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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 lungs from being overworked and allows the right ventricle to strengthen.
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. A nonfunctional vestige of the DA, called the
Ligamentum Arteriosum , remains in the adult heart.
In PDA, the newborn's ductus arteriosus does not close, but remains patent. Patent DA 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.
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 and
Cyanotic . 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.
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.
Both
Surgical and non-surgical methods of treatment are available. Surgically, the DA may be closed by ligation, wherein the DA is manually tied shut, or with intravascular coils or plugs that leads to formation of a thrombus in the DA.
Fluid restriction and
Prostaglandin 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.
