What is the management of Paroxysmal Supraventricular Tachycardia (PSVT) versus Supraventricular Tachycardia (SVT)?

Management of PSVT vs SVT

PSVT (Paroxysmal Supraventricular Tachycardia) and SVT (Supraventricular Tachycardia) are managed identically—the term "paroxysmal" simply describes the episodic nature of SVT with sudden onset and termination, but does not change treatment approach. 1, 2, 3

Terminology Clarification

• PSVT is a subset of SVT characterized by abrupt onset and termination, typically including AVNRT (atrioventricular nodal reentrant tachycardia) and AVRT (atrioventricular reentrant tachycardia) 4, 5
• The management algorithms are identical regardless of whether the arrhythmia is labeled "PSVT" or "SVT" 1
• Treatment decisions are based on hemodynamic stability, presence of pre-excitation, and whether acute versus long-term management is needed—not on the "paroxysmal" designation 1, 2

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

For hemodynamically UNSTABLE patients:

• Immediate synchronized cardioversion is the treatment of choice 1, 2, 3
• Initial energy: 50-100 J biphasic 2
• Increase energy stepwise if initial shock fails 2

For hemodynamically STABLE patients, proceed sequentially:

Step 2: Vagal Maneuvers (First-Line)

• Vagal maneuvers are Class I recommendation as initial therapy 1, 3
• Modified Valsalva maneuver (most effective): Patient supine, bears down against closed glottis for 10-30 seconds (30-40 mmHg pressure), then immediately lies flat with legs elevated 1, 3, 6
  • Success rate: 43% with modified technique 4, 6
  • Superior to standard Valsalva 6
• Carotid sinus massage: After confirming no carotid bruit, apply steady pressure over carotid sinus for 5-10 seconds 1, 3
• Cold stimulus: Apply ice-cold wet towel to face (diving reflex) 1, 3
• Overall success rate when techniques used sequentially: 27.7% 1, 3

Step 3: Adenosine (Second-Line)

• Adenosine 6 mg IV rapid push through large vein, followed by 20 mL saline flush 2
• If ineffective, give 12 mg IV rapid push 2
• Effectiveness: 90-95% 3, 4
• Critical caveat: Avoid in patients with pre-excitation (WPW syndrome) as it can precipitate ventricular fibrillation if atrial fibrillation develops 2

Step 4: AV Nodal Blocking Agents (Third-Line)

• Intravenous diltiazem or verapamil (calcium channel blockers) 1, 2
  • Effectiveness: 64-98% in hemodynamically stable patients 3
  • Contraindicated in pre-excited atrial fibrillation or VT as they may cause hemodynamic collapse or accelerate ventricular rate 1
• Beta blockers are reasonable but less effective than calcium channel blockers for acute termination 1, 2

Long-Term Management Algorithm

First-Line: Catheter Ablation

• Catheter ablation is Class I recommendation as first-line therapy for recurrent symptomatic PSVT/SVT 1, 2, 4
• Single procedure success rates: 94.3-98.5% for AVNRT and AVRT 1, 4
• Low complication rates, provides definitive cure without need for chronic medications 1
• Cost-effectiveness data favor ablation over medical therapy for patients with monthly episodes 1

Second-Line: Pharmacological Therapy

For patients who decline ablation, lack access to electrophysiologist, or have contraindications:

Option A: AV Nodal Blockers (Class I)

• Oral beta blockers, diltiazem, or verapamil 1, 3
• Dosing: Verapamil up to 480 mg/day, diltiazem titrated to effect 1
• Only for patients WITHOUT ventricular pre-excitation during sinus rhythm 1
• Reduces episode frequency and duration 1

Option B: Class IC Antiarrhythmics (Class IIa)

• Flecainide (100-300 mg/day) or propafenone (450-900 mg/day) 1, 7, 8
• 12-month effective treatment probability: 86% for propafenone, 93% for flecainide 1
• Absolutely contraindicated in structural heart disease or ischemic heart disease due to proarrhythmia risk 1, 8
• FDA-approved specifically for prevention of PSVT in patients without structural heart disease 7, 8
• Often combined with beta blockers to prevent 1:1 AV conduction if atrial flutter develops 1

Option C: Class III Agents (Class IIb)

• Sotalol may be reasonable 1
• Can be used in structural heart disease (unlike Class IC agents) 1
• Requires monitoring for proarrhythmia (torsades de pointes) 1
• Dofetilide: 50% complete symptomatic suppression over 6 months, but requires inpatient initiation for QT monitoring 1
• Amiodarone: Reserved for refractory cases due to significant toxicity profile 1

"Pill-in-the-Pocket" Approach

• Single-dose oral therapy for infrequent, prolonged but well-tolerated episodes 1
• Diltiazem 120 mg plus propranolol 80 mg is superior to placebo and flecainide 1
• Requires absence of structural heart disease, sinus bradycardia, or pre-excitation 1
• Patients must be educated on proper self-administration 1

Critical Caveats for Pre-Excitation (WPW Syndrome)

If pre-excitation is present on ECG:

• AVOID adenosine, beta blockers, calcium channel blockers, and digoxin 2, 3
• These agents can accelerate conduction through accessory pathway and precipitate ventricular fibrillation if atrial fibrillation develops 1, 2
• For pre-excited atrial fibrillation:
  • Hemodynamically unstable: Synchronized cardioversion 2
  • Hemodynamically stable: Ibutilide or IV procainamide 2
• All patients with WPW should be evaluated for catheter ablation 2

Patient Education Components

• Teach proper vagal maneuver technique (Class I recommendation) 1, 2
• Emphasize supine position for Valsalva maneuver 1, 3
• Provide clear instructions on when to seek emergency care 2
• Discuss shared decision-making regarding ablation versus chronic medical therapy 1

Common Pitfalls to Avoid

• Never give verapamil or diltiazem for wide-complex tachycardia until VT is excluded—can cause hemodynamic collapse 1
• Never use AV nodal blockers in pre-excited atrial fibrillation—can be fatal 1, 2
• Do not use Class IC agents in structural heart disease—increased mortality risk 1, 8
• Do not assume vagal maneuvers were performed correctly—technique matters significantly, and modified Valsalva is superior to standard technique 1, 6
• Do not overlook catheter ablation as first-line option—it is more effective and cost-effective than chronic medical therapy for recurrent symptomatic episodes 1, 4