This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'The following statements are true of patent ductus arteriosus(PDA) except – a) Spontaneous closure occurs in some term infantsb) Pulmonary hypertension developsc) Bacterial endocarditis is more frequent with small PDAd) Recurrent chest infection and congestive failure may develope) Anatomic existence of PDA is an indication for surgery \nSelect and explain. \nA. a, B. b, C. ae, D. ad', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Spontaneous closure of PDA\n1) In premature infants\n\nIn premature infants, spontaneous closure of PDA may occur because in these infants PDA is due to unresponsiveness to oxygen and there is no structural abnormality.\n\n2) In Full-term infants\n\nUnlike that in premature infants, spontaneous closure of a PDA does not usually occur in full-term infants.\nThis is because the PDA in term infants results from a structural abnormality of the ductal smooth muscle.\n\nClinical manifestations of PIA\n\nPatient may be asymptomatic\nSymptoms develop early and CHF may develop at 6 to 8th weeks of age.\nCommon symptoms → Dysnea on exertion, palpitation and frequent chest infections.\n\nSigns\n\nTachypnea & Tachycardia\nBounding pulse with wide pulse pressure (with elevated systolic and lower diastolic pressure).\nHyperkinetic cardiac impulse\nSystolic or continuous thrill.\nAccentuated S1\nThe narrow or paradoxical split of S2 (But it may be masked by continuous murmur since the maximum intensity of continuous murmur occurs at S2).\nContinuous (machinery) murmur → Murmur starts after S and reaches the peak at S2. It then diminishes and is audible only during a part of the diastole. Murmur is best heard at second left intercostal space and is also heard below left clavicle.\nS3 may occur at apex followed by a delayed diastolic murmur.', 'role': 'assistant'}]