DESCRIPTION

Functional closure of the ductus arteriosus usually occurs within the 1st 24 hr of life. Complete obliteration of the lumen usually is completed in the 1st wk of life.

EPIDEMIOLOGY

• In the U.S. as an isolated lesion, a persistent PDA has been estimated to occur in 1/2,000–1/5,000 live births and represents 9–12% of all congenital heart lesions.
• Predominant sex: Female > Male

RISK FACTORS

• Prematurity and hypoxemia contribute to persistent patency of the ductus arteriosus.
• Rubella infection early in pregnancy has a high association with persistent patency of the ductus arteriosus.
• Children born at high altitudes have a higher incidence of persistent PDA than do those born at sea level.

Genetics

A genetic factor may be present in some cases. Siblings of patients with a PDA have as high as a 2–4% incidence of having a PDA themselves.

PATHOPHYSIOLOGY

• With persistence of the ductus arteriosus in a neonate, when pulmonary vascular resistance has dropped below the systemic vascular resistance, blood flows from the aorta into the pulmonary artery, resulting in a net left-to-right shunt. This results in an increased volume load on the left atrium and LV. 2 major factors control the degree of shunting:
  • Diameter and length of the ductus arteriosus.
  • Systemic and pulmonary vascular resistance.
• If the left-to-right shunt is significant, symptoms of pulmonary overcirculation develop.

COMMONLY ASSOCIATED CONDITIONS

PDA can be an isolated lesion or can be associated with virtually all other congenital heart defects.

Outline

• Description
• Epidemiology
• Risk Factors
  • Genetics
• Pathophysiology
• Commonly Associated Conditions

History

The clinical history of patients with PDA varies from those who are asymptomatic to those with severe CHF or Eisenmenger syndrome.

Physical Exam

• The clinical findings depend on the magnitude of left-to-right shunt through the PDA and the ability of the heart to manage the extra volume load.
• Premature infants:
  • Diagnosis often made in 1st wk of life, because left-to-right shunt begins early; premature infants usually have low pulmonary vascular resistance from birth.
  • Classical machinery murmur usually is not present.
  • Systolic murmur, which may extend into early diastole, is heard best at the left sternal border in the 2nd and 3rd intercostal spaces.
  • Hyperactive precordium
  • Widened pulse pressure
  • Prominent pulses
  • If a large shunt is present, patients have signs of CHF.
• Term infants, older children:
  • Small PDA:
    • Usually not symptomatic
    • Normal 1st and 2nd heart sounds
    • Murmur usually systolic in infancy and then continuous murmur heard best at 2nd left intercostal space in older child
    • Prominent peripheral pulses
    • Slightly increased arterial pulse pressure
  • Moderate PDA:
    • Patients may have signs of CHF in infancy.
    • Loud continuous murmur with machinery quality at left upper sternal border
    • Increased heart rate
    • Bounding pulses
    • Widened pulse pressure
    • Hyperdynamic precordium
  • Large PDA:
    • Usually have signs of CHF in 1st few months of life
    • Murmur usually is continuous.
    • Increased heart rate
    • Bounding pulses
    • Widened pulse pressure
    • Hyperdynamic precordium
    • May have mid-diastolic rumble at apex
    • May eventually progress to pulmonary vascular disease if untreated; patients with Eisenmenger syndrome are cyanotic and may have differential cyanosis. The classic continuous murmur is absent. There may be no murmur because shunting may be minimal. There may be high-frequency diastolic decrescendo murmur of pulmonary regurgitation or holosystolic murmur of tricuspid regurgitation. Pulmonic component of a single 2nd heart sound will be increased.

DIAGNOSTIC TESTS & INTERPRETATION

ECG:

• Small ductus: ECG is normal.
• Larger ductus: Increased LV forces, occasionally left atrial enlargement
• Larger ductus with pulmonary HTN: Increased biventricular forces, right atrial enlargement

Imaging

• CXR:
  • The radiographic findings vary in proportion to the degree of left-to-right shunting.
  • With a larger shunt, cardiomegaly is present, with enlargement of the LV, left atrium, and prominent pulmonary vasculature
• Echo:
  • The ductus is best imaged in a high left parasternal view.
  • Color flow mapping is essential to demonstrate flow through the ductus.
  • Pulsed and continuous wave Doppler of the ductus are useful for assessing direction of ductal flow and estimating the pulmonary artery pressure.
  • Additional assessment of pulmonary artery pressure by measurement of peak velocity of tricuspid regurgitation jet to estimate RV pressure, Doppler velocity of pulmonary regurgitation flow to estimate pulmonary artery pressure, interventricular septal systolic position to estimate RV pressure, assessment for RV hypertrophy.
  • If a significant shunt exists, left atrial and LV dilatation are seen.
  • Echo has a critical role in excluding other significant intracardiac lesions, especially ductal-dependent lesions.

Diagnostic Procedures/Surgery

Catheterization is rarely needed to make the diagnosis.

Pathological Findings

The normal ductus arteriosus develops embryologically from the dorsal portion of the left 6th aortic arch. The ductus is a muscular artery with intima, media, and adventitia, but histologically, these layers differ from the adjacent pulmonary trunk and aorta.

DIFFERENTIAL DIAGNOSIS

The following lesions also cause continuous or to-and-fro murmurs:

• Venous hum
• Aortopulmonary window
• Arteriovenous fistula
• Ruptured sinus of Valsalva
• Truncus arteriosus
• Absent pulmonary valve
• Ventricular septal defect with aortic insufficiency

Outline

• History
• Physical Exam
• Diagnostic Tests & Interpretation
  • Imaging
  • Diagnostic Procedures/Surgery
  • Pathological Findings
• Differential Diagnosis

• Indomethacin or more recently ibuprofen, another cyclooxygenase inhibitor, has been used successfully to close a PDA in a large proportion of premature infants. It is not effective in term infants.
• Infants with signs of CHF can be managed briefly with anticongestive medications; standard treatment for symptomatic patients is elimination of the ductus arteriosus on an immediate basis.
• A patient with a PDA does not require bacterial endocarditis prophylaxis, according to recommended AHA guidelines.

ADDITIONAL TREATMENT

General Measures

• The classic small to large ductus arteriosus should be eliminated, the timing of which is determined by the presence or absence of symptoms.
• The term silent ductus refers to echocardiographic findings of a minimal color Doppler shunt diagnostic or suggestive of a tiny PDA in a patient with no other physical or laboratory evidence of a PDA. In most cases, the echo study was done for a nonspecific systolic murmur that might well have been classified by a cardiologist as functional without a US study. These patients are often followed without intervention. Endocarditis with silent ductus specifically is virtually unreported.

SURGERY

• Using modern surgical techniques, surgical closure has achieved nearly a 100% success rate with almost no mortality risk and low morbidity.
• Neither the size of the patient nor that of the ductus arteriosus is a limiting factor. Although there have been reports of recanalization after ligation alone, and other rare complications (injury to the recurrent laryngeal nerve, injury to the thoracic duct with chylothorax, or accidental ligation of the left pulmonary artery, descending aorta, or carotid artery), surgical ligation or division of the ductus arteriosus has been the standard for >60 yr:
  • More recently, some institutions have begun video-assisted thorascopic ligation of the PDA. This approach may reduce the postoperative convalescence period and may be associated with less chest wall deformity. A potential drawback is greater difficulty controlling intraoperative bleeding. More experience with this procedure will determine the future role it may play in ductal closure.
• Catheter closure:
  • Catheter closure of a PDA was 1st introduced >20 yr ago and is now accepted as the preferred therapy at most institutions. In patients beyond early infancy, the size of the ductus is not usually a limiting factor for closure. The ductus usually is closed via occluder device or coils.
  • Studies report high success rates with few complications, which include coil embolization, left pulmonary artery stenosis, flow disturbance in the aorta, or hemolysis.

Outline

• Additional Treatment
  • General Measures
• Surgery

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

The follow-up of patients s/p PDA closure should be tailored to the individual patient, based on symptomatology before repair, evidence of pulmonary vascular disease, and mechanism of PDA closure.

PROGNOSIS

• In premature infants, persistent patency of the PDA is common. The great majority will close as the patient matures, but in the context of respiratory distress syndrome, early pharmacologic or surgical intervention often is required.
• Term infants with PDA rarely have spontaneous closure.
• Patients with untreated PDA are at risk for the possible complications listed below.
• The long-term prognosis for children with repaired PDA, and no evidence of vascular disease, is excellent.

COMPLICATIONS

• CHF, usually in young infants with a large ductus arteriosus. Patent ductus arteriosus has been implicated in the occurrence of diminished renal function, and necrotizing enterocolitis in premature infants.
• Bacterial endocarditis
• Aneurysm of the ductus arteriosus
• Pulmonary vascular disease

Outline

• Follow-Up Recommendations
  • Patient Monitoring
• Prognosis
• Complications

CODES

ICD9

747.0 Patent ductus arteriosus

SNOMED

83330001 patent ductus arteriosus (disorder)

ADDITIONAL READING

• Balzer DT, Spray TL, McMullin D, et al. Endarteritis associated with a clinically silent patent ductus arteriosus. Am Heart J. 1993;125:1192.
• Gersony WM, Peckham GJ, Ellison RC, et al. Effects of indomethacin in premature infants with patent ductus arteriosus: Results of a national collaborative study. J Pediatr. 1983;102:895.
• Kirklin JW, Barratt-Boyles BG. Patent ductus arteriosus. In: Cardiac surgery, 2nd ed. New York: Churchill Livingstone, 1993:851.
• Magee AG, Huggon IC, Seed PT, et al. Transcatheter coil occlusion of the arterial duct: Results of the European Registry. Eur Heart J. 2001;22:1817.
• Moore JW, Levi DS, Moore SD, et al. Interventional treatment of patent ductus arteriosus in 2004. Catheter Cardiovasc Interv. 2005;64:91.
• Moore P, Brook MM, Heymann MA. Patent ductus arteriosus and aortopulmonary window. In: Moss and Adams’ Heart Disease in Infants, Children, and Adolescents, 7th ed. Baltimore: Williams & Wilkins, 2008:683–702.
• Pass RH, Hijazi Z, Hsu D, et al. Multicenter USA Amplatzer patent ductus arteriosus occlusion device trial: Initial and one-year results. J Am Coll Cardiol. 2004;44:513.
• Schneider DJ, Moore JW. patent ductus arteriosus. Circulation. 2006;114:1873–1882.
• Villa E, Eynden FV, Le Bret E, et al. Paediatric video-assisted thorascopic clipping of patent ductus arteriosus: Experience in more than 700 cases. Eur J Cardiothorac Surg. 2004;25:387.
• Wang J, Wu M, Hwang J, et al. Transcatheter closure of moderate to large patent ductus arteriosus with the Amplatzer Duct Occluder. Catheter Cardiovasc Interv. 2007;69:572–578.
• Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. A guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation. 2007;115:1–19.

Karen Altmann

Welton M. Gersony