What is the hallmark of a wide-complex tachycardia that suggests ventricular tachycardia?

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Multiple Choice

What is the hallmark of a wide-complex tachycardia that suggests ventricular tachycardia?

Recognizing ventricular tachycardia among wide-complex tachycardias comes down to seeing that the ventricle is pacing independently of the atria. The most telling clue is a wide QRS complex, typically lasting more than 120 ms, which points to a ventricular origin or severe aberrancy. But what solidifies VT is the pattern of atrioventricular dissociation: P waves and QRS complexes do not march together, so the atrial rate runs independently from the ventricular rate. Another strong sign is the appearance of capture or fusion beats. A capture beat is a normal-looking QRS that briefly occurs during VT when an atrial impulse happens to conduct to the ventricle, and a fusion beat is a hybrid QRS morphology that results from simultaneous activation by both the ventricular rhythm and the supraventricular impulse. These findings—especially AV dissociation with capture or fusion beats—are classic indicators that the tachycardia is ventricular in origin. The absence of discrete P waves during the tachycardia further supports dissociation, reinforcing the VT diagnosis. In contrast, a prolonged PR interval with a normal QRS points to first-degree AV block rather than VT. A narrow QRS tachycardia with a regular rhythm suggests a supraventricular mechanism with possible aberrancy, not VT. P waves that clearly precede each QRS with intact AV conduction describes normal sinus or AV nodal conduction, not VT.

Recognizing ventricular tachycardia among wide-complex tachycardias comes down to seeing that the ventricle is pacing independently of the atria. The most telling clue is a wide QRS complex, typically lasting more than 120 ms, which points to a ventricular origin or severe aberrancy. But what solidifies VT is the pattern of atrioventricular dissociation: P waves and QRS complexes do not march together, so the atrial rate runs independently from the ventricular rate.

Another strong sign is the appearance of capture or fusion beats. A capture beat is a normal-looking QRS that briefly occurs during VT when an atrial impulse happens to conduct to the ventricle, and a fusion beat is a hybrid QRS morphology that results from simultaneous activation by both the ventricular rhythm and the supraventricular impulse. These findings—especially AV dissociation with capture or fusion beats—are classic indicators that the tachycardia is ventricular in origin. The absence of discrete P waves during the tachycardia further supports dissociation, reinforcing the VT diagnosis.

In contrast, a prolonged PR interval with a normal QRS points to first-degree AV block rather than VT. A narrow QRS tachycardia with a regular rhythm suggests a supraventricular mechanism with possible aberrancy, not VT. P waves that clearly precede each QRS with intact AV conduction describes normal sinus or AV nodal conduction, not VT.

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