Interrupted Aortic Arch: Causes, Surgery, and Outcomes

Interrupted aortic arch is a rare congenital heart defect in which the aorta simply stops partway along its curve, leaving a gap between the part that rises from the heart and the part that carries blood down to the body. Without surgical repair, the condition is almost universally fatal in the first weeks of life. The story of how babies with this defect are diagnosed, stabilized, and ultimately repaired involves genetics, prenatal imaging, a critical medication, and operations that have improved markedly over the past few decades.

What the Defect Actually Looks Like

The aorta normally forms a continuous arch: blood leaves the left ventricle, rises through the ascending aorta, curves over the top of the heart while branching off arteries to the head and arms, and then descends through the chest and abdomen to supply the rest of the body. In interrupted aortic arch, that arch has a complete break somewhere along the curve. There is no narrowing or partial blockage; the two segments simply do not connect.

The interruption is classified by where the gap falls. Type A means the break is just beyond the left subclavian artery, the last major branch off the arch. Type B, the most common form, has the break between the left common carotid artery and the left subclavian artery. Type C, which is very rare, places the break between the brachiocephalic (innominate) artery and the left common carotid. The type matters because it determines which vessels still receive blood directly from the heart and which ones are stranded downstream of the gap.

Almost all babies with interrupted aortic arch also have other heart defects. In one large series, about 87% of patients without complex additional anatomy had a ventricular septal defect, a hole between the two lower chambers of the heart. Roughly a quarter also had some degree of obstruction in the left ventricular outflow tract, the passageway through which blood exits the heart into the aorta.

Why It Happens

During early fetal development, the aortic arch forms from a series of paired blood vessels called pharyngeal arch arteries. The fourth pair of these embryonic vessels is responsible for building the segment of the aortic arch that most commonly fails in interrupted aortic arch type B. When molecular signals that guide the development of these vessels go wrong, the fourth arch artery on the left side can fail to form or regress entirely, leaving a gap in the final aorta.

Mouse studies have identified several genes whose loss disrupts fourth pharyngeal arch artery development and produces interrupted aortic arch. Embryos lacking the Gbx2 gene, for example, show cardiovascular defects including type B interruption and abnormal origin of the right subclavian artery.

The 22q11 Deletion and Type B

In humans, one genetic cause stands out. A microdeletion on chromosome 22, known as the 22q11.2 deletion, is found in roughly half of all patients with type B interrupted aortic arch. In a study of 22 patients with the type B form, 11 tested positive for the deletion. That makes type B one of the most genetically uniform congenital heart defects known. The deletion may or may not come with the broader features of DiGeorge syndrome, such as immune problems, low calcium, and characteristic facial features, so the recommendation is that any baby diagnosed with type B interrupted aortic arch should be tested for the 22q11 deletion regardless of whether other signs are present.

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This genetic link has practical consequences. If the deletion is confirmed, families can be counseled about the roughly 50% chance of passing it to future children. Babies with the deletion also need closer monitoring for the immune and endocrine complications that accompany the syndrome, and those complications can complicate the surgical recovery.

Why the First Days of Life Are Critical

Before birth, the gap in the aortic arch does not cause a crisis. A fetal blood vessel called the ductus arteriosus connects the pulmonary artery to the descending aorta, effectively bypassing the missing segment. Blood flows through the ductus to reach the lower body. The trouble begins after delivery, when falling levels of prostaglandin in the newborn’s blood cause the ductus arteriosus to close naturally. Once it closes, the lower body is cut off from blood flow.

If the defect has not been detected on a prenatal ultrasound, the baby typically presents in shock as the ductus narrows and shuts.

⁶ Pulses in the legs disappear, the kidneys and gut stop receiving adequate blood, and metabolic acidosis builds rapidly. This is a medical emergency, and outcomes are dramatically better when the defect is known about before delivery so that a plan is already in place.

Catching It Before Birth

Prenatal diagnosis has improved as fetal echocardiography has become more refined. Certain ultrasound views can raise suspicion of the defect even during routine screening. A discrepancy in the size of the aorta compared to the main pulmonary artery on the three-vessel view is a key clue: in type B, the aorta is much smaller than normal relative to the pulmonary artery. A ventricular septal defect visible on the four-chamber view adds to the suspicion. In a study of eight prenatally diagnosed cases, all had a ventricular septal defect on the four-chamber view, and the ratio of aorta to pulmonary artery diameter was markedly low in type B cases.

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Distinguishing between type A and type B before birth is possible using the same views. Type B tends to show a left-to-right ventricular diameter ratio close to 1.0, while type A shows a smaller left ventricle relative to the right. In some type B cases, the thymus gland is absent or small on ultrasound, another marker of the 22q11 deletion. These prenatal clues allow the delivery to be planned at a center with pediatric cardiac surgery on site, which is one of the single biggest improvements in survival over the past several decades.

Prostaglandin E1 as a Bridge to Surgery

The first step in stabilizing a newborn with interrupted aortic arch is preventing the ductus arteriosus from closing. An intravenous infusion of prostaglandin E1 (PGE1) keeps the ductus open, restoring blood flow to the lower body and buying time for the surgical team to prepare.

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The use of PGE1 for this purpose dates back to the late 1970s, when researchers demonstrated that infusing it into the pulmonary artery of an infant with interrupted aortic arch dilated the ductus and improved systemic perfusion.

⁹ In an early series of eight infants treated within their first four days of life, five of six who received PGE1 responded with return of lower-limb pulses and correction of their acidosis, with no adverse effects attributed to the drug itself.¹⁰ PGE1 can cause side effects like apnea and low blood pressure, so babies on the infusion are typically monitored in an intensive care unit and may need ventilator support, but the drug transformed what had been an almost uniformly fatal presentation into a manageable stabilization period.

Surgical Repair

Once the baby is stable on PGE1, the definitive treatment is open-heart surgery to reconstruct the aortic arch and repair any associated defects. The basic surgical goal is to reconnect the two disconnected segments of the aorta so that blood can flow continuously from the heart to the lower body. In many centers, the descending aorta is brought up and sewn directly to the underside of the aortic arch, sometimes using the bases of the head and neck vessels to widen the connection. A patch of tissue, often from a pulmonary homograft, may be used to reconstruct the concavity of the arch.

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The ventricular septal defect is usually closed at the same time. Whether to address left ventricular outflow tract obstruction in the same operation or in a later procedure is a harder call and varies by center and by the severity of the obstruction.

One-Stage Versus Staged Repair

A major strategic decision is whether to fix everything in a single operation or spread the work across two. For straightforward cases (arch interruption plus a ventricular septal defect, without severe outflow obstruction), most centers now favor a single-stage complete repair. In a large series of 181 patients, about 72% underwent one-stage repair.

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When the anatomy is more complex, especially when significant left ventricular outflow tract obstruction is present, staged repair may be safer. In a comparison of primary versus staged approaches for these complex cases, neonates who had the staged approach experienced fewer major complications (about 36% vs. 61%) and a trend toward lower operative mortality (roughly 5% vs. 12%), though that mortality difference did not reach statistical significance given the numbers studied.

¹³ The choice depends on the specific anatomy, the baby’s clinical condition, and institutional experience.

Complications That Come Later

Even after a technically successful repair, several problems can develop during follow-up. The most common is re-narrowing of the aortic arch at the surgical repair site. Another is left ventricular outflow tract obstruction, which can emerge or worsen over time as the child grows. The reported incidence of post-repair outflow obstruction ranges widely, from under 4% to as high as 67% depending on how it is defined and how closely patients are monitored. Somewhere between 14% and 38% of those who develop it will need a re-intervention.

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Factors that predict this complication include a small aortic valve annulus relative to the baby’s weight, the presence of an abnormally originating right subclavian artery, and the type of material used for the arch repair. Babies with small or medium-sized ventricular septal defects, paradoxically, appear to be at higher risk than those with large defects, possibly because the smaller defect limits blood flow through the outflow tract and masks the obstruction until it becomes severe.

When subaortic obstruction is already severe at the time of diagnosis, simple arch repair and VSD closure may not be enough. In such cases, surgeons have used a modified version of the Norwood procedure, connecting the proximal pulmonary artery to the aorta along with arch reconstruction, to bypass the obstructed outflow tract entirely.

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A less common but potentially serious complication is compression of the bronchi or trachea by the reconstructed arch. Pulling the descending aorta forward to meet the ascending aorta can kink or squeeze the left main bronchus, causing breathing difficulties that may not appear until weeks or months after surgery. Reinterventions for airway compression, residual arch narrowing, and outflow obstruction account for the bulk of re-operations in long-term follow-up.

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Neurodevelopmental Outcomes

Surviving the surgery is one thing; developing normally is another. Neonatal open-heart surgery, especially when it requires periods of deep hypothermic circulatory arrest (temporarily stopping blood flow to the brain while the body is cooled), carries risks for brain development. In a study of children who underwent neonatal repair of interrupted aortic arch, both mental and motor developmental scores at age two were below average. Children without chromosomal abnormalities scored higher but still fell below population norms, with mental scores averaging around 83 and motor scores around 79 on a scale where 100 is the population mean.

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Children with chromosomal abnormalities, particularly the 22q11.2 deletion, had even lower scores, and the presence of a chromosomal abnormality accounted for nearly a third of the variability in developmental outcomes. Among those without chromosomal issues, the duration of circulatory arrest during surgery and the baby’s condition at birth (as reflected by five-minute Apgar scores) were the strongest predictors of how well the child would develop. These findings underline why surgical techniques have increasingly tried to minimize or eliminate circulatory arrest in favor of continuous blood flow to the brain during repair.

Adults Who Were Never Diagnosed

In extremely rare cases, people with interrupted aortic arch survive to adulthood without ever having surgery. Only a handful of such cases have been reported in the medical literature.

¹⁸ The key to their survival is the development of extensive collateral blood vessels, networks of smaller arteries that grow over time to bridge the gap. These collaterals typically arise from the internal mammary arteries, intercostal arteries, and other branches that connect the arterial systems above and below the interruption.

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These adults usually have isolated interrupted aortic arch without the ventricular septal defect and other intracardiac defects that make infancy so dangerous. They often present with high blood pressure in the arms and low blood pressure in the legs, or are found incidentally during imaging for another reason. Their collateral networks can be impressively elaborate, involving the vertebral arteries, the subclavian arteries, and dozens of small chest wall vessels. While they have survived, they are not truly healthy: the collateral circulation puts chronic strain on the heart and blood vessels, and surgical or endovascular repair in adulthood is usually recommended once the diagnosis is made.

Three-Dimensional Printing in Surgical Planning

One of the more recent advances in managing interrupted aortic arch is the use of 3D-printed models of the baby’s heart and vessels. Complex congenital defects are difficult to appreciate fully on a flat screen, and when the anatomy is unusual, even experienced surgeons benefit from holding a physical replica. In one reported case, a 3D model was used to plan the repair of a neonate who had both an aortopulmonary window (an abnormal connection between the aorta and the pulmonary artery) and interrupted aortic arch, helping the team devise a novel surgical approach for a combination of defects that few surgeons ever encounter.

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The technology has also been applied to adult aortic arch surgery. Printed models allow surgeons to rehearse their approach to the arch, test graft sizing, and anticipate difficulties before making an incision.

²¹ For a defect as rare as interrupted aortic arch, where each case presents slightly different anatomy, having a tactile model of the patient’s specific vessels can reduce surprises in the operating room.

Growing Up After Repair

Most children who undergo successful repair of interrupted aortic arch will need medical follow-up for the rest of their lives. The repaired arch may narrow over time, the outflow tract may develop new obstruction, and the heart itself can show long-term effects of the early surgery. As survival rates have improved, the population of adults living with repaired congenital heart disease has grown enormously, and interrupted aortic arch is part of that wave.

The transition from pediatric to adult cardiac care is a recognized challenge for this group. Adolescents who have been followed by a pediatric cardiologist since infancy need to shift to an adult congenital heart disease specialist, and that handoff does not always go smoothly. Gaps in care during the transition years are common and can lead to missed surveillance of known complications. Building self-management skills, maintaining continuity of records, and establishing care with a team experienced in adult congenital heart disease are all recommended as part of a structured transition process.

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For families, the diagnosis of interrupted aortic arch in a newborn is terrifying. But the trajectory of this defect over the past four decades has been one of steadily improving outcomes: better prenatal detection, PGE1 stabilization, refined surgical techniques, and now long-term follow-up programs that carry patients into adulthood. The condition remains serious and the road is long, but the majority of babies born with it today will survive to face the kinds of challenges that come with living with a repaired heart rather than fighting for survival in the first week of life.

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