Cardiology - Arrhythmias: Bradycardias Flashcards
In bradycardia induced intrinsically by coronary artery disease, which territory is associated?
Inferior infarcts
What is the most common cause of sinus bradycardia?
Age related myocardial fibrosis
Familial sinus bradycardia: SSS1
SSS1: - autosomal RECESSIVE - mutation: SCN5A gene on Ch3 (Cardiac Na channel gene) - prominent atrial inexcitability
Familial sinus bradycardia: SSS2
SSS2
- autosomal DOMINANT
- mutation: HCN4 on Ch15
(Pacemaker current If gene)
Familial Sinus Bradycardia: SSS3
SSS3
- SA node dysfunction
- mutation: myosin heavy chain 6 (MYH6)
Familial sick sinus syndrome:
Which mutation in SSS1
SCN5A on Ch3
Familial sick sinus syndrome:
Which mutation is SSS2?
HCN4 on Ch15
Familial sick sinus syndrome:
Which mutation in SSS3?
MYH6 gene
SCN5A mutation on which chromosome and which familial syndrome?
SCN5A on Ch3 in SSS1
HCN4 mutation on which chromosome and which familial syndrome?
HCN4 on Ch15 in SSS2
Which neuromuscular conditions are associated with sinus bradycardia?
- Kearns-Sayre Syndrome
- Myotonic dystrophy
- Freidreich’s ataxia
Treatment of sinus bradycardia?
Treatment is aimed at symptoms
Sinus node dysfunction DOES NOT increase MORTALITY
Indication for PPM in sinus bradycardia?
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
What electrolyte or endocrine caused for AV block?
- hypERkalaemia
- hypERmagnesaemia
- hyPOthyroidism
- adrenal insufficiency
Drug related causes of AV block?
Beta blocker or CCB Digoxin Adenosine Class I and III Antiarrhythmics Lithium
Infectious Diseases associated with AV block?
- endocarditis
- Lyme disease
- diphtheria
- TB
- Chagas’ disease
- Syphilis
Inflammatory and Infiltrative diseases associated with AV block?
SLE RA MCTD Scleroderma Amyoidosis Sarcoidosis Haemochrlmatosis
Neoplastic disease associated with AV block?
Lymphoma
Mesothelioma
Melanoma
RTx
Degenerative Diseases associated with AV block?
Lev’s disease
Lenegre disease
Definition of 1st degree AV Block?
PR > 200ms
Management of 1st degree AV block?
Usually benign
NOT indication for PPM
Although 1st degree AV block is generally considered benign, what adverse outcomes is it associated with?
- increased risk AF
- increased risk PPM requirement
- increased all-cause mortality
2nd degree AV Block: definitions
Type 1: Wenkebach
- progressive prolongation with single nonconducted P wave with pause
Type 2
-CONSTANT PR interval but non-conducted P waves
Where is the block located in Type 1 versus type 2 second degree AV block?
In Type 1 the block is at the AV node
In Type 2 the block is lower down in the conduction system
Management of Type I vs Type II 2nd degree block?
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
Treatment of Third Degree heart block?
- PPM indicated (unless asymptomatic with rate >40bpm)
- poor prognosis if it is associated with an anterior MI
What gives a particularly poor prognosis in 3rd degree AV block?
Association with an anterior MI
Maternal antibodies associated with congenital complete heart block?
Anti-Ro (SS-A)
Anti-La (SS-B)
Other than maternal antibodies what other rheumatological condition is associated with congenital complete heart block?
Maternal lupus
What are Morgagni-Adams-Stokes (MAS) episodes?
Syncopal episodes due to bradycardia
Biventricular versus RV-Only PPM - when might a biventricular be especially indicated?
Biventricular is better in HF with AV block
- reduced hospitalisation
- increased SURVIVAL
Indications for PPM in AV Block?
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
Indications for TEMPORARY PACING?
- 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
Between Anterior and Inferior myocardial infarction associated AV block which is better?
AV block post inferior MI is COMMON and can be managed conservatively if stable and asymptomatic
Complications of pacing?
- tamponade
- haemothorax
- pneumothorax
- PPM dysfunction
- lead fracture
Best test to decide if CRT indicated?
TTE and ECG
- LVEF<35%
- ECG with LBBB
These have EXERCISE TOLERANCE and a QOL benefit
What happens with a magnet on either a PPM or ICD?
Turns PPM on
Turns ICD off
