Junctional Rhythms And AV Blocks

Question 1

Where is the AV node located?

Answer 1

In the lower portion of the right atrium

Question 2

What creates the AV junction?

Answer 2

The Av node + Bundle of His

Question 3

Does the Av node have any pacemaker cells?

Answer 3

No

Question 4

What is the main function of the AV node?

Answer 4

1. To slow conduction
   *and allow complete atrial depolarization and contraction before ventricular contraction

Question 5

What is a junctional rhythm?

Answer 5

Dysrrhythmias originating in the AV junction

Question 6

What is the difference between a PAC and a PJC?

Answer 6

1. PAC has a normal PR interval
2. PAC are more common than PJC

Question 7

How do Junctional Escape Beats happen?

Answer 7

1. SA node suffers a transient sinus block which causes
   *One missed pacing cycle and creates a pause
   *A Junctional automaticity focus will escape and overdrive suppression to create a Junctional escape beat
2. Can produce an inverted P waves immediately before the QRS or after the QRS or hidden

Question 8

What are Accelerated Junctional Rhythms?

Answer 8

Rate: 60-100bpm
Rhythm: regular
P-Waves: INVERTED, hidden, after, or before QRS complex
PR: <0.10 short
QRS: normal

Question 9

What are AV blocks?

Answer 9

1. A block that either excessively slows or eliminates conduction from the atria to the ventricles
2. Or the block can slow AND eliminate the conduction from the atria to the ventricles

Question 10

What are the different types of AV blocks?

Answer 10

1. First degree
2. 2nd degree Wenckbach, Mobitz
3. Third degree

Question 11

What does a first degree AV block do?

Answer 11

Lengthens the delay between atrial and ventricular depolarization

Question 12

What does a third degree AV block do?

Answer 12

Completely blocks conduction of atrial stimuli to the ventricles

Question 13

What are some special characteristics of a first degree AV block?

Answer 13

1. The PR interval is CONSISTENTLY longggggg for each beat
   *>0.20 seconds

Question 14

If a patient has a first degree AV block what could they develop later in Life?

Answer 14

A-fib or a pacemaker

Question 15

What do second degree AV block allow

Answer 15

1. They allow some atrial depolarizations to conduct to ventricles
2. Some are blocked
   *which will leave a lone P without associated QRS

Question 16

What are special characteristics about 2 degree AV block Wenckeback

Answer 16

1. Group beating
   *There will be repeating patterns of rhythms
2. The cycle of progressive blocking will continue until the final P wave is totally blocked

Question 17

What is a third degree AV block?

Answer 17

1. Complete heart block
   *Absence of conduction from atria to ventricles
   *The ventricles are pacing themselves