Paediatric Imaging

Cyanosis

bluish discolouration of the skin and mucous membrane as a result of an increased concentration of reduced haemoglobin. The amount of reduced haemoglobin in the cutaneous veins has to reach a critical level of about 5g/ml for clinical cyanosis to be appreciated.

Cyanosis from congenital heart disease occurs either as a result of right to left shunts or the mis-direction of venous blood into the aorta. Decrease in the pulmonary blood flow tends to worsen the cyanosis. Common cyanotic heart diseases include transposition of great arteries, truncus arteriosus, single ventricle, tetralogy of Fallot, tricuspid atresia, pulmonary atresia and total anomalous pulmonary venous return.

Cyanosis can occur from non-cardiac causes and these include inadequate alveolar ventilation, increased deoxygenation in the capillaries such as congestive cardiac failure and abnormal haemoglobin.

Consequences and complications of prolonged cyanosis include polycythaemia, clubbing, hypoxic spells, decreased IQ, bleeding disorders, hyperuricaemia, gout, scoliosis and central nervous system complications such as brain abscess and cerebrovascular accidents. See transposition of great arteries corrected, transposition of great arteries complete, truncus arteriosus, Fallot tetralogy of, atresia tricuspid, pulmonary atresia, total anomalous pulmonary venous return

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