Supraventricular Tachycardia (SVT)

Background

• Supraventricular tachycardia (SVT) is a tachyarrhythmia that originates from or has a critical dependence on atrial or atrioventricular nodal tissues.
• Most types are due to reentry and are further classified based on location of electrical reentry circuit or foci.
• Conditions associated with SVTs include preexcitation syndromes, atrial septal defects, acute myocardial infarction, and chronic lung disease (congenital heart disease, such as Ebstein anomaly of the tricuspid valve, and glycogen storage disorder may also be present).
• Causes or contributing factors for initiation of SVT include premature beats, alcohol, or adrenergic stimulants.
• Complications include tachycardia-mediated cardiomyopathy, myocardial ischemia and/or infarction.

Evaluation

• Suspect SVT in a patient with palpitations, although patients may have other symptoms or be asymptomatic.
• Differential diagnosis includes narrow complex irregular tachycardias such as atrial fibrillation and wide complex tachycardias that are often ventricular in origin.
• Obtain a 12-lead electrocardiogram (ECG), during symptoms if possible. Findings on the ECG may suggest a specific type of SVT.
• If tachycardia is not present during the evaluation, consider:
  • ambulatory 24-hour Holter monitor or event loop recorder
  • testing to provoke tachycardia that may include:
    • esophageal stimulation (transesophageal atrial recordings and stimulation)
    • invasive electrophysiological investigation, especially if preexcitation or disabling symptoms, and tachycardias with wide QRS complexes of unknown origin
• Urgently refer patients with structural heart disease for further cardiac evaluation.

Management

Acute management

• Perform emergent direct current (DC) synchronized shock if the patient is hemodynamically unstable (cardiogenic shock) or has acute heart failure (Strong recommendation).
• For narrow QRS complex and wide QRS complex with bundle branch block in patients who are hemodynamically stable:
  • Attempt vagal stimulation (Strong recommendation).
  • Use the following intravenous medications if the arrhythmia does not respond to vagal stimulation (Strong recommendation):
    • adenosine unless asthma or structural heart disease
      • dosing of adenosine: start with 6 mg rapid-bolus dose, then give 12 mg if no response within 1-2 minutes
    • if there is no response to adenosine consider intravenous (IV) beta blocker or a calcium-channel blocker including: (Weak recommendation)
      • verapamil 5-10 mg (0.075-0.15 mg/kg) IV bolus over 2 minutes; if there is no response, an additional 10 mg (0.15 mg/kg) may be given 30 minutes after the first dose, then 0.005 mg/kg/minute IV infusion
      • diltiazem 0.25 mg/kg IV bolus over 2 minutes, then 5-10 mg/hour IV infusion, up to 15 mg/hour
  • Use synchronized DC cardioversion if pharmacological treatment ineffective or contraindicated (Strong recommendation)
• For wide QRS complex in patients who are hemodynamically stable:
  • with preexcitation or atrial fibrillation use procainamide, flecainide, or ibutilide (Strong recommendation)
  • with tachycardia of unknown origin and
    • without impaired left ventricular function or signs of heart failure use procainamide or sotalol (Strong recommendation)
    • with poor left ventricular function or signs of heart failure use amiodarone or lidocaine (Strong recommendation)

Chronic management

• Medications and ablation therapy are treatment options for patients with recurrent SVT
• Offer catheter ablation to symptomatic patients with (Strong recommendation):
  • atrioventricular nodal reentrant tachycardia (AVNRT)
  • atrioventricular reentrant tachycardia (AVRT) and/or preexcitation
• Prophylactic medications are generally reserved for:
  • minimizing symptoms while awaiting catheter ablation
  • patients who decline catheter ablation
  • patients who are contraindicated for catheter ablation
• Selection of prophylactic medications is based on SVT type.