Patent ductus arteriosus


Patent ductus arteriosus

Description, Causes and Risk Factors:

Abbreviation: PDA.

The ductus arteriosus is an opening in the heart between the aorta (major artery leaving the heart) and the pulmonary artery (blood vessel that takes blood to the lungs). The ductus arteriosus normally stays open before birth so that the baby can get oxygen from the mother, since the baby's lungs are not fully developed. After a baby is born and his or her lungs are working, the ductus arteriosus closes. A patent ductus arteriosus occurs when the ductus arteriosus does not close after birth. This allows a large amount of blood to travel to the lungs. The severity of the baby's symptoms depends on the size of the PDA.

PDA is a very common heart defect, accounting for 5 to 10 percent of all types of congenital heart disease (CHD). Though an exact incidence of PDA is difficult to determine, researchers estimate that eight or nine in every 1,000 children are affected. PDA can occur in full-term infants, but it is seen most often in preterm infants, infants born at a high altitude, and babies whose mothers had a rubella infection during pregnancy. PDA occurs in individuals of every ethnic origin and does not occur more often in any one country or ethnic population; however, it is two to three times more common in females than males.

PDA can be caused by environmental exposure before birth or the inheritance of a specific changed or mutated gene or genes. It can be a symptom of a genetic syndrome or may be caused by a combination of genetic and environmental factors (multifactorial).

Environmental exposures that can increase the chance for a baby to be affected by PDA include fetal exposure to rubella before birth, preterm delivery, and birth at a high altitude location.

PDA can be an inherited condition in families with isolated PDA or part of a genetic syndrome. In either case, there are specific gene changes or mutations which lead to a defect in the elastic tissue forming the walls of the ductus arteriosus. As of 2004 the genes causing isolated PDA have not been identified, but it is known that PDA can be inherited through a family in an autosomal dominant pattern or an autosomal recessive pattern. Every person has approximately 30,000 genes, which tell the body how to grow and develop correctly. Each gene is present in pairs since one is inherited from the mother and one is inherited from the father. In an autosomal dominant condition, only one specific changed or mutated copy of the gene for PDA is necessary for a person to have PDA. If a parent has an autosomal dominant form of PDA, there is a 50 percent chance for each child to have the same or similar condition.

PDA can also be inherited in an autosomal recessive manner. A recessive condition occurs when a child receives two changed or mutated copies of the gene for a particular condition, such as PDA (one copy from each parent). Individuals with a single changed or mutated copy of a gene for a recessive condition are known as carriers and have no health problems related to the condition. However, when two people who each carry a changed or mutated copy of the same gene for a recessive condition have children, there is a chance with each pregnancy for the child to inherit the two changed or mutated copies from each parent. In this case, the child would have PDA. For two known carriers, there is a 25 percent risk with each child to have a child with PDA, a 50 percent chance to have a child who is a carrier, and a 25 percent chance to have a child who is neither affected nor a carrier.

Most cases of PDA occur as the result of multifactorial inheritance which is caused by the combination of genetic factors and environmental factors. The combined factors lead to isolated defects in the elastic tissue forming the walls of the ductus arteriosus.

The prognosis is generally considered excellent in patients in whom the patent ductus arteriosus (PDA) is the only problem. In premature infants who have other sequelae of prematurity, these sequelae tend to dictate prognosis of patent ductus arteriosus (PDA).

Symptoms:

Patent ductus arteriosus symptoms vary with the size of the defect and the gestational age of the infant at birth. A small PDA may cause no signs or symptoms, and may go undetected for some time, even until adulthood. A large PDA can cause signs of heart failure soon after birth.

Your doctor may first suspect a heart defect during a regular checkup while listening to your baby's heart through a stethoscope.

A large PDA, found during infancy or childhood, may cause:

    Poor eating, poor growth.

  • Sweating with crying or eating.

  • Persistent fast breathing or breathlessness.

  • Easy tiring.

  • Rapid heart rate.

  • A bluish or dusky skin tone.

Diagnosis:

Diagnosis is most often made by detecting the characteristic "machinery" heart murmur heard by a doctor through a stethoscope. Tests such as a chest x-ray, echocardiograph, and ECG are used to support the initial diagnosis and to determine the severity of the PDA.

CBC and metabolic panel: A complete blood cell (CBC) count with differential and a chemistry profile are obtained to determine the overall health of the child. However, findings are usually within reference ranges in patients with this condition. Polycythemia may be present if the child has other congenital heart defects.

Pulse oximetry/ABG: Pulse oximetry/arterial blood gas (ABG) analysis usually demonstrate normal saturation because of pulmonary overcirculation. A large ductus arteriosus could cause hypercarbia and hypoxemia from congestive heart failure (CHF) and air space disease (atelectasis or intra-alveolar fluid/pulmonary edema).

In the event of pulmonary artery hypertension (PAH), right-to-left intracardiac shunting of blood, hypoxemia, cyanosis, and acidemia may be present.

Treatment:

If the PDA is small, it doesn't make the heart and lungs work harder. Surgery and other treatments may not be needed. Small PDAs often close on their own within the first few months of life.

Most children can have the PDA closed by inserting catheters (long thin tubes) into the blood vessels in the leg to reach the heart and the PDA, and a coil or other device can be inserted through the catheters into the PDA like a plug. If surgery is needed, an incision is made in the left side of the chest, between the ribs. The ductus is closed by tying it with suture (thread-like material) or by permanently placing a small metal clip around the ductus to squeeze it closed. If there's no other heart defect, this restores the child's circulation to normal. In premature newborn babies, medicine can often help the ductus close. After the first few weeks of life, medicine won't work as well to close the ductus and surgery may be required.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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