Bradycardia

Exam Cram

• Bradycardia defined as a heart rate below 60 bpm

• Classified by presence of unstable features, type of arrhythmia and underlying cause

• DC cardioversion shock if unstable features (hypotension, myocardial infarction, syncope, heart failure)

• Pacemaker required for heart block stage 2.2 or 3, asystolic pauses > 3 seconds or symptomatic bradycardia

Outline

Assessment

History

• Symptomatic: chest pain, dizziness & loss of consciousness, shortnes of breath, 

Examination

• Bi-basal crepitations

Investigation

• ECG

• FBC, urea & electrolytes + TFT & calcium/ magnesium/ phosphate

• Consider troponin, d-dimer, ECHO

Diagnosis

Diagnostic criteria: HR < 60

Classification

1. Severity

   • Unstable (1/4)

     1. SBP < 90 or diastolic < 60

     2. Ischaemia (ongoing chest pain)

     3. Ongoing (pre)syncope

     4. Acute heart failure- e.g. pulmonary oedema

   • Stable

2. Aetiology

   • Heart Block- 3.0, 2.2, 2.1, 1

   • Bifasicular and Trifasicular Block

   • Asystole

   • Sinus Bradycardia

Management

Acute

1. Atropine if unstable features (1/4)

   • 500mcg, can be repeated x3

2. Secondary measures

   • Isoprenaline

   • Adrenaline

   • Transcutanous pacing

   • Senior support, resus, peri-arrest buzzer

Long term

• Indications for a permanent pacemaker

  1. Heart block

     • Complete (type 3)

     • Mobitz type 2

  2. Tri-fascicular block

     • Bi-fascicular block + unexplained syncope for consideration of pacemaker

  3. Pauses > 3 seconds

  4. Symptomatic bradycardia

Resources and References

1. iRESUS Bradycardia Guidelines

Scope

• Body systems: Cardiovascular System 

• Specialties: Cardiology 

Written in 2025