What are the treatment options for tachycardia?

Treatment Options for Tachycardia

For hemodynamically stable patients with supraventricular tachycardia, begin with vagal maneuvers followed by IV adenosine (6 mg rapid bolus, then 12 mg if needed), and if unsuccessful, use IV beta-blockers (metoprolol 2.5-5 mg) or calcium channel blockers (diltiazem 5-10 mg or verapamil 5-10 mg over 60 seconds). 1, 2

Initial Assessment: Hemodynamic Stability Determines Treatment Path

Unstable patients require immediate action:

• Synchronized cardioversion is mandatory for hemodynamically unstable patients (systolic BP ≤90 mmHg, chest pain, heart failure, or rate ≥150 bpm with adverse signs) 1, 2
• Start with 100J, then 200J, then 360J if initial attempts fail 1
• Do not delay cardioversion to attempt pharmacological conversion 2

Stable patients follow a stepwise medication approach 1, 2

First-Line Treatment Algorithm for Stable Patients

Step 1: Vagal Maneuvers (Always Try First)

• Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds, generating at least 30-40 mmHg pressure 1
• Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruit 1
• Cold stimulus: Apply ice-cold wet towel to face 1
• Success rate approximately 28% when switching between techniques 1

Step 2: Adenosine (First-Line Pharmacotherapy)

• Dosing: 6 mg rapid IV bolus followed by saline flush; if no response in 1-2 minutes, give 12 mg; can repeat 12 mg once more 1, 2, 3
• Efficacy: Terminates approximately 95% of AVNRT cases within 30 seconds 1, 2, 3
• Mechanism: Selectively blocks AV nodal conduction with extremely short half-life 1
• Critical caveat: Must be given in monitored environment (ICU, ED) as it can cause transient complete heart block 1
• Contraindications: Avoid in asthmatics (can precipitate bronchospasm) 1
• Drug interactions: Enhanced by dipyridamole, reduced by theophylline 1

Step 3: IV Beta-Blockers or Calcium Channel Blockers

Metoprolol (preferred beta-blocker):

• Dosing: 2.5-5 mg IV slow bolus over 2 minutes, repeat every 10 minutes up to 3 doses (maximum 15 mg) 2, 3
• Mechanism: Slows AV nodal conduction and reduces heart rate 4
• Avoid in: Severe pulmonary disease (especially bronchospastic), acute decompensated heart failure, severe conduction abnormalities 1, 4

Diltiazem or Verapamil (calcium channel blockers):

• Dosing: Diltiazem 5-10 mg IV over 60 seconds; Verapamil 5-10 mg IV over 60 seconds 1, 2
• Efficacy: Particularly effective for converting AVNRT to sinus rhythm 1, 2
• Critical warning: Never combine with beta-blockers (risk of profound bradycardia and hypotension) 1
• Absolute contraindication: Do not use in wide-complex tachycardia that might be ventricular tachycardia (can cause hemodynamic collapse) 2, 5
• Also avoid in: Wolff-Parkinson-White syndrome with SVT (may precipitate VT/VF by allowing conduction through accessory pathway) 1

Type-Specific Considerations

Multifocal Atrial Tachycardia (MAT)

• Acute treatment: IV metoprolol or verapamil 2
• Ongoing management: Oral metoprolol 25-50 mg, verapamil, or diltiazem 1, 2
• Adjunct therapy: IV magnesium may help even with normal magnesium levels 2
• Essential: Address underlying conditions (pulmonary disease, electrolyte abnormalities) 2

Wide-Complex Tachycardia (Assume Ventricular Tachycardia)

• Critical principle: Treat as VT until proven otherwise 2
• Stable monomorphic VT: Procainamide or amiodarone 2
• Amiodarone dosing: 5 mg/kg (300 mg) over one hour; in life-threatening situations, give over 15 minutes 1, 2
• Never use: Verapamil or diltiazem (can cause cardiovascular collapse) 2

Long-Term Management Options

Oral Medications for Recurrent Episodes

• Beta-blockers: First-line for chronic management 2, 5
• Calcium channel blockers: Diltiazem or verapamil as alternatives 2, 5
• Target heart rate: <100 bpm to prevent tachycardia-induced cardiomyopathy 2

Definitive Treatment

• Catheter ablation: Curative option for recurrent SVT with high success rates and low complication rates 5
• Consider early: For patients with frequent episodes or those unable to tolerate medications 5, 6

Critical Pitfalls to Avoid

Misdiagnosis of wide-complex tachycardia:

• Using calcium channel blockers for VT misdiagnosed as SVT causes hemodynamic collapse 2
• Always assume wide-complex is VT unless proven otherwise 2

Beta-blocker/calcium channel blocker combination:

• Never give together (profound bradycardia and hypotension) 1

Adenosine administration errors:

• Must give as rapid bolus with saline flush (short half-life requires rapid delivery) 1
• Requires continuous monitoring (can cause transient complete heart block) 1

Cardioversion ineffectiveness:

• Does not work for automatic focal atrial tachycardia or MAT 2

Abrupt beta-blocker discontinuation:

• Can precipitate severe angina, MI, or ventricular arrhythmias in patients with coronary artery disease 4
• Taper over 1-2 weeks when discontinuing 4