What is the management approach for a patient with tachycardia in the Advanced Cardiovascular Life Support (ACLS) setting?

ACLS Tachycardia Management

Immediate Assessment: Stable vs. Unstable (This Determines Everything)

If the patient shows signs of hemodynamic instability—acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or shock—proceed immediately to synchronized cardioversion without delay. 1, 2

Initial Stabilization Steps

• Assess oxygenation first by looking for tachypnea, intercostal retractions, suprasternal retractions, or paradoxical abdominal breathing, and provide supplemental oxygen if needed 1, 2
• Attach cardiac monitor, establish IV access, and measure blood pressure 1, 2
• Obtain a 12-lead ECG to define the rhythm, but never delay cardioversion in unstable patients to get this 1, 2

The Critical Rate Threshold

• Heart rates >150 bpm are more likely to cause symptoms from the arrhythmia itself 1
• Heart rates <150 bpm are usually secondary to an underlying condition (fever, dehydration, anemia, hypotension) unless ventricular function is impaired 1

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Rhythm-Specific Management for Stable Patients

Sinus Tachycardia

Do not treat sinus tachycardia with antiarrhythmic drugs—this is a physiologic response that requires identification and treatment of the underlying cause. 1, 2

• The upper limit of sinus tachycardia is approximately 220 minus the patient's age in years 1
• When cardiac function is poor, cardiac output depends on the rapid heart rate, and "normalizing" the rate can be detrimental 1
• Direct therapy toward the underlying cause: fever, hypovolemia, anemia, hypoxia, hyperthyroidism, or drugs (caffeine, alcohol, nicotine, salbutamol, aminophylline, amphetamines, cocaine) 1

Narrow-Complex Regular Tachycardia (SVT)

The treatment sequence is: vagal maneuvers → adenosine → synchronized cardioversion. 1, 2

• Attempt vagal maneuvers first (carotid massage, Valsalva) 1, 2
• Give adenosine 6 mg rapid IV push; if no response, give 12 mg 2
• Alternative agents include IV verapamil or diltiazem 1
• For patients not hypotensive with regular narrow-complex SVT, adenosine may be given while preparing for synchronized cardioversion (Class IIb) 1
• Record an ECG during drug administration—termination with a P wave after the last QRS suggests AVRT or AVNRT; termination with a QRS suggests atrial tachycardia; continuation with AV block indicates atrial tachycardia or flutter 1

Wide-Complex Tachycardia

Assume ventricular tachycardia until proven otherwise, and treat accordingly. 1, 2

For Hemodynamically Stable Wide-Complex Tachycardia:

• Electrical cardioversion should be the first-line approach 1
• IV procainamide is recommended for patients without severe heart failure or acute MI 1
• IV amiodarone (150-300 mg) is preferred for patients with impaired left ventricular function or signs of heart failure 1
• IV sotalol is more effective than lidocaine 1
• IV lidocaine is only moderately effective and inferior to other options 1

For Hemodynamically Unstable Wide-Complex Tachycardia:

• Immediate synchronized cardioversion is mandatory 1
• If the patient is hypotensive but conscious, give immediate sedation before cardioversion 1

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Synchronized Cardioversion Technique

• Establish IV access before cardioversion if possible and administer sedation if the patient is conscious 1, 2
• Do not delay cardioversion if the patient is extremely unstable 1, 2
• Start defibrillation at maximum output 1
• In patients with an ICD, place defibrillator patches at least 8 cm from the generator 1

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Critical Pitfalls to Avoid

• Never give calcium channel blockers or beta-blockers for wide-complex tachycardia unless VT is definitively ruled out—this can cause cardiovascular collapse 2
• Never treat compensatory sinus tachycardia with rate-control agents—when stroke volume is limited, normalizing the heart rate can be detrimental 1, 2
• Never delay cardioversion in unstable patients to obtain a 12-lead ECG 1, 2
• Never assume narrow-complex tachycardia is benign—always assess hemodynamic stability first 2
• Always have a defibrillator ready when giving adenosine—it may precipitate rapid atrial fibrillation in patients with WPW syndrome 2
• With ventricular rates <150 bpm in the absence of ventricular dysfunction, the tachycardia is more likely secondary to an underlying condition rather than the cause of instability 1