Management of Supraventricular Tachycardia (SVT)
Vagal maneuvers should be used as first-line treatment for acute SVT in hemodynamically stable patients, followed by adenosine if vagal maneuvers fail, and synchronized cardioversion for hemodynamically unstable patients or when pharmacological therapy is ineffective. 1, 2
Acute Management Algorithm
Step 1: Initial Assessment and Vagal Maneuvers
- Perform vagal maneuvers in the supine position as first-line intervention 1, 2:
- Standard Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) 1
- Modified Valsalva maneuver: Most effective vagal technique with significantly higher conversion rates 3
- Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruits 1, 2
- Cold stimulus: Apply ice-cold wet towel to face 1
- Success rate of switching between different vagal techniques is approximately 27.7% 1, 2
Step 2: Pharmacological Intervention
- If vagal maneuvers fail, administer adenosine as first-line drug 1, 2:
- For hemodynamically stable patients who don't respond to adenosine, consider 1, 2:
Step 3: Electrical Cardioversion
- Perform synchronized cardioversion for 1, 2:
- Hemodynamically unstable patients
- Patients who fail to respond to pharmacological therapy
- Patients with contraindications to pharmacological therapy
Special Considerations
Pre-excited Atrial Fibrillation
- For hemodynamically unstable patients with pre-excited AF, perform immediate synchronized cardioversion 1, 2
- For hemodynamically stable patients with pre-excited AF, administer ibutilide or intravenous procainamide 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 2
Pregnancy
- Vagal maneuvers are first-line treatment for SVT in pregnant patients 1
- Adenosine is recommended when vagal maneuvers fail, with minimal risk to the fetus due to its short half-life 1
Long-term Management
Catheter Ablation
- Catheter ablation is the most effective therapy to prevent recurrent PSVT with success rates of 94.3-98.5% 4
- Should be considered first-line therapy for prevention of recurrent SVT 4
Pharmacological Options
- Oral beta-blockers, diltiazem, or verapamil for long-term management in patients without pre-excitation 1, 4
- Flecainide can be used for prevention of PSVT in patients without structural heart disease 5
- Propafenone is effective for prevention of paroxysmal SVT 6
Important Caveats and Pitfalls
- Never apply pressure to the eyeball as this practice is dangerous and has been abandoned 1, 2
- Perform carotid sinus massage only after confirming absence of carotid bruits 1, 2
- Avoid calcium channel blockers and beta-blockers in patients with suspected pre-excited AF, ventricular tachycardia, or systolic heart failure 1, 2
- Flecainide should not be administered in patients with structural heart disease or significant ventricular dysfunction due to increased risk of proarrhythmic effects 1, 5
- Ensure proper ECG diagnosis before treatment to distinguish SVT from ventricular tachycardia 2