Which finding would most strongly suggest a ventricular origin of tachycardia?

Which finding would most strongly suggest a ventricular origin of tachycardia?

• A. Low heart rate
• B. Regular rhythm
• C. Narrow QRS complex
• D. Wide QRS complex

Answer: (D)

The main idea is how the heart’s electrical impulse travels to activate the ventricles. Tachycardias can originate above the ventricles (supraventricular) or in the ventricles themselves. When the rhythm starts in the ventricles, the impulse spreads through the ventricular muscle rather than the fast His-Purkinje system, so ventricular depolarization takes longer and appears as a wide QRS complex on the ECG. This broad, abnormally shaped QRS is the strongest clue that the tachycardia is of ventricular origin. In contrast, tachycardias that originate above the ventricles use the normal conduction pathways, producing a narrower QRS because ventricular activation is rapid and synchronized via the His-Purkinje system. Regular rhythm or a low heart rate aren’t as informative for distinguishing the origin.

The main idea is how the heart’s electrical impulse travels to activate the ventricles. Tachycardias can originate above the ventricles (supraventricular) or in the ventricles themselves. When the rhythm starts in the ventricles, the impulse spreads through the ventricular muscle rather than the fast His-Purkinje system, so ventricular depolarization takes longer and appears as a wide QRS complex on the ECG. This broad, abnormally shaped QRS is the strongest clue that the tachycardia is of ventricular origin.

In contrast, tachycardias that originate above the ventricles use the normal conduction pathways, producing a narrower QRS because ventricular activation is rapid and synchronized via the His-Purkinje system. Regular rhythm or a low heart rate aren’t as informative for distinguishing the origin.