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

Which type of ischemia is likely present in a patient with ST Elevations in leads V1 and V2?

1. Anterolateral transmural ischemia

2. Inferolateral subendocardial ischemia

3. Anteroseptal transmural ischemia

4. Inferoposterior subendocardial ischemia

The correct answer is: Anteroseptal transmural ischemia

The presence of ST elevations in leads V1 and V2 is indicative of an ischemic event affecting the anterior part of the heart. In particular, these leads correspond to the anterior and septal walls of the left ventricle, which are supplied by the left anterior descending artery (LAD). Transmural ischemia occurs when there is a complete occlusion of a coronary artery, leading to full thickness damage of the myocardial wall. The term "anteroseptal" specifically refers to ischemia that affects both the anterior and septal walls of the left ventricle, which aligns perfectly with the ST elevation observed in V1 and V2. Given this understanding, anteroseptal transmural ischemia is a direct consequence of the type of ST elevation seen in these leads, supporting the fact that there is significant damage referred to the supplied regions with full thickness myocardial injury. Other types of ischemia listed, such as inferolateral or inferoposterior ischemia, would not show ST elevations in V1 and V2 as they primarily affect different areas of the heart. Thus, recognizing the leads corresponding to various ischemic changes is crucial in correlating the electrocardiographic findings with the underlying pathoph