ECG- heart block

Question 1

What is heart block?

Answer 1

Block in conduction between AV node and the ventricles causing a prolonged PR interval

Question 2

Types of heart block? (4)

Answer 2

First degree
Second degree Mobitz I
Second degree Mobitz II
Complete heart block

Question 3

What are the most common underlying cause of heart block? (2)

Answer 3

MI or ischaemic heart disease

Drugs e.g. beta blockers, calcium blockers

Question 4

How are Mobitz I and Mobitz II differentiated?

Answer 4

Mobitz I- progressive lengthening of PR interval until a beat is dropped.
Mobitz II- intermittent failure of conduction through the AV node (e.g. every three P waves)

Question 5

What defines third degree (complete) heart block?

Answer 5

No relationship between P waves and QRS complexes

Question 6

How is ventricular contraction caused in 3rd degree block and what is typically the rate?

Answer 6

Ventricular escape rhythm around 30-40bpm

Question 7

When is permanent pacemaker insertion recommended for heart block?

Answer 7

Symptomatic Mobitz I
Mobitz II
Complete heart block

Question 8

When is atropine used in heart block? How does it work?

Answer 8

In acute situations accompanied with clinical deterioration. Anti-muscarinic effect- increases the heart rate

Question 9

What are the two shockable cardiac arrest rhythms?

Answer 9

Pulseless ventricular tachycardia

V. Fibrillation

Question 10

What are the two non-shockable cardiac arrest rhythms?

Answer 10

Pulseless electrical activity

Asystole

Question 11

What are the reversible causes of cardiac arrest?

Answer 11

Hypoxia
Hypothermia
Hypovolaemia
Hypo/hyperkalaemia
Tamponade
Tension pneumothorax
Thromboembolisn
Toxins/metabolic

Question 12

When should adrenaline/amiodarone be given in cardiac arrest?

Answer 12

After the 3rd shock, then every 3-5 minutes afterwards (adrenaline only)

Question 13

When is adrenaline given for non-shockables?

Answer 13

Immediately, then every 3-5 minutes afterwards