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': 'True about TGA – \nSelect and explain. \nA. Cyanotic disease, B. Aorta anterior to pulmonary artery, C. VSD, D. All of these', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In TGA aorta lies anterior and to the right of puhnonary artery.\nIn patients with TGA the oxygenated pulmonary venous blood recirculates in the lungs whereas deoxygenated systemic venous blood recirculates in the systemic circulation --> Pulmonary artery saturation is always higher than aortic saturation (opposite to normal person).\nBecause oxygenated blood is not available for systemic circulation, survival depends on the mixing available between the two circulation.\nSo, patients with TGA can be divided into : -\n\n\nTGA with intact ventricular septum\nTGA with VSD.\n\ni) TGA with intact septum\n\nThe mixing of blood depends on atrial communication.\nMost of the time atrial communication is a patent foramen ovale.\nAs patent foramen ovale is very small communication, mixing of oxygenated blood with deoxygenated blood is inadequate —> Patients are symptomatic and cyanotic at birth, and CHF may develop during first week.\n\nii) TGA with VSD\n\nPresence of VSD of adequate size results in good mixing of blood.\n\na Patients become symptomatic, at 4-8 weeks when fetal pulmonary vasculature regresses maximally —> CHF\ndevelops at this time.\n\nThe failing left ventricle and large pulmonary blood flow cause increase in left atrial pressure —> T back pressure Pulmonary venous hypertension and pulmonary plethora.\nThe presence of a large VSD equalizes the pressure in the two ventricles as well as in two great vessels.\nPulmonary artery carries large flow —) patients with TGA and large VSD develop pulmonary vascular obstructive disease (Eisenmenger physiology) early in life.', 'role': 'assistant'}]