EKG TEST 3 2026 STUDY GUIDE | CARDIAC
RHYTHM PRACTICE QUESTIONS, ANSWERS
& RATIONALES
| GRADED A+ | GUARANTEED SUCCESS
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales Included
, sinus node block sinus node fires normally, but wave of depolarization is immediately blocked and
not transmitted into the atrial tissue.
AV block any conduction block between the SA node and terminal Purkinje fibers (includes
AV node and His bundle)
Bundle branch block bundle branch block = a conduction block in one or both of the ventricular
bundle branches
First degree AV blocks prolonged delay in conduction at AV node or His bundle. Wave of depolarization
spreads normally from sinus node thru atria but gets delayed at AV node -->
prolonged PR
Dx of first-degree AV block requires only that the PR interval be longer than 0.2
seconds (one small box)
every atrial impulse does make it through the AV node and activate the ventricles,
so its not really a block but more like a delay
Every QRS has a p wave
second-degree AV block (general) not every atrial impulse is able to pass thru AV node into the ventricles. Some p
waves fail to conduct thru the ventricles, ratio of p waves to QRS complexes = > 1:1
2 types: Mobitz type I and II
Mobitz Type I second-degree AV block (Wenckebach) block w/in the AV node
block/delay is variable, increasing with each impulse. Each successive atrial
impulse encounters a longer and longer delay in the AV node until one impulse
(usually every third or fourth) fails to make it through.
Progressive lengthening of PR interval w/ ea beat and then a p wave is not
followed by a QRS (dropped beat). After this initial drop beat, sequence repeats
itself over and over
4:3 Wenckebach block = beat, beat, beat, p wave, DROPPED QRS, beat beat beat
DROP, beat beat beat
4 p waves : 3 QRS
RHYTHM PRACTICE QUESTIONS, ANSWERS
& RATIONALES
| GRADED A+ | GUARANTEED SUCCESS
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales Included
, sinus node block sinus node fires normally, but wave of depolarization is immediately blocked and
not transmitted into the atrial tissue.
AV block any conduction block between the SA node and terminal Purkinje fibers (includes
AV node and His bundle)
Bundle branch block bundle branch block = a conduction block in one or both of the ventricular
bundle branches
First degree AV blocks prolonged delay in conduction at AV node or His bundle. Wave of depolarization
spreads normally from sinus node thru atria but gets delayed at AV node -->
prolonged PR
Dx of first-degree AV block requires only that the PR interval be longer than 0.2
seconds (one small box)
every atrial impulse does make it through the AV node and activate the ventricles,
so its not really a block but more like a delay
Every QRS has a p wave
second-degree AV block (general) not every atrial impulse is able to pass thru AV node into the ventricles. Some p
waves fail to conduct thru the ventricles, ratio of p waves to QRS complexes = > 1:1
2 types: Mobitz type I and II
Mobitz Type I second-degree AV block (Wenckebach) block w/in the AV node
block/delay is variable, increasing with each impulse. Each successive atrial
impulse encounters a longer and longer delay in the AV node until one impulse
(usually every third or fourth) fails to make it through.
Progressive lengthening of PR interval w/ ea beat and then a p wave is not
followed by a QRS (dropped beat). After this initial drop beat, sequence repeats
itself over and over
4:3 Wenckebach block = beat, beat, beat, p wave, DROPPED QRS, beat beat beat
DROP, beat beat beat
4 p waves : 3 QRS
