
B) occurs when an impulse arises from a supraventricular site and travels through the AV node to the ventricles more quickly than normal.
C) leads to a longer than normal PR interval.
D) produces a characteristically abnormal slurring at the onset of the QRS complex and a short PR interval.

Question 10

When a P' follows the QRS complex the PR interval is referred to as the:

A) P'R interval
B) P double R' interval
C) RP' interval
D) PR' interval

Question 11

The most common cause of longer than normal PR intervals is:

A) 1st-degree AV heart block.
B) Premature junctional complexes.
C) Idioventricular rhythm.
D) 2nd-degree AV heart block.

Question 12

The P'R intervals may vary from beat to beat in:

A) sinus dysrhythmia.
B) junctional escape.
C) wandering atrial pacemaker.
D) 3rd - degree AV block.

Question 13

The PR intervals get progressively longer in:

A) sinus dysrhythmia.
B) 2nd - degree AV heart block, Type I.
C) 1st - degree AV heart block.
D) 3rd - degree AV heart block.

Question 14

The PR intervals are not measurable in:

A) wandering atrial pacemaker.
B) atrial flutter.
C) 2nd - degree AV heart block, Type I.
D) premature atrial complexes.

Question 15

With 3rd-degree AV heart block the PR intervals are:

A) prolonged.
B) shorter than normal.
C) absent.
D) progressively longer in duration.

Question 16

With atrial fibrillation the PR intervals are:

A) absent.
B) shorter than normal.
C) prolonged.
D) progressively longer in duration.

Question 17

With 2nd-degree AV heart block, Type II, the PR intervals associated with the P waves which are followed by a QRS complex will be:

A) shorter than normal.
B) constant.
C) variable.
D) constantly changing.

Question 18

The PR interval denotes depolarization of the heart from the SA node through the atria, AV node, and His-Purkinje system.

Question 19

With atrial tachycardia the P'R interval can be shorter than normal if the ectopic site is closer to the AV node.

Question 20

1st-degree AV heart block can occur with any rhythm originating in the SA node, such as sinus rhythm, bradycardia, or tachycardia.