AV Block (Medical Students)
An 8 year old child presents with exercise intolerance and syncope. An ECG was done as part of the investiations.
1. Describe the key findings.
I will first confirm the name of the patient, date, and note the settings.
- Atrioventricular (AV) dissociation: P waves and QRS complexes occur independently with no relationship between them.
- Regular R–R intervals (escape ventricular rhythm), but at a slower rate than P waves.
- Bradycardia: Ventricular rate is approximately ~50 bpm (or lower for age, depending on the strip)
Findings are consistent with third-degree (complete) AV heart block.
2. Name 3 important etiologies to consider.
- Infectious / inflammatory causes: Myocarditis, Acute rheumatic fever
- Post-surgical cause: Following repair of congenital heart disease (e.g., VSD, AV canal defects)
- Congenital / autoimmune causes: Maternal anti-Ro/SSA or anti-La antibodies (congenital heart block) (unlikely to present at 8 years of age).
3. What is management and definitive treatment.
Immediate management
- Assess ABCDE
- Place on continuous cardiac monitoring
- Obtain IV access
- Assess haemodynamic unstable: prepare for urgent temporary pacing (transcutaneous or transvenous)
- Oxygen if required
Definitive treatment: Permanent pacemaker implantation