SA node disorders

Question 1

What is sinus arrest also known as?

Answer 1

Asystole

Characterized by absence of electrical impulses or cardiac contractions

Question 2

What is the primary requirement when sinus arrest occurs?

Answer 2

Initiation of CPR and administration of a vasopressor (e.g., Epinephrine)

Results in no cardiac output

Question 3

What does PEA stand for?

Answer 3

Pulseless Electrical Activity

Also referred to as electromechanical dissociation

Question 4

What is the characteristic of PEA?

Answer 4

Heart rhythm present on ECG but absence of a pulse

Leads to no cardiac output

Question 5

What is sinus pause?

Answer 5

SA node fails to initiate an impulse due to disorder of automaticity

Disrupts timing of SA node causing underlying rhythm not to resume on time

Question 6

What is the classification criterion for sinus pause?

Answer 6

R - R interval delay < 3.0 sec

SA block not confirmed

Question 7

What is the classification criterion for sinus arrest?

Answer 7

R - R interval delay > 3.0 sec

Indicates a longer disruption in impulse initiation

Question 8

What causes sinus pause?

Answer 8

Causes include:
* Age-related fibrosis
* Increased vagal tone
* Myocardial ischemia or infarction
* Drug effects

These factors disrupt the automaticity of the SA node

Question 9

What is sinus exit block?

Answer 9

Isolated impulses fail to emerge due to disorder of conductivity

Conductivity disorder in tissue surrounding SA node blocks impulses

Question 10

How does sinus exit block affect the timing of the underlying rhythm?

Answer 10

Does not disrupt timing of underlying rhythm

R - R interval twice or 3 times preceding R - R cycle may indicate SA block

Question 11

What are the causes of sinus exit block?

Answer 11

Causes include:
* Increased vagal tone
* Myocardial ischemia or infarction
* Drug effects

Similar to causes of sinus pause

Question 12

What is sick sinus syndrome?

Answer 12

Dysfunction of sinus node

Manifests on ECG as bradycardia episodes alternating with tachyarrhythmias

Question 13

What symptoms are associated with sick sinus syndrome?

Answer 13

Symptoms include:
* Dizziness
* Fainting
* Shortness of breath
* Chest pain

Prolonged sinus pauses/arrest often occur after tachyarrhythmia

Question 14

True or False: Sinus pause is a disorder of automaticity.

Answer 14

True

Question 15

True or False: Sinus exit block is a disorder of automaticity.

Answer 15

False

Question 16

What disrupts the timing of the RR interval?

Answer 16

Sinus pause

Sinus exit block does not disrupt timing