A wide QRS complex is seen in which conditions?

A wide QRS complex is seen in which conditions?

• A. SVT with block in one or more parts of HPS network or propagation of SVT over an AP into ventricle (antegrade conduction)
• B. SVT with narrow QRS without block
• C. VT with aberrancy
• D. Atrial tachycardia with 2:1 conduction

Answer: (A)

A wide QRS complex signals that ventricular activation is not using the normal His-Purkinje system. In a supraventricular tachycardia, this happens when the impulse to the ventricles is conducted abnormally: either there is a block somewhere in the His-Purkinje network, so the ventricles are activated via slower, non-ideal pathways (aberrant conduction), or there is antegrade conduction over an accessory pathway outside the normal conduction system (pre-excitation). Both scenarios cause the ventricles to depolarize in a less synchronized, broader way, producing a wide QRS despite the tachycardia originating above the ventricles. SVT with normal conduction keeps the QRS narrow, while a true ventricular tachycardia also yields a wide QRS but arises from ventricular tissue itself rather than from supraventricular conduction abnormalities. Atrial tachycardia with 2:1 conduction typically maintains normal ventricular activation unless another disturbance is present, so it isn’t the classic cause of a wide QRS here.

A wide QRS complex signals that ventricular activation is not using the normal His-Purkinje system. In a supraventricular tachycardia, this happens when the impulse to the ventricles is conducted abnormally: either there is a block somewhere in the His-Purkinje network, so the ventricles are activated via slower, non-ideal pathways (aberrant conduction), or there is antegrade conduction over an accessory pathway outside the normal conduction system (pre-excitation). Both scenarios cause the ventricles to depolarize in a less synchronized, broader way, producing a wide QRS despite the tachycardia originating above the ventricles. SVT with normal conduction keeps the QRS narrow, while a true ventricular tachycardia also yields a wide QRS but arises from ventricular tissue itself rather than from supraventricular conduction abnormalities. Atrial tachycardia with 2:1 conduction typically maintains normal ventricular activation unless another disturbance is present, so it isn’t the classic cause of a wide QRS here.