Ladder diagrams

Question 2

What is a ladder diagram

Answer 2

Graphic illustration of a cardiac impulse formation and conduction (see image)
* Normal atrial conduction: 1st vertical line
* Normal AV nodal conduction with normal delay: 2nd slanted line
* Normal ventricular conduction: 3rd vertical line

Question 3

Nodal escaped rhythm

Answer 3

• Impulse formation starts in AV nodal region: high, nodal or low
• Propagate to ventricles
• Could also propagate to atria

Question 4

1AVB

Answer 4

• Long PR interval → conduction delay represented by steep slope in AV node region

Question 5

2AVB

Answer 5

• Mobitz type I: progressive lengthening of the PR until block
• Mobitz type II: blocked P waves with stable PR intervals

Question 6

VPC with retrograde AV conduction

Answer 6

• Retrograde activation from VPC → concealed conduction to AV node
  o Prolonged PR interval of following sinus beat
  o Constant bombardment of AV node by antegrade and retrograde impulse → progressive prolongation of PR until block
  o Physiologic 2AVB type I
• Post extrasystolic pauses
  o Non compensatory pause: retrograde conduction through AV node → enter SA node → reset sinus rhythm
   Pause is <2RR = less than compensatory
   Retrograde P wave often obscured by T wave

Question 7

SVT

Answer 7

Depend on mehcanism
Can be blocked at AV node

Question 8

V arrhythmias

Answer 8

Fast rates from ventricles blocked at AV junction

Question 9

Sinoatrial Wenckebach periodicity