Patent ductus arteriosus
Encyclopedia
Patent ductus arteriosus (PDA) is a congenital disorder
in the heart
wherein a neonate's ductus arteriosus
fails to close after birth
. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain. With age, the PDA may lead to congestive heart failure if left uncorrected.
, the ductus arteriosus (DA) is the vascular connection between the pulmonary artery
and the aortic arch
that allows most of the blood from the right ventricle
to bypass the fetus' fluid-filled compressed 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 vascular resistance decreases. After birth, the lungs release bradykinin
to constrict the smooth muscle
wall of the DA and reduce bloodflow through the DA as it narrows and completely closes, usually within the first few weeks of life. In most newborns with a patent ductus arteriosus the blood flow is reversed from that of in utero flow, i.e. the blood flow is from the higher pressure aorta to the now lower pressure pulmonary arteries.
In normal newborns, the DA is substantially closed within 12–24 hours after birth, and is completely sealed after three weeks. The primary stimulus for the closure of the ductus is the increase in neonatal blood oxygen content. Withdrawal from maternal circulating prostaglandins also contributes to ductal closure. The residual scar tissue from the fibrotic remnants of DA, called the ligamentum arteriosum
, remains in the normal adult heart.
A patent ductus arteriosus allows a portion of the oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta (which has higher pressure) to the pulmonary artery. If this shunt is substantial, the neonate becomes short of breath: the additional fluid returning to the lungs increases lung pressure to the point that the neonate has greater difficulty inflating the lungs. This uses more calories than normal and often interferes with feeding in infancy. This condition, as a constellation of findings, is called congestive heart failure
.
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.
.
, in which sound waves are used to capture the motion of the heart, and associated Doppler studies are the primary methods of detecting PDA. Electrocardiography (ECG), in which electrode
s are used to record the electrical
activity of the heart, is not particularly helpful as there are no specific rhythms or ECG patterns which can be used to detect PDA.
A chest X-ray
may be taken, which reveals the overall size of neonate's heart (as a reflection of the combined mass of the cardiac chambers) and the appearance of the blood flow to the lungs. A small PDA most often shows a normal sized heart and normal blood flow to the lungs. A large PDA generally shows an enlarged cardiac silhouette and increased blood flow to the lungs.
and non-surgical methods. Surgically, the DA may be closed by ligation (though support in premature infants is mixed), wherein the DA is manually tied shut, or with intravascular coils or plugs that leads to formation of a thrombus in the DA. This was first performed in humans by Robert E. Gross
.
Because Prostaglandin E1
is responsible for keeping the ductus patent, NSAIDS (inhibitors of prostaglandin synthesis) such as indomethacin or a special form of ibuprofen
have been used to help close a PDA. This is an especially viable alternative for premature infants.
In certain cases it may be beneficial to the neonate to prevent closure of the ductus arteriosus. For example, in transposition of the great vessels
, a PDA may prolong the newborn's life until surgical correction is possible. The ductus arteriosus can be induced to remain open by administering prostaglandin
analogs such as alprostadil
or misoprostol
(prostaglandin E1 analogs).
More recently, PDAs can be closed by percutaneous interventional method. Via the femoral vein or femoral artery, a platinum coil can be deployed via a catheter, which induces thrombosis (coil embolization). Alternatively, a PDA occluder device (AGA Medical), composed of nitinol mesh, is deployed from the pulmonary artery through the PDA. The larger skirt of the device sits on the aortic side while the ampulla of the device hugs the walls of the PDA, with care taken to avoid occlusion of the pulmonary arterial lumen by the device. These methods permit closure without open heart surgery.
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
in the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
wherein a neonate's ductus arteriosus
Ductus arteriosus
In the developing fetus, the ductus arteriosus , also called the ductus Botalli, is a shunt connecting the pulmonary artery to the aortic arch. It allows most of the blood from the right ventricle to bypass the fetus's fluid-filled lungs. Upon closure at birth, it becomes the ligamentum arteriosum...
fails to close after birth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain. With age, the PDA may lead to congestive heart failure if left uncorrected.
Etiology
A patent ductus arteriosus can be idiopathic (i.e. without an identifiable cause), or secondary to another condition. Some common contributing factors in humans include:- Preterm birth
- Congenital rubella syndromeCongenital rubella syndromeCongenital rubella syndrome can occur in a developing fetus of a pregnant woman who has contracted rubella during her first trimester. If infection occurs 0–28 days before conception, there is a 43% chance the infant will be affected. If the infection occurs 0–12 weeks after conception, there is a...
- Chromosomal abnormalities such as Down syndromeDown syndromeDown syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...
Normal ductus arteriosus closure
In the developing fetusFetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
, the ductus arteriosus (DA) is the vascular connection between the pulmonary artery
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
and the aortic arch
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
that allows most of the blood from the right ventricle
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
to bypass the fetus' fluid-filled compressed lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
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 vascular resistance decreases. After birth, the lungs release bradykinin
Bradykinin
Bradykinin is a peptide that causes blood vessels to dilate , and therefore causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to lower blood pressure, increase bradykinin further lowering blood pressure...
to constrict the smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
wall of the DA and reduce bloodflow through the DA as it narrows and completely closes, usually within the first few weeks of life. In most newborns with a patent ductus arteriosus the blood flow is reversed from that of in utero flow, i.e. the blood flow is from the higher pressure aorta to the now lower pressure pulmonary arteries.
In normal newborns, the DA is substantially closed within 12–24 hours after birth, and is completely sealed after three weeks. The primary stimulus for the closure of the ductus is the increase in neonatal blood oxygen content. Withdrawal from maternal circulating prostaglandins also contributes to ductal closure. The residual scar tissue from the fibrotic remnants of DA, called the ligamentum arteriosum
Ligamentum arteriosum
The ligamentum arteriosum is a small ligament attached to the superior surface of the pulmonary trunk and the inferior surface of the aortic arch...
, remains in the normal adult heart.
Patent ductus arteriosus
The ductus arteriosus is a normal fetal blood vessel that closes soon after birth. In a patent ductus arteriosus (PDA) the vessel does not close and remains "patent" resulting in irregular transmission of blood between two of the most important arteries close to the heart, the aorta and the pulmonary artery. PDA is common in neonates 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 a portion of the oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta (which has higher pressure) to the pulmonary artery. If this shunt is substantial, the neonate becomes short of breath: the additional fluid returning to the lungs increases lung pressure to the point that the neonate has greater difficulty inflating the lungs. This uses more calories than normal and often interferes with feeding in infancy. This condition, as a constellation of findings, is called congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
.
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.
Prognosis
Without treatments, the disease may progress from left-to-right (noncyanotic heart) shunt to right-to-left shunt (cyanotic heart) called Eisenmenger's syndromeEisenmenger's syndrome
Eisenmenger's syndrome is defined as the process in which a left-to-right shunt caused by a congenital heart defect causes increased flow through the pulmonary vasculature, causing pulmonary hypertension, which in turn, causes increased pressures in the right side of the heart and reversal of the...
.
Signs and symptoms
While some cases of PDA are asymptomatic, common symptoms include:- tachycardiaTachycardiaTachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
- respiratory problems
- dyspneaDyspneaDyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
- shortness of breath - continuous machine-like heart murmurHeart murmurMurmurs are extra heart sounds that are produced as a result of turbulent blood flow that is sufficient to produce audible noise. Most murmurs can only be heard with the assistance of a stethoscope ....
- cardiomegalyCardiomegalyCardiomegaly is a medical condition wherein the heart is enlarged. It is generally categorized in the following manner:* Cardiomegaly due to dilation* Cardiomegaly due to ventricular hypertrophy** Left ventricular hypertrophy...
- enlarged heart - left subclavicular thrill
- bounding pulseBounding pulseBounding pulse is a medical sign characterized as a leaping and forceful pulse that quickly disappears. To feel a bounding pulse, the radial artery is lightly palpated at the distal palmar edge. It is best detected when the arm is held aloft....
- widened pulse pressure
- patients typically present in good health, with normal respirations and heart rate. If the ductus is moderate or large, widened pulse pressure and bounding peripheral pulses are frequently present, reflecting increased left ventricular stroke volume and diastolic runoff of blood into the initially lower-resistant pulmonary vascular bed. Prominent suprasternal and carotid pulsations may be noted secondary to increased left ventricular stroke volume.
- poor growth
- differential cyanosisCyanosisCyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
, i.e. cyanosis of the lower extremities but not of the upper body.
Diagnosis
PDA is usually diagnosed using non-invasive techniques. EchocardiographyEchocardiography
An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
, in which sound waves are used to capture the motion of the heart, and associated Doppler studies are the primary methods of detecting PDA. Electrocardiography (ECG), in which electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s are used to record the electrical
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
activity of the heart, is not particularly helpful as there are no specific rhythms or ECG patterns which can be used to detect PDA.
A chest X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
may be taken, which reveals the overall size of neonate's heart (as a reflection of the combined mass of the cardiac chambers) and the appearance of the blood flow to the lungs. A small PDA most often shows a normal sized heart and normal blood flow to the lungs. A large PDA generally shows an enlarged cardiac silhouette and increased blood flow to the lungs.
Treatment
Neonates without adverse symptoms may simply be monitored as outpatients, while symptomatic PDA can be treated with both surgicalSurgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
and non-surgical methods. Surgically, the DA may be closed by ligation (though support in premature infants is mixed), wherein the DA is manually tied shut, or with intravascular coils or plugs that leads to formation of a thrombus in the DA. This was first performed in humans by Robert E. Gross
Robert E. Gross (surgeon)
Robert E. Gross was a surgeon famous for being the first to cure patent ductus arteriosus by ligating it.-Sources:...
.
Because Prostaglandin E1
Prostaglandin E1
Prostaglandin E1 , known pharmaceutically as alprostadil, is a prostaglandin. It is a drug used in the treatment of erectile dysfunction and has vasodilatory properties.-Sexual dysfunction:...
is responsible for keeping the ductus patent, NSAIDS (inhibitors of prostaglandin synthesis) such as indomethacin or a special form of ibuprofen
Ibuprofen
Ibuprofen is a nonsteroidal anti-inflammatory drug used for relief of symptoms of arthritis, fever, as an analgesic , especially where there is an inflammatory component, and dysmenorrhea....
have been used to help close a PDA. This is an especially viable alternative for premature infants.
In certain cases it may be beneficial to the neonate to prevent closure of the ductus arteriosus. For example, in transposition of the great vessels
Transposition of the great vessels
Transposition of the great vessels is a group of congenital heart defects involving an abnormal spatial arrangement of any of the primary blood vessels: superior and/or inferior vena cavae , pulmonary artery, pulmonary veins, and aorta...
, a PDA may prolong the newborn's life until surgical correction is possible. The ductus arteriosus can be induced to remain open by administering prostaglandin
Prostaglandin
A prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring....
analogs such as alprostadil
Alprostadil
Prostaglandin E1 , known pharmaceutically as alprostadil, is a prostaglandin. It is a drug used in the treatment of erectile dysfunction and has vasodilatory properties.-Sexual dysfunction:...
or misoprostol
Misoprostol
Misoprostol is a drug that is used for the prevention of non steroidal anti inflammatory drug induced gastric ulcers, for early abortion, to treat missed miscarriage, and to induce labor. The latter use is controversial in the United States. Misoprostol was invented and marketed by G.D...
(prostaglandin E1 analogs).
More recently, PDAs can be closed by percutaneous interventional method. Via the femoral vein or femoral artery, a platinum coil can be deployed via a catheter, which induces thrombosis (coil embolization). Alternatively, a PDA occluder device (AGA Medical), composed of nitinol mesh, is deployed from the pulmonary artery through the PDA. The larger skirt of the device sits on the aortic side while the ampulla of the device hugs the walls of the PDA, with care taken to avoid occlusion of the pulmonary arterial lumen by the device. These methods permit closure without open heart surgery.
History
Robert E. Gross, MD performed the first successful ligation of a patent ductus arteriosus on an eight year old girl at Children's Hospital Boston in 1938.External links
- Patent Ductus Arteriosus information from Seattle Children's Hospital Heart Center
- Patent Ductus Arteriosus Causes from US Department of Health and Human Services
- Patent Ductus Arteriosus from Merck
- Fetal Circulation at berkeley.edu
- Information about PDA - The Hospital for Sick Children
- Down's Heart Group Easy to understand diagram and explanation of PDA.
- PDA Occluder Amplatzer PDA occluder device used for percutaneous closure of PDAs.
- Children's Hospital Boston Archives