From the Guidelines
Wide QRS complexes are primarily caused by ventricular tachycardia (VT), supraventricular tachycardia (SVT) with aberrancy, pre-excited tachycardias, and ventricular paced rhythms. The most common forms of wide-complex tachycardia are VT or VF, SVT with aberrancy, pre-excited tachycardias, and ventricular paced rhythms 1. Other causes of wide QRS complexes include bundle branch blocks, hyperkalemia, sodium channel blocking medication effects, and pre-excitation syndromes like Wolff-Parkinson-White syndrome.
Key Causes of Wide QRS Complexes
- Ventricular tachycardia (VT)
- Supraventricular tachycardia (SVT) with aberrancy
- Pre-excited tachycardias
- Ventricular paced rhythms
- Bundle branch blocks
- Hyperkalemia
- Sodium channel blocking medication effects
- Pre-excitation syndromes like Wolff-Parkinson-White syndrome
The management of wide QRS-complex tachycardia depends on the stability of the patient and the specific diagnosis. If the patient is unstable, immediate cardioversion should be performed 1. For stable patients, the management includes obtaining a 12-lead ECG to evaluate the rhythm and considering the need for expert consultation. The QRS width criteria can help differentiate between VT and SVT with aberrancy, but are not helpful in differentiating VT from SVT with AV conduction over an accessory pathway 1.
Management of Wide QRS-Complex Tachycardia
- Immediate cardioversion for unstable patients
- Obtain a 12-lead ECG to evaluate the rhythm for stable patients
- Consider expert consultation for stable patients
- Pharmacologic termination using IV procainamide, sotalol, or amiodarone for stable wide QRS-complex tachycardia 1
From the Research
Causes of Wide QRS Complex
- A wide QRS complex can be caused by:
- Ventricular tachycardia 2
- Supraventricular tachycardia with bundle branch block, which may be preexisting or due to aberrant conduction 2, 3
- Supraventricular tachycardia with conduction of impulses to the ventricles over an accessory pathway (preexcited tachycardia) 2, 4
- Fixed bundle branch block, functional (intermittent) bundle branch block, preexcitation, or toxic/metabolic causes 3
- Aberrant conduction can be caused by long-short aberrancy (usually physiologic) or acceleration/deceleration dependent aberrancy (usually pathologic) 3
Diagnostic Considerations
- The origin of a wide QRS complex tachycardia can be reliably identified using a "holistic" approach, taking into account all available items 2
- Electrocardiographic signs, such as atrio-ventricular dissociation, second degree ventriculo-atrial block, fusion and/or capture beats, and concordant precordial pattern, can aid in diagnosis 2
- Analysis of QRS configuration in leads V1 and V6 is a key factor in distinguishing the origin of wide QRS tachycardia 2
- A new algorithm based on analysis of lead aVR only can also help diagnose ventricular tachycardia 2
Specific Conditions
- Preexcited tachycardia can be ruled out in the presence of negative precordial concordance or deep q waves in a precordial lead other than V1 2
- A QRS morphology not consistent with any of the typical patterns observed in the various locations of the accessory pathways can also rule out preexcited tachycardia 2
- Alternating bundle branch block aberration can occur in patients with atrial bigeminy 5
- Wide QRS complex tachycardia with multiple distinct left bundle branch block morphologies can occur in patients with sinus rhythm and left bundle branch block 4