What does the QRS for tachycardia (excluding ventricular tachycardia and ventricular fibrillation) look like?

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Multiple Choice

What does the QRS for tachycardia (excluding ventricular tachycardia and ventricular fibrillation) look like?

When a tachycardia originates above the ventricles and the impulse travels through the normal His-Purkinje system, the ventricles depolarize quickly and in a coordinated fashion. This produces a narrow QRS complex, typically under 120 ms. That’s why most non-ventricular tachycardias have a narrow QRS. If the tachycardia were ventricular or if there is aberrant conduction, the QRS would widen due to slower, less synchronized ventricular activation. Since ventricular tachycardia and ventricular fibrillation are excluded, the expected QRS appearance is narrow.

When a tachycardia originates above the ventricles and the impulse travels through the normal His-Purkinje system, the ventricles depolarize quickly and in a coordinated fashion. This produces a narrow QRS complex, typically under 120 ms. That’s why most non-ventricular tachycardias have a narrow QRS. If the tachycardia were ventricular or if there is aberrant conduction, the QRS would widen due to slower, less synchronized ventricular activation. Since ventricular tachycardia and ventricular fibrillation are excluded, the expected QRS appearance is narrow.

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