What is the treatment for a patient with tachycardia?

Treatment for Tachycardia with Heart Rate 160 bpm

For a patient with heart rate 160 bpm, immediate assessment of hemodynamic stability is critical: if unstable (hypotension, chest pain, altered mental status, or signs of shock), perform immediate synchronized cardioversion; if stable, determine if the rhythm is narrow-complex or wide-complex and treat accordingly with vagal maneuvers followed by adenosine for narrow-complex tachycardia, or assume ventricular tachycardia and use procainamide or amiodarone for wide-complex tachycardia. 1, 2, 3

Initial Assessment: Hemodynamic Stability

Unstable patients require immediate action:

• Synchronized cardioversion is mandatory for any tachycardia causing hemodynamic instability (systolic BP <90 mmHg, chest pain, dyspnea with poor perfusion, altered mental status) 1, 2, 3
• Do not delay cardioversion to attempt pharmacologic conversion in unstable patients 2, 3
• Sedate conscious patients prior to cardioversion 3
• Initial energy: 100J, then 200J, then 360J if initial attempts fail 2

Stable patients allow time for rhythm identification and pharmacologic management 1, 2

Narrow-Complex Tachycardia (QRS <120 ms)

First-Line Treatment Sequence:

1. Vagal Maneuvers (attempt first):

• Valsalva maneuver: bearing down against closed glottis for 10-30 seconds (30-40 mmHg pressure) in supine position 1, 2
• Carotid sinus massage: 5-10 seconds of steady pressure after confirming no bruit 1
• Ice-cold wet towel to face (diving reflex) 1
• Success rate approximately 27.7% when switching between techniques 1

2. Adenosine (if vagal maneuvers fail):

• Dose: 6 mg rapid IV push, followed by 12 mg if needed 2, 3
• Terminates AVNRT in approximately 95% of cases 1
• Short half-life makes it ideal for both diagnosis and treatment 2
• Caution: May precipitate ventricular fibrillation in coronary disease or cause rapid ventricular rates in pre-excited atrial fibrillation 3

3. Alternative IV Agents (if adenosine fails or contraindicated):

• IV metoprolol: 5 mg slow IV bolus (can repeat if tolerated) 2
• IV diltiazem: 5-10 mg over 60 seconds 2
• IV verapamil: 5-10 mg over 60 seconds 2
• Conversion rates 80-98% for these agents 1
• Critical warning: Do not give verapamil if beta-blockers already administered 2

Important Caveats for Narrow-Complex Treatment:

• Avoid calcium channel blockers in patients with severe conduction abnormalities, sinus node dysfunction, or pre-excited atrial fibrillation 2
• Avoid in suspected systolic heart failure 1
• Beta-blockers should be used cautiously in severe pulmonary disease 2

Wide-Complex Tachycardia (QRS ≥120 ms)

Assume ventricular tachycardia until proven otherwise 2, 3

For Stable Wide-Complex Tachycardia:

1. Procainamide (first-line for monomorphic VT without severe heart failure or acute MI):

• Dose: 10 mg/kg IV 1
• Superior to lidocaine for VT termination 1

2. Amiodarone (for all stable monomorphic VT, especially with heart failure or acute MI):

• Dose: 150-300 mg IV bolus (5 mg/kg over one hour), followed by 15 mg/kg (up to 900 mg) over next 24 hours 1, 2, 4
• Conversion rates 20-40% 1
• Primary side effect is hypotension 1
• FDA-approved for hemodynamically unstable VT and frequently recurring VF 4

3. Avoid lidocaine:

• Less effective than sotalol, procainamide, and amiodarone 1
• Poorly effective in retrospective analyses 1

Critical Pitfall for Wide-Complex Tachycardia:

Never use verapamil or diltiazem for wide-complex tachycardia of uncertain etiology—these can cause hemodynamic collapse and ventricular fibrillation if the rhythm is actually VT 2, 3

Special Considerations

For Atrial Fibrillation with Rapid Ventricular Response:

• High risk (rate >150, chest pain, breathlessness, poor perfusion): attempt electrical cardioversion after heparinization 1
• Intermediate/low risk: rate control with beta-blockers or calcium channel blockers 1

For Multifocal Atrial Tachycardia:

• IV metoprolol or verapamil for acute treatment 2
• IV magnesium may be helpful even with normal magnesium levels 2, 5
• Address underlying conditions (pulmonary disease, electrolyte abnormalities) 2, 5

Correct electrolyte abnormalities (potassium, magnesium, calcium) before or during antiarrhythmic therapy to reduce proarrhythmic risk 3

When Pharmacologic Therapy Fails

Synchronized cardioversion is recommended for stable patients when:

• Pharmacologic therapy fails to terminate tachycardia 1
• Drugs are contraindicated 1
• Highly effective for terminating SVT (including AVRT and AVNRT) 1

Note: Cardioversion is ineffective for automatic forms of focal atrial tachycardia and multifocal atrial tachycardia 2, 3