In order to obtain an 18-lead EKG, which lead is moved to the posterior 3rd rib?

To perform an 18-lead EKG, one of the standard precordial leads is indeed repositioned to capture additional views of the heart, particularly focusing on areas that may not be effectively assessed with a standard 12-lead EKG. In this case, V4 is moved to the posterior region at the 3rd rib position, a location anticipated to provide essential data about the posterior aspect of the heart.

Positioning V4 at the posterior 3rd rib allows for better visualization of posterior wall myocardial ischemia, which is crucial in certain clinical scenarios. The standard V4 lead is typically located in the 5th intercostal space at the midclavicular line, but repositioning it helps clinicians evaluate regions that might show abnormalities during ischemic events.

By using this approach, the EKG interpretation becomes more comprehensive, allowing for a better understanding of cardiac function and potential pathologies affecting the posterior heart, thereby enhancing the diagnostic capability of the EKG.