Heart Block

Question 1

What causes atrioventricular heart block.

Answer 1

It is due to damage to the atrial node, AV node or His/Purkinje system.

Question 2

What are the causes of heart block. (13)

Answer 2

Myocardial infarction. 
Drugs. 
Myocarditis. 
Acute rheumatic fever.
infection 
Sarcoid.
Sick sinus syndrome.
Athletes.
Idiopathic. 
Congenital.
Aortic valve calcification.
Cardiac surgery. 
Infiltration.

Question 3

What kind of drugs can cause heart block. (3)

Answer 3

Digitalis.
Calcium channel blockers.
Beta blockers.

Question 4

Give an example of an infection that can cause heart block.

Answer 4

Lyme disease.

Question 5

What are the symptoms of heart block. (3)

Answer 5

Syncope.
Dyspnoea.
Heart failure.

Question 6

What are the types of heart block. (4)

Answer 6

1st degree heart block.
2nd degree heart block (Mobitz type 1).
2nd degree heart block (Mobitz type 2).
3rd degree heart block (complete heart block).

Question 7

What are the characteristics of 1st degree heart block.

Answer 7

Prolonged PR interval. (>0.20s).

Question 8

What are the characteristics of 2nd degree heart block (Mobitz type 1).

Answer 8

The PR interval gradually increases in length until there is a ‘missed beat’.

Question 9

What is the implication of 2nd degree heart block.

Answer 9

Some atrial impulses fail to conduct to the ventricles.

Question 10

What are the characteristics of 2nd degree heart block (Mobitz type 2).

Answer 10

Occasional dropped QRS complex, which is not related to changes in the PR interval.
Fixed PR interval, with occasional P waves not being conducted to the ventricles.

Question 11

What are the characteristics of 3rd degree heart block.

Answer 11

Atrial and ventricular impulses are completely dissociated.

The wide QRS complex is the result of a spontaneous escape rhythm of 35-40BPM.