A 1-year-old child is brought into your surgery for a routine examination. His parents are worried that he is too small for his age. On further questioning, his parents explain he is difficult to feed and eats a milk and soft food-based diet. He is otherwise asymptomatic.
On general examination, he looks healthy but is on the 3rd centile for weight. Cardiac examination reveals a systolic murmur in the pulmonary area and a fixed splitting to the second heart sound. Pulses are all palpable and within normal range.
What is the most likely diagnosis?
a) Atrial septal defect (ASD)
b) Ventricular septal defect (VSD)
c) Tetralogy of Fallot
d) Patent ductus arteriosus (PDA)