eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Patent Ductus Arteriosus

Author: Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine
Contributor Information and Disclosures

Updated: Jul 23, 2009

Introduction

Background

Patent ductus arteriosus (PDA) is one of the more common congenital heart defects. The presentation widely varies. Depending on the size of the patent ductus arteriosus, the gestational age of the neonate, and the pulmonary vascular resistance, a premature neonate may develop life-threatening pulmonary overcirculation in the first few days of life. Conversely, an adult with a small patent ductus arteriosus may present with a newly discovered murmur well after adolescence.

During fetal life, the ductus arteriosus is a normal structure that allows most of the blood leaving the right ventricle to bypass the pulmonary circulation and pass into the descending aorta. Typically, only about 10% of the right ventricular output passes through the pulmonary vascular bed.

The ductus arteriosus is a remnant of the distal sixth aortic arch and connects the pulmonary artery at the junction of the main pulmonary artery and the origin of the left pulmonary artery to the proximal descending aorta just after the origin of the left subclavian artery. Most typically, it is a left aortic remnant. A right-sided patent ductus arteriosus can occur, or the ductus arteriosus can be present on both the right and the left. Although a left ductus arteriosus is a normal structure during normal fetal development, the presence of a right ductus arteriosus is usually associated with other congenital abnormalities of the cardiovascular system, most typically involving the aortic arch or conotruncal development.

Pathophysiology

A patent ductus arteriosus produces a left-to-right shunt. In other words, it allows blood to go from the systemic circulation to the pulmonary circulation. Therefore, pulmonary blood flow is excessive.

Schematic diagram of left-to-right shunt of blood...

Schematic diagram of left-to-right shunt of blood flow from descending aorta via patent ductus arteriosus (PDA) to main pulmonary artery

Schematic diagram of left-to-right shunt of blood...

Schematic diagram of left-to-right shunt of blood flow from descending aorta via patent ductus arteriosus (PDA) to main pulmonary artery


The magnitude of the excess pulmonary blood flow depends on relatively few factors. The larger the internal diameter of the narrowest portion of the ductus arteriosus, the larger the left-to-right shunt. If the ductus arteriosus is restrictive, then the length of the narrowed area also affects the magnitude of the shunt. A longer ductus is associated with a smaller shunt. Finally, the magnitude of the left-to-right shunt is partially controlled by the relationship of the pulmonary vascular resistance to the systemic vascular resistance.

If the systemic vascular resistance is high and/or the pulmonary vascular resistance is low, the flow through the ductus arteriosus is potentially large. Beginning at the ductus arteriosus, the course of blood flow in a typical patent ductus arteriosus with pulmonary overcirculation is as follows: patent ductus arteriosus, pulmonary arteries, pulmonary capillaries, pulmonary veins, left atrium, left ventricle, aorta, patent ductus arteriosus. Therefore, a large left-to-right shunt through a patent ductus arteriosus results in left atrial and left ventricular enlargement. Additionally, the pulmonary veins and the ascending aorta can be dilated with a sufficiently large patent ductus arteriosus. Also, if little or no restriction is present at the level of the patent ductus arteriosus, pulmonary hypertension results.

The ductus arteriosus is normally patent during fetal life. This patency is promoted by continual production of prostaglandin E2 (PGE2) by the ductus. Prostaglandin antagonism, such as maternal use of nonsteroidal anti-inflammatory medications, can cause fetal closure of the ductus arteriosus. This can be associated with severe fetal cardiovascular compromise.

Normally, functional closure of the ductus arteriosus occurs by about 15 hours of life in healthy infants born at term. This occurs by abrupt contraction of the muscular wall of the ductus arteriosus, which is associated with increases in the partial pressure of oxygen (PO2) coincident with the first breath. This was first demonstrated by multiple experiments in the 1940s and has been subsequently confirmed. Although the neonatal ductus appears to be highly sensitive to changes in arterial oxygen tension, the actual reasons for closure or persistent patency are complex and involve manipulation by the autonomic nervous system, chemical mediators, and the ductal musculature.

Although functional closure usually occurs in the first few hours of life, true anatomic closure, in which the ductus loses the ability to reopen, may take several weeks. Cassels et al defined true persistence of the ductus arteriosus as a patent ductus arteriosus present in infants older than 3 months.1

Frequency

United States

The estimated incidence in children born at term is between 0.02% and 0.006% of live births. This incidence is increased in children who are born prematurely, children with a history of perinatal asphyxia, and, possibly, children born at high altitude. Perinatal asphyxia usually only delays the closure of the ductus, and, over time, the ductus typically closes without specific therapy.

Mortality/Morbidity

Low birthweight premature infants

As many as 20% of neonates with respiratory distress syndrome have a patent ductus arteriosus. In babies who are less than 1500 g at birth, many studies show the incidence of a patent ductus arteriosus to exceed 30%. The increased patency in these groups is thought to be due to both hypoxia in babies with respiratory distress and immature ductal closure mechanisms in premature babies. Premature babies, particularly low birthweight neonates, are more likely to have problems related to patent ductus arteriosus. Spontaneous closure of the patent ductus arteriosus in premature neonates is common, but respiratory distress and impaired systemic oxygen delivery (congestive heart failure) often drive the need for therapy to effect ductal closure in this group. Low birthweight neonates with a patent ductus arteriosus are more likely to develop chronic lung disease.

Otherwise healthy infants, children, adolescents, and adults
 
In the preantibiotic era, Campbell et al estimated the natural history mortality rates for untreated patent ductus arteriosus to be 0.42% per year from age 2-19 years, 1-1.5% per year in the third decade, 2-2.5% per year in the fourth decade, and 4% per year in persons older than 40 years.2 Currently, with the availability of antibiotics to treat endocarditis and low-risk surgery and catheter techniques to obliterate the patent ductus arteriosus, the mortality rate appears to be quite low except in the extremely premature infant.

Sex

The female-to-male ratio is 2:1 if not associated with other risk factors. In patients in whom the patent ductus arteriosus is associated with a specific teratogenic exposure, such as congenital rubella, the incidence is equal between the sexes.

Age

The ductus arteriosus is always patent in the fetus if the cardiovascular system is otherwise normal. Normally, the ductus arteriosus closes functionally in the first 10-18 hours of life. Prematurity, perinatal distress, and hypoxia delay closure of the ductus arteriosus; however, most children who are found to have a ductus arteriosus have no history of precedent risk factors.

Clinical

History

The typical child with a patent ductus arteriosus (PDA) is asymptomatic.

  • A history of premature birth, perinatal distress, or perinatal hypoxia may be present.
  • Some series have suggested that children born at extreme altitude have an increased incidence of a persistent patent ductus arteriosus.
  • Occasionally, a history of feeding difficulties and poor growth during infancy, described as failure to thrive, is found. However, frank symptoms of congestive heart failure are rare.
  • In the low birthweight premature infant, diagnosing a patent ductus arteriosus on auscultation may be difficult. Babies that have a more severe clinical course of hyaline membrane disease may have a higher prevalence of patent ductus arteriosus. The exact reason for this is unclear.

Physical

As many as one third of children with patent ductus arteriosus are small for their age. In the presence of significant pulmonary overcirculation, tachypnea, tachycardia, and a widened pulse pressure may be found.

  • Findings upon cardiac examination include the following:
    • If the left-to-right shunt is large, precordial activity is increased, with the magnitude of increased activity related to the magnitude of left-to-right shunt.
    • The apical impulse is laterally displaced. A thrill may be present in the suprasternal notch or in the left infraclavicular region.
    • The first heart sound (S1) is typically normal. The second heart sound (S2) is often obscured by the murmur. Phonocardiographic data from the past suggested the occurrence of paradoxical splitting of S2 related to premature closure of the pulmonary valve and a prolonged ejection period across the aortic valve.
    • In 1898, Gibson described the classic murmur. Subsequently, the classic patent ductus arteriosus murmur has been referred to as a machinery murmur, which is continuous. The murmur may be accentuated in systole. Typically, the murmur is loudest at the left upper chest. If the pulmonary-to-systemic blood ratio approaches or exceeds 2:1, an apical flow rumble, caused by high flow into the left ventricle, is frequently present. Also, because flow through the left ventricle into the aorta is increased, an aortic ejection murmur may be present. If the patent ductus arteriosus is small, the amplitude of the murmur may increase with inspiration as pulmonary impedance drops.
  • The peripheral pulses are often referred to as bounding. This is related to the high left ventricular stroke volume, which may cause systolic hypertension. The phenomenon of bounding pulses also is caused by the low diastolic pressure in the systemic circulation as blood runs off from the aorta into the pulmonary circulation.
  • In the low birthweight premature infant, the classic signs of a patent ductus arteriosus are usually absent. The classic continuous murmur is rarely heard. A rough systolic murmur may be present along the left sternal border, but a small baby with a large patent ductus arteriosus and significant pulmonary overcirculation may have no murmur. In that case, typically, precordial activity is increased and peripheral pulses are bounding. The increased precordial activity is caused by the large left ventricular stroke volume. Bounding pulses are caused by the relatively low systemic arterial blood pressure due to the continuous runoff of blood from the aorta into the pulmonary artery.

Causes

  • Familial cases of patent ductus arteriosus have been recorded, but a genetic cause has not been determined. In infants born at term who have a persistent patent ductus arteriosus, the recurrence rate among siblings is 5%. Some early evidence suggests that as many as one third of cases are caused by a recessive trait labeled PDA1, located on chromosome 12, at least in some populations. 
  • Several chromosomal abnormalities are associated with persistent patency of the ductus arteriosus. Implicated teratogens include congenital rubella (associated with patent ductus arteriosus and pulmonary artery branch stenosis), fetal alcohol syndrome, maternal amphetamine use, and maternal phenytoin use.

More on Patent Ductus Arteriosus

Overview: Patent Ductus Arteriosus
Differential Diagnoses & Workup: Patent Ductus Arteriosus
Treatment & Medication: Patent Ductus Arteriosus
Follow-up: Patent Ductus Arteriosus
Multimedia: Patent Ductus Arteriosus
References

References

  1. Cassels DE, Bharati S, Lev M. The natural history of the ductus arteriosus in association with other congenital heart defects. Perspect Biol Med. Summer 1975;18(4):541-72. [Medline].

  2. Campbell DC, Hood RH Jr, Dooley BN. Patent ductus arteriosus. Review of literature and experience with surgical corrections. J Lancet. Oct 1967;87(10):415-8. [Medline].

  3. [Best Evidence] Ohlsson A, Walia R, Shah S. Ibuprofen for the treatment of patent ductus arteriosus in preterm and/or low birth weight infants. Cochrane Database Syst Rev. Jan 23 2008;CD003481. [Medline].

  4. Sekar KC, Corff KE. Treatment of patent ductus arteriosus: indomethacin or ibuprofen?. J Perinatol. May 2008;28 Suppl 1:S60-2. [Medline].

  5. Brion LP, Soll RF. Diuretics for respiratory distress syndrome in preterm infants. Cochrane Database Syst Rev. Jan 23 2008;CD001454. [Medline].

  6. [Best Evidence] Attridge JT, Kaufman DA, Lim DS. B-type natriuretic peptide concentrations to guide treatment of patent ductus arteriosus. Arch Dis Child Fetal Neonatal Ed. May 2009;94(3):F178-82. [Medline].

  7. Bose CL, Laughon MM. Patent ductus arteriosus: lack of evidence for common treatments. Arch Dis Child Fetal Neonatal Ed. Nov 2007;92(6):F498-502. [Medline].

  8. Cambier PA, Kirby WC, Wortham DC, Moore JW. Percutaneous closure of the small (less than 2.5 mm) patent ductus arteriosus using coil embolization. Am J Cardiol. Mar 15 1992;69(8):815-6. [Medline].

  9. Corbet AJ. Medical manipulation of the ductus arteriosus. In: The Science and Practice of Pediatric Cardiology. Lippincott Williams & Wilkins; 1997:2489-514.

  10. Dudell GG, Gersony WM. Patent ductus arteriosus in neonates with severe respiratory disease. J Pediatr. Jun 1984;104(6):915-20. [Medline].

  11. Gross RE, Hubbard JP. Surgical ligation of a patent ductus arteriosus. JAMA. 1939;112:729-31.

  12. Heymann MA, Rudolph AM. Control of the ductus arteriosus. Physiol Rev. Jan 1975;55(1):62-78. [Medline].

  13. [Best Evidence] Madan JC, Kendrick D, Hagadorn JI, Frantz ID 3rd. Patent ductus arteriosus therapy: impact on neonatal and 18-month outcome. Pediatrics. Feb 2009;123(2):674-81. [Medline].

  14. Mahony L, Carnero V, Brett C, et al. Prophylactic indomethacin therapy for patent ductus arteriosus in very- low-birth-weight infants. N Engl J Med. Mar 4 1982;306(9):506-10. [Medline].

  15. [Best Evidence] Malviya M, Ohlsson A, Shah S. Surgical versus medical treatment with cyclooxygenase inhibitors for symptomatic patent ductus arteriosus in preterm infants. Cochrane Database Syst Rev. Jan 23 2008;CD003951. [Medline].

  16. Mullins CE, Pagotto L. Patent ductus arteriosus. In: The Science and Practice of Pediatric Cardiology. Lippincott Williams & Wilkins; 1997:1181-98.

  17. Ramsay JM, Murphy DJ Jr, Vick GW 3rd, et al. Response of the patent ductus arteriosus to indomethacin treatment. Am J Dis Child. Mar 1987;141(3):294-7. [Medline].

  18. Rashkind WJ, Mullins CE, Hellenbrand WE, Tait MA. Nonsurgical closure of patent ductus arteriosus: clinical application of the Rashkind PDA Occluder System. Circulation. Mar 1987;75(3):583-92. [Medline].

  19. Reller MD, Colasurdo MA, Rice MJ, McDonald RW. The timing of spontaneous closure of the ductus arteriosus in infants with respiratory distress syndrome. Am J Cardiol. Jul 1 1990;66(1):75-8. [Medline].

  20. Van Overmeire B, Smets K, Lecoutere D, et al. A comparison of ibuprofen and indomethacin for closure of patent ductus arteriosus. N Engl J Med. Sep 7 2000;343(10):674-81. [Medline].

Further Reading

Keywords

patent ductus arteriosus, patent arterial duct, PDA, congenital heart defect, aorticopulmonary shunt, aorticopulmonary communication, ductus arteriosus, pulmonary hypertension, respiratory distress syndrome, congestive heart failure, rubella, fetal alcohol syndrome

Contributor Information and Disclosures

Author

Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine
Steven R Neish, MD, SM is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, and American Heart Association
Disclosure: Nothing to disclose.

Medical Editor

Christopher Johnsrude, MD, Associate Professor of Pediatrics, Director of Electrophysiology, University of Louisville School of Medicine; Consulting Staff, Pediatric Cardiology Associates, PSC
Christopher Johnsrude, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Cardiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Hugh D Allen, MD, Professor, Department of Pediatrics, Division of Pediatric Cardiology and Department of Internal Medicine, Ohio State University College of Medicine
Hugh D Allen, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, American Pediatric Society, American Society of Echocardiography, Society for Pediatric Research, Society of Pediatric Echocardiography, and Western Society for Pediatric Research
Disclosure: Nothing to disclose.

CME Editor

Gilbert Z Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College; Consulting Staff, Department of Pediatrics, Sound Shore Medical Center
Gilbert Z Herzberg, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Chief Editor

Stuart Berger, MD, Professor of Pediatrics, Division of Cardiology, Medical College of Wisconsin; Chief of Pediatric Cardiology, Medical Director of Pediatric Heart Transplant Program, Medical Director of The Heart Center, Children's Hospital of Wisconsin
Stuart Berger, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American College of Chest Physicians, American Heart Association, and Society for Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

 
 
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