Heart block

Question 1

Definition of heart block

Answer 1

Impairment of AV node conduction

Question 2

Prolonged conduction through AV node (more than 0.20 seconds)

Answer 2

First degree block

Question 3

Progressive prolongation of the PR interval

Answer 3

Second degree Mobitz I

Question 4

Intermittent failure of QRS to follow a P-wave, often with a ratio (e.g. 2:1)

Answer 4

Second degree Mobitz II

Question 5

Complete dissociation of P waves and QRS complexes

Answer 5

Complete heart block

Question 6

Why are the QRS complexes in complete heart block often wide?

Answer 6

They are ventricular escape complexes

Question 7

Commonest causes of heart block (3)

Answer 7

Ischaemic heart disease
Infection (e.g. rheumatic fever, endocarditis)
Drugs (e.g. digoxin, calcium blockers)

Question 8

What are Stokes Adams attacks?

Answer 8

Syncope caused by asystole

Question 9

Symptoms of heart block (3)

Answer 9

Syncope
Palpitations
Dizziness

Question 10

Management of chronic heart block

Answer 10

If symptomatic Mobitz I, or Mobitz II/CHB: permanent pacing

Question 11

Management of acute heart block

Answer 11

IV atropine (antimuscarinic) and consider temporary external pacing