WBR0043

Author	PageAuthor::Gonzalo Romero
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Embryology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 17 yo male patient presents to the clinic with his father complaining of severe headache and nosebleeds for the last six months. He has been noticing that his feet get very cold at night for which he has been using two pairs of thick socks. At school he gets cramps in his legs and gets out of breath when running so he has to stop for a couple of minutes. He denies taking any drugs. His school grades are stable overtime and he has a girlfriend. He denies intercourse with her, as well as fever. On physical exam his vitals are RR:15 BP: 170/95 on the upper extremities and 100/70 in the lower extremities. Neck supple no LAD. Clear breath sounds bilaterally and 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 finding on CXR?]]
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 PA radiograph, and in the substernal region on lateral radiographs. These lines are present when interstitial edema is present, therefore not being specific for aortic coarctation.]]
Answer B	AnswerB::Ribs notching
Answer B Explanation	[[AnswerBExp::The following are radiologic findings in aortic coarctation: Irregularities or notching of the inferior margins of the posterior ribs results from collateral flow through dilated and pulsatile intercostal arteries. These collateral appear after 6 years of age if the coarctation is significant. An inverted "3" sign of the barium-filled esophagus or a "3" sign on a highly penetrated chest radiograph may be visualized. Post-stenotic dilation of the aorta results in a classic reverse 3 sign on x-ray. The characteristic bulging of the sign is caused by dilatation of the aorta due to an indrawing of the aortic wall at the site of cervical rib obstruction, with consequent post-stenotic dilation. This physiology results in the reversed 3 image for which the sign is named. Signs of congestive heart failure Cardiomegaly, pulmonary edema,and prominent pulmonary vasculature are evident. The signs of CHF are not specific to this condition. Aortic coarctation]]
Answer C	AnswerC::Cardiomegaly
Answer C Explanation	[[AnswerCExp::Cardiomegaly causes There are many causes of cardiomegaly, including medications, genetic conditions, endocrine conditions, infectious processes, toxins and iatrogenic causes. Therefore is not a specific radiologic finding.]]
Answer D	AnswerD::Pleural effusion
Answer D Explanation	[[AnswerDExp::Pleural effusion The most common causes of transudative pleural effusions in the United States are left ventricular failure, pulmonary embolism, and cirrhosis (causing hepatic hydrothorax), while 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. Therefore pleural effusion is not specific for aortic coarctation.]]
Answer E	AnswerE::Patchy alveolar infiltrates
Answer E Explanation	[[AnswerEExp::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 not being 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. It may be associated with a bicuspid aortic valve. It is more common in males than females with a ratio of 2:1. Clinically the patient has 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 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. Aortic coarctation Educational Objective: Aortic coarctation can produce specific signs on CKR such as: irregularities or notching of the inferior margins of the posterior ribs, an inverted "3" sign of the barium-filled esophagus Educational Objective: References: ]]
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