Bradycardia is having a heart rate of <60 beats/minute that may not affect the hemodynamic status of some patients.
A heart rate that is inadequate for the patient's current condition and may not be able to support life is a clinically significant bradycardia.

Bradycardia can be caused by problems in the sinoatrial node, problems in the conduction pathways of the heart, metabolic problems or heart attack/disease that caused damage to the heart.

The different types of bradycardia are sinus bradycardia, sick sinus syndrome, tachycardia-bradycardia syndrome, hypersensitive carotid sinus syndrome, sinus pause/arrest, sinoatrial node exit block and atrioventricular block.

Bradycardia Treatment

Principles of Therapy

  • Management of sinus bradycardia is not necessary unless with inadequate cardiac output and/or with life-threatening arrhythmia
  • Observation and monitoring is recommended for hemodynamically stable patients
  • Second-line therapy and transcutaneous pacing may be considered only when a patient with acute symptomatic bradycardia is unresponsive to Atropine


1st-Line Agent


  • Used for symptomatic sinus bradycardia, hypersensitive carotid sinus syndrome, and atrioventricular (AV) blocks
  • Reverses cholinergic-mediated decrease in heart rate by exerting its parasympathomimetic effect on the myocardium
  • Improves signs and symptoms and cardiac rate
  • Use cautiously in patients with acute myocardial infarction or acute coronary ischemia
  • May not be effective in patients who have undergone cardiac transplantation
  • Temporizing measure for pending transcutaneous pacing
  • Prepare for transcutaneous pacing if symptomatic bradycardia does not improve after Atropine administration

2nd-Line Agents

  • Consider in patients with unsatisfactory response to Atropine and as temporizing measure while awaiting pacemaker insertion


  • Epinephrine infusion may be used in patients with symptomatic bradycardia, especially associated with hypotension, in whom Atropine may be inappropriate or after Atropine and transcutaneous pacing fails
  • Strong alpha- and beta-adrenergic agonist


  • May be used in patients with symptomatic bradycardia, especially associated with hypotension, in whom Atropine may be inappropriate or after Atropine fails
  • Dopamine infusion may be given in addition to Epinephrine or may be administered alone
  • Has both alpha- and beta-adrenergic agonist actions


  • Consider if the potential cause for bradycardia is overdose of a beta-blocker or Calcium channel antagonist
  • Vasoactive peptide that counteracts the effects of beta blockers by activating hepatic adenyl cyclase which promotes glycogenesis

Isoproterenol (Isoprenaline)

  • May be considered for transient heart block but should be used with utmost caution
    • Not to be used in patients with acute MI
  • Increases heart rate or atrioventricular-nodal conduction in patients with acute symptomatic bradyarrhythmia
  • Nonselective beta agonist with chronotropic and inotropic effects

Other Agents:

  • Aminophylline, Theophylline, Glycopyrrolate, Terbutaline

Device-Based Therapies

  • Indication is determined by severity of bradycardia
  • Recommended for patients with symptomatic sinus bradycardia, atrioventricular (AV) block, hypersensitive carotid sinus syndrome
  • May be considered for patients at risk of asystole, hemodynamically unstable, and those unresponsive to Atropine
    • Also in patients ≥40 years old with recurrent unpredictable reflex syncope and/or documented symptomatic pauses due to sinus arrest or atrioventricular (AV) block, patients with history of syncope with asymptomatic pauses of >6 seconds secondary to sinus arrest, sinoatrial (SA) block, or atrioventricular (AV) block

Temporary Pacing

  • Emergency intervention used during the interval prior to permanent pacemaker implantation or resolution of bradycardia

Transcutaneous Pacing

  • Non-invasive intervention applicable for symptomatic bradycardias
  • Recommended for patients who fail to respond to Atropine therapy or if hemodynamically unstable especially those with high-degree atrioventricular (AV) blocks
  • Hemodynamic stability and electrocardiogram (ECG) results should be monitored during pacing

Transvenous Pacing

  • Invasive intervention involving the insertion of a temporary pacemaker wire to acquire venous access into the thoracic region
    • Most common insertion sites are the internal jugular vein and subclavian vein
  • Performed if Atropine therapy and transcutaneous pacing fails
  • Should only be used in patients with high degree atrioventricular (AV) block without escape rhythm, and life-threatening bradyarrhythmias
  • Should be used for a minimum period necessary as back-up pacing or to provide hemodynamic support to prevent asystole in order to avoid complications

Permanent Pacemaker Implantation

  • Prevents recurrence of syncope, improves symptoms, and increases survival rates
  • Indications include:
    • Symptomatic sinus bradycardia
    • Symptomatic patients with atrioventricular (AV) block
      • Patients with intermittent or paroxysmal intrinsic 2nd- to 3rd-degree atrioventricular (AV) block
      • Patients with type I 2nd-degree atrioventricular (AV) block should be symptomatic if being considered
      • Patient with type II 2nd-degree  atrioventricular (AV) block with wide QRS interval should be considered regardless if symptomatic or not
    • Symptomatic sinus node dysfunction with heart rate <40 beats per minute
    • Patients with sinus node dysfunction without symptoms but with heart rate of <40 beats per minute
    • Patients with unexplained syncope with abnormal findings in electrophysiological studies (EPS)
    • Patients with recurrent syncope accompanied by ventricular asystole of >3 seconds due to spontaneously occurring carotid sinus stimulation and pressure
  • Also recommended for acute myocardial infarction (MI) patients with atrioventricular (AV) block, congenital atrioventricular (AV) block, and atrioventricular (AV) block associated with enhanced vagal tone
  • May be considered in patients with neuromuscular diseases ie myotonic muscular dystrophy, Erb dystrophy, peroneal muscular atrophy with bifascicular block or any fascicular block, regardless if with symptoms or not
  • Should be excluded if bradycardia is due to reversible causes, asymptomatic 1st-degree atrioventricular block, asymptomatic 2nd-degree Mobitz I with supra-Hisian conduction block, or atrioventricular (AV) block expected to resolve

Modes of Pacing:

  • Single chamber pacemaker is considered for patients needing a single-lead atrial sensing ventricular pacemaker
  • Dual chamber pacing is beneficial for patients with history of stroke, embolism, atrial fibrillation, reduced exercise capacity, pacemaker syndrome compared to single chamber pacing but with more complications recorded
  • Dual chamber pacemaker is preferred for patients with sinus node disease, acquired atrioventricular (AV) block when rate response is desired
    • Reduces risk of atrial fibrillation, stroke, pacemaker syndrome and improves overall quality of life
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS Cardiology - Malaysia digital copy today!
Sign In To Download
Editor's Recommendations
Most Read Articles
Roshini Claire Anthony, 11 Dec 2020

Treatment with the nonsteroidal, selective mineralocorticoid receptor antagonist finerenone reduced chronic kidney disease (CKD) progression and cardiovascular (CV) event risk in patients with CKD and type 2 diabetes (T2D), according to the FIDELIO-DKD* study presented at ASN Kidney Week 2020.

Stephen Padilla, 22 Jun 2020
A dietary pattern (DP) characterized by high intakes of eggs, fish, milk, and other dairy products appears to confer protective benefits against incident cardiovascular disease (CVD) in women, reveals a study.