CVS Practice Test 2026 - Free CVS Practice Questions and Study Guide

The QT interval on an electrocardiogram (ECG) represents the total time for both ventricular depolarization and ventricular repolarization. This interval encompasses the electrical activities associated with the contraction of the ventricles and their subsequent recovery, making it an important indicator in assessing the heart's rhythm and function.

The QT interval does not signify ventricular systole exclusively, as ventricular systole refers only to the period of contraction when the ventricles pump blood. It is crucial to recognize that the QT interval includes the depolarization phase, which is when the ventricles contract, and the repolarization phase, during which the heart muscles recover to their resting state after contraction.

While the selection regarding Phase 2 of the ventricular action potential holds relevance, this phase specifically indicates the plateau phase of the action potential that corresponds largely to the initial part of ventricular contraction and does not encompass the entire duration signified by the QT interval. Therefore, the action potential represented by the QT interval is better correlated with the complete cycle of depolarization and repolarization rather than just the systolic phase alone.

Understanding that the QT interval reflects the entire process of ventricular electrical activity enhances the grasp of cardiac physiology and the clinical implications of the QT interval in assessing abnormalities