A 70-year-old male with a history of two previous myocardial infarctions is admitted to the hospital with severe chest pain. ECG reveals a new myocardial infarction and ventricular arrhythmia. Coronary angiography reveals that the right coronary artery is blocked just distal to the origin of the right marginal artery in a right coronary dominant circulation. Which of the following structures would most likely be affected after such a blockade?

The atrioventricular (AV) node is most commonly supplied by a branch of the right coronary artery. This branch arises at the crux of the heart (the point of junction of all four cardiac chambers posteriorly); this is the location of the occlusion. The right atrium is supplied by the right coronary artery, which additionally supplies the sinoatrial node. The left marginal artery supplies the lateral wall of the left ventricle. The anterior portion of the interventricular septum is supplied by the anterior interventricular artery.