| Interrupted aortic arch | |
|---|---|
| Other names | IAA |
| Specialty | Cardiology,Cardiothoracic surgery |
| Symptoms | Cyanosis, circulatory collapse, differential blood pressure between the upper and lower extremities |
| Complications | Heart failure, shock, multi‑organ failure |
| Usual onset | Neonatal |
| Causes | Congenital developmental defect; frequently associated withDiGeorge syndrome (22q11.2 deletion syndrome) |
| Diagnostic method | Echocardiography,Computed tomography,Magnetic resonance imaging |
| Differential diagnosis | Coarctation of the aorta |
| Treatment | Surgical repair; administration of prostaglandin E1 to maintain ductal patency in the neonatal period |
| Prognosis | Poor without intervention; early surgical repair significantly improves outcomes |
| Frequency | 3 per million live births |
Interrupted aortic arch is a very rareheart defect (affecting 3 per million live births)[1] in which theaorta is not completely developed. There is a gap between the ascending and descendingthoracic aorta. In a sense it is the complete form of acoarctation of the aorta. Almost all patients also have other cardiac anomalies, including a ventricular septal defect (VSD), aorto-pulmonary window, and truncus arteriosus. There are three types of interrupted aortic arch, with type B being the most common. Interrupted aortic arch (especially Type B) is often associated withDiGeorge syndrome.
Patients with an interrupted aortic arch usually have symptoms from birth, with nearly all presenting symptoms within two weeks (when theductus arteriosus is usually closed).[2]
It is thought that an interrupted aortic arch occurs through excessiveapoptosis in the developing, embryonic aorta.[3] Around 50% of patients haveDiGeorge syndrome.[2][4]
It can be diagnosed with a standardechocardiogram.[4] An echocardiogram can also aid in classifying the type of defect.[4] The diagnosis can also be made prior to birth viaultrasound.[3] Patients will have a loss of appetite, appear tired and weak, and exhibitrapid breathing and arapid heart rate.[5] If the condition progresses, the infant may turn pale, feel cold in the lower half of the body, and have a weak pulse due to insufficient blood flow.[5] The pattern of pulse abnormalities is dependent upon the classification; e.g., for type B interrupted aortic arch, theright brachial pulse will bepalpable and the left brachial andfemoral pulses will be impalpable due to closure of theductus arteriosus.[3] Rarely, an interrupted aortic arch can be associated with anintracranial aneurysm.[6] Signs ofischemia due to interrupted aortic arch can be separated by the organ system involved:[3]
CHARGE syndrome, a specific, rare pattern of genetic abnormalities, commonly featuresconotruncal andaortic arch heart defects, which can include an interrupted aortic arch.[7]
There are three primary classifications for an interrupted aortic arch, on the basis of the specific, anatomic anomaly.[5] They are:
Each class can be divided into two subgroups, based upon whether theright subclavian artery originated in a normal, anatomical position (subgroup 1) or if it originateddistal to theleft subclavian artery and continues behind the esophagus (subgroup 2).[8] However, these subgroups do not affect how the disease is diagnosed or treated.[8]
If the diagnosis is made prenatally,prostaglandin E1 (PGE1) is started after birth to avoid closure of theductus arteriosus.[3] Prostaglandin therapy is performed via acontinuous infusion, due to how quickly prostaglandins are metabolized in the body.[9] However, the diagnosis may go undetected, delaying treatment until closure of the ductus arteriosus produces symptoms.[3]
Curative treatment consists ofopen heart surgery soon after birth, preferably immediately after diagnosis.[2] Often, a synthetic patch is used to recreate the lost section of aorta.[2] Recent research has revealed that an initial single-stage repair using direct anastomoses and repair of any existing cardiac defects is the preferred surgical technique, as opposed to a two-stage surgical repair.[10] Awaiting surgery,prostaglandin can be administered to keep theductus arteriosus open, thereby allowing blood flow to the lower body. After successful treatment, the patient is monitored for the rest of their life by aspecialist to ensure that problems do not occur.[5]
Failure to treat the condition yields a mortality rate of 90% at a median age of 4 days.[1] Death occurs due to increased blood flow from the left side of the heart (oxygenated blood) to the right side (deoxygenated blood), inducing heart failure;pulmonary edema; and eventual closing of the ductus arteriosus.[8] For an infant with an interrupted aortic arch, apatent (open) ductus arteriosus allows for blood to bypass the "interruption," without which blood will be unable to reach the lower half of the body.[11] As a result, thekidneys fail andthe blood becomes acidic, resulting in death.[8]
With modern surgical techniques, 81% of children with an interrupted aortic arch survive to be 15 years-old.[6] The fate of survivors in the long-term is still unclear.[1]
The most common, early complication of surgery isbleeding, the risk of which can be increased byprematurity, prolongedacidosis prior to surgery, and excessive tension on theanastamosis due to inadequate mobilization of the ascending and descending aorta.[3] Other early complications include damage to the leftrecurrent laryngeal nerve and thephrenic nerve.[3] Late complications include obstruction of the graft and obstruction of theleft main bronchus (which passes underneath the aortic arch).[3]
The incidence of an interrupted aortic arch is extremely rare, occurring between three[1] and twenty times per 1,000,000 births.[12] In the context of other congenital cardiac abnormalities, interrupted aortic arch represents about 1.5% of cases.[2][3]
The condition was first identified by Dr. Raphael Steidele, Professor of Obstetrics at theUniversity of Vienna, in 1778.[13] In the case Steidele described, the infant had a type A interrupted aortic arch, and survived only for "a few hours."[13] In homage to the discoverer, the terminology of "Steidele's complex" has been used to describe an interrupted aortic arch.[13] The first type B interrupted aortic arch was reported by Seidel in 1818, and the first type C was reported by Weisman and Kesten in 1948.[8] The classification system (Types A, B, and C) were defined by Celoria and Patton in 1959.[1]
The first successful repair of a Type A interrupted aortic arch was reported in 1961, in which the left subclavian artery was grafted into thedescending thoracic aorta in a 14-year-old male patient.[8] The first successful repair of a Type A interrupted aortic arch in an infant was in a 12-day-old infant in 1969, in which the left subclavian artery wasconnected to the descending thoracic aorta, thepatent ductus arteriosus was closed, and the mainpulmonary artery was banded.[8]
The first successful repair of a Type B interrupted aortic arch was in 1954, in which the 16 year-old, female patient'sown aorta was grafted from the arch to the descending thoracic aorta and the left subclavian artery wasligated.[8] The first successful repair on a type B interrupted aortic arch in an infant was in 1973, in which a vein was used to connect the ascending aorta and the descending aorta.[8]
The first successful repair of a Type C interrupted aortic arch was in 1964, in which the 16-year-old female patient's ascending aorta was grafted to the descending thoracic aorta.[8] As of 1984, there had been no successful repairs on infants under one year old.[8]
The use ofPGE1 dramatically improved the mortality rate after its introduction in 1976.[3]
While PGE1 is the standard of care for maintaining the ductus arteriosus, there is insufficient data on the proper dose, duration of therapy, safety, and long-term consequences of PGE1 on infants with ductal-dependent congenital heart defects (like interrupted aortic arch).[14]