1st degree Atrioventricular block (AVB)

Question 1

Description of 1st degree AVB

Answer 1

Electrical impulses from the SA node are delayed on their journey to the AV node before being transmitted to the ventricles.

The SA node depolarising is represented by P wave interval.

Question 2

How do I recognise 1st degree AVB

Answer 2

• P wave present
• PR interval persistently greater than or equal to 0.2 seconds or 1 large square.

Question 3

Leads that 1 degree AVB is present in?

Answer 3

All leads
however commonly present in leads LII and V1.

Question 4

Signs and symptoms

Answer 4

• Extertional induced shortness of breath
• Extertional or chronic lethargy

Question 5

1st degree AVB significance

Answer 5

AVB are typically progressive in nature for example 2AVB and 3AVB.

• Often 1AVB patient present asymptomatic but it is important to treat any underlying signs and symptoms and also consider any associated causes.