What is the initial management for a patient presenting to the Emergency Department (ED) with supraventricular tachycardia (SVT) on electrocardiogram (ECG) after a fall?

Initial Management of SVT in the Emergency Department

For a hemodynamically stable patient presenting with SVT after a fall, adenosine is the initial pharmacologic treatment of choice after attempting vagal maneuvers. 1

Immediate Assessment and Stabilization

Determine hemodynamic stability first – this is the critical decision point that dictates all subsequent management:

• Unstable patients (hypotension, altered mental status, signs of shock, chest pain with ischemia) require immediate synchronized cardioversion without delay 1
• Stable patients proceed with a stepwise approach starting with vagal maneuvers 1, 2

Management Algorithm for Stable SVT

Step 1: Vagal Maneuvers (First-Line)

• Modified Valsalva maneuver is the most effective vagal technique with 43% success rate 2
• In younger patients, have them blow through a narrow straw 1
• Apply ice to the face in infants and young children without occluding the airway 1
• Carotid sinus massage in older children and adults 1
• Do not delay if IV/IO access is readily available – proceed directly to adenosine 1

Step 2: Adenosine (Drug of Choice)

• Adenosine is first-line pharmacologic therapy with 91% effectiveness for terminating SVT 1, 2
• Initial dose: 6 mg rapid IV bolus 1
• If ineffective, give 12 mg rapid IV bolus (can repeat once) 1
• Adenosine has minimal and transient side effects, making it the safest option 1

Step 3: Alternative Agents (If Adenosine Fails)

• Calcium channel blockers (diltiazem or verapamil) or beta-blockers are second-line options 1, 3, 4
• These agents have longer half-lives, so avoid combining them serially to prevent profound bradycardia 1

Step 4: Synchronized Cardioversion

• If pharmacologic therapy fails and patient remains stable, proceed to synchronized cardioversion 3, 5
• If patient becomes unstable at any point, immediately cardiovert 1

Critical Contraindications and Pitfalls

NEVER use adenosine in:

• Irregular wide-complex tachycardia 1
• Polymorphic wide-complex tachycardia 1
• Unstable patients (cardiovert immediately instead) 1

NEVER use AV nodal blockers (calcium channel blockers, beta-blockers, digoxin) in:

• Pre-excited atrial fibrillation (Wolff-Parkinson-White with AF) – these drugs can accelerate ventricular rate and cause ventricular fibrillation 1, 6
• This is an absolute contraindication that can be fatal 6

Amiodarone is NOT first-line for SVT:

• Amiodarone has higher toxicity and proarrhythmic risk compared to adenosine 1
• Reserve amiodarone for ventricular tachycardia or refractory cases 1, 7
• The American Heart Association explicitly states antiarrhythmic medications are "less desirable alternatives" for SVT 1

Why Not the Other Options?

• CPR (Option 2): Only indicated if patient is pulseless or in cardiac arrest – not appropriate for SVT with perfusion 1
• Cardioversion (Option 3): Reserved for hemodynamically unstable patients or after failed pharmacologic therapy in stable patients 1, 3
• Amiodarone (Option 4): Not first-line for SVT due to higher toxicity profile; appropriate for ventricular arrhythmias 1, 7

Post-Acute Management

• Obtain 12-lead ECG in sinus rhythm to evaluate for pre-excitation patterns (delta waves) indicating WPW syndrome 1, 6
• Refer all symptomatic patients to cardiac electrophysiology for consideration of catheter ablation, which has 94-98% success rates 6, 2
• Teach patients vagal maneuvers for self-termination of future episodes 6