The mother of a 10-month-old infant tells the nurse that she has noticed that her son becomes blue when he is crying and that the frequency of this is increasing. He is also not crawling yet. During the examination the nurse palpates a thrill at the left lower sternal border and auscultates a loud systolic murmur in the same area. What would be the most likely cause of these findings?

A) Tetralogy of Fallot
B) Atrial septal defect
C) Patent ductus arteriosus
D) Ventricular septal defect

Question

Palak Sarin · Accepted Answer

Final Answer : A, Explanation :  The cause of these findings is tetralogy of Fallot. Its subjective findings include (1) severe cyanosis, not in the first months of life but developing as the infant grows, and right ventricle outflow the murmur is systolic, loud, and crescendo-decrescendo. Atrial septal defect (ASD) is an abnormal opening in the atrial septum, resulting usually in left-to-right shunt and causing large increase in pulmonary blood flow. However, this defect is tolerated well and infants rarely have symptoms but a sternal lift is often present and S 2  has a fixed split. Patent ductus arteriosus is the persistence of the channel joining left pulmonary artery to aorta (usually closes spontaneously within hours of birth). There are usually no symptoms in early childhood but the blood pressure will have a wide pulse pressure and bounding peripheral pulses from rapid runoff of blood into low-resistance pulmonary bed during diastole. Thrill is often palpable at left upper sternal border and a continuous murmur heard in systole and diastole is called a machinery murmur. Ventricular septal defect (VSD) is an abnormal opening in the septum between the ventricles. Small defects are asymptomatic but infants with large defects have poor growth and slow weight gain. A loud, harsh holosystolic murmur can be heard best at the left lower sternal border and may be accompanied by a thrill.

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