USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which heart defect is often seen in Turner's syndrome and manifests as a nonstenotic bicuspid aortic valve with an early systolic, high-frequency click over the right second intercostal space?

1. Atrial septal defect

2. Pulmonary valve stenosis

3. Mitral valve prolapse

4. Bicuspid aortic valve

The correct answer is: Bicuspid aortic valve

The correct answer is the defect that is commonly found in individuals with Turner’s syndrome and is characterized by a bicuspid aortic valve. A nonstenotic bicuspid aortic valve is a valve that has two cusps instead of the normal three, which can lead to various complications over time, such as aortic regurgitation or premature aortic stenosis, though in this case, it is nonstenotic. The early systolic click is a characteristic auscultatory finding associated with the condition that occurs due to the abnormal valve structure. It is distinctly heard in the right second intercostal space, aligning with the position of the aortic valve. This feature solidifies the recognition of a bicuspid aortic valve as a key element associated with this heart defect. In patients with Turner’s syndrome, congenital anomalies, especially of the cardiovascular system, are prominent, and the prevalence of a bicuspid aortic valve is notably higher in this population. This makes it a significant finding when evaluating patients with Turner's syndrome. The other conditions mentioned, like atrial septal defect and pulmonary valve stenosis, while they each have their own clinical associations, do not have the specific link to Turner’s syndrome nor the defining feature