II. Approach: Step 1 - Is patient unstable

  1. Criteria
    1. Altered Mental Status
    2. Chest Pain persistent
    3. Hypotension
  2. Management
    1. Stable
      1. Go to Step 2
    2. Unstable:
      1. Go to Unstable Tachycardia for Synchronized Cardioversion

III. Approach: Step 2 - Regular or Irregular Narrow Complex Tachycardia

  1. Regular Narrow Complex Tachycardia
    1. Vagal Maneuvers
    2. Valsalva Maneuver
      1. See Valsalva for positional modifications (increased efficacy)
    3. Adenosine 6 mg IV (may repeat at 12 mg IV)
      1. Some patients may prefer Diltiazem to the brief adverse Sensation to Adenosine
        1. However, Diltiazem risks Hypotension, whereas Adenosine effects are transient
      2. Adenosine and Diltiazem are similarly effective
        1. Alabed (2017) Cochrane Database Syst Rev 10: CD005154 +PMID:29025197 [PubMed]
    4. Go to Step 3 below
  2. Irregular Narrow Complex Tachycardia
    1. Causes
      1. Atrial Fibrillation (most likely)
      2. Atrial Flutter
      3. Multifocal Atrial Tachycardia
    2. Management
      1. See Atrial Fibrillation with Rapid Ventricular Response
      2. Consider Consultation with cardiology
      3. Avoid Adenosine in irregular Narrow Complex Tachycardia (due to risk of Ventricular Fibrillation)
      4. Consider Synchronized Cardioversion if known onset
      5. Rate control
        1. Diltiazem
          1. Protocol 1
            1. Bolus 1: 20 mg (0.25 mg/kg) IV bolus over 2 min
            2. Bolus 2: 25 mg (0.35 mg/kg) IV bolus over 2 min (if indicated, at least 15 min after first)
            3. Drip: 10 mg/hour (typical range: 5-15 mg/hour)
          2. Protocol 2
            1. Diltiazem 2.5 mg/min titrated slowly to a maximum of 50 mg/min
            2. Cardioversion by 12 mg in 50% and 18 mg in 75%
              1. Lim (2009) Resuscitation 80(5): 523-8 [PubMed]
        2. Metoprolol (Lopressor)
          1. Avoid in acute CHF or COPD exacerbation
          2. Bolus: 2.5 to 5 mg IV every 2-5 min (maximum 15 mg in 15 min)

IV. Approach: Step 3 - Regular Narrow Complex Tachycardia

  1. Rhythm converts with basic measures in step 2 (Vagal Maneuvers and Adenosine)
    1. Suggests Reentry Supraventricular Tachycardia
    2. Recurrence management
      1. Adenosine or
      2. AV nodal blocking agent (e.g, Diltiazem, Beta Blocker)
        1. See Diltiazem and Metoprolol dosing under rate control above
  2. Rhythm does not convert
    1. Causes
      1. Atrial Flutter
      2. Ectopic Atrial Tachycardia
      3. Junctional Tachycardia
    2. Management
      1. Consider Consultation with cardiology
      2. Consider Synchronized Cardioversion if known onset (e.g. Atrial Flutter with rapid ventricular response)
      3. Treat underlying cause
        1. See Reversible Causes of Cardiopulmonary Arrest (5H5T)
      4. Rate control
        1. See Diltiazem and Metoprolol dosing under rate control as above

V. Management: Pregnancy

  1. Monitor both mother and fetus
  2. Women in pregnancy are more prone to supraventricular and ventricular Arrhythmias
    1. Increased Heart Rate, decreased Peripheral Vascular Resistance, increased Stroke Volume
  3. Safe measures
    1. Vagal Maneuvers
    2. AV Nodal Blockers (avoid in pre-excitation syndromes such as WPW)
      1. Adenosine
      2. Calcium Channel Blockers
        1. Teratogenicity in animals but not humans
        2. Risk of Fetal Bradycardia
    3. Procainamide
      1. Safe and well tolerated in pregnancy
    4. Cardioversion
      1. Avoid placing cardioversion pads over the Abdomen (place in typical chest positions)
      2. Minimal electrical penetration into Uterus
    5. Sedation
      1. Aspiration risk
      2. Avoid Hypotension
      3. Preferred sedation with Propofol or Ketamine
  4. Medications to avoid
    1. Beta Blockers
      1. IUGR risk
    2. Amiodarone
      1. Risk of exposing fetal Thyroid to high Iodine
      2. Risk of IUGR
      3. Risk of Preterm Labor
  5. References
    1. DeMeester and Cormack in Herbert (2021) EM:Rap 21(9): 10-2

VI. Management: Long-term management

  1. Infrequent episodes ("pill in the pocket" prn strategy)
    1. Diltiazem 120 mg orally AND Propranolol 80 mg orally once prn
    2. Flecainide 3 mg/kg orally once prn
    3. Alboni (2001) J Am Coll Cardiol 37(2): 548-53 [PubMed]
  2. Frequent episodes
    1. Medication options
      1. Diltiazem 240 to 360 mg orally daily
      2. Metoprolol 25 to 100 mg orally twice daily
      3. Flecainide 50-100 mg orally daily divided every 8-12 hours
        1. Typically not prescribed by primary care (limited to cardiology in most cases)
    2. Do not use long-term prophylaxis in Wolff-Parkinson-White Syndrome (WPW)
      1. Risk of Ventricular Fibrillation
      2. Consult for catheter ablation in symptomatic patients
  3. Radiofrequency ablation
    1. Accessory Pathway (e.g. WPW)
    2. Atrioventricular nodal reentrant Tachycardia
    3. Atrial Tachycardia

VII. References

  1. Swaminathan and Morgenstern in Herbert (2018) EM:Rap 18(7): 17-8
  2. (2000) Circulation, 102(Suppl I):86-9
  3. Helton (2015) Am Fam Physician 92(9): 793-800 [PubMed]

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