Down syndrome (Trisomy 21) Quiz: Ace Your Exams

A 6-week-old infant is brought to the office because of difficulty feeding. The mother reports that whenever she tries to breastfeed the infant, he begins to sweat and grunt after a few minutes and stops feeding.  The patient was born via normal vaginal delivery at 38 weeks gestation to a 35-year-old mother. The infant’s mother did not receive prenatal care. Family history is unremarkable for hereditary disorders. Temperature is 37°C (98.6°F), pulse is 160/min, respirations are 30/min and blood pressure is 90/50 mmHg. Physical examination shows a single crease on both palms, a gap between the first two toes and prominent epicanthal folds. Auscultation reveals a fixed split S2 and grade 2/6 systolic ejection murmur best heard at the left upper sternal border. Bibasilar crackles are present. Which of the following is the most likely to be found in association with this patient’s cardiac examination findings?