What are the signs, symptoms, treatment, and management of symptomatic bradycardia?

Symptomatic Bradycardia: Signs, Symptoms, Treatment, and Management

Symptomatic bradycardia requires immediate intervention with atropine 0.5 mg IV every 3-5 minutes (maximum 3 mg) as first-line therapy, followed by dopamine or epinephrine if needed, while addressing underlying causes. 1, 2

Signs and Symptoms of Symptomatic Bradycardia

Symptomatic bradycardia typically presents with:

• Altered mental status
• Ischemic chest discomfort
• Acute heart failure
• Hypotension
• Signs of shock
• Lightheadedness or syncope
• Increased work of breathing (tachypnea, intercostal retractions)

The working definition of bradycardia is a heart rate <50 beats per minute, though clinical significance depends on whether the rate is inappropriate for the patient's condition 1.

Initial Assessment

1. Assess airway, breathing, and circulation
2. Monitor vital signs - Heart rate, blood pressure, oxygen saturation
3. Obtain 12-lead ECG to identify specific conduction abnormalities
4. Establish IV access
5. Provide supplemental oxygen if hypoxemic
6. Identify potentially reversible causes:
   • Medications (beta-blockers, calcium channel blockers, digoxin)
   • Electrolyte disturbances
   • Hypothyroidism
   • Increased intracranial pressure
   • Acute myocardial infarction
   • Severe hypothermia
   • Sleep apnea 1, 2

Treatment Algorithm

1. Immediate Management for Symptomatic Bradycardia

• First-line pharmacologic therapy:

  • Atropine 0.5 mg IV every 3-5 minutes (maximum total: 3 mg)
  • Caution: Doses <0.5 mg may paradoxically worsen bradycardia
  • Avoid atropine in Type II second-degree AV block, third-degree AV block with wide QRS, cardiac transplant patients, and infranodal blocks 1, 2

• If atropine ineffective, second-line options:

  • Dopamine 2-10 μg/kg/min IV infusion
  • Epinephrine 2-10 μg/min IV infusion 2

• For beta-blocker induced bradycardia:

  • Glucagon 3-10 mg IV bolus followed by infusion of 3-5 mg/h 2

2. Specific Management Based on Severity

• Moderate bradycardia (HR 30-40) with symptoms:

  • Begin with atropine (or glucagon if beta-blocker induced)
  • Add dopamine if needed 2

• Severe bradycardia (HR <30) with hemodynamic compromise:

  • Aggressive therapy with atropine/glucagon and dopamine
  • Prepare for transcutaneous pacing 2

3. Pacing Therapy

• Transcutaneous pacing: Indicated when drug therapy fails
• Transvenous pacing: Consider when transcutaneous pacing ineffective or for prolonged support
• Permanent pacemaker implantation: Indicated for:
  • Symptomatic bradycardia with conduction system disease
  • Symptomatic sinus bradycardia
  • Bradycardia due to necessary medical treatment
  • Tachy-brady syndrome
  • Symptomatic chronotropic incompetence
  • Recurrent vasovagal syncope with documented bradycardia 1, 2

Management of Specific Conduction Disorders

• First-degree AV block (PR interval >0.20 second): Generally benign, typically requires no treatment
• Mobitz type I second-degree AV block: Block at AV node, often transient and asymptomatic
• Mobitz type II second-degree AV block: Block usually below AV node, often symptomatic with potential to progress to complete block
• Third-degree AV block: No impulses pass between atria and ventricles, may require permanent pacing 1

Common Pitfalls to Avoid

1. Treating asymptomatic bradycardia: Patients with asymptomatic sinus bradycardia do not require acute treatment or permanent pacing 1, 2

2. Using atropine in inappropriate situations:

   • Type II second-degree AV block
   • Third-degree AV block with wide QRS
   • Cardiac transplant patients
   • Infranodal blocks 2

3. Overlooking reversible causes:

   • Always discontinue or reduce offending medications first
   • Treat underlying metabolic or endocrine disorders 1, 2

4. Unnecessary permanent pacing:

   • Permanent pacing should be avoided in asymptomatic patients
   • Pacing carries procedural risks and long-term management implications 1

5. Delaying treatment in symptomatic patients with hemodynamic compromise 2

By following this structured approach to symptomatic bradycardia management, clinicians can effectively address this potentially life-threatening condition while avoiding unnecessary interventions in patients with benign bradycardia.