Cardiac Medicine Certification (CMC) Practice Exam

Which artery occlusion may lead to both posterior wall and inferior wall myocardial infarctions?

1. Left anterior descending artery

2. Right coronary artery

3. Circumflex artery

4. Posterior descending artery

The correct answer is: Right coronary artery

The right coronary artery is primarily responsible for supplying the inferior wall of the heart and, in many individuals, provides collateral circulation to the posterior wall as well. An occlusion in the right coronary artery can disrupt blood flow to both the inferior and posterior aspects of the left ventricle, potentially leading to myocardial infarctions in those regions. In a typical right-dominant coronary circulation, the right coronary artery supplies the inferior wall through its branches, including the posterior descending artery, which specifically perfuses the inferior portion of the left ventricle and the interventricular septum. Therefore, when the right coronary artery is occluded, it directly affects these myocardial territories, resulting in infarction. The left anterior descending artery is chiefly focused on the anterior wall and part of the interventricular septum, while the circumflex artery mainly supplies the lateral wall and posterior wall in a left-dominant system. The posterior descending artery given in the options is a branch of the right coronary artery but does not itself cause both types of infarctions without the main vessel being occluded. Thus, the right coronary artery's role in supplying blood to the inferior wall and collateral support for the posterior wall establishes its connection to both myocardial infarctions.