Dysrhythmias Below The Atria

Question 1

AV junction becomes primary pacemaker instead of SA node
“Escape rhythm”
No P wave before every QRS
HR 40-60bpm

Answer 1

Junctional rhythm

Question 2

Junctional rhythm HR…

Answer 2

40-60bpm

Question 3

Junctional rhythm

Answer 3

AV junction becomes primary pacemaker of ventricles –> AV natural rate < SA node
“Escape rhythm”
No P wave before every QRS
R-R regular

Question 4

Why is the QRS duration normal c junctional rhythm?

Answer 4

Bc the AV node is in atrial tissue (above the ventricles), so the QRS is normal bc the ventricles are unaffected

Question 5

Junctional rhythm possible causes…

Answer 5

SA pathology
Increased vagal tone
Digoxin toxicity (increases contractility for HR)
MI
Drop in CO (20%) (bc no P wave - atrial depolarization - no atrial kick contributing to CO)
Atropine (increases HR)
Pacemaker

Question 6

Which coronary may be to blame in someone who has an MI and then a resulting junctional rhythm?

Answer 6

R coronary a.

Question 7

How much does the atrial kick contribute to CO?

Answer 7

~20%