PSVT Treatment Guideline

About This PSVT Treatment Guideline

This interactive tool walks clinicians through the standard PSVT treatment guideline, based on the latest American Heart Association (AHA) ACLS Tachycardia Algorithm. Paroxysmal Supraventricular Tachycardia (PSVT) is a common arrhythmia, and this tool helps ensure a systematic, evidence-based approach to its management. By answering a series of simple questions, users receive clear, actionable recommendations for both stable and unstable patients.

The PSVT Algorithm Explained

The step-by-step logic of this PSVT treatment guideline is as follows:

1. Assess Stability: Determine if the patient is stable or unstable (e.g., hypotensive, altered mental status).
2. Unstable Pathway: Immediate synchronized electrical cardioversion.
3. Stable Pathway:
   • Confirm Rhythm: First, ensure the rhythm is regular and narrow-complex (QRS < 0.12s). If irregular, suspect AFib.
   • Vagal Maneuvers: The initial, non-invasive treatment is to attempt vagal maneuvers. The modified Valsalva maneuver is highly recommended for its superior success rate.
   • Adenosine: If vagal maneuvers fail and there are no contraindications, administer adenosine. This can terminate the arrhythmia and/or reveal the underlying rhythm.
   • Second-Line Agents: If adenosine is ineffective or contraindicated, IV beta-blockers or non-dihydropyridine calcium channel blockers (diltiazem) are the next step.

Key Dosing & Procedures

• Modified Valsalva Maneuver: The patient blows forcefully into a 10-mL syringe for 15 seconds, then is immediately laid flat while their legs are raised to 45 degrees for 15 seconds.
• Adenosine: First dose is 6 mg rapid IV push, followed immediately by a 20 mL saline flush. If no effect, the second dose is 12 mg rapid IV push. Use a reduced initial dose (~3 mg) in heart transplant recipients, patients on dipyridamole or carbamazepine, and central-line administration; theophylline/caffeine antagonize adenosine.
• Avoid AV-nodal blockers (adenosine, non-DHP CCB, beta-blockers, digoxin) in pre-excited (WPW) atrial fibrillation or wide-complex tachycardia of uncertain origin — risk of accelerating accessory-pathway conduction and ventricular fibrillation.
• Synchronized Cardioversion: Initial recommended energy for PSVT is 50-100 Joules (biphasic).

Frequently Asked Questions (FAQ)

1. How does the response to Adenosine help with diagnosis?

Adenosine’s response is a key part of the PSVT treatment guideline. If the rhythm terminates and converts to sinus, it’s almost certainly PSVT. If it transiently slows down, revealing underlying flutter or atrial tachycardia waves, the diagnosis is different. If there’s no effect, the rhythm may not be AV-node dependent.

2. What are the main contraindications to Adenosine?

Adenosine should not be given to patients with a 2nd or 3rd-degree AV block or sick sinus syndrome (without a pacemaker). It must be avoided in pre-excited (WPW) atrial fibrillation, where AV-nodal blockade can accelerate conduction down the accessory pathway and precipitate ventricular fibrillation. Use caution in severe, active bronchospasm (asthma/COPD). It is also not effective for atrial fibrillation or flutter.

3. When should the adenosine dose be reduced?

Use a lower initial dose (about 3 mg) in heart transplant recipients (denervation hypersensitivity), patients taking dipyridamole or carbamazepine (which potentiate adenosine), and when administering through a central line. Theophylline and caffeine antagonize adenosine and may require a higher dose or an alternative agent.

4. What if the QRS complex is wide?

A wide-complex (QRS ≥ 0.12s) tachycardia should be treated as Ventricular Tachycardia until proven otherwise. AV nodal blockers can be dangerous, especially in pre-excited atrial fibrillation. The ACLS algorithm for wide-complex tachycardia should be followed instead.

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