USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

What is the potential consequence of ST Elevations in V5, V6, I, and aVL?

1. Posterior wall myocardial infarction

2. Interventricular septum ischemia

3. Right ventricular ischemia

4. Anterolateral wall ischemia

The correct answer is: Interventricular septum ischemia

When interpreting ST elevations in V5, V6, I, and aVL, it is essential to recognize the anatomical territories these leads represent. The leads V5 and V6 are positioned over the left lateral wall of the heart, while leads I and aVL also capture electrical activity in this region. ST elevations in these leads typically indicate an acute phase of ischemia affecting the anterolateral wall of the heart due to obstruction in blood flow, often caused by a left coronary artery occlusion. The correct answer aligns with the common observations associated with ST elevations in these leads, indicating a myocardial infarction primarily involving the anterolateral wall. This can occur due to occlusion of specific branches of the left coronary artery, such as the left anterior descending artery or the circumflex artery. Although septum ischemia can lead to significant changes on an ECG, the elevation in these leads is more directly indicative of anterior and lateral wall involvement. Understanding the locations of the leads and their corresponding myocardial territories can help in identifying the type of myocardial infarction or ischemia present and guide appropriate management strategies for the affected patient. In this context, the mention of interventricular septum ischemia does not typically correlate with the ST elevation pattern observed in