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

Management of Supraventricular Tachycardia (SVT)

The most effective approach for managing SVT is to start with vagal maneuvers, followed by adenosine for hemodynamically stable patients, and immediate synchronized cardioversion for unstable patients. 1, 2

Acute Management Algorithm

First-Line Approach

• Vagal maneuvers should be performed with the patient in a supine position as the initial intervention 1, 2:
  • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) 1
  • Modified Valsalva maneuver (MVM): Most effective vagal technique with significantly higher success rates than standard techniques 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
  • Switching between techniques can increase overall success rate to approximately 27.7% 1, 2

Second-Line Approach (If Vagal Maneuvers Fail)

• For hemodynamically stable patients:

  • Adenosine: First-line drug with 91-95% effectiveness 1, 2, 4
    • Initial dose: 6 mg IV rapid bolus
    • If ineffective, up to 2 subsequent doses of 12 mg may be administered 1
  • Calcium channel blockers (diltiazem or verapamil): Highly effective for converting AVNRT to sinus rhythm 1, 2
    • Contraindicated in patients with suspected pre-excitation, ventricular tachycardia, or systolic heart failure 2
  • Beta-blockers: Less effective than calcium channel blockers but have excellent safety profile 1, 2

• For hemodynamically unstable patients:

  • Synchronized cardioversion: Should be performed immediately when adenosine and vagal maneuvers fail or aren't feasible 1, 2

Special Considerations

• For pre-excited AF (WPW with AF):
  • Synchronized cardioversion for hemodynamically unstable patients 1, 2
  • Ibutilide or IV procainamide for hemodynamically stable patients 1, 2
  • AVOID AV nodal blocking agents (verapamil, diltiazem, beta-blockers) as they may accelerate ventricular rate and lead to ventricular fibrillation 2

Long-Term Management

Catheter Ablation

• Recommended as first-line therapy to prevent recurrence with 94.3-98.5% success rates 4
• Particularly effective for AVNRT and accessory pathway-mediated tachycardias 4

Pharmacological Options

• Beta-blockers: Good safety profile but moderate effectiveness 1, 4
• Calcium channel blockers: Effective for AVNRT 1, 4
• Flecainide: Indicated for prevention of PSVT in patients without structural heart disease 5
  • AVOID in patients with recent myocardial infarction or structural heart disease due to proarrhythmic effects 5
  • Should not be used in patients with ventricular dysfunction or complex heart disease 1
• Propafenone: Effective for prevention of recurrent episodes 6

Important Pitfalls and Caveats

• NEVER apply pressure to the eyeball as this practice is dangerous 1, 2
• Carotid massage should only be performed after confirming absence of carotid bruits 1, 2
• Proper ECG diagnosis is essential before treatment to distinguish SVT from ventricular tachycardia 2
• AV nodal blocking agents must be avoided in patients with suspected pre-excitation syndromes 2
• Flecainide can cause new or worsened arrhythmias, particularly in patients with structural heart disease 5
• Monitor for tachycardia-mediated cardiomyopathy in patients with frequent or persistent SVT episodes (occurs in approximately 1% of cases) 4