Aortopulmonary Septal Defect

Updated: Feb 01, 2021
  • Author: Barry A Love, MD; Chief Editor: Stuart Berger, MD  more...
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Aortopulmonary septal defect (APSD), an uncommon congenital cardiac defect, is a deficiency in the septum between the aorta and pulmonary artery, resulting in a communication between the two. This defect is present as an isolated lesion in about one half of patients and in conjunction with another defect or more complex heart disease in the other half of patients. [1]

Developmentally, the defect results from incomplete separation of the common tube of the truncus arteriosus and the aorticopulmonary trunk. [2, 3] During early embryonic development, the aorta and pulmonary arteries separate by growth of a spiral septum dividing the common trunk into the aorta and the pulmonary artery. The spiral septum is created by fusion of a truncal septum growing cephalad from the semilunar valves and the aorticopulmonary spiral septum growing caudally from the pulmonary bifurcation. Incomplete development of these septa results in aortopulmonary septal defect.

van Mierop subdivided aortopulmonary septal defect into three subtypes. [4] The first subtype is believed to result from nonfusion between the aorticopulmonary septum above and the truncal septum below, resulting in a small-to-moderate defect midway between the semilunar valves and the pulmonary bifurcation. The second type is also believed to arise from a failure of fusion of the aorticopulmonary septum above and the truncal septum below; however, this failure of fusion results in a large, nonrestrictive defect without a continuous posterior border, in which the defect describes more than one spiral turn. The third type is absence of the aorticopulmonary septum; the defect is large and without a posterior border, and the right pulmonary artery may arise directly from the aorta. Although this classification system may correlate with the various embryologic origins of aortopulmonary septal defect itself, it does not account for other anomalies encountered with aortopulmonary septal defect.

Patent ductus arteriosus (PDA) is encountered in almost three fourths of patients with aortopulmonary septal defect. [5, 6] An interrupted aortic arch type A or severe coarctation is present in 10-15% of patients with aortopulmonary septal defect. [7] Discontinuity of the aorta in interrupted aortic arch type A occurs distal to the left subclavian artery, as in a severe form of aortic coarctation. This is quite different developmentally from interrupted aortic arch type B, in which discontinuity occurs between the left carotid artery and left subclavian arteries. Interrupted aortic arch type B is frequently associated with DiGeorge/velocardiofacial/22q-chromosome arm deletion, unlike interrupted aortic arch type A. When interrupted aortic arch occurs without a ventricular septal defect (VSD), an aortopulmonary septal defect is usually present. [8]

Tetralogy of Fallot and anomalous coronary from pulmonary artery are each present in about 5% of cases. [9, 10] Other reported anomalies associated with aortopulmonary septal defect include VSD, aortic atresia, transposition of the great arteries, [11, 12] double aortic arch, and other more complex heart diseases.

Aortopulmonary septal defect has been described in other mammals including dogs, cats, and horses. [13]



The fetus is unaffected by this defect. Problems arise after birth with the fall in pulmonary vascular resistance (PVR) that typically takes place over the first days and weeks of life. As PVR falls, progressive shunting of blood from the systemic circuit to the pulmonary circuit results in pulmonary edema and signs and symptoms of congestive heart failure (CHF) similar to those seen with a large VSD or PDA. Left untreated, irreversible pulmonary vascular obstructive disease (PVOD) is likely to develop. In some cases, PVR does not fall significantly after birth and the phase of CHF is not apparent. In these instances, PVOD is a consequence nonetheless.



Aortopulmonary septal defect is likely caused by multifactorial genetic etiologies. No clear inheritance pattern is noted in most patients. Although this defect appears to have clinical similarities with truncus arteriosus and interrupted aortic arch type B, aortopulmonary septal defect is not associated with the 22q-/DiGeorge syndrome as are the other malformations. Note that the aortic arch interruption commonly associated with aortopulmonary septal defect occurs as type A rather than type B.

Rarely, aortopulmonary septal defect has been described in children affected by other syndromes, including vertebral, anorectal, cardiac, tracheoesophageal, renal, and limb (VACTERL) association, with one case report of an infant with terminal 2q deletion. [14]

One small case series described three unrelated children with iris hypoplasia and aortopulmonary septal defect. [15] The hypothesized association between the two problems is an error in neural crest development.



United States data

Aortopulmonary septal defect is a rare defect that comprises about 0.1-0.3% of congenital heart diseases in children. No attempt to assess regional or worldwide variation in incidence has been made.

International data

A large case series from India reported an overall frequency of surgery for aortopulmonary septal defect of 0.6% of all surgeries performed for congenital heart disease. [16]

Race-, sex-, and age-related demographics

No racial predilection is observed.

The male-to-female ratio is approximately 1.8:1.

As a congenital disease, all cases are present from birth. The diagnosis is typically made in infancy but may be delayed if persistently elevated PVR occurs. Because of improved fetal ultrasonography, prenatal diagnosis of aortopulmonary septal defect has also been reported. [17, 18]



Infants with an isolated aortopulmonary septal defect have an excellent prognosis for normal cardiac function and a normal lifestyle. [1]

Patients with a more guarded prognosis include older patients with pulmonary resistance of greater than 8 Wood U/m2 at preoperative assessment and those with more complex associated malformations where prognosis depends more on those lesions than on aortopulmonary septal defect.

A small incidence of reintervention for stenosis of the great arteries has been reported.


Left untreated, an aortopulmonary window results in irreversible pulmonary vascular changes and early mortality. With surgical treatment in the absence of PVOD, the prognosis for isolated aortopulmonary window is good. In the presence of more complex heart disease, prognosis depends more on the nature of other lesions. [19]


The most concerning complication in the repair of aortopulmonary septal defect is perioperative death from pulmonary hypertensive crisis in the child with pulmonary vascular obstructive disease (PVOD).

Other generic surgical complications include, but are not limited to, infection, brain injury, and permanent heart block. Although these are considerations, they should be of no higher risk in this procedure than they are in other cardiac procedures using cardiopulmonary bypass.

Specific anatomic risks of repair include incomplete closure of the defect and aortic or pulmonary artery distortion. Other complications may relate to repair of associated defects.


Patient Education

An experienced healthcare team comprised of nurses, social workers, and spiritual counselors can provide important support to parents of infants with newly diagnosed congenital heart disease.

For patient education resources, see the Heart Health Center and Tetralogy of Fallot.