Supraventricular Tachycardia — Emergency Management

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Hemodynamic assessment
   Is the patient hemodynamically stable? (SVT = narrow-QRS (<120 ms) regular fast rhythm, often 150–220/min. Unstable = hypotension, altered consciousness, ischemic chest pain, acute heart failure, shock.)
   • Unstable → Unstable → synchronized cardioversion
   • Stable → Vagal maneuvers
2. [End] Unstable → synchronized cardioversion
   Immediate synchronized cardioversion (narrow-QRS regular: start 50–100 J, escalate as needed); a single dose of adenosine may be tried if it does not delay cardioversion (regular narrow QRS). Sedate, monitor, find and treat the trigger.
3. [Decision] Vagal maneuvers
   Did vagal maneuvers convert it? (First-line vagal maneuvers: modified Valsalva (supine strain 10–15 s then leg raise), carotid sinus massage (exclude bruit first, caution in the elderly).)
   • Converted → Converted
   • Not converted → adenosine → Adenosine and beyond
4. [End] Adenosine and beyond
   Rapid IV push adenosine through a large vein: 6 mg fast push + saline flush; if no effect in 1–2 min → 12 mg (may repeat 12 mg). Still ineffective or contraindicated → IV diltiazem/verapamil or a beta-blocker; drug-refractory → synchronized cardioversion. Caution/contraindication: asthma, high-grade AV block, sick sinus; in pre-excitation with AF do not use AV-nodal blockers (may precipitate VF). (Note: If adenosine reveals atrial flutter/tachycardia, switch to a longer-acting AV-nodal blocker for rate control.)
5. [End] Converted
   Restored to sinus rhythm: monitor, find and treat triggers (electrolytes, hyperthyroidism, caffeine/sympathomimetics); record an ECG to define the mechanism (AVNRT/AVRT) and assess long-term therapy or catheter ablation.

Source guidelines & references

• 2015 ACC/AHA/HRS Guideline for management of adult SVT. Circulation 2016
• AHA ACLS adult tachycardia (with pulse) algorithm

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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