Heart Block

Question 1

Define heart block.

Answer 1

Cardiac electric disorder characterised by delayed (or absent) conduction from the atria to the ventricles.

Question 2

Explain the aetiology/risk factors of heart block.

Answer 2

Hypertension
Increased vagal tone
AV-nodal blocking agents
Chronic stable CAD
Acute coronary syndrome
CHF
Hypertension
Cardiomyopathy

Question 3

Summarise the epidemiology of heart block.

Answer 3

The epidemiology of AV block is not well characterised.

Advanced AV block (usually type II second-degree and third-degree) is usually anatomically infranodal and is seen in advanced His-Purkinje disease.

Question 4

Recognise the presenting symptoms of heart block.

Answer 4

Syncope
Bradycardia <40 bpm
Fatigue
Dyspnoea
Chest pain
Palpitations
Nausea/vomiting

Question 5

Recognise the signs of heart block on physical examination.

Answer 5

High blood pressure
Sometimes low blood pressure

Question 6

Identify appropriate investigations for heart block and interpret the results.

Answer 6

ECG
Serum troponin
Serum potassium
Serum calcium
Serum pH
Serum digitalis level

Question 7

Generate a management plan for first degree or second degree Type I heart block.

Answer 7

Asymptomatic
1st line: Monitoring

Symptomatic
1st line: Discontinuation of AV-nodal blocking medications.
2nd line: Infrequently: PPM (permanent pacemaker) or cardiac resynchronisation therapy ± ICD placement.

Question 8

Generate a management plan for second degree Type II or third degree heart block.

Answer 8

Asymptomatic or mildly to moderately symptomatic
1st line: Condition-specific management and discontinuation of AV node-blocking drugs.
2nd line: PPM or cardiac resynchronisation therapy ± ICD placement

Severely symptomatic
1st line: Condition-specific management, discontinuation of AV-nodal blocking drugs, and temporary (transcutaneous or transvenous) pacing.
2nd line: PPM or cardiac resynchronisation therapy ± ICD placement.

Question 9

Identify the possible complications of heart block and its management.

Answer 9

In the short term, periprocedurally, the risks associated with pacemaker implantation are low: in the range of 2% to 3%. These include bleeding, infection, vascular trauma, pneumothorax, cardiac tamponade, lead dislodgement, and pocket haematoma development. The risk of MI, stroke, and death is <1%.

Long-term complications include pulse generator or lead malfunction and infection. The pulse generators run on batteries that average 7 to 10 years in longevity. Battery depletion requires replacing the pulse generator.

Over a lifetime, there is some risk of infection of the lead, which may require extraction, a complex procedure that should be performed at specialised centres.

Question 10

Summarise the prognosis for patients with heart block.

Answer 10

The prognosis is related to the degree of AV block and the severity of associated symptoms. In certain conditions, such as sarcoid or amyloid heart disease or acute anterior MI, the underlying condition strongly determines prognosis.