What are the treatment options for Supraventricular Tachycardia (SVT) and Ventricular Tachycardia (VTach)?

Treatment of Supraventricular Tachycardia (SVT) and Ventricular Tachycardia (VTach)

Supraventricular Tachycardia (SVT) Management

Hemodynamically Unstable SVT

Immediate synchronized cardioversion is the definitive treatment for hemodynamically unstable SVT when vagal maneuvers and adenosine fail or are not feasible 1.

• Look for signs of instability: hypotension, altered mental status, shock, chest pain, or acute heart failure 2
• Synchronized cardioversion is highly effective at terminating SVT and must be performed promptly to restore sinus rhythm 1
• If time permits before cardioversion, attempt vagal maneuvers and adenosine, but do not delay cardioversion in truly unstable patients 1

Hemodynamically Stable SVT

Begin with vagal maneuvers, followed immediately by adenosine if unsuccessful, then proceed to IV calcium channel blockers or beta-blockers as third-line therapy 1, 3, 2.

First-Line: Vagal Maneuvers

• Perform Valsalva maneuver with patient supine: bear down against closed glottis for 10-30 seconds at 30-40 mmHg pressure 1
• Modified Valsalva technique achieves approximately 43% success rate 3
• Alternative: carotid sinus massage for 5-10 seconds after confirming absence of bruit 1
• Alternative: apply ice-cold wet towel to face or facial immersion in 10°C water 1, 3
• Switching between techniques yields overall 27.7% success rate 1, 2

Second-Line: Adenosine

• Adenosine terminates AVNRT in approximately 95% of patients and serves both therapeutic and diagnostic purposes 1, 3
• Adenosine unmasks atrial activity in atrial flutter or atrial tachycardia, aiding diagnosis 1, 3
• Brief side effects occur in approximately 30% of patients but last less than 1 minute 3, 2

Third-Line: IV Calcium Channel Blockers or Beta-Blockers

• IV diltiazem or verapamil are particularly effective with 80-98% conversion rates 1, 2
• IV beta-blockers are reasonable alternatives with excellent safety profile, though diltiazem is more effective than esmolol 1

Critical Pitfall: Never give calcium channel blockers or beta-blockers if VT or pre-excited atrial fibrillation is suspected, as this can precipitate ventricular fibrillation 1.

• Ensure absence of VT before administering these agents 1
• Avoid in patients with suspected systolic heart failure 1
• For pre-excited AF, use ibutilide or IV procainamide instead 3, 2

Fourth-Line: IV Amiodarone

• Consider IV amiodarone when other therapies are ineffective or contraindicated in stable patients 1
• Effective in small studies for terminating AVNRT 1
• Short-term use avoids long-term toxicity concerns 1

Refractory Cases

• Synchronized cardioversion remains highly effective even in stable patients when pharmacological therapy fails 1
• Second drug bolus or higher dose of initial agent often effective before resorting to cardioversion 1

Long-Term SVT Management

• Oral verapamil or diltiazem for ongoing management in patients not pursuing catheter ablation 1, 3
• Catheter ablation is most effective long-term therapy with 94.3-98.5% success rates 2

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Ventricular Tachycardia (VTach) Management

Hemodynamically Unstable VTach

Immediate electrical cardioversion is mandatory for hemodynamically unstable ventricular tachycardia 4, 5.

• Do not delay for pharmacological therapy when patient shows signs of hemodynamic compromise 4
• Follow cardioversion with IV amiodarone or class I antiarrhythmics to prevent recurrence 5

Hemodynamically Stable VTach

IV amiodarone is indicated for initiation of treatment and prophylaxis of frequently recurring VF and hemodynamically unstable VT refractory to other therapy 6.

• IV amiodarone rapidly suppresses recurrent VF or hemodynamically unstable VT 6
• Studies show 85% reduction in VT episodes compared to baseline with IV amiodarone 6
• Median rate reduced from 1.7 episodes per day (low dose) to 0.5 episodes per day (high dose) 6
• Class I antiarrhythmics (lidocaine, ajmaline) are alternative first-line agents for stable sustained VT 5
• Most patients require acute IV therapy for 48-96 hours until arrhythmias stabilize 6
• Transition to oral amiodarone after stabilization 6

Long-Term VTach Management

• Beta-blockers and/or amiodarone are the only effective drugs for primary prevention of sudden cardiac death 5
• Implantable cardioverter-defibrillator (ICD) is superior to drugs for secondary prevention and improves prognosis 5

Critical Distinction: The management algorithms for SVT and VTach differ fundamentally—calcium channel blockers and adenosine that work for SVT are contraindicated or ineffective in VTach, making accurate rhythm diagnosis essential before treatment 1, 4.