What is the epidemiology of a patent ducts arterioles?

A new patient is brought into the office for their annual evaluation. The child is a 6-year-old and appears a bit small for their age but not so small that any alarm bells are set off. The vitals are: P = 116, R = 22, T = 98.6 F, BP = 110/50. (The normal vitals in a 6-year-old are P = 75 – 120, R = 16 – 22, T = 98.6 , BP = (85-115)1(48-64). Examination of the lungs is normal, HEENT is normal, as is the abdominal exam. The heart however, seems laterally displaced and there appears to be only a continuous murmur which can be described as crescendo/decrescendo systolic murmur that extends into diastole. Because, you were trained at Chamberlain College of Nursing you immediately know that this is probably a patent ductus arteriosus.
Explain the murmur from a mechanistic view of the hearts physiological functioning? What is the epidemiology of a patent duct’s arterioles? How is a patent ductus arteriosus treated?