Definition Patent ductus arteriosus (PDA) is the failure of a duct, or passageway, between two specific blood vessels to close. The blood vessels involved are the pulmonary artery and the aorta, two of the largest arteries in the body. It is a congenital heart disease, or a defect present at birth.
What is going on in the body? The pulmonary artery carries blood to the lungs. The aorta receives all the blood from the left ventricle of the heart and sends it to the rest of the body. In the normal heart, the passageway that connects these two blood vessels, called the ductus arteriosus, closes soon after birth. The closing of the duct helps keep the blood flowing in the right direction. If the duct does not close, PDA results. In PDA, some of the blood flows out of the aorta back into the duct instead of going to the rest of the body. This forces the lungs and heart to work much harder.
What are the signs and symptoms of the condition? Serious cases of patent ductus arteriosus are diagnosed at birth. The infant will have abnormal pulses and heart murmurs that can be found during a physical examination. Sometimes a person with patent ductus arteriosus has no symptoms until middle age. In severe cases, the strain on the heart and lungs can cause congestive heart failure.
What are the causes and risks of the condition? The cause of patent ductus arteriosus is unknown. One theory about the cause of PDA has to do with the action of a chemical made by the body. In the normal heart, levels of this chemical drop and the duct closes soon after birth. But in PDA, the chemical remains active and the duct stays open. The rubella virus has also been associated with a higher risk of developing PDA>
What can be done to prevent the condition? Proper vaccination with the MMR vaccine may minimise the incidence of PDA that is rubella-related. In most cases, nothing can be done to prevent PDA..
How is the condition diagnosed? Tests used to diagnose patent ductus arteriosus include:
These tests show the size of the heart and the amount of blood flowing through the duct.
What are the long-term effects of the condition? Long-term effects depend on the severity of the PDA. Sometimes no effects are noticed until adulthood. In other cases, the duct closes by itself. But if the defect places too much strain on the heart, congestive heart failure and congestion in the lungs can result.
What are the risks to others? There are no risks to others.
What are the treatments for the condition? Milder cases of PDA are treated with medications as needed. Over time, the duct will often close by itself.
If time and medications fail to close a PDA, open heart surgery may be needed. Newborns with severe PDA may need surgery in the first month of life. In those with less severe forms of PDA, surgery can be postponed for several months or even years.
What happens after treatment for the condition? There are usually few problems after recovery from PDA closure.
How is the condition monitored? The person makes routine visits to the doctor and the symptoms are monitored. Any new or worsening symptoms should be reported to the doctor.
Author: Eric Berlin, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 17/1/2005 Contributors Potential conflict of interest information for reviewers available on request
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