In which lead is the QRS typically negative?

In which lead is the QRS typically negative?

• A. Lead I
• B. Lead II
• C. Lead V2
• D. Lead AVF

Answer: (C)

In standard electrocardiography, the QRS complex represents depolarization of the ventricles, and its deflection can vary depending on the lead being examined. The QRS complex is typically negative in Lead V2, which is positioned in the precordial area over the right ventricle and the septum. This lead often reflects a strong electrical vector directed away from it, particularly in individuals with a typical leftward heart axis.

When examining the orientation of heart depolarization, if the majority of electrical activity is moving away from the lead's position, the QRS complex will display a negative deflection. In V2, due to its anatomical placement, it often records negative or predominantly negative QRS complexes, especially in cases of certain conduction abnormalities or if the heart's electrical axis is directed inappropriately.

In contrast, leads like I, II, and AVF typically exhibit positive QRS complexes as they are oriented more favorably toward the general direction of ventricular depolarization in the normal physiological state. This is key in identifying findings in an EKG, especially when assessing for abnormalities in the heart's electrical conduction system.