A 5-week-old infant born at 32 weeks' gestation is receiving care in the neonatal intensive care unit. Cardiopulmonary examination shows a grade 4/6 continuous murmur heard best at the left infraclavicular area. Echocardiography reveals a patent ductus arteriosus and a dilated left atrium. During surgical ligation of the ductus arteriosus, the surgeons perform a left-sided thoracotomy, visualize the ductus, and place a small metal clamp across the vessel. Which of the following changes is most likely to take place immediately after ligation?

Question

A 5-week-old infant born at 32 weeks' gestation is receiving care in the neonatal intensive care unit. Cardiopulmonary examination shows a grade 4/6 continuous murmur heard best at the left infraclavicular area. Echocardiography reveals a patent ductus arteriosus and a dilated left atrium.  During surgical ligation of the ductus arteriosus, the surgeons perform a left-sided thoracotomy, visualize the ductus, and place a small metal clamp across the vessel.  Which of the following changes is most likely to take place immediately after ligation?

Quizplus · Accepted Answer

Eductional Objective: Closure of a patent ductus arteriosus results in decreased pulmonary venous return to the left atrium (decreased left ventricular preload) and increased diastolic blood pressure in the aorta (increased left ventricular afterload).  Together, these changes acutely lower left ventricular stroke volume and cardiac output.

A 5-Week-Old Infant Born at 32 Weeks' Gestation Is Receiving