A patient presents with a wide QRS complex tachycardia, no identifiable P waves, and tachycardia; the patient is 72 with history of heart disease and collapsed. What is the most likely diagnosis?

A patient presents with a wide QRS complex tachycardia, no identifiable P waves, and tachycardia; the patient is 72 with history of heart disease and collapsed. What is the most likely diagnosis?

• A. Atrial fibrillation with rapid ventricular response
• B. Ventricular tachycardia
• C. Ventricular fibrillation
• D. Sinus tachycardia

Answer: (B)

A wide QRS complex tachycardia with no identifiable P waves points to a ventricular origin of the rhythm. When the ventricles drive the rhythm, the activation spreads abnormally through ventricular tissue, producing broad (wide) QRS complexes. The atria may beat independently, so P waves are often hidden or dissociated, and the rhythm tends to be rapid and regular—classic for ventricular tachycardia. In contrast, true ventricular fibrillation shows no organized QRS complexes at all—just chaotic, irregular activity and is associated with immediate collapse and no pulse. Sinus tachycardia would have visible P waves with a normal, narrow QRS, and atrial fibrillation would have absent identifiable P waves but typically a more irregular rhythm with often normal-width QRS. Given the patient’s age, history of heart disease, and collapse, ventricular tachycardia is the most likely diagnosis.

A wide QRS complex tachycardia with no identifiable P waves points to a ventricular origin of the rhythm. When the ventricles drive the rhythm, the activation spreads abnormally through ventricular tissue, producing broad (wide) QRS complexes. The atria may beat independently, so P waves are often hidden or dissociated, and the rhythm tends to be rapid and regular—classic for ventricular tachycardia.

In contrast, true ventricular fibrillation shows no organized QRS complexes at all—just chaotic, irregular activity and is associated with immediate collapse and no pulse. Sinus tachycardia would have visible P waves with a normal, narrow QRS, and atrial fibrillation would have absent identifiable P waves but typically a more irregular rhythm with often normal-width QRS. Given the patient’s age, history of heart disease, and collapse, ventricular tachycardia is the most likely diagnosis.