Wide Complex Tachycardias
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Article at a Glance
- Clinicians should assume regular wide complex tachyarrhythmias are ventricular tachycardia (VT) until proven otherwise.
- If the patient is stable, providers may seek expert consultation to diagnose the rhythm and determine the best treatment plan.
- A stable patient with monomorphic VT can be treated with medication. If the patient becomes unstable, synchronized cardioversion may be required.
- A stable patient with polymorphic VT may be treated with magnesium. If the patient becomes unstable, unsynchronized cardioversion is required.
Adult Tachycardia with a Pulse Algorithm
If the patient is stable but tachyarrhythmia persists, clinicians determine if the QRS complex is narrow or wide. Common forms of wide complex regular tachyarrhythmias include ventricular tachycardia and supraventricular tachycardia with aberrancy. It’s difficult to distinguish one from the other, so clinical consultation is often necessary.1 Generally, wide QRS complex tachycardia is considered ventricular tachycardia and receives the same treatment. In this case, adenosine usage is safe. If the patient responds to adenosine, they’re diagnosed with supraventricular tachycardia with aberrancy. A defibrillator should be on stand-by when using adenosine as a test to diagnose the rhythm. Read: The Unstable PatientWide QRS Complex: VT, or SVT with Aberrancy?
Antiarrhythmic medication options for treating monomorphic ventricular tachycardia include intravenous procainamide, amiodarone, or sotalol. When a stable patient has persistent monomorphic ventricular tachycardia, clinicians consider intravenous antiarrhythmics such as procainamide, amiodarone, or sotalol. If antiarrhythmic therapy fails, synchronized cardioversion should be applied, and expert consultation should be considered. Procainamide may terminate hemodynamically stable monomorphic VT. It’s administered via IV infusion at a rate of 20–50 mg/minute until the arrhythmia stops or an adverse reaction occurs.2 Common adverse reactions include hypotension and a prolongation of QRS duration. Clinicians administer a maintenance infusion at a rate of 1–4 mg/minute. Procainamide is contraindicated in patients with congestive heart failure and patients who already have a prolonged QT interval. Amiodarone can be used to prevent recurrent monomorphic VT, or to treat patients with coronary artery disease with low ejection fractions experiencing refractory ventricular arrhythmias. It is administered at a dose of 150 mg and given a slow IV push over 10 minutes. It can be repeated as needed if VT recurs. A maintenance infusion is given at a rate of 1 mg/minute up to a maximum dose of 2.2 grams per 24 hours. Sotalol at a dosage of 100 mg via slow IV push over 5 minutes can treat monomorphic VT in hemodynamically stable patients. Sotalol is also contraindicated in patients with a prolonged QT interval.Ventricular Tachycardia (Monomorphic VT)
Related Video – ECG Rhythm Review – Ventricular Tachycardia
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Unstable polymorphic VT is treated the same as ventricular fibrillation (VF), via defibrillation rather than synchronized cardioversion, which would normally be used for unstable tachyarrhythmias. Recurrent polymorphic VT treatment must address the underlying cause of VT. Management also depends on whether the patient has a prolonged QR interval. If a prolonged QT interval is present, medications known to increase the QT interval, such as procainamide and sotalol, must be discontinued. The clinician must also address electrolyte imbalances or acute precipitants such as drug overdose or poisoning, which are common causes of this arrhythmia. Polymorphic ventricular tachycardia is a complication of a prolonged QT interval (or prolonged ventricular repolarization). Polymorphic Ventricular Tachycardia – Torsades de PointesPolymorphic Ventricular Tachycardia
Related Video – ECG Rhythm Review – Polymorphic Ventricular Tachycardia (Torsades de Pointes)
Torsades de Pointes (French for “twisting of peaks”) is a polymorphic ventricular tachycardia. Magnesium is a common treatment. Some studies show isoproterenol or ventricular pacing as a viable treatment for torsades associated with bradycardia and drugs causing a prolonged QT interval.3 The primary treatment for patients with familial long QT syndrome is intravenous magnesium. Other therapies include cardiac pacing or β-blockers. However, clinicians shouldn’t administer isoproterenol to these patients. Polymorphic VT is associated with acquired long QT syndrome and is treated with magnesium. If the polymorphic VT is associated with bradycardia or precipitated by pauses in rhythm or pacing, isoproterenol may be considered. Myocardial ischemia is the most common cause of polymorphic VT if there isn’t a prolonged QT interval. Amiodarone or β-blockers reduce arrhythmia recurrence. Polymorphic VT can also be precipitated by catecholaminergic VT. They may be responsive to β-blockers. Brugada syndrome may be responsive to isoproterenol.Polymorphic VT – Torsades de Pointes
Related Video – Transcutaneous Pacing
Related Video – Beta Blockers – ACLS Drugs
If the patient has a regular wide complex tachyarrhythmia, clinicians assume it’s ventricular tachycardia. Stable patients with monomorphic VT are treated with medication, while stable patients with polymorphic VT are treated with magnesium. Monomorphic patients may require synchronized cardioversion, while polymorphic patients require unsynchronized cardioversion. Summary
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Editorial Sources
ACLS Certification Association (ACA) uses only high-quality medical resources and peer-reviewed studies to support the facts within our articles. Explore our editorial process to learn how our content reflects clinical accuracy and the latest best practices in medicine. As an ACA Authorized Training Center, all content is reviewed for medical accuracy by the ACA Medical Review Board.
1. John B Garner and John M Miller. Wide Complex Tachycardia – Ventricular Tachycardia or Not Ventricular Tachycardia, That Remains the Question. Arrhythmia & Electrophysiology Review. 2013.
2. Brian Pritchard; Holly Thompson. Procainamide. National Library of Medicine. 2022.
3. Barbara J Drew. Prevention of Torsade de Pointes in Hospital Settings: A Scientific Statement From the American Heart Association and the American College of Cardiology Foundation. Circulation. 2010.
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