Disorders Of The AV Node

Question 1

Characteristics of cells located in the AV node

Answer 1

Relatively higher resting membrane potentials than surrounding atrial and ventricular myocytes
Exhibit spontaneous depolarization during phase 4
Slower phase 0 depolarization (calcium influx vs sodium influx in ventricular tissue)

Question 2

Only reliable therapy for symptoms arising from AV condition block

Answer 2

Permanent pacing

Question 3

True or false. AV node is highly innervated with thr postganglionic sympathetic and parasympathetic nerves

Answer 3

True.

Question 4

True or False. Bundle of His and distal conducting system is strongly influenced by autonomic tone.

Answer 4

False. Minimally.

Question 5

Metabolic/endocrine etiologies of AV block

Answer 5

Hyperkalemia
Hypermagnesemia
Hypothyroidism
Adrenal insufficiency

Question 6

Infectious etiologies of AV block

Answer 6

Endocarditis
Lyme
Chagas
Syphilis
TB 
Diphtheria 
Toxoplasmosis

Question 7

First degree AV block

Answer 7

PR interval more than 200ms

Question 8

Type 1 second degree AV block

Answer 8

Progressively lengthening PR interval, shortening of the RR interval, and a pause that is less than two times the immediately preceding RE interval on the ECG.

Question 9

Type II second degree AV block

Answer 9

Intermittent failure of conduction of the P wave without changes in the preceding PR or RR interval.