Congenital Heart Defects Quiz

See Cyanotic Heart Defects. Option C is correct because hypoplastic left heart syndrome is a group of defects in which the left side of the heart is severely underdeveloped (hypoplastic means smaller and underdeveloped). The left ventricle is tiny, and the mitral valve, the aortic valve and the first part of the aorta (the ascending aorta) are also underdeveloped, often with the aortic valve completely closed (aortic atresia). Blood returning from the lungs to the left atrium cannot pass forwards, so it crosses an atrial septal defect into the right atrium. There it mixes with deoxygenated blood, and the right ventricle then has to supply both the lungs and the body, the body supply passing through the patent ductus arteriosus (the foetal channel between the pulmonary artery and the aorta). If the ductus closes after birth, the baby develops cardiogenic shock within days, so the ductus is kept open with a prostaglandin infusion until surgery.

• Defect: Severe underdevelopment of the left side of the heart, with a tiny left ventricle and small mitral and aortic valves.
• Circulation: Blood crosses the atrial septal defect and the right ventricle supplies lungs and body via the patent ductus arteriosus.
• Risk: If the ductus closes the baby develops cardiogenic shock, so a prostaglandin infusion keeps it open until surgery.