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?

**Core Concept**
The question tests understanding of coronary artery anatomy and its relation to myocardial infarction. The **right coronary artery (RCA)** supplies blood to the right ventricle, right atrium, and in a **right dominant circulation**, it also supplies the posterior descending artery (PDA) and thus the inferior part of the left ventricle.

**Why the Correct Answer is Right**
Given the blockade is just distal to the origin of the **right marginal artery**, structures supplied by the RCA distal to this point would be affected. This includes the **inferior wall of the left ventricle** and the **posterior part of the right ventricle**, as the RCA wraps around the heart to supply these areas. The **AV node** and the **SA node** are also typically supplied by the RCA, but the question focuses on the area affected by the blockade in relation to the myocardial infarction and ventricular arrhythmia.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it's not directly related to the area typically supplied by the RCA distal to the right marginal artery.
**Option B:** Incorrect as it's not the most directly affected structure given the described anatomy.
**Option C:** Incorrect because, although the RCA does supply parts of the right ventricle, the description points more specifically to areas beyond the right marginal artery's origin.

**Clinical Pearl / High-Yield Fact**
In a **right dominant circulation**, the RCA gives off the **posterior descending artery (PDA)**, which is crucial for supplying the inferior part of the left ventricle. Blockage in this area can lead to significant myocardial infarction and potentially life-threatening arrhythmias.

**Correct Answer:** D. Inferior wall of the left ventricle.

✓ Correct Answer: C. AV node