A 4 year old girl is found to have bounding pulse and continuous machinery murmur. What is the most probable diagnosis?

The key is D. PDA. [Patent ductus arteriosus (PDA) is a medical condition in which the ductus arteriosus fails to close after birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta, which has a higher pressure, to the pulmonary artery.Continuous mechinary murmur is well known feature of PDA. Other features are bounding pulse, widened pulse pressure, increased cardiac output, differential cyanosis (cyanosis of the lower extremities but not of the upper body].