Blonder - AV Block

Question 1

Is a 1st degree AV block rate dependent or independent?

Answer 1

Rate dependent

Question 2

What is the physiologic significance of the prolongation of the PR interval in 1st degree AV block?

Answer 2

Loss of atrial kick effect for ventricular filling

Question 3

Major causes of AV Block

Answer 3

Increased vagal tone

Fibrosis and sclerosis of conduction system

Ischemic heart disease

Cardiomyopathy/myocarditis

Congenital heart disease

Question 4

What major classes of drugs can cause AV blockade?

Answer 4

Ca⁺⁺Ch Blockers, esp the non-DHPs like verapamil and diltiazem

β-blockers

Question 5

What is the difference between 3rd degree AV block and AV dissociation?

Answer 5

In 3rd degree AV block, atria and ventricles are each going at their own rate and V-rate is slow

In AV dissociation, atrial conduction firing at its intrinisc rate, but V-rate is very fast (vtach) and overdriving the atria

Question 6

What is syncope with a 3rd degree AV block called?

Answer 6

Stokes-Adams attack