MRCPCH 1: Essential Questions in Paediatrics - PasTest

8CARDIOLOGY – ANSWERSas coarctation of the aorta and hypoplastic left heart syndrome, tend topresent with acidosis and weak pulses in the first few days of life.1.4 Persistent ductus arteriosus: D EThere is abnormal persistence of the ductus arteriosus beyond 1 monthafter the date the baby should have been born. Those children affected areusually asymptomatic and rarely develop heart failure. On auscultation, acontinuous ‘machinery’ or systolic murmur at the left infraclavicular area isheard. The murmur is initially systolic but, as the pulmonary vascularresistance falls, it becomes continuous in nature because there is acontinual run-off of blood from the aorta to the pulmonary artery (as thepressure in the aorta is greater than in the pulmonary artery throughoutthe cardiac cycle). Other clinical features include bounding pulses and widepulse pressure. If the duct is large, chest radiography can demonstratecardiomegaly and pulmonary plethora. Management is usually by closure inthe cardiac catheter laboratory with a coil or device when the infant is1 year of age. However, if the duct is large, surgical ligation can beundertaken when the infant is aged 1–3 months. The presence of a ductusarteriosus in a pre-term baby is not congenital heart disease, but thesechildren have a higher incidence of persistent ductus arteriosus.1.5 Transposition of the great arteries: A B D EIn this condition, the aorta usually arises anteriorly from the right ventricleand the pulmonary artery arises posteriorly from the left ventricle.Deoxygenated blood is therefore returned to the body, while oxygenatedblood goes back to the lungs. If these two parallel circuits were completelyseparate, the condition would be incompatible with life. These childrenhave high pulmonary blood flow and are very cyanosed, unless there is anatrial septal defect, a ductus arteriosus, or a ventricular septal defect,allowing mixing of the two circulations. Babies become cyanosed when theduct closes, thus reducing the mixing between the systemic and pulmonarycirculations, but there is usually no murmur. Transposition of the greatarteries may be associated with ventricular septal defect, coarctation of theaorta or pulmonary stenosis. Management is to resuscitate the baby,followed by a balloon atrial septostomy (preferably via the umbilical vein)at a cardiac centre in about 20% of cases. In the sick, cyanosed newbornbaby, a continuous intravenous infusion of prostaglandin E 1or E 2should becommenced to keep the duct open. Definitive repair in the form of thearterial switch operation will usually be undertaken before the baby is2 weeks of age.