What is the treatment for Supraventricular Tachycardia (SVT)?

Treatment for Supraventricular Tachycardia (SVT)

Begin with the modified Valsalva maneuver in the supine position with immediate leg elevation, followed by adenosine 6 mg rapid IV push if vagal maneuvers fail, and proceed to synchronized cardioversion only if the patient becomes hemodynamically unstable. 1, 2

Acute Management Algorithm

Step 1: Initial Stabilization and Vagal Maneuvers

Vagal maneuvers are the mandatory first-line intervention for all hemodynamically stable patients with SVT. 1

• Modified Valsalva maneuver is superior to standard techniques, achieving the highest conversion rates (SUCRA: 0.9992) compared to carotid sinus massage. 3
• Perform with the patient bearing down against a closed glottis for 10-30 seconds (generating 30-40 mm Hg intrathoracic pressure), then immediately position supine with legs raised. 1, 2
• Carotid sinus massage is an alternative: apply steady pressure over the carotid sinus for 5-10 seconds after confirming absence of bruit by auscultation. 1
• Ice-cold wet towel to the face (diving reflex) is another effective option. 1
• Switching between vagal maneuver techniques increases overall success to 27.7%. 1

Critical pitfall: Never apply pressure to the eyeball—this practice is dangerous and abandoned. 1

Step 2: Pharmacological Therapy (If Vagal Maneuvers Fail)

Adenosine is the first-line medication with 90-95% effectiveness. 1, 2

• Administer 6 mg rapid IV bolus followed immediately by saline flush. 2
• Adenosine terminates AVNRT in approximately 95% of patients and serves dual therapeutic and diagnostic purposes by unmasking atrial activity. 1
• If initial dose fails, a second bolus or higher dose is often effective. 1

Alternative agents for hemodynamically stable patients who don't respond to adenosine: 1

• IV diltiazem or verapamil are particularly effective with 80-98% success rates in converting AVNRT to sinus rhythm. 1
• IV beta blockers have an excellent safety profile but are less effective than calcium channel blockers. 1
• Oral beta blockers combined with diltiazem may be reasonable but lack robust evidence for acute termination. 1

Critical contraindications: Avoid diltiazem, verapamil, and beta blockers in patients with:

• Pre-excited atrial fibrillation (Wolff-Parkinson-White syndrome with AF)—these patients may develop ventricular fibrillation. 1
• Suspected systolic heart failure. 1
• Wide-complex tachycardia until ventricular tachycardia is excluded. 1

Step 3: Electrical Cardioversion

Synchronized cardioversion is mandatory for hemodynamically unstable patients when adenosine and vagal maneuvers fail or are not feasible. 1

• Synchronized cardioversion is highly effective, terminating SVT in the vast majority of cases. 1
• For hemodynamically stable patients, cardioversion is recommended only when pharmacological therapy fails or is contraindicated. 1

Long-Term Management

Catheter ablation is the most effective definitive therapy with single-procedure success rates of 94.3-98.5%. 4

• The American College of Cardiology recommends catheter ablation as first-line therapy for preventing recurrent PSVT, particularly for patients with frequent symptomatic episodes, medication intolerance/ineffectiveness, or patient preference for non-pharmacological approach. 2, 4

Pharmacological prevention options: 2

• Beta blockers are first-line for long-term prevention. 2
• Calcium channel blockers are an alternative to beta blockers. 2
• Evidence for long-term pharmacotherapy effectiveness is limited compared to ablation. 4

Special Populations

Pregnancy

Vagal maneuvers remain safe and first-line during pregnancy. 2, 5

• Adenosine is considered safe due to its short half-life. 2, 5
• Synchronized cardioversion can be performed safely at all stages of pregnancy if necessary. 2, 5
• Avoid atenolol and verapamil due to teratogenic effects. 5

Pre-excitation Syndromes

For patients with Wolff-Parkinson-White syndrome and pre-excited AF, avoid all AV nodal blocking agents. 2

• Use IV procainamide or ibutilide for hemodynamically stable pre-excited AF. 2
• Proceed directly to synchronized cardioversion if hemodynamically unstable. 1

Essential Diagnostic Consideration

Always obtain a 12-lead ECG during tachycardia before initiating treatment to differentiate SVT from ventricular tachycardia. 2

• Distinguishing SVT with aberrancy from ventricular tachycardia is essential before administering AV nodal blocking agents. 2
• All patients treated for SVT require heart rhythm specialist referral. 6