USMLE题库Cardiology(一)11-20.pptx

Cardiology 1 题库 Q 11 Many congenital heart diseases result in an anomalous connection between cardiac chambers. Which of the following findings is considered a variant of normal in an adult patient? A.Endocardial cushion defect B. Persistent truncus arteriosus C.Fenestrae in membranous ventricular septum D.Patent ductus arteriosus E.Patent foramen ovale A 11 Correct answer: E The foramen ovale is patent in 20-30% of normal adults. In most individuals, it remains functionally closed because the left atrial pressure is greater than the right atrial pressure. However, any condition that raises the right atrial pressure above the left atrial pressure can produce a right-to-left shunt across a patent foramen ovale. Hypoxemia and paradoxical embolization may result. A patent foramen ovale should be suspected in any patient who has evidence of deep venous thrombosis of the extremities and has developed a stroke. (Choice A) An endocardial cushion defects the result of failure of complete fusion of the endocardial cushions in the atrioventricular canal during embryonic development. The result is usually a persistent atrioventricular (AV) canal, combined with a continuous lower atrial and upper ventricular septal defect. Moreover, the atrial and ventricular components of the septal defect are separated by abnormal AV valves. Endocardial cushion defects are commonly associated with Down syndrome. (Choice B) Persistent truncus arteriosus accounts for less than 1% of congenital heart defects. It results from incomplete embryonic development of the aorticopulmonary septum, resulting a single great vessel leaving the heart. The aorta, pulmonary artery, and coronary vessels originate from an ascending portion of this solitary vessel. In patients with persistent truncus arteriosus, there is always an associated ventricular septal defect. This defect causes cyanosis, and, if not corrected, results in death due to congestive heart failure within the first year of life. Obviously, t