What is Interrupted Aortic Arch?
Congenital heart disease refers to a condition in which the heart or blood vessels around it don’t develop correctly. It is a fairly common condition affecting around 8 in every thousand babies born across the world and about 1% of births (40,000) each year in the U.S. These cases are considered serious in about 25% of the infants. In fact, this disease accounts for 4.5% of all newborn deaths in America. The chances of a child with congenital heart disease surviving will depend on how severe the condition is, how quickly it is diagnosed, and the treatment they receive. Roughly 97% of babies born with a less severe form of this disease live past their first year, and about 95% can expect to live into their late teens.
One uncommon type of congenital heart disease is called an interrupted aortic arch, or IAA, seen in around 1.5% of patients with this disease. IAA is one of the most severe variants, in which there is a break in the aorta, the main artery carrying blood from the heart. The break disrupts the flow of this blood. In this situation, another blood vessel, called the ductus, becomes the only path for blood to reach parts of the body beyond the break. Roughly 73% of people with IAA also have a ventricular septal defect, an abnormal opening between the heart’s lower chambers, caused by an irregularity in another part of the heart, called the conal septum. This irregularity can potentially block blood flow out of the left side of the heart. Apart from this defect, IAA can also be linked to other more complex heart abnormalities, like the transposition of great arteries, truncus arteriosus, aortopulmonary window, single ventricle, aortic valve atresia, right-sided ductus, and double-outlet right ventricle.
What Causes Interrupted Aortic Arch?
Around half of the people diagnosed with a condition called interrupted aortic arch (IAA) also have a gene deletion in the 22q11.2 region. This gene deletion is known to cause DiGeorge syndrome. Among those with the 22q11.2 deletion, about 75% to 85% have been found to have heart defects present from birth. These heart issues can vary greatly, ranging from those that cause no symptoms at all, to ones that are extremely severe and need immediate medical attention right after birth.
In addition to IAA, patients with this gene deletion can also experience other types of heart defects, which can be categorized into two groups: branchial arch defects and conotruncal defects.
Branchial arch defects are problems related to the development of certain arteries and can include conditions like IAA, narrowing of the aorta (called coarctation), and a right aortic arch (where the aorta, a major blood vessel, is in a different position than usual).
Conotruncal defects include a collection of heart conditions like tetralogy of Fallot (a combination of four heart defects), ventricular septal defects (holes in the wall between the heart’s lower chambers), double-outlet right ventricle (where two arteries, instead of one, come out of the right chamber of the heart), and truncus arteriosus (a single large blood vessel, instead of two separate ones, coming out of the heart).
There’s also another syndrome, called CHARGE, which can also come with an IAA.
Risk Factors and Frequency for Interrupted Aortic Arch
Interrupted aortic arch (IAA) is a condition that occurs in about 2 out of every 100,000 newborns. Typically, babies with IAA start showing symptoms within the first two weeks of their life when a blood vessel known as the ductus arteriosus closes. Often, the signs become noticeable from the first day of life.
Signs and Symptoms of Interrupted Aortic Arch
In simple terms, when a baby has a certain heart condition, they may not show any symptoms until a small blood vessel near the heart, called the ductus arteriosus, closes. After it closes, the baby may start breathing rapidly, struggle with feeding, show signs of respiratory distress, turn bluish due to a lack of oxygen (cyanosis), and stop passing urine (anuria). All these events can lead to shock and, in some cases, death. A physical check-up may reveal that the pulses are not detectable and that there is a difference in blood pressure between the baby’s right arm and lower body parts. Sometimes, there may also be a difference in oxygen levels between the left and right sides of the body.
- Breathing rapidly
- Feeding difficulties
- Respiratory distress
- Bluish coloration (cyanosis)
- Urinary stoppage (anuria)
- Difference in blood pressure between right arm and lower body parts
- Varying oxygen levels between left and right sides of the body
Testing for Interrupted Aortic Arch
If your doctor suspects a particular diagnosis, they would typically start by doing a few tests. These can include a blood gas test, chest X-ray, electrocardiogram (EKG), and echocardiogram. A blood gas test checks the amount of certain gases in your blood, and can help to identify metabolic acidosis, a condition where there’s too much acid in your body.
A chest X-ray can reveal issues like an enlarged heart (a condition known as cardiomegaly) or increased pulmonary markings, which are indicative of a condition affecting the lungs. An EKG is a test that measures the electrical activity of your heartbeat and can help identify heart problems like right or left ventricle enlargement.
An echocardiogram uses sound waves to create detailed pictures of your heart’s structure and function. This test is helpful in identifying any disruptions in the heart’s normal structure or functioning.
If the doctor needs more detailed information about the structure of your heart, they might use other imaging techniques. These can include cardiac angiography, which is a type of X-ray used to see if the coronary arteries are blocked or narrowed; a computed tomography (CT) scan of the chest, which uses X-rays and a computer to produce detailed images of the heart and lungs; and magnetic resonance angiography (MRA), which uses a magnetic field and radio waves to provide detailed images of blood vessels.
Alongside these imaging studies, all patients should have a test called fluorescence in situ hybridization (FISH). This is because there is a high association with a genetic condition known as DiGeorge syndrome, which is caused by a deletion in chromosome 22q11. If you have DiGeorge syndrome, you may also have a low serum calcium level, which can be determined with a blood test.
Treatment Options for Interrupted Aortic Arch
Prostaglandin E1 is a drug used to avoid sudden heart failure and death. This medication helps keep a vital blood vessel, called the ductus arteriosus, open. This vessel ensures blood flow to the lower part of the body until surgery can be performed to correct the issue. If the patient starts to experience shock, drugs that strengthen the heart’s function (inotropes) might be used to help stabilize them.
After diagnosis, immediate surgery is the typical treatment. The goal of this surgery is to ensure a clear structural connection between the two main sections of the aorta (the body’s main artery), called the ascending and descending aorta. The surgery also fixes any other related heart problems, like holes in the walls between heart chambers (atrial and/or ventricular septum defect). The repairs involve using the patient’s own arterial tissue or a vessel patch harvested from another person (homograft) or an autograft (a graft from the patient’s own body). For a ventricular septal defect (a hole in the wall that separates the heart’s lower chambers), special synthetic patches, made from materials like polyester or polytetrafluoroethylene (ePTFE), are used to close the hole.
There is another way of performing the surgery – a two-step process where the first step involves reconstruction and placement of a band on the pulmonary artery (which carries blood from the heart to the lungs). The second step involves closing the hole in the ventricular septum and is done at a later time. During the second step, the band placed on the pulmonary artery is removed.
Sometimes, if there’s a significant blockage in the path that blood takes to flow out of the heart, a mix of two complex surgeries named Norwood and Rastelli procedures may be needed.
What else can Interrupted Aortic Arch be?
Here are some medical conditions that can affect different parts of the heart and body:
- Atrial Septal Defect (ASD)
- Bicuspid aortic valve
- Coarctation of the aorta
- DiGeorge syndrome
- Neonatal sepsis
- Patent Ductus Arteriosis (PDA)
- Transportation of the great vessels
- Truncus Arteriosis
- Velocardiofacial syndrome
- Ventral septal defect
