Bradyarrhythmias

Question 1

Percent of SA nodal artery arises from RCA

Answer 1

55-60%

Question 2

Percent of SA nodal artery arises from Lcx

Answer 2

40-45%

Question 3

SA node cells exhibit the most rapid __ phase of depolarization

Answer 3

4

Question 4

Absence of autonomic influence of SA node leads to an intrinsic HR that is normally ___ bpm

Answer 4

100-110 bpm

Question 5

Intrinsic HR declines ___ bpm for each decade of age

Answer 5

5-6 bpm

Question 6

Most common cause of tachycardia in tachy-brady syndrome

Answer 6

AF

Question 7

Formula for max HR

Answer 7

208- (0.7x age)

Question 8

Sinus bradycardia is common in ___ and ___ MI

Answer 8

acute inferio and posterior

Question 9

Principal tx for sinus node dysfunction

Answer 9

Permanent pacemaker

Question 10

Class I indication for pacing in SA node dysfunction (3)

Answer 10

documented symptomatic bradycardia, SND associated long term drug therapy for which there is no alternative and symptomatic chronotropic incompetence

Question 11

Normal automaticity rate of AV node

Answer 11

20-60 bpm

Question 12

Channels responsible for phase 0

Answer 12

ICa-L (L type Calcium channels)

Question 13

Channels responsible for phase 4 (4)

Answer 13

If, ICa-L, ICa-T,Incx

Question 14

Percent Av node artery arises from RCA

Answer 14

90%

Question 15

Percent Av node artery arises from Lcx

Answer 15

10%

Question 16

Grouped beating is seen in what type of AV block

Answer 16

Mobitz Type 1 Av block

Question 17

Most common causes of acquired conduction disease accounting for 50% of av block

Answer 17

Fibrosis and sclerosis

Question 18

Highest risk of causing iatrogenic Av block

Answer 18

AV and TV valve surgery

Question 19

AV block transiently develops in __ % of patients

Answer 19

10-25%

Second degree and higher grade AV block tends to occur more often in inferior rather than anterior acute MI

Question 20

High grade AV block associated with inferior wall MI is often located PROXIMAL to bundle of his in ___ % of px

Answer 20

90%. Temporary pacing often not required

On the other hand, high grade av block in the setting of ANTERIOR MI is typically indicative of extensive infarction , is more often DISTAL to AV node and has high mortality rate. Temporary pacing typically indicated

Question 21

Most common infectious cause of AV block

Answer 21

Lyme disease due to Borrelia burdorferi

Question 22

In patients with congenital complete heart block, exercise typically _____ HR

Answer 22

increases

By contrast those with ACQUIRED particularly with wide QRS do not respond to exercise with an increased HR

Question 23

Time from the most rapid deflection of the atrial electrogram in the his bundle to the His electrogram

Answer 23

AH interval

Question 24

Normal AH interval

Answer 24

< 130 ms

Question 25

Time from His electrogram to the earliet onset of QRS

Answer 25

HV interval

Question 25

Normal HV interval

Answer 25

<= 55 ms

Question 26

First line strategies for management of AV block

Answer 26

Eliminate reversible causes and determine the imediate safety and reliability of the heart rhythm the lower the conduction system that an escape rhythm is occurring, the lower is the reliability of the escape rhythm

Question 27

Permanent pacing is recommended regardless of ssx for which subset of patients with AV node dse?

Answer 27

ACQUIRED Mobitz type II, high grade AV block or 3rd degree av block that is NOT reversible/ physiologic

Question 28

Only instance where in it is a Class I recommendation to do permanent pacing in a patient with Mobitz Type 1

Answer 28

If it is associated with neuromuscular disease associated with progressive conduction tissue disorder