What does a larger initial component of the diphasic P wave in lead V1 typically indicate?

What does a larger initial component of the diphasic P wave in lead V1 typically indicate?

• A. Left atrial enlargement
• B. Right atrial enlargement
• C. Ventricular hypertrophy
• D. Myocardial infarction

Answer: (B)

A larger initial component of the diphasic P wave in lead V1 typically indicates right atrial enlargement. In lead V1, the P wave reflects the electrical activity of the atria as they depolarize. When the right atrium becomes enlarged, it can lead to a greater amplitude in the initial upward component of the P wave due to increased electrical activity associated with the larger mass of the atrial tissue.

This correlation is particularly significant in lead V1 because it is positioned near the right atrium and is sensitive to changes in its size and conduction. In contrast, other cardiac conditions like left atrial enlargement, ventricular hypertrophy, or myocardial infarction may present with different EKG features that do not specifically highlight changes in the right atrium's electrical activity as clearly as right atrial enlargement does. Therefore, the presence of a larger initial component in the diphasic P wave is a key indicator of right atrial enlargement.