What finding during tachycardia would most strongly suggest ventricular tachycardia rather than SVT with aberrancy?

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Multiple Choice

What finding during tachycardia would most strongly suggest ventricular tachycardia rather than SVT with aberrancy?

The key idea is that ventricular tachycardia (VT) can run independently of the atria, so the atrial and ventricular activities are dissociated during the tachycardia. When you see AV dissociation with capture or fusion beats, it means the ventricles are being driven by a ventricular focus rather than the atrial impulse, and you may also observe occasional P waves that do not govern the QRS or, in rare cases, a normal-looking QRS that occurs with a competing conduction event (capture) or a blended QRS morphology (fusion). This combination—AV dissociation plus capture or fusion beats—is highly specific for VT. Regular P waves preceding every QRS suggests the atria are driving the rhythm with intact AV conduction, which fits SVT with aberrancy rather than VT. A prolonged PR interval is nonspecific and can occur in many rhythms. Delta waves point to pre-excitation (WPW) and don’t by themselves distinguish VT from SVT during tachycardia. So the presence of AV dissociation with capture or fusion beats best indicates VT.

The key idea is that ventricular tachycardia (VT) can run independently of the atria, so the atrial and ventricular activities are dissociated during the tachycardia. When you see AV dissociation with capture or fusion beats, it means the ventricles are being driven by a ventricular focus rather than the atrial impulse, and you may also observe occasional P waves that do not govern the QRS or, in rare cases, a normal-looking QRS that occurs with a competing conduction event (capture) or a blended QRS morphology (fusion). This combination—AV dissociation plus capture or fusion beats—is highly specific for VT.

Regular P waves preceding every QRS suggests the atria are driving the rhythm with intact AV conduction, which fits SVT with aberrancy rather than VT. A prolonged PR interval is nonspecific and can occur in many rhythms. Delta waves point to pre-excitation (WPW) and don’t by themselves distinguish VT from SVT during tachycardia. So the presence of AV dissociation with capture or fusion beats best indicates VT.

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