Which lead is considered best for detecting right axis deviation?

Which lead is considered best for detecting right axis deviation?

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

Answer: (B)

Right axis deviation occurs when the electrical activity of the heart is directed away from the normal axis, typically indicating some underlying pathology, such as right ventricular hypertrophy or other conditions affecting the right side of the heart. The best lead for detecting right axis deviation is Lead I because it is positioned horizontally, allowing for the greatest sensitivity in assessing the frontal plane of the heart's electrical activity.

Lead I measures the difference in electrical potential between the left arm and right arm, providing insights into the horizontal electrical activity and axis of the heart. In the case of right axis deviation, the QRS complex in Lead I will typically show a negative deflection or diminished positivity. This pattern is a clear indicator of a rightward shift in the heart's electrical axis, as a normal heart axis would show a more positive QRS in Lead I.

Other leads, while useful, do not provide the same level of clarity for diagnosing right axis deviation. For instance, Lead II measures electrical activity in a different plane and may not reflect the same changes accurately. Understanding the characteristics of these leads and their orientation is crucial for effective EKG interpretation.