WBR0043
| Author | PageAuthor::Gonzalo Romero (Reviewed by Will Gibson) |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Embryology |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 17-year-old male is brought to his pediatrician by his father for severe headache and nosebleeds over the last six months. He complains that his feet become very cold at night for which he has been wearing two pairs of thick socks. At school he gets occasional cramps in his legs and is easily winded when running in gym class. He denies using any drugs or drinking alcohol. His grades are stable and he has a girlfriend, but is not sexually active. On physical exam his vitals are heart rate of 80 beats/min, respiratory rate of 15/min, blood pressure of 170/95 mm Hg in the upper extremities and 100/70 mm Hg in the lower extremities. He has clear breath sounds bilaterally, but a continuous murmur is heard over the inter-scapular area. A chest x-ray is ordered and is shown below.
 Which of the following is the most specific radiographic finding for the patient's condition?]] |
| Answer A | AnswerA::Kerley B lines |
| Answer A Explanation | [[AnswerAExp::Kerley lines are short parallel lines at the lung periphery. These lines represent distended interlobular septa, which are usually less than 1 cm in length and parallel to one another at right angles to the pleura. They are located peripherally in contact with the pleura, but are generally absent along fissural surfaces. They may be seen in any zone but are most frequently observed at the lung bases at the costophrenic angles on the posterior-anterior radiograph, and in the substernal region on lateral radiographs. These lines are present when interstitial edema is present, and are therefore not specific for aortic coarctation.]] |
| Answer B | AnswerB::Rib notching |
| Answer B Explanation | [[AnswerBExp::The following are radiologic findings in aortic coarctation:
|
| Answer C | AnswerC::Cardiomegaly |
| Answer C Explanation | [[AnswerCExp::There are many causes of cardiomegaly, including medications, genetic conditions, endocrine conditions, infectious processes, toxins and iatrogenic causes. Therefore cardiomegaly is not a specific radiologic finding. In particular, cardiomegaly is not associated with this patient's underlying condition, coarctation of the aorta.]] |
| Answer D | AnswerD::Pleural effusion |
| Answer D Explanation | [[AnswerDExp::The most common causes of transudative pleural effusions in the United States are left ventricular failure, pulmonary embolism, and cirrhosis (causing hepatic hydrothorax). Conversely, the most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism. Pleural effusion therefore, is not a specific finding in general, and furthermore, pleural effusion is not associated with aortic coarctation.]] |
| Answer E | AnswerE::Patchy alveolar infiltrates |
| Answer E Explanation | [[AnswerEExp::Patchy alveolar infiltrates are not associated with coarctation of the aorta. Cardiogenic pulmonary edema can be distinguished from noncardiogenic pulmonary edema by the presence of redistribution of blood flow to the upper lobes (increased blood flow to the higher parts of the lung) and interstitial edema. In contrast, patchy alveolar infiltrates with air bronchograms are more indicative of noncardiogenic edema. Therefore patchy alveolar infiltrates are not specific for aortic coarctation. [[1]]]] |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::This teenager is presenting with symptoms of post-ductal aortic stenosis, which is a localized narrowing or abrupt constriction of the aortic arch after the ligamentum arteriosum. This condition is also referred to as coarctation of the aorta. Aortic coarctation may be associated with a bicuspid aortic valve and it is is more common in males than females with a ratio of 2:1. Clinically, patients often present with headaches, epistaxis, dizziness, syncope, dyspnea, chest pain, cold feet or legs, leg cramps with exercise, differential hypertension, poor growth and decreased exercise performance. There are 3 potential sources of a murmur: multiple arterial collaterals (continuous murmur), an associated bicuspid aortic valve (systolic ejection click) and the coarctation itself, which can be heard over the left infraclavicular area and under the scapula. The chest X ray shows irregular notching of the inferior margins of the posterior ribs resulting from collateral flow through dilated and pulsatile intercostal arteries.
 Educational Objective: Aortic coarctation can produce specific signs on chest x-ray such as: irregularities or notching of the inferior margins of the posterior ribs and an inverted "3" sign of the barium-filled esophagus. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Heart, WBRKeyword::Aorta, WBRKeyword::Vessels, WBRKeyword::Vasculature, WBRKeyword::Coarctation, WBRKeyword::Cardiology, WBRKeyword::Pulmonology, WBRKeyword::Radiology, WBRKeyword::Chest, WBRKeyword::Chest X ray |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
Image [[WBRImage::|]] Caption WBRImageCaption::no-display Position [[WBRImagePlace::|]]