Cardiology - Arrhythmias: Bradycardias

Question 1

In bradycardia induced intrinsically by coronary artery disease, which territory is associated?

Answer 1

Inferior infarcts

Question 2

What is the most common cause of sinus bradycardia?

Answer 2

Age related myocardial fibrosis

Question 3

Familial sinus bradycardia: SSS1

Answer 3

SSS1:
- autosomal RECESSIVE
- mutation: SCN5A gene on Ch3
(Cardiac Na channel gene)
- prominent atrial inexcitability

Question 4

Familial sinus bradycardia: SSS2

Answer 4

SSS2
- autosomal DOMINANT
- mutation: HCN4 on Ch15
(Pacemaker current If gene)

Question 5

Familial Sinus Bradycardia: SSS3

Answer 5

SSS3

• SA node dysfunction
• mutation: myosin heavy chain 6 (MYH6)

Question 6

Familial sick sinus syndrome:

Which mutation in SSS1

Answer 6

SCN5A on Ch3

Question 7

Familial sick sinus syndrome:

Which mutation is SSS2?

Answer 7

HCN4 on Ch15

Question 8

Familial sick sinus syndrome:

Which mutation in SSS3?

Answer 8

MYH6 gene

Question 9

SCN5A mutation on which chromosome and which familial syndrome?

Answer 9

SCN5A on Ch3 in SSS1

Question 10

HCN4 mutation on which chromosome and which familial syndrome?

Answer 10

HCN4 on Ch15 in SSS2

Question 11

Which neuromuscular conditions are associated with sinus bradycardia?

Answer 11

• Kearns-Sayre Syndrome
• Myotonic dystrophy
• Freidreich’s ataxia

Question 12

Treatment of sinus bradycardia?

Answer 12

Treatment is aimed at symptoms

Sinus node dysfunction DOES NOT increase MORTALITY

Question 13

Indication for PPM in sinus bradycardia?

Answer 13

Class 1 Indications:

• SYMPTOMS associated
• AF with bradycardia and pauses >5 seconds

Class 2 Indications:

• Sinus node dysfunction with rate <40bpm
• syncope without known cause and evidence of Sinus Node Dysfunction on EP Study

Question 14

What electrolyte or endocrine caused for AV block?

Answer 14

• hypERkalaemia
• hypERmagnesaemia
• hyPOthyroidism
• adrenal insufficiency

Question 15

Drug related causes of AV block?

Answer 15

Beta blocker or CCB
Digoxin
Adenosine
Class I and III Antiarrhythmics 
Lithium

Question 16

Infectious Diseases associated with AV block?

Answer 16

• endocarditis
• Lyme disease
• diphtheria
• TB
• Chagas’ disease
• Syphilis

Question 17

Inflammatory and Infiltrative diseases associated with AV block?

Answer 17

SLE
RA
MCTD
Scleroderma
Amyoidosis
Sarcoidosis
Haemochrlmatosis

Question 18

Neoplastic disease associated with AV block?

Answer 18

Lymphoma
Mesothelioma
Melanoma
RTx

Question 19

Degenerative Diseases associated with AV block?

Answer 19

Lev’s disease

Lenegre disease

Question 20

Definition of 1st degree AV Block?

Answer 20

PR > 200ms

Question 21

Management of 1st degree AV block?

Answer 21

Usually benign

NOT indication for PPM

Question 22

Although 1st degree AV block is generally considered benign, what adverse outcomes is it associated with?

Answer 22

• increased risk AF
• increased risk PPM requirement
• increased all-cause mortality

Question 23

2nd degree AV Block: definitions

Answer 23

Type 1: Wenkebach
- progressive prolongation with single nonconducted P wave with pause

Type 2
-CONSTANT PR interval but non-conducted P waves

Question 24

Where is the block located in Type 1 versus type 2 second degree AV block?

Answer 24

In Type 1 the block is at the AV node

In Type 2 the block is lower down in the conduction system

Question 25

Management of Type I vs Type II 2nd degree block?

Answer 25

Type I:

• usually benign, normal fit patients
• improves with exercise or increased sympathetic tone
• NOT an indication for PPM

Type II:

• HIGHER risk of progression to complete heart block
• needs PPM if symptoms or if very bradycardic

Question 26

Treatment of Third Degree heart block?

Answer 26

• PPM indicated (unless asymptomatic with rate >40bpm)

- poor prognosis if it is associated with an anterior MI

Question 27

What gives a particularly poor prognosis in 3rd degree AV block?

Answer 27

Association with an anterior MI

Question 28

Maternal antibodies associated with congenital complete heart block?

Answer 28

Anti-Ro (SS-A)

Anti-La (SS-B)

Question 29

Other than maternal antibodies what other rheumatological condition is associated with congenital complete heart block?

Answer 29

Maternal lupus

Question 30

What are Morgagni-Adams-Stokes (MAS) episodes?

Answer 30

Syncopal episodes due to bradycardia

Question 31

Biventricular versus RV-Only PPM - when might a biventricular be especially indicated?

Answer 31

Biventricular is better in HF with AV block

• reduced hospitalisation
• increased SURVIVAL

Question 32

Indications for PPM in AV Block?

Answer 32

1) 3rd degree with:
- symptoms
- episodes of asystole >3 seconds or AWAKE RATE <40bpm
- post op AV block not expected to resolve
- AV node ablation
- presence of neuromuscular disease

2) second degree block with symptoms
3) Type II second degree with wide QRS
4) Exercise induced 2nd or 3rd block WITHOUT ischaemia
5) AF with pause >5 seconds

Question 33

Indications for TEMPORARY PACING?

Answer 33

• symptomatic or unstable bradycardia not responding to atropine
• Post-ANTERIOR MI with Type 2 second degree or third degree block
• Trifascicular block prior to surgery

Question 34

Between Anterior and Inferior myocardial infarction associated AV block which is better?

Answer 34

AV block post inferior MI is COMMON and can be managed conservatively if stable and asymptomatic

Question 35

Complications of pacing?

Answer 35

• tamponade
• haemothorax
• pneumothorax
• PPM dysfunction
• lead fracture

Question 36

Best test to decide if CRT indicated?

Answer 36

TTE and ECG

• LVEF<35%
• ECG with LBBB

These have EXERCISE TOLERANCE and a QOL benefit

Question 37

What happens with a magnet on either a PPM or ICD?

Answer 37

Turns PPM on

Turns ICD off