Definition

HR>100 with a QRS duration >0.12s (120ms). Classified as regular or irregular.  Can be either aberrant intraventricular conduction of supraventricular impulse or a ventricular impulse.

Differential Diagnosis

See below for additional details for each.

Evaluation

• Quickly determine if the patient is hemodynamically stable or unstable. If unstable or in doubt, call “code blue” and initiate ACLS unstable WCT protocol for unstable VT/VF.
• Involve the cardiology and/or ICU team with these patients as they may deteriorate quickly.
• If stable, obtain 12-lead ECG, Troponin, and electrolyte panel including magnesium.
• Look for precipitating cause and treat accordingly (i.e. ischemia, prolonged QT).
• Evaluate medication list for QT prolonging agents.
• Examine prior EKGs for evidence of aberrant conduction pathways (bundle branch blocks, interventricular conduction delays).

Management

• Replete electrolytes.
• Discontinue QT prolonging agents. Magnesium Sulfate 2g IV should be given if patients have a prolonged QTc (>450 ms in women, >470 ms in men).
• Stable VT: see ACLS Stable VT section for anti-arrhythmic recommendations

Regular Wide Complex Tachycardias:

Monomorphic ventricular tachycardia (VT): only one QRS morphology on EKG. Given the seriousness of VT, any patient with heart disease and a wide QRS tachycardia should be assumed to have VT until proven otherwise. See ACLS: Stable Ventricular tachycardia.

Causes: predisposing factors include cardiomyopathy, prior myocardial infarction, electrolyte abnormalities (K, Mg), and conduction abnormalities.

Diagnosis: only one QRS morphology on EKG. Identification is made by the Brugada Criteria: see Cardiology: Diagnosis of Wide Complex Tachycardia.

• Non-sustained VT: self terminates in <30 sec
• Sustained VT: self terminates in >30 sec or continues indefinitely

Treatment: Replete electrolytes, antiarrhythmics. See ACLS: Stable/Unstable VT Protocol.

SVT with aberrancy:

Causes: supraventricular impulse that has aberrant intraventricular conduction in the setting of a bundle branch block.

Diagnosis: use the Brugada Criteria to differentiate from VT. See Cardiology: Diagnosis of Wide Complex Tachycardia.

Treatment: if confident of SVT with aberrancy, treat as SVT.

Pre-excitation tachycardia:

Causes: accessory pathway that conducts at a different rate and causes a widening of the QRS complex due to the presence of delta waves.  Considered an antidromic AVRT and may be impossible to distinguish between this and VT.

Irregular Wide Complex Tachycardias:

Ventricular fibrillation: a form of pulseless arrest, unorganized ventricular rhythm and requires immediate ACLS initiation and defibrillation.  This is an ischemic rhythm.

Polymorphic ventricular tachycardia: an organized ventricular rhythm with beat-to-beat variability in morphology that deteriorates to pulseless arrest and VF quickly and should be treated per ACLS protocols immediately. Torsades de pointes is an example of polymorphic VT that occurs in the setting of QT interval prolongation. Polymorphic ventricular tachycardia with a normal QT interval often represents new ischemia.

Irregular SVT with aberrancy: likely related to atrial fibrillation or flutter with variable block. If delta waves are present, this could represent atrial fibrillation in WPW. Adenosine should be avoided in this case (and if there is any doubt) to avoid precipitation of VT or VF.

Key points

• A wide complex tachycardia should be treated as ventricular tachycardia until proven otherwise.
• Evaluate for hemodynamic stability immediately.
• Check potassium and magnesium levels treat for K>4.0 and Mg >2.0
• Irregular WCT is likely a sign of ischemia or a result of prolonged QT interval.
• Do not hesitate to call a “Code Blue” for appropriate back up and initiating ACLS protocol.
• Consult Cardiology early for aid in management.

2015 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 7.18: Tachyarrhythmias. https://eccguidelines.heart.org/circulation/cpr-ecc-guidelines/

Brugada, P; Brugada, J; et al. “A New Approach to the Differential Diagnosis of a regular tachycardia with a wide QRS.” Circulation 1999; 83:1649-1659.