Persistent fetal circulation is a condition caused by a failure in the systemic circulation and pulmonary circulation to convert from the antenatal circulation pattern to the "normal" pattern. Infants experience a high mean arterial pulmonary artery pressure and a high afterload at the right ventricle. This means that the heart is working against higher pressures, which makes it more difficult for the heart to pump blood.In a fetus, there is high pulmonary vascular resistance (PVR) and low pulmonary blood flow as the fetus does not use the lungs for oxygen transfer, but instead relies on the placenta for oxygen. When the baby is born, the lungs are needed for oxygen transfer and need high blood flow which is encouraged by low PVR. The failure of the circulatory system of the newborn to adapt to these changes by lowering PVR leads to persistent fetal circulation. The newborn is therefore born with elevated PVR, which leads to pulmonary hypertension. Because of this, the condition is also widely known as persistent pulmonary hypertension of the newborn (PPHN). This condition can be either acute or chronic, and is associated with significant morbidity and mortality. Presentation
Complications
PPHN can range from mild to severe disease. In the most severe form, infants experience severe hypoxemia resulting in cardiac and pulmonary complications.
Pegvaliase, sold under the brand name Palynziq, is a medication for the treatment of the genetic disease phenylketonuria. Chemically, it is a pegylated derivative of the enzyme phenylalanine ammonia-lyase that metabolizes phenylalanine to reduce its blood levels.It was approved by the Food and Drug Administration for use in the United States in 2018. The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication. References
External links
"Pegvaliase". Drug Information Portal. U.S. National Library of Medicine.