What does the QT interval represent?

What does the QT interval represent?

• A. Atrial Depolarization
• B. Ventricular Depolarization And Repolarization
• C. Ventricular Repolarization Only
• D. AV Nodal Conduction

Answer: (B)

The main idea is that the QT interval tracks the total time the ventricles take to go from activation to recovery. It starts at the beginning of the Q wave (when ventricular depolarization begins) and ends at the end of the T wave (when ventricular repolarization is complete). So it encompasses both the depolarization, driven through the ventricular myocardium, and the subsequent repolarization as the ventricles reset for the next beat. This is why the QT interval reflects ventricular electrical activity as a whole. It would not be simply atrial depolarization (that’s the P wave), nor would it be ventricular depolarization alone (that would stop at the end of the QRS), nor AV nodal conduction (which is shown by the PR interval).

The main idea is that the QT interval tracks the total time the ventricles take to go from activation to recovery. It starts at the beginning of the Q wave (when ventricular depolarization begins) and ends at the end of the T wave (when ventricular repolarization is complete). So it encompasses both the depolarization, driven through the ventricular myocardium, and the subsequent repolarization as the ventricles reset for the next beat.

This is why the QT interval reflects ventricular electrical activity as a whole. It would not be simply atrial depolarization (that’s the P wave), nor would it be ventricular depolarization alone (that would stop at the end of the QRS), nor AV nodal conduction (which is shown by the PR interval).