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

Management of Supraventricular Tachycardia

Acute Management Algorithm

For hemodynamically stable SVT, perform vagal maneuvers first, followed immediately by adenosine if unsuccessful, then proceed to IV calcium channel blockers or beta-blockers as second-line agents. 1, 2, 3

First-Line: Vagal Maneuvers

• The modified Valsalva maneuver is the most effective vagal technique, performed by having the patient bear down against a closed glottis for 10-30 seconds (equivalent to 30-40 mmHg intrathoracic pressure) while supine, then immediately lying flat with legs raised 1, 2, 4
• The modified Valsalva achieves approximately 43% conversion rate and is superior to standard Valsalva or carotid sinus massage 4, 5
• Alternative vagal maneuvers include carotid sinus massage (5-10 seconds of steady pressure after confirming absence of bruit) or applying ice-cold wet towel to the face (diving reflex) 1, 3
• Switching between vagal maneuver techniques increases overall success to 27.7% 1, 3

Second-Line: Adenosine

• Adenosine is the first-line pharmacologic agent with 91-95% effectiveness, administered as 6 mg rapid IV bolus followed by saline flush 1, 2, 3, 5
• If the initial 6 mg dose fails, administer up to two subsequent 12 mg doses 1
• Adenosine serves dual diagnostic and therapeutic purposes, terminating AVNRT while unmasking atrial activity in other arrhythmias like atrial flutter 1

Third-Line: IV Calcium Channel Blockers or Beta-Blockers

• IV diltiazem or verapamil are highly effective for converting AVNRT to sinus rhythm with Class IIa recommendation for hemodynamically stable patients 1, 3
• IV beta-blockers have Class IIa recommendation but are less effective than calcium channel blockers 1, 3
• Critical caveat: Never use calcium channel blockers or beta-blockers if pre-excitation (WPW) is suspected, as they may accelerate ventricular rate and precipitate ventricular fibrillation 1, 3
• Avoid these agents in patients with suspected ventricular tachycardia or systolic heart failure 1, 3

Hemodynamically Unstable Patients

• Perform immediate synchronized cardioversion for any hemodynamically unstable patient when vagal maneuvers and adenosine fail or are not feasible (Class I recommendation) 1, 3
• Synchronized cardioversion is highly effective for terminating all forms of SVT 1

Long-Term Management Strategy

Pharmacologic Prevention

• Beta-blockers are the first-line option for long-term prevention of recurrent SVT in patients without ventricular pre-excitation 2, 3
• Calcium channel blockers (diltiazem or verapamil) serve as alternative first-line agents, reducing frequency and duration of episodes 2, 3
• For patients without structural heart disease who are not ablation candidates, flecainide or propafenone are reasonable alternatives 3, 6, 7
• Flecainide is contraindicated in patients with structural heart disease, recent myocardial infarction, or ventricular dysfunction due to proarrhythmic risk 1, 6

Definitive Treatment: Catheter Ablation

• Catheter ablation is the most effective long-term therapy with single-procedure success rates of 94.3-98.5% and should be considered first-line for symptomatic recurrent SVT 2, 3, 5
• Ablation provides potential cure without need for chronic pharmacotherapy and has low complication rates 2, 3, 5
• Indications include frequent symptomatic episodes, medication intolerance or ineffectiveness, patient preference for non-pharmacologic approach, or occupational requirements 3

Special Population Considerations

Pregnancy

• Vagal maneuvers remain first-line treatment during pregnancy with excellent safety profile 1, 2
• Adenosine is safe during pregnancy due to its short half-life preventing fetal circulation exposure 1, 2
• Synchronized cardioversion can be performed safely at all stages of pregnancy if necessary 2

Pre-Excitation Syndromes (WPW)

• For hemodynamically stable pre-excited atrial fibrillation, use ibutilide or IV procainamide (Class I recommendation) 2, 3
• For hemodynamically unstable pre-excited AF, perform immediate synchronized cardioversion 3
• Absolutely avoid AV nodal blocking agents (adenosine, verapamil, diltiazem, beta-blockers) as they may cause life-threatening ventricular fibrillation 1, 3

Adult Congenital Heart Disease

• Flecainide should not be used in ACHD patients with significant ventricular dysfunction due to increased cardiac arrest risk 1

Critical Pitfalls to Avoid

• Never apply pressure to the eyeball—this dangerous practice has been abandoned 1, 3
• Always obtain 12-lead ECG to differentiate SVT from ventricular tachycardia before treatment 2, 3
• Confirm absence of carotid bruits before performing carotid sinus massage 1, 3
• Do not use flecainide in chronic atrial fibrillation, as this has not been adequately studied 6

Patient Education

• Teach all SVT patients proper vagal maneuver techniques for self-management of future episodes, specifically the modified Valsalva technique in supine position 2, 3
• All patients treated for SVT should receive cardiology referral for rhythm specialist evaluation 8