What is the treatment for tachycardia (elevated heart rate)?

Treatment for Elevated Heart Rate (Tachycardia)

The treatment of tachycardia depends critically on hemodynamic stability: unstable patients require immediate synchronized cardioversion, while stable patients should receive treatment based on the specific type of tachycardia identified on ECG. 1

Initial Assessment and Stabilization

First, assess hemodynamic stability immediately by checking for:

• Systolic blood pressure <90 mmHg
• Acute altered mental status
• Ischemic chest discomfort
• Acute heart failure
• Signs of shock 1

If the patient is unstable with any of these signs, proceed directly to synchronized cardioversion without delay for pharmacologic attempts. 1 Use initial energy of 100J, then 200J, then 360J if initial attempts fail. 1

For all patients, provide supplementary oxygen if hypoxemia or increased work of breathing is present, as hypoxemia is a common cause of tachycardia. 1 Attach cardiac monitor, establish IV access, and obtain a 12-lead ECG to define the rhythm (but do not delay cardioversion if unstable). 1

Critical Pitfall: Sinus Tachycardia

If the rhythm is sinus tachycardia (heart rate >100 bpm but <220 minus patient's age), do NOT treat the tachycardia itself. 1 Sinus tachycardia results from physiologic stimuli such as fever, anemia, hypotension, or shock. 1 Treatment directed at "normalizing" the heart rate can be detrimental when cardiac function is poor and cardiac output depends on the rapid rate. 1 Instead, identify and treat the underlying cause. 1

Important exception: With ventricular rates <150 bpm in the absence of ventricular dysfunction, the tachycardia is more likely secondary to the underlying condition rather than the cause of instability. 1

Treatment Algorithm for Stable Narrow-Complex Tachycardia (SVT)

First-Line: Vagal Maneuvers

Attempt vagal maneuvers first in stable patients: Valsalva maneuver (forced exhalation against closed glottis) or unilateral carotid massage. 1, 2 Do not perform carotid massage if carotid bruit is present due to stroke risk. 1

Second-Line: Adenosine

If vagal maneuvers fail, adenosine is the drug of choice for AVNRT and most SVTs. 1, 2

• Dosing: 6 mg rapid IV bolus followed immediately by saline flush 2
• If no effect after 1-2 minutes: 12 mg IV 1
• Maximum dose: 12 mg 1

Adenosine advantages: Extremely short half-life, does not depress myocardial contractility, can be given with beta-blockers. 1

Contraindications: Active bronchospasm, severe COPD (risk of respiratory failure requiring prolonged mechanical ventilation), asthma (can precipitate bronchospasm). 1, 3

Side effects: Flushing and chest pain are common but last <60 seconds; can cause transient complete heart block, so must be given in monitored environment. 1

Third-Line: Beta-Blockers or Calcium Channel Blockers

If adenosine fails or is contraindicated, use IV beta-blockers or calcium channel blockers. 2

Metoprolol (preferred beta-blocker):

• 5 mg slow IV bolus over 2 minutes 2
• May repeat every 5 minutes to maximum 15 mg 4
• Caution: Can precipitate heart failure and cardiogenic shock; use cautiously in patients with bronchospastic disease 4

Diltiazem:

• 5-10 mg IV over 60 seconds 2, 5
• Similar efficacy to verapamil for most SVTs 2

Verapamil:

• 5-10 mg IV over 60 seconds 1, 2
• Critical contraindication: Do NOT use if beta-blockers have already been given (risk of profound bradycardia and hypotension) 1
• Do NOT use for SVT with Wolff-Parkinson-White syndrome (may precipitate VT/VF by allowing conduction through accessory pathway) 1
• Avoid in patients with severe conduction abnormalities, sinus node dysfunction, or pre-excited atrial fibrillation 2

Treatment for Multifocal Atrial Tachycardia (MAT)

MAT requires different management than other SVTs. 2, 3

First-line: IV metoprolol or IV verapamil 2

• Verapamil is preferred in respiratory failure patients as it does not exacerbate pulmonary disease 3
• Beta-blockers should be used cautiously and only AFTER correction of hypoxia 3

Adjunctive therapy: IV magnesium may be helpful even with normal magnesium levels 2

Critical pitfall: Cardioversion is ineffective for MAT and should not be attempted 2, 3

Treatment for Wide-Complex Tachycardia (Presumed Ventricular Tachycardia)

Assume all wide-complex tachycardia is ventricular tachycardia until proven otherwise. 2

For Stable Monomorphic VT:

Amiodarone is the preferred agent:

• 5 mg/kg (300 mg) IV over 1 hour 1, 6
• In life-threatening situations: can give over 15 minutes and repeat after 1 hour 1
• Loading dose: 15 mg/kg (up to 900 mg) over next 24 hours 1
• Note: Antiarrhythmic effect may take up to 30 minutes 1

Alternative: Lidocaine (Lignocaine):

• 1-3 mg/kg IV (100 mg bolus for cardiac arrest) 1
• May repeat after 5-10 minutes 1
• Maintenance infusion: 2-4 mg/min 1
• Has no effect on SVT 1

For Unstable VT:

Proceed immediately to synchronized cardioversion at 100J 1

Special Considerations

Atrial Fibrillation/Flutter with Rapid Ventricular Response:

• Acute rate control: Verapamil is preferred over digitalis or beta-blockers 1
• Cardioversion energy: 120-200J biphasic for atrial fibrillation; 50-100J for atrial flutter 1
• Beta-blockers and digoxin are effective for rate control in many cases 1

Patients on Nicardipine or Other Vasodilators:

If reflex tachycardia develops, add beta-blockade. 7

• Esmolol preferred: 0.5-1 mg/kg IV bolus, then 50-300 mcg/kg/min infusion 7
• This combination is explicitly endorsed for acute coronary syndromes and aortic dissection 7

Respiratory Failure Patients:

• Correct hypoxia aggressively first (SaO2 >90%) 3
• Avoid beta-blockers during acute respiratory decompensation; wait until hypoxia is corrected 3
• Verapamil is preferred over beta-blockers in active pulmonary disease 3
• Avoid adenosine in severe COPD or active bronchospasm 3

Critical Warnings

Never use verapamil or diltiazem for wide-complex tachycardia of uncertain origin - if it is actually VT, these can cause hemodynamic collapse. 2

Do not delay cardioversion in unstable patients to attempt pharmacologic conversion or establish IV access. 1

Avoid calcium channel blockers in hypotensive patients (systolic BP <90 mmHg). 3

Establish IV access and administer sedation before cardioversion if possible, but do not delay if patient is extremely unstable. 1