Cardiac Medicine Certification (CMC) Practice Exam

What finding is indicative of an occlusion in the circumflex artery or a branch from the LAD artery?

1. ST elevation in II, III, aVF

2. ST elevations in leads I and aVL

3. ST elevation in V1

4. Reciprocal ST elevation in lead aVR

The correct answer is: ST elevations in leads I and aVL

The finding indicative of an occlusion in the circumflex artery or a branch from the left anterior descending (LAD) artery is the presence of ST elevations in leads I and aVL. These leads correspond to the lateral wall of the heart, which is supplied by the circumflex artery. When there is an occlusion in this artery or a branch of the LAD that supplies the lateral region, it typically results in ST segment elevation that is noted in these specific leads due to the ischemic changes affecting that area of the myocardium. In contrast, other leads that would show ST elevation correspond to different regions of the heart. For instance, ST elevation in leads II, III, and aVF suggests an inferior wall myocardial infarction, which is typically related to the right coronary artery. ST elevation in V1 may indicate an anteroseptal involvement primarily associated with LAD artery occlusion but not specifically tied to the circumflex artery. Reciprocal ST elevation in lead aVR typically suggests ongoing ischemia or infarction, but it does not provide a direct indication of an occlusion in the circumflex artery or LAD branches. Thus, the specific change in leads I and aVL aligns with obstruction in the vessels supplying the lateral wall, making