If the QRS complexes in leads V1 and V2 become isoelectric, what does it indicate?

If the QRS complexes in leads V1 and V2 become isoelectric, what does it indicate?

• A. Leftward rotation in the horizontal plane
• B. Rightward rotation in the horizontal plane
• C. No significant rotation
• D. Left atrial enlargement

Answer: (B)

When the QRS complexes in leads V1 and V2 become isoelectric, this indicates rightward rotation in the horizontal plane. In the context of the EKG, a isoelectric QRS complex means that there is equal positive and negative deflection, suggesting that the electrical activity of the heart, as viewed from the vantage point of those leads, is balanced front-to-back.

Rightward rotation occurs when the heart's electrical axis shifts toward the right side of the body, and this can be reflected in the lead placement. In essence, when the right side of the heart is producing stronger electrical forces or the left side is less active, this can lead to the observed isoelectric pattern in those precordial leads.

Understanding the positioning of the heart and how the electrical activity travels through it is essential for interpreting these changes correctly. In terms of clinical implications, recognizing rightward rotation can assist in diagnosing various conditions, such as right ventricular hypertrophy or other structural changes in the heart.