What to do when heart rate is very high and the individual has tachycardia?

Management of Very High Heart Rate (Tachycardia)

When confronted with a very high heart rate, immediately assess whether the patient is stable or unstable—if the patient shows signs of hemodynamic compromise (altered mental status, chest pain, acute heart failure, hypotension, or shock), proceed directly to synchronized cardioversion; if stable, identify the underlying cause and rhythm type to guide specific treatment. 1

Initial Assessment and Stabilization

Evaluate oxygenation first, as hypoxemia is a common reversible cause of tachycardia. 1

• Check for signs of increased work of breathing (tachypnea, intercostal retractions, suprasternal retractions, paradoxical abdominal breathing) and measure oxygen saturation by pulse oximetry. 1
• Provide supplemental oxygen if oxygenation is inadequate or work of breathing is increased. 1
• Attach cardiac monitor, evaluate blood pressure, and establish IV access. 1
• Obtain a 12-lead ECG to define the rhythm, but do not delay cardioversion if the patient is unstable. 1

Determine Stability: Critical Decision Point

Assess for rate-related cardiovascular compromise: 1

• Acute altered mental status 1
• Ischemic chest discomfort 1
• Acute heart failure 1
• Hypotension or other signs of shock 1

If any of these signs are present and suspected to be due to the tachyarrhythmia, proceed immediately to synchronized cardioversion. 1

Important Caveat on Rate Thresholds

With ventricular rates <150 beats per minute in the absence of ventricular dysfunction, the tachycardia is more likely secondary to an underlying condition rather than the cause of instability—focus on treating the underlying cause rather than the rate itself. 1

Management Based on Rhythm Type

Sinus Tachycardia (Heart Rate >100 bpm)

Do not treat sinus tachycardia with rate-controlling medications—instead, identify and treat the underlying cause (fever, anemia, hypotension/shock, dehydration, pain, anxiety). 1

• The upper rate of sinus tachycardia is age-related (approximately 220 minus patient's age in years). 1
• Critical pitfall: When cardiac function is poor, cardiac output may be dependent on a rapid heart rate; "normalizing" the heart rate can be detrimental in compensatory tachycardias where stroke volume is limited. 1

Narrow Complex Supraventricular Tachycardia (SVT)

For stable patients: 1

• Try vagal maneuvers first (Valsalva maneuver, carotid massage). 1
• Adenosine is the first-choice drug for narrow complex SVT. 1
• If the patient has adverse signs despite vagal maneuvers, attempt electrical cardioversion, supplemented if necessary with amiodarone. 1
• In the absence of adverse signs, choose one drug from esmolol, verapamil, amiodarone, or digoxin. 1

For unstable patients or pulseless with rate >250 bpm: 1

• Proceed directly to electrical cardioversion. 1
• If not hypotensive, adenosine may be given while preparing for synchronized cardioversion (Class IIb). 1

Atrial Fibrillation and Flutter

Risk stratification based on heart rate and symptoms: 1

High risk patients (rate >150 bpm with chest pain, breathlessness, or poor perfusion):

• Attempt electrical cardioversion after heparinization. 1

Intermediate risk patients (rate 100-150 bpm):

• Treatment depends on presence of impaired hemodynamics or structural heart disease and whether onset is known to be within 24 hours. 1

For rate control in stable patients: 1

• IV beta blockers (esmolol, metoprolol, propranolol) or nondihydropyridine calcium channel antagonists (verapamil, diltiazem) are recommended to slow ventricular response in the acute setting, exercising caution in patients with hypotension or heart failure. 1
• IV digoxin or amiodarone is recommended to control heart rate in patients with atrial fibrillation and heart failure who do not have an accessory pathway. 1

Cardioversion energy doses: 1

• Initial biphasic energy dose for atrial fibrillation: 120-200 J. 1
• Atrial flutter and other SVTs generally require less energy: initial 50-100 J. 1
• If initial shock fails, increase dose in stepwise fashion. 1

Broad Complex Tachycardia

If no pulse is present, follow the VF algorithm. 1

If pulse is present but patient has adverse signs or rhythm is unresponsive to drugs:

• Attempt electrical cardioversion. 1
• Antiarrhythmic options include amiodarone or lidocaine. 1

Synchronized Cardioversion Technique

Synchronization is critical to avoid shock delivery during the relative refractory period, which could produce ventricular fibrillation. 1

• If possible, establish IV access and administer sedation if patient is conscious. 1
• Do not delay cardioversion if the patient is extremely unstable. 1
• Synchronized cardioversion is recommended for: unstable SVT, unstable atrial fibrillation, unstable atrial flutter, and unstable monomorphic VT. 1
• If synchronization is impossible, use high-energy unsynchronized shocks (defibrillation doses). 1

Common Pitfalls to Avoid

Never use rate-controlling medications in compensatory sinus tachycardia, especially when hypotension is present—the tachycardia is maintaining cardiac output and slowing it can cause cardiovascular collapse. 2

Do not assume tachycardia is "just anxiety" without proper cardiac evaluation, as supraventricular tachycardia is frequently misdiagnosed as panic disorder due to identical symptoms. 3, 4

Avoid AV nodal blocking agents if pre-excitation (Wolff-Parkinson-White syndrome) is present on ECG, as this can be dangerous if atrial fibrillation develops. 3

Do not routinely use multiple antiarrhythmic drugs together, as all antiarrhythmic drugs have proarrhythmic properties. 1