What is the most appropriate management for a patient with sudden onset of supraventricular tachycardia (SVT), presenting with symptoms of tachycardia, shortness of breath, dizziness, and sweating, with an electrocardiogram (EKG) showing narrow QRS complex tachycardia?

Management of Supraventricular Tachycardia (SVT)

Vagal maneuvers should be performed as first-line treatment for this hemodynamically stable patient with narrow QRS complex tachycardia (SVT). 1

Initial Management Algorithm

1. Vagal Maneuvers (Class I recommendation)

   • Standard Valsalva maneuver: Have patient bear down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg pressure) while in supine position 1
   • Modified Valsalva maneuver: After standard Valsalva strain, immediately position patient to lie flat with legs elevated (more effective with 43% conversion rate compared to 17% with standard technique) 2, 3
   • Carotid sinus massage: After confirming absence of carotid bruit, apply steady pressure over carotid sinus for 5-10 seconds 1

2. If vagal maneuvers fail → Adenosine (Class I recommendation)

   • Administer 6 mg IV rapid bolus followed by saline flush 1
   • If ineffective, can increase to 12 mg IV (can repeat once if needed)
   • Adenosine terminates approximately 95% of AVNRT cases 1
   • Brief side effects (flushing, chest discomfort, dyspnea) resolve within seconds

3. If adenosine fails → IV calcium channel blockers or beta blockers (Class IIa recommendation)

   • IV diltiazem or verapamil (64-98% effective) 1
   • IV beta blockers (e.g., metoprolol) 1
   • These should only be used in hemodynamically stable patients

4. If pharmacological therapy fails → Synchronized cardioversion (Class I recommendation)

   • Performed with adequate sedation for hemodynamically stable patients 1

Important Clinical Considerations

• Patient presentation (rapid heartbeat, shortness of breath, dizziness, sweating) is typical for SVT
• Narrow QRS complex tachycardia on EKG suggests supraventricular origin, most commonly AVNRT
• Previous episodes suggest paroxysmal nature, common in SVT
• Alcohol trigger (glass of wine) is a known precipitant for SVT

Cautions and Pitfalls

• Avoid verapamil or diltiazem if there's any suspicion of pre-excited AF (can accelerate ventricular rate and lead to ventricular fibrillation) 1
• Avoid beta blockers in patients with decompensated heart failure or severe bronchospastic lung disease 1
• Adenosine should be used with caution in patients with severe asthma or those taking theophylline (may require higher doses) 1
• Ensure proper technique for vagal maneuvers to maximize effectiveness - supine positioning is critical 1
• Monitor for transient asystole with adenosine administration (expected and brief)

Monitoring and Follow-up

• Continuous cardiac monitoring during treatment
• 12-lead ECG before and after conversion to sinus rhythm
• Consider cardiology referral for electrophysiology study and possible catheter ablation if episodes are recurrent, especially if they impact quality of life

The evidence strongly supports starting with vagal maneuvers, particularly the modified Valsalva technique which has shown superior efficacy, followed by adenosine if needed, as the most appropriate initial management for this stable patient with SVT 1, 2.