Cyanotic heart disease Specific types of congenital heart defects that cause blood to pass directly from the right side of the heart to the left side result in cyanosis. In these defects, some of the blood that is pumped to the body has not been oxygenated by the lungs and therefore will appear more<unk> . Infants with these types of heart defects may have a constant bluish tint to their skin, or they may have temporary episodes of cyanosis. The degree of cyanosis is dependent on how much deoxygenated blood is mixed with oxygenated blood before being pumped to the body. Cardiac conditions in which there is decreased blood flow to the lungs such as, tetralogy of Fallot or pulmonary valve atresia, result in less blood becoming oxygenated. There are also cardiac conditions such as transposition of the great arteries or truncus arteriosus, that results in an overall increase in blood flow to the lungs but with limited flow of the oxygenated blood to the rest of the body. Conditions in which there is poor blood flow to the systemic circulation, such as coarctation of the aorta suggests that the body does not receive the oxygenated blood it requires with resultant cyanosis. The five most common cyanotic heart defects that may result in<unk>  include the following: Pathology Brief Description Epidemiology Diagram 1. Persistent (or patent) truncus arteriosus Instead of two separate major blood vessels leaving the heart, there is one common outgoing vessel. 3-5/100,000 births 256x256px 2. Transposition of the great vessels The positions of the pulmonary artery and the aorta are switched, with the aorta connecting to the right ventricle and the pulmonary artery connecting to the left ventricle. 1-5/10,000 births 256x256px 3. Tricuspid atresia The heart valve connecting the right atrium to the right ventricle does not form properly, disrupting blood flow in the heart. 1-9/100,000 births 256x256px 4. Tetralogy of Fallot A heart defect with 4 features including a narrow pulmonary artery, a thick right ventricle, an aorta that connects to both the right and left ventricles, and a hole in the ventricular wall. 1-5/10,000 births 256x256px 5. Anomalous pulmonary venous connection The pulmonary veins returning oxygenated blood from the lungs do not connect properly to the heart. 6-12/100,000 births 256x256px Methemoglobinemia Hemoglobin oxygenation dissociation curve. In the case of methemoglobinemia the curve is shifted to the left given the higher affinity for oxygen. Methemoglobinemia which can be acquired or congenital, occurs when the iron in hemoglobin is oxidized from Fe2+ to Fe3+, leading to poor binding of oxygen. Additionally, the oxygen that is already bound is held more tightly to the hemoglobin due to a higher affinity, resulting in less oxygen delivery. A methemoglobin level >1.5g/dL causes cyanosis. The most common congenital cause is a deficiency in the enzyme cytochrome b5 reductase which reduces methemoglobin in the blood. However, in infants the most common cause of methemoglobinemia is acquired through the ingestion of nitrates through well water or foods. Infants younger than 4 months are at greater risk given that they drink more water per body weight, they have a lower NADH- cytochrome b5 reductase activity, and they have a higher level of fetal hemoglobin which converts more easily to methemoglobin. Additionally, infants are at an increased risk after an episode of gastroenteritis due to the production of nitrites by bacteria. The sources of nitrate can include fertilizers used in agricultural lands, waste dumps or pit latrines. For example, nitrate levels are subject to monitoring to comply with drinking water quality standards in the United States and other countries. The link between<unk>  and nitrates in drinking water is widely accepted, but some studies indicate that other contaminants, or dietary nitrate sources, may also play a role in the syndrome.
Blue baby syndrome
Gray baby syndrome
Michelin tire baby syndrome
Shaken baby syndrome
Omphalitis of newborn
Neonatal diabetes
Neonatal jaundice
Hemolytic disease of the newborn