Bradyarrhythmia

Question 1

What are the types of bradyarrhythmia seen on ECG?

Answer 1

Sinus bradycardia (HR <60bpm)
Heart block
- 1st degree heart block 
- 2nd degree heart block (Mobitz 1 and Mobitz 2)
- 3rd degree/complete heart block

Question 2

What are the causes of sinus bradycardia?

Answer 2

Physical fitness 
Vasovagal attacks 
Sick sinus syndrome 
Drugs 
- beta-blockers, digoxin, amiodarone 
Hypothyroidism 
Hypothermia 
Increased intracranial pressure 
Cholestasis 
Post-MI

Question 3

Definition of heart block

Answer 3

Disrupted passage of electrical impulse through the AV node

Question 4

Describe 1st degree heart block

Answer 4

Prolonged PR interval
No missed beats
Not in itself a risk to health

Question 5

Describe Mobitz type 1 (2nd degree heart block)

Answer 5

There is an intermittent QRS complex (blockage between the AV node and the ventricle)
PR interval becomes longer and longer until a QRS is missed
Pattern restarts

Question 6

Describe Mobitz type 2 (2nd degree heart block)

Answer 6

There is an intermittent QRS complex (blockage between the AV node and the ventricle)
Regular rhythm and constant PR interval
QRS complexes are regularly missed
e.g. P-P-QRS-P-P-QRS
More dangerous than type 1 as it is more likely to progress to complete heart block

Question 7

Describe 3rd degree/complete heart block

Answer 7

No impulses are passed from the atria to the ventricles, so the P waves and QRS complexes are independent of each other (broad QRS)
- ventricular escape rhythm
Requires urgent treatment (pacemaker) as it can quickly become unstable

Question 8

What are the causes of 3rd degree heart block?

Answer 8

MI
Chronic - fibrosis around bundle of His OR bundle branch
Aortic valve calcification
Cardiac surgery/trauma
Dignoxin toxicity
Infiltration - abscess, granuloma, tumour, parasites

Question 9

What are the clinical feature of bradycardia?

Answer 9

Asymptomatic 
Fatigue 
Nausea
Dizziness
Syncope, chest pain or SOB are adverse signs

Question 10

Briefly describe the management of a bradyarrhythmia.

Answer 10

Oxygen 
Identify reversible causes 
No adverse signs
- continue monitoring if not at risk of asystole 
Adverse signs 
- IV Atropine 500mcg 
- seek expert help
- repeat every 5 mins (up to 3mg) as needed 
- transcutaneous pacing 
- isoprenaline 5mcg/min
- adrenaline 2-10mcg/min

Question 11

What are the adverse signs of bradyarrhythmias?

Answer 11

Shock
Syncope 
Heart failure
Myocardial ischaemia 
- chest pain 
SOB

Question 12

What factors means a patient with a bradyarrhythmia is more at risk of asystole?

Answer 12

Recent asystole
Mobitz type 2
3rd degree/complete heart block
Ventricular pause greater than 3 seconds