WBR0460
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Anatomy |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 56 year old male patient presents to the emergency department with chest pain and shortness of breath. Appropriate work-up is rapidly initiated. Patient’s blood work-up reveals elevated levels of Troponin. His electrocardiogram (ECG) shows ST-segment elevation in more than one lead. The diagnosis of ST-elevation myocardial infarction (STEMI) is made. Cardiac catheterization shows occlusion of the right coronary artery (RCA). Which of the following components of the heart is most likely to be affected as a result of the patient’s STEMI?]] |
| Answer A | AnswerA::Anterior interventricular septum |
| Answer A Explanation | AnswerAExp::Blood supply to the anterior interventricular septum is most commonly from the LAD |
| Answer B | AnswerB::Left atrium |
| Answer B Explanation | AnswerBExp::Blood supply to the left atrium is most commonly from the left main coronary artery. |
| Answer C | AnswerC::Anterolateral papillary muscle |
| Answer C Explanation | AnswerCExp::The anterior papillary muscle most commonly receives dual blood supply from the LAD and the LCx. |
| Answer D | AnswerD::Sinoatrial (SA) node |
| Answer D Explanation | AnswerDExp::Blood supply to the SA node is most commonly from the RCA. |
| Answer E | AnswerE::Apex |
| Answer E Explanation | AnswerEExp::The apex of the heart receives dual supply from the LAD and the PDA. The LDA provides most of the blood supply to the apex. |
| Right Answer | RightAnswer::D |
| Explanation | [[Explanation::The cardiac circulation is characterized by 2 main arteries that contain several branches as they descend from their sinuses at the base of the aorta. They are the left main artery and the right coronary artery (RCA). The left main artery is further divided into the left anterior descending (LAD) artery, also called the “widow maker” because it is the most severe and the most common artery to be occluded in myocardial infarction and subsequent death, and the Left circumflex (LCx) artery. The LCx gives rise to the posterior descending artery (PDA) in approximately 35% of the case.
On the other hand, the RCA gives rise to the PDA in more than 65% of the cases. The RCA supplies the SA node. Educational Objective:
The right coronary artery (RCA) is the most common arterial supply to the sinoatrial (SA) node. |
| Approved | Approved::No |
| Keyword | WBRKeyword::coronary, WBRKeyword::artery, WBRKeyword::sinoatrial, WBRKeyword::node, WBRKeyword::sinoatrial node, WBRKeyword::SA, WBRKeyword::right, WBRKeyword::blood, WBRKeyword::supply |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |