A 3-week-old male infant with Down's syndrome is brought by his parents to your office due to feeding difficulties. According to the mother, the infant becomes short of breath and his face turns blue during feeding, and when he cries. On chest auscultation, there is a harsh holosystolic murmur heard best over the lower left sternal border. There are no rales or wheezing over the lung fields.
Which of the following is the most useful test for diagnostic evaluation?

Question

A 3-week-old male infant with Down's syndrome is brought by his parents to your office due to feeding difficulties.  According to the mother, the infant becomes short of breath and his face turns blue during feeding, and when he cries.  On chest auscultation, there is a harsh holosystolic murmur heard best over the lower left sternal border.  There are no rales or wheezing over the lung fields.
Which of the following is the most useful test for diagnostic evaluation?

Quizplus · Accepted Answer

Explanation: This child most likely has an endocardial cushion defect, which is the most common congenital heart disease in children with Down's syndrome. Other malformations that are frequent in Down's syndrome include duodenal atresia, Hirschsprung's disease, atlanto-axial instability, and hypothyroidism. Among the propositions given, echocardiography is the most useful test for diagnostic evaluation of the patient. Echocardiography has the advantage of identifying the defect and determining its position and size. Chest radiograph, EKG, and hyperoxia test can all help in narrowing the differential diagnosis and evaluate the extent of cardiac damage, but these cannot confirm the diagnosis. (Choice A) A chest radiograph may show the degree of cardiomegaly and pulmonary marking. (Choice B) An EKG evaluates the heart rate and rhythm, and it can determine if ischemia, atrial dilation, or ventricular hypertrophy is present. (Choice C) The hyperoxia test measures the PO2 levels in the preductal arterial blood with the neonate breathing room air, and then 100% oxygen. This test allows for the differentiation between cyanotic heart disease and pulmonary disease. (Choice E) Cardiac catheterization is evidently more accurate than echocardiography for diagnostic evaluation, but this modality is reserved for cases in which the size of the shunt is uncertain, laboratory data and clinical findings are equivocal, or when pulmonary vascular disease is suspected. Educational objective: Endocardial cushion defect is the most common congenital heart lesion in patients with Down's syndrome. Echocardiography is the most useful test for diagnostic evaluation of this condition.

A 3-Week-Old Male Infant with Down's Syndrome Is Brought by His