Treatment of SVT
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"supraventricular tachycardia" AND treatment
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Treatment of Supraventricular Tachycardia (SVT)
SVT encompasses several distinct arrhythmias — most commonly AVNRT (AV nodal reentrant tachycardia), AVRT (AV reentrant tachycardia, including WPW), and focal atrial tachycardia — all arising above or within the AV node. Treatment is stratified by hemodynamic stability and the underlying mechanism.
Step 1: Assess Hemodynamic Stability
| Status | Action |
|---|---|
| Unstable (hypotension, altered consciousness, respiratory distress) | Immediate synchronized DC cardioversion |
| Stable | Sequential pharmacologic approach below |
Step 2: Stable Patient — Acute Termination
1. Vagal Maneuvers (first-line)
Most PSVTs depend on AV nodal conduction and respond to vagotonic stimulation.
- Modified Valsalva (preferred): Patient semi-recumbent at 45°, exhales against closed glottis for 10–15 s, then immediately repositioned supine with passive leg raise at 45° for 15 s. Higher success rate than standard Valsalva.
- Standard Valsalva: Supine, forced exhalation against closed glottis for 10–15 s.
- Carotid sinus massage: Steady pressure for 5–10 s at one carotid sinus; avoid in patients with prior stroke (within 3 months), carotid stenosis/bruit, or history of ventricular arrhythmia.
- Cold stimulus (especially in children/infants): Ice pack/ice-water washcloth to forehead or bridge of nose for ≤30 s.
2. Adenosine (first-line if vagal maneuvers fail)
"Intravenous adenosine will terminate the vast majority of PSVT episodes by transiently blocking conduction in the AV node." — Harrison's Principles of Internal Medicine, 22e
- Dose: 6 mg IV rapid bolus with rapid NS flush → if no conversion, 12 mg IV; may repeat 12 mg once
- Mechanism: Slows AV nodal conduction; interrupts reentry pathways
- Side effects: Transient chest pain, dyspnea, anxiety, flushing; may precipitate AF in up to 15%
- Contraindications/Cautions:
- Contraindicated in prior cardiac transplantation (hypersensitivity due to surgical sympathetic denervation)
- Use cautiously in WPW (adenosine-induced AF can cause hemodynamic instability)
- Caution in asthma (can aggravate bronchospasm)
If adenosine converts the rhythm → probable re-entry SVT. Observe for recurrence.
3. If Adenosine Ineffective: Non-DHP CCB or Beta-Blocker
IV verapamil, diltiazem, or esmolol are second-line options — effective but carry a risk of hypotension and have longer duration of action. These can also be given orally for outpatient "pill-in-pocket" use (patient takes at onset of episode, combined with Valsalva).
4. If No Conversion (atrial flutter, ectopic AT, junctional tachycardia suspected)
- Rate control: calcium channel blockers or beta-blockers (use beta-blockers cautiously in pulmonary disease or CHF)
- Treat underlying cause
- Consider expert consultation
SVT Subtypes and Special Situations
AVNRT (most common in adults)
Treated with vagal maneuvers → adenosine → CCB/beta-blocker. Patients with frequent recurrences are candidates for prophylaxis (beta-blocker or CCB) or catheter ablation.
AVRT / WPW Syndrome
- Orthodromic AVRT (narrow complex): Treated the same as AVNRT — vagal maneuvers → adenosine → CCB/beta-blocker.
- Antidromic AVRT (wide complex): Wide QRS, potentially very rapid (≥200 bpm). Treat as VT unless diagnosis is certain.
- Pre-excited AF + WPW: Avoid AV nodal blockers (adenosine, digoxin, verapamil) — they can precipitate lethal arrhythmias by accelerating conduction through the accessory pathway. Use cardioversion or IV procainamide/ibutilide.
- Definitive treatment: Radiofrequency catheter ablation (~95% efficacy).
Wide-Complex SVT (SVT with Aberrancy)
- Treat as VT until proven otherwise.
- If the rhythm is regular and the patient is stable, a trial of IV adenosine is reasonable.
- Very irregular wide-complex tachycardia = likely preexcited AF → cardioversion or IV procainamide/ibutilide.
Junctional Tachycardia
- Address underlying cause (structural heart disease, metabolic disturbance, drug toxicity).
- Trial of nodal blockade (CCB or beta-blocker) if rate is deleterious.
Pediatric SVT
- Vagal maneuvers first (e.g., ice to face, blowing into a syringe)
- Adenosine 6 mg IV → 12 mg IV if no conversion
- If unstable: synchronized cardioversion 0.5 J/kg (up to 1 J/kg)
- Always consult Cardiology
Long-Term / Recurrence Management
| Option | Indication |
|---|---|
| Beta-blocker or non-DHP CCB (daily or "pill-in-pocket") | Frequent, symptomatic recurrences |
| Flecainide, propafenone | Refractory cases without structural heart disease (avoid in WPW) |
| Catheter ablation | Recurrent PSVT; drug-intolerant; desired by patient; WPW with high-risk pathway. Success ~95% |
Key Drug Contraindications Summary
| Drug | Avoid in |
|---|---|
| Verapamil, Digoxin | WPW with pre-excitation / antidromic AVRT |
| Flecainide | WPW syndrome |
| Adenosine | Cardiac transplant; caution in asthma, WPW |
| Beta-blockers | Severe asthma, decompensated HF (relative) |
Sources: Harrison's Principles of Internal Medicine 22e; Tintinalli's Emergency Medicine; Rosen's Emergency Medicine; Washington Manual of Medical Therapeutics; Harriet Lane Handbook 23e.
Treatment
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The previous response already covers SVT treatment comprehensively. Here's a concise summary of what was covered:
SVT Treatment — Quick Reference
Unstable Patient
→ Immediate synchronized DC cardioversion
Stable Patient — Sequential Approach
Step 1 — Vagal maneuvers
- Modified Valsalva (best success rate)
- Standard Valsalva, carotid sinus massage, cold stimulus (face)
Step 2 — Adenosine IV (if vagal maneuvers fail)
- 6 mg rapid IV bolus → 12 mg → repeat 12 mg once
- Terminates the vast majority of PSVT
Step 3 — Non-DHP CCB or Beta-blocker (if adenosine fails)
- IV verapamil, diltiazem, or esmolol
Step 4 — Cardioversion (refractory or unstable)
Long-Term / Recurrence
- Beta-blocker or CCB — daily prophylaxis or pill-in-pocket
- Catheter ablation — first-line for recurrent/refractory SVT (~95% success)
Critical Caveats
- WPW + pre-excited AF: avoid adenosine, verapamil, digoxin → use cardioversion or IV procainamide
- Wide-complex tachycardia: treat as VT until proven otherwise
- Pediatric: vagal maneuvers → adenosine → cardioversion 0.5–1 J/kg
Is there a specific aspect of SVT treatment you'd like me to expand on (e.g., a specific drug, ablation, pediatric dosing, WPW management)?
Dose
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Here are the doses for all SVT drugs, organized by line of treatment:
Drug Doses for SVT Treatment
First-Line: Adenosine (IV)
| Step | Adult Dose | Pediatric Dose |
|---|---|---|
| Initial | 6 mg rapid IV bolus | 0.1 mg/kg (max 6 mg) |
| 2nd dose (if no conversion in 1–2 min) | 12 mg rapid IV bolus | 0.2 mg/kg (max 12 mg) |
| 3rd dose (repeat if needed) | 12 mg rapid IV bolus | — |
Administration: Rapid push over 1–2 seconds via peripheral IV, followed immediately by 20 mL NS flush. Patients typically experience transient asystole (<5 sec).
Dose adjustments:
- Reduce to 3 mg initial dose in: cardiac transplant patients, patients on dipyridamole or carbamazepine, central line administration
- Higher doses may be needed in patients on caffeine or theophylline
Second-Line: Non-DHP Calcium Channel Blockers (IV)
| Drug | Dose | Notes |
|---|---|---|
| Verapamil | Up to 10 mg IV over 1–2 min; may repeat equal dose in 30 min. Continuous infusion: 0.005 mg/kg/min | Monitor BP and rhythm. Terminates 60–90% of PSVT. Contraindicated in WPW + pre-excited AF |
| Diltiazem | 0.25 mg/kg IV bolus over 2 min; second dose in 15 min if needed | Generally better tolerated (less hypotension) than verapamil |
Oral (maintenance/prevention): Verapamil 240–480 mg/day in divided doses; Diltiazem 120–360 mg/day.
Second-Line: Beta-Blockers (IV)
| Drug | Dose | Notes |
|---|---|---|
| Esmolol | Loading: 500 mcg/kg IV over 1 min; Maintenance: 50–200 mcg/kg/min infusion | Short-acting (half-life ~9 min), titratable; preferred when transient effect is desired |
| Propranolol | 1–3 mg/dose IV slow push; may repeat every 2–5 min up to 5 mg total | Non-selective; avoid in asthma |
| Metoprolol | 2.5–5 mg IV bolus over 2 min; up to 3 doses | Cardioselective |
Unstable Patient: Synchronized Cardioversion
| Patient | Energy |
|---|---|
| Adult | 50–100 J (biphasic); escalate as needed |
| Pediatric | 0.5 J/kg (up to 1 J/kg) |
WPW + Pre-excited AF (AV nodal blockers contraindicated)
| Drug | Dose |
|---|---|
| Procainamide (preferred) | 15–18 mg/kg IV at 25–50 mg/min |
| Ibutilide | 1 mg IV over 10 min; may repeat once |
| Amiodarone | 150 mg IV over 10 min if unstable/polymorphic VT |
Sources: Tintinalli's Emergency Medicine; Braunwald's Heart Disease; Harrison's Principles of Internal Medicine 22e; Rosen's Emergency Medicine.
SVT ECG changes
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