What is the treatment for Ventricular Tachycardia (Vtach) and Supraventricular Tachycardia (SVtach)?

Treatment of Ventricular Tachycardia and Supraventricular Tachycardia

For hemodynamically unstable VTach or SVTach, perform immediate synchronized cardioversion; for stable VTach, use IV amiodarone or procainamide as first-line pharmacologic therapy, while for stable SVTach, begin with vagal maneuvers followed by adenosine.

Ventricular Tachycardia (VTach) Management

Hemodynamically Unstable VTach (Pulseless or with Adverse Signs)

• Immediate synchronized DC cardioversion is the definitive treatment for pulseless VT or VT with adverse signs (systolic BP ≤90 mmHg, chest pain, heart failure, or rate ≥150 bpm) 1
• Use escalating energy levels: 100 J, then 200 J, then 360 J if initial attempts fail 1
• If VT is pulseless, follow the VF protocol with immediate defibrillation as pharmacologic treatment is secondary to early defibrillation 1
• After successful cardioversion, anticipate atrial or ventricular premature complexes that may reinitiate tachycardia, requiring antiarrhythmic drugs for prevention 1

Hemodynamically Stable VTach

Pharmacologic options in order of preference:

• Amiodarone is FDA-approved for frequently recurring VF and hemodynamically unstable VT refractory to other therapy, administered as 150 mg IV over 10 minutes, followed by 1 mg/min for 6 hours, then 0.5 mg/min maintenance 2

  • For breakthrough episodes, repeat the 150 mg bolus 2
  • Amiodarone demonstrated 78% immediate VT termination versus 27% with lidocaine in head-to-head comparison, with 67% of patients alive and VT-free at 1 hour versus 9% with lidocaine 3
  • Antiarrhythmic effect may take up to 30 minutes, so it's not ideal for rapid conversion unless the patient is clinically stable 1

• Procainamide shows the greatest efficacy among medical options for stable monomorphic VT, administered at 10 mg/kg at 50-100 mg/min IV over 10-20 minutes with continuous blood pressure and ECG monitoring 4

• Lidocaine was historically considered first-choice for VT at 1-3 mg/kg IV (100 mg bolus in cardiac arrest, repeatable after 5-10 minutes), followed by 2-4 mg/min infusion 1

  • However, lidocaine has significantly lower efficacy than amiodarone (27% vs 78% termination rate) and higher drug failure rates (91% vs 33%) 3
  • Lidocaine has no effect on SVT and should not be used for supraventricular arrhythmias 1

• Magnesium may be effective for VF/VT, particularly when associated with acute myocardial infarction: 8 mmol bolus followed by 2.5 mmol/h infusion 1

Critical Caveat for VTach Treatment

• Direct current cardioversion must always be available in the emergency setting, as approximately 50% of patients will ultimately require electrical therapy even if initially stable 5
• Hemodynamic instability and death occur significantly more often when VT occurs during acute myocardial infarction (65% unstable vs 21% in non-AMI patients) 5

Supraventricular Tachycardia (SVTach) Management

Hemodynamically Unstable SVTach

• Immediate synchronized cardioversion is the treatment of choice for decompensated patients (hypotensive, heart failure, angina, or HR >150 bpm) 1
• Perform after adequate sedation/anesthesia in stable patients, but immediately without delay in unstable patients 1

Hemodynamically Stable SVTach

Step-wise algorithmic approach:

1. Vagal maneuvers are first-line intervention 6

   • Modified Valsalva maneuver has approximately 43% success rate 6
   • Carotid sinus massage: apply steady pressure over right or left carotid sinus for 5-10 seconds 1
   • Ice-cold wet towel to face or facial immersion in 10°C water 1, 6
   • Switching between techniques achieves overall 27.7% success rate 1, 6

2. Adenosine is second-line treatment with 90-95% success rate for orthodromic AVRT and approximately 95% for AVNRT 1, 6

   • Serves both therapeutic and diagnostic purposes by unmasking atrial activity in flutter or atrial tachycardia 6
   • Brief side effects (<1 minute) occur in approximately 30% of patients 1, 6
   • Critical warning: Electrical cardioversion must be immediately available as adenosine may precipitate AF that conducts rapidly to ventricles, potentially causing ventricular fibrillation 1

3. IV calcium channel blockers or beta-blockers if adenosine fails 6

   • Diltiazem or verapamil are particularly effective for converting AVNRT to sinus rhythm 6
   • Success rates of 80-98% for verapamil, diltiazem, or adenosine in most stable patients 1

Special Situation: Pre-excited Atrial Fibrillation (Accessory Pathway)

This is a life-threatening emergency requiring different management:

• Synchronized cardioversion for hemodynamically unstable patients with pre-excited AF 1

• Ibutilide or IV procainamide for hemodynamically stable pre-excited AF 1, 6

  • These agents decrease ventricular rate by slowing conduction over the accessory pathway and may terminate AF 1

• NEVER use calcium channel blockers (diltiazem, verapamil) or beta-blockers in patients with pre-excitation on ECG 1, 6

  • These agents may enhance conduction over the accessory pathway if SVT converts to AF, potentially leading to ventricular fibrillation and death 6
  • This is a critical pitfall that can be fatal 1, 6

Administration Considerations

• All life-threatening arrhythmia drugs should be given IV 1
• Peripheral IV drugs must be followed by 20 mL saline bolus to aid central circulation delivery 1
• When no venous access exists, drugs (particularly epinephrine) may be given endotracheally in double or triple doses 1