Bradycardia Treatment

• 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

Atropine

• 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

• 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

Dopamine

• 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

Glucagon

• 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

• 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