A 55 year old male presented with angina. Coronary angiography revealed a block in the right coronary aery. The condition is likely to cause a decrease in blood supply through all of the following blood vessels except
**Core Concept**
The right coronary artery (RCA) supplies blood to the right ventricle, the right atrium, and the sinoatrial (SA) node. A block in the RCA can lead to a decrease in blood supply to these areas, potentially resulting in ischemia or infarction.
**Why the Correct Answer is Right**
The RCA gives off several branches, including the posterior descending artery (PDA), which supplies blood to the posterior aspect of the left ventricle, and the acute marginal artery, which supplies blood to the lateral aspect of the right ventricle. A block in the RCA can lead to a decrease in blood supply through these branches, resulting in ischemia or infarction in the corresponding areas.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely to be a distractor, as the RCA does not directly supply blood to the left main coronary artery. However, a block in the RCA may lead to a decrease in blood supply through the left circumflex artery (LCx) in some individuals, particularly those with a dominant RCA.
**Option B:** The RCA gives off the posterior descending artery (PDA), which supplies blood to the posterior aspect of the left ventricle. A block in the RCA can lead to a decrease in blood supply through the PDA.
**Option C:** The RCA gives off the acute marginal artery, which supplies blood to the lateral aspect of the right ventricle. A block in the RCA can lead to a decrease in blood supply through the acute marginal artery.
**Clinical Pearl / High-Yield Fact**
The RCA is a dominant coronary artery in approximately 80% of individuals, supplying blood to the posterior descending artery and the acute marginal artery. In these individuals, a block in the RCA can lead to a decrease in blood supply to the posterior aspect of the left ventricle and the lateral aspect of the right ventricle.
**Correct Answer:** D.