When performing right-sided electrocardiography, which lead should you place at the fifth intercostal space in the right midaxillary line?

• A. RV4
• B. V5
• C. RV6
• D. RV1

Answer: (C)

Placing right-sided precordial leads involves mirroring the left-sided positions on the right chest to evaluate the right ventricle. The fifth intercostal space at the right midaxillary line is the mirror image of the left fifth intercostal space at the left midaxillary line where V6 sits, so the corresponding right-sided lead is RV6. This position targets the lateral wall of the right ventricle, making it the best choice for detecting right ventricular involvement, which is particularly important when an inferior myocardial infarction is suspected. Other right-sided positions don’t align with the lateral RV wall as directly, so they’re less informative for RV assessment.