What does it indicate if the QRS is negative in lead I and positive in lead AVF?

What does it indicate if the QRS is negative in lead I and positive in lead AVF?

• A. Left axis deviation
• B. Normal axis
• C. Right axis deviation (RAD)
• D. No significant finding

Answer: (C)

When the QRS complex is negative in lead I and positive in lead AVF, it reflects a specific pattern in the axis of the heart's electrical activity. This specific combination of leads is indicative of right axis deviation (RAD).

In the context of the heart's electrical conduction system, lead I is oriented horizontally and looks at the heart from the left side, while lead AVF looks at the heart from the feet. A negative QRS in lead I indicates that the electrical activity of the heart is directed away from the left side of the body, which is characteristic of an axis shift that points more towards the right side. Simultaneously, a positive QRS in lead AVF suggests that the electrical activity is directed downward towards the feet, which is consistent with RAD.

This relationship means that the overall electrical activity of the heart reflects a shift that occurs commonly in conditions that affect the right ventricle. Therefore, the combination of a negative QRS in lead I and a positive QRS in lead AVF distinctly points to right axis deviation.