What are the management options for Supraventricular Tachycardia (SVT)?

Management of Supraventricular Tachycardia (SVT)

The management of SVT should follow a stepwise approach, starting with vagal maneuvers, followed by adenosine administration for hemodynamically stable patients, and synchronized cardioversion for unstable patients or when pharmacological therapy fails. 1, 2

Acute Management

First-Line Interventions

• Vagal maneuvers should be performed first in hemodynamically stable patients 1, 2:
  • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) in supine position 1
  • Modified Valsalva maneuver (MVM): Most effective vagal technique with highest conversion rate 3
  • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruits 1, 2
  • Cold stimulus: Applying ice-cold wet towel to face 1
  • Overall success rate of switching between techniques is approximately 27.7% 1, 2

Second-Line Interventions

• Adenosine is recommended when vagal maneuvers fail 1, 2:
  • Highly effective (90-95% conversion rate) 1, 2
  • Initial dose: 6 mg rapid IV bolus, followed by up to two 12 mg doses if ineffective 1
  • Brief side effects (<1 minute) occur in approximately 30% of patients 1

Third-Line Interventions for Stable Patients

• Calcium channel blockers (diltiazem, verapamil) are reasonable for hemodynamically stable patients 1, 2:

  • Particularly effective for AVNRT conversion 1
  • Contraindicated in suspected pre-excitation, ventricular tachycardia, or systolic heart failure 1, 2

• Beta blockers are reasonable alternatives but less effective than calcium channel blockers 1, 2:

  • Have excellent safety profile 1

For Hemodynamically Unstable Patients

• Synchronized cardioversion is recommended when 1, 2:
  • Patient is hemodynamically unstable
  • Adenosine and vagal maneuvers fail
  • Pharmacological therapy is contraindicated

Special Considerations

Pre-excited AF

• Synchronized cardioversion is first-line for hemodynamically unstable patients with pre-excited AF 1, 2
• Ibutilide or intravenous procainamide are recommended for hemodynamically stable patients with pre-excited AF 1, 2
• AVOID AV nodal blocking agents (verapamil, diltiazem, beta-blockers) in patients with suspected pre-excitation as they may accelerate ventricular rate and lead to ventricular fibrillation 1, 2

Pregnancy

• Vagal maneuvers remain first-line treatment 1
• Adenosine is the first-line drug for pregnant patients when vagal maneuvers fail 1
• Adenosine's short half-life makes adverse fetal effects unlikely 1

Long-term Management Options

• Catheter ablation is recommended as first-line for long-term management of recurrent, symptomatic SVT 4:

  • High success rate and curative in majority of patients 5

• Oral medications for prevention:

  • Beta blockers, diltiazem, or verapamil for AVNRT 1
  • Flecainide for prevention of PSVT in patients without structural heart disease 6
    • Should NOT be used in patients with significant ventricular dysfunction 1
  • Propafenone can reduce recurrence rates of paroxysmal SVT 7

Important Pitfalls and Caveats

• NEVER apply pressure to the eyeball as this practice is dangerous 1, 2
• Perform carotid sinus massage ONLY after confirming absence of carotid bruits 1, 2
• Ensure proper ECG diagnosis before treatment to distinguish SVT from ventricular tachycardia 2
• Have electrical cardioversion equipment available when administering adenosine, as it may precipitate AF that could conduct rapidly to ventricles 1
• Calcium channel blockers and beta blockers should be AVOIDED in patients with:
  • Suspected pre-excited AF 1, 2
  • Ventricular tachycardia 1, 2
  • Systolic heart failure 1, 2