What is the management of symptomatic tachycardia?

Management of Symptomatic Tachycardia

For hemodynamically unstable patients with symptomatic tachycardia, immediate synchronized cardioversion is the treatment of choice; for stable patients, begin with vagal maneuvers followed by adenosine, then proceed to AV nodal blocking agents if these fail. 1

Initial Assessment and Stabilization

Hemodynamic Status Determines Management Pathway

• Unstable patients (acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or other signs of shock) require immediate synchronized cardioversion with prior sedation if conscious 1
• Record a 12-lead ECG immediately to differentiate tachycardia mechanisms and distinguish ventricular tachycardia from supraventricular tachycardia (SVT) with aberrancy 1, 2
• Critical pitfall: Never administer verapamil or diltiazem if ventricular tachycardia or pre-excited atrial fibrillation (Wolff-Parkinson-White syndrome) is suspected, as this may cause hemodynamic collapse or ventricular fibrillation 1

Management Algorithm for Hemodynamically Stable Patients

First-Line: Vagal Maneuvers

Modified Valsalva maneuver is the most effective vagal technique with 43% success rate and should be attempted first 2, 3

• Technique: Patient bears down against a closed glottis for 10-30 seconds (equivalent to 30-40 mm Hg intrathoracic pressure) in the supine position 1
• Alternative: Carotid sinus massage for 5-10 seconds after confirming absence of carotid bruit by auscultation 1
• Ice-cold towel to face (diving reflex) is another effective option 1
• Avoid eyeball pressure as this is potentially dangerous and has been abandoned 1, 2

Second-Line: Adenosine

Adenosine is 95% effective in terminating AVNRT and should be administered if vagal maneuvers fail 1, 2

• Dosing: 6 mg IV rapid push through a large vein, followed immediately by 20 mL saline flush 4
• Serves dual purpose as both therapeutic and diagnostic agent, unmasking atrial activity in atrial flutter or atrial tachycardia 1
• Contraindication: Do not use for irregular or polymorphic wide-complex tachycardias as it may precipitate ventricular fibrillation 1

Third-Line: AV Nodal Blocking Agents

Intravenous diltiazem or verapamil are highly effective (64-98% success rate) when adenosine fails 2, 4

• Diltiazem is more effective than beta blockers for acute termination of SVT 1
• Verapamil similarly effective with 88% conversion rate for paroxysmal SVT within 3 minutes 5, 6
• Beta blockers (metoprolol, esmolol) are reasonable alternatives with excellent safety profile, though less effective than calcium channel blockers 1
• Critical safety check: Confirm absence of ventricular tachycardia, pre-excited atrial fibrillation, and systolic heart failure before administration 1, 5

Fourth-Line: Synchronized Cardioversion

If pharmacological therapy fails or is contraindicated in stable patients, proceed to synchronized cardioversion 1

• Initial energy: 50-100 J biphasic, increase stepwise if initial shock fails 4
• Success rate approaches 100% for terminating SVT 1

Special Considerations

Wide-Complex Tachycardia

• If rhythm cannot be determined and QRS is monomorphic and regular, adenosine is relatively safe for both treatment and diagnosis 1
• Precordial thump may be considered for witnessed, monitored unstable ventricular tachycardia only if defibrillator not immediately available 1

Wolff-Parkinson-White Syndrome with Pre-excited Atrial Fibrillation

• Avoid all AV nodal blocking agents (adenosine, beta blockers, calcium channel blockers, digoxin) as they may accelerate ventricular rate 4, 5
• Unstable patients: Immediate synchronized cardioversion 4
• Stable patients: Ibutilide or intravenous procainamide 4

Multifocal Atrial Tachycardia

• First-line: Treat underlying condition (pulmonary disease, electrolyte abnormalities) 1
• Intravenous metoprolol or verapamil can be useful for rate control 1
• Cardioversion is not effective for this rhythm 1

Monitoring Requirements

• Continuous ECG monitoring and frequent blood pressure measurements are mandatory during intravenous therapy 5
• Defibrillator and emergency equipment must be readily available 5
• Hypotension following diltiazem may persist 1-3 hours; 3.2% of patients require intervention (IV fluids, Trendelenburg position) 5