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Heart cross-section with PDA
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Ductus+Arteriosus,+Patent
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('''PDA''') is a
Congenital Heart defect wherein a child's
Ductus Arteriosus fails to close after
Birth . Symptoms include
Shortness Of Breath and
Cardiac Arrhythmia , and may progress to
Congestive Heart Failure if left uncorrected.
In the developing
Fetus , the ductus arteriosus (DA) is a shunt connecting the
Pulmonary Artery to the
Aortic Arch that allows much of the blood from the
Right Ventricle to bypass the fetus' fluid-filled
Lung s. During fetal development, this shunt protects the right ventricle from pumping against the high resistance in the lungs, which can lead to right ventricular failure if the DA closes in-utero.
When the newborn takes its first breath, the lungs open and pulmonary
Pressure decreases below that of the left heart. At the same time, the lungs release
Bradykinin to constrict the
Smooth Muscle wall of the DA and reduce bloodflow. Additionally, because of reduced pulmonary resistance, more blood flows from the pulmonary arteries to the lungs and thus the lungs deliver more
Oxygen ated blood to the left heart. This further increases aortic pressure so that blood no longer flows from the pulmonary artery to the aorta via the DA.
In normal newborns, the DA is closed within 15 hours after birth, and is completely sealed after three weeks. The fall in circulating maternal
Prostaglandins contributes to this. A nonfunctional vestige of the DA, called the
Ligamentum Arteriosum , remains in the normal adult heart.
Patent ductus arteriosus, or PDA, is a
Heart crisis that happens almost immediately following birth in some babies. In PDA, there is an irregular transmission of blood amid two of the most important
Arteries in close proximity to the heart. Although the
Ductus Arteriosus normally seals off within a few days, in PDA, the newborn's ductus arteriosus does not close, but remains patent. PDA is common in infants with persistent
Respiratory problems such as
Hypoxia , and has a high occurrence in
Premature Children . In hypoxic newborns, too little
Oxygen reaches the lungs to produce sufficient levels of bradykinin and subsequent closing of the DA. Premature children are more likely to be hypoxic and thus have PDA because of their underdeveloped heart and lungs.In some babies, on the other hand, the ductus arteriosus remains open. This opening permits
Blood to surge unswervingly starting from the
Aorta into the
Pulmonary Artery .
A patent ductus arteriosus allows oxygenated blood to flow down its
Pressure Gradient from the aorta to the pulmonary arteries. Thus, some of the infant's oxygenated blood does not reach the body, and the infant becomes short of breath. The
Heart Rate hastens, thereby increasing the speed with which blood is oxygenated and delivered to the body. Left untreated, the infant will likely suffer from
Congestive Heart Failure , as his heart is unable to meet the
Metabolic demands of his body.
In some cases, such as in transposition of the great vessels (the pulmonary artery and the aorta), a PDA may need to remain open. In this cardiovascular condition, the PDA is the only way that oxygenated blood can mix with deoxygenated blood. In these cases, prostaglandins are used to keep the patent ductus arteriosus open.
While some cases of PDA are asymptomatic, common symptoms include:
PDA is usually diagnosed using non-invasive techniques.
Electrocardiography (ECG), in which
Electrode s are used to record the
Electrical activity of the heart, can be used to detect cardiac
Arrhythmia s associated with PDA.
A chest
X-ray may be taken, which reveals the structure of the infant's heart and the size and configuration of its chambers. In some instances, the X-ray itself may reveal a patent ductus arteriosus.
Echocardiography , in which
Sound Wave s are used to capture the motion of the heart, is also useful in detecting PDA.
Infants without adverse symptoms may simply be monitored as inhibitors such as
Indomethacin have also been used in successful non-surgical closure of the DA. This is an especially viable alternative for premature infants.
In certain cases it may be beneficial to the newborn to prevent closure of the ductus arteriosus. For example, in
Transposition Of The Great Vessels a PDA may prolong the child's life until surgical correction is possible. The ductus arteriosus can be induced to remain open by administering prostaglandin analogs.
