Persistent Pulmonary Hypertension of the Newborn (PPHN) is a life-threatening heart and lung birth defect. PPHN has been linked to Paxil. While PPHN can exist in newborns that have not been exposed to SSRI antidepressants, the babies of pregnant women who have taken Paxil after the 20th week of pregnancy have a 600% increased risk of developing PPHN.
PPHN is characterized by abnormally high blood pressure in the lungs, preventing blood pumped from the heart to be oxygenated in the lungs. PPHN is often the result of a birth condition known as persistent patent ductus arteriosus (persistent PDA). Normally, in unborn children, the ductus arteriosus blood vessel serves as a shunting mechanism, allowing blood to bypass the fluid-filled lungs, promoting heart strength and preventing dangerous stress on both the lungs and heart. At birth, as soon as the newborn begins breathing, the ductus arteriosus closes and seals itself to allow blood to enter the lungs and receive oxygen. In newborn children with persistent PDA, the ductus arteriosus does not close itself properly after birth, and persists in an open state. With the ductus arteriosus in a persistent open state, the blood pressure in the lungs becomes elevated, leading to PPHN. PPHN can in turn lead to hypoxia, a condition where the body does not receive enough oxygen, placing all organs and body systems at risk of failure.
The Nemours Foundation (www.kidshealth.org) describes PPHN as follows:
|In the womb, the pathway of your baby’s blood circulation is different than it is after birth.
In the uterus, a baby’s circulation bypasses the lungs. The lungs are not needed to exchange oxygen because the placenta (the organ that nourishes and protects your developing baby) supplies the baby with oxygen through the umbilical cord. The pulmonary artery – which, after birth, will carry blood from the heart to the lungs – instead sends blood directly back to the heart through a fetal blood vessel called the ductus arteriosus.
Normally, when a baby is born and begins to breathe air, his circulatory system quickly adapts to the outside world. The pressure in the lungs changes as air enters and inflates the lungs. As a result, the ductus arteriosus, which previously supplied the fetal heart with blood, permanently closes. Blood returning to the heart from the body can now be pumped into the lungs, where oxygen and carbon dioxide are exchanged. The blood is then returned to the heart and pumped back out to the body in an oxygen-rich state.
In a baby with PPHN, however, the fetal circulatory system does not “switch over.” The ductus arteriosus remains open, and the baby’s blood flow continues to bypass the lungs. Even though the baby is breathing, oxygen in the breathed air will not reach the bloodstream. Because the blood returning from the body is unable to enter the lungs properly – and instead flows through the still-open ductus arteriosus – it returns to the heart in an oxygen-poor state. This condition is known as persistent fetal circulation, or PFC.
“The baby’s circulation has not made the normal transition from fetal circulation to normal newborn circulation, because pressure in the lungs is increased and this causes distress,” says Neal Cohn, MD, a pediatrician. Depending on the degree of PPHN causing the persistent fetal circulation, the oxygen in the air your baby breathes into his lungs is not adequately picked up and carried by the blood to other areas of the body that need it (such as the brain, kidneys, liver, and other organs). These organs soon become stressed from lack of oxygen.
PPHN sometimes develops as the result of another event during delivery or from a disease or congenital condition affecting the newborn (usually one that either directly affects the lungs or oxygen supply to the baby before or during birth). Often, however, PPHN occurs as an isolated condition, and its cause is not known. It is usually seen soon after birth, often within 12 hours after birth. PPHN occurs in approximately one in 700 births.
Researchers are still uncertain of exactly how Paxil increases the risk of PPHN, but Dr. Christina Chambers of the University of California at San Diego, who conducted the study in question, has put forth a few theories. Paxil appears to accumulate in the lungs. By design, Paxil reduces the amount of serotonin, a chemical in the brain, that is absorbed back in to presynaptic cells for the purpose of allowing a higher level of serotonin to bind to postsynaptic cells. In unborn children, this extra serotonin pools in the lungs. Serotonin has the property of increasing pulmonary vascular resistance, requiring the heart to work harder. Serotonin also has an effect on smooth-muscle cells in the lungs, a characteristic of PPHN.
One other theory put forth is the effect of Paxil on the body’s ability to synthesize nitric oxide, a chemical that regulates dilation of the blood vessels. In one test, the release of nitric oxide was directly related to the amount of fluoxetine present in a cell culture. In a different test, heart disease patients who were treated with paroxetine (Paxil) experienced lower activities of nitric oxide synthase, and also had lower levels of nitrite and nitrate after the treatment.
Women who are pregnant or may become pregnant should consult with a physician if they are currently taking, considering taking, or considering discontinuation of Paxil (paroxetine) or any other selective serotonin reuptake inhibitor (SSRI) antidepressant.
If you or a loved one has taken Paxil during pregnancy and has given birth to a child with heart defects, The Law Offices of Larry H. Parker wants to help. Larry H. Parker and his team of attorneys form a highly recognized legal practice with the knowledge and resources to quickly conclude your case. Larry’s talented team of attorneys has been researching Paxil related birth defects for over a decade.
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