Wide complex tachycardia overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Wide complex tachycardia is a cardiac rhythm of more than 100 beats per minute with a QRS duration of 120 milliseconds or more. It is critical to differentiate whether the wide complex tachycardia is of ventricular origin and is ventricular tachycardia (VT), or if it is of supraventricular origin with aberrant conduction (SVT with aberrancy). Rapid differentiation between these two causes of wide complex tachycardia is absolutely critical because the treatment options are quite different for VT versus SVT with aberrancy.
Causes
A wide complex tachycardia is either of ventricular origin (ventricular tachycardia or VT), or is of supraventricular origin with aberrant conduction (SVT with aberrancy) such as occurs with conduction down a bypass tract.
Differential Diagnosis of Wide Complex Tachycardia: Distinguishing VT from SVT
Differentiating between VT and SVT as the cause of wide complex tachycardia is absolutely critical because the treatment options are quite different for VT versus SVT with aberrancy.
The diagnosis of VT is more likely if:
- There is a history of myocardial infarction or structural heart disease
- The electrical axis is -90 to -180 degrees (a “northwest” or “superior” axis)
- The QRS is > 140 msec
- There is AV dissociation
- There are positive or negative QRS complexes in all the precordial leads
- The morphology of the QRS complexes resembles that of a previous premature ventricular contraction (PVC).
For more detailed information regarding how to differentiate VT from SVT please view the differential diagnosis page or click here.
Epidemiology and Demographics
The underlying cause of wide complex tachycardia tends to be ventricular tachycardia (VT) in older patients and supraventricular tachycardia (SVT) with aberrancy in younger patients.
Risk Factors
Wide complex tachycardia will be due to VT in 80% of cases if there is a history of myocardial infarction (MI). Only 7% of patients with SVT with aberrancy will have had a prior myocardial infarction (MI). Wide complex tachycardia will be due to VT in 98% of cases if there's a history of structural heart disease.
Electrocardiogram
Laboratory Studies
Electroyte abnormalities such as hypokalemia (which can be associated with ventricular tachycardia), hypomagnesemia (which can lead to Torsade de Pointes) and hyperkalemia (which can cause a sinusoidal rhythm) should be ruled out.