CHDFNigeria
Interrupted aortic arch (IAA) is a very rare heart defect (affecting 3 per million live births) in which the aorta is not completely developed. There is a gap between the ascending and descending thoracic aorta. IAA can be associated with other more complicated cardiac anomalies; for example, ventricular septal defect (VSD), transposition of the great arteries, truncus arteriosus, aortopulmonary window, single ventricle, aortic valve atresia, right-sided ductus, and double-outlet right ventricle.
Classification
According to the Celoria and Patton classification, Interrupted aortic arch can be grouped into three types:
- Type A: The disruption is located distal to the left subclavian artery; this is the second most common disruption represents approximately 13% of the cases.
- Type B: The disruption is located between the left carotid artery and the left subclavian artery; this is the most common anomaly, representing approximately 84% of the cases, and is the classification most often associated with DiGeorge syndrome.
- Type C: The disruption is located between the innominate artery and the left carotid artery; this is a rare type represents approximately 3% of all cases.
Epidemiology
The incidence of interrupted aortic arch (IAA) is about 2 cases per 100,000 live births. Nearly all patients with IAA present in the first 2 weeks of life when the ductus arteriosus closes. Most patients present in the first day of life.
Pathophysiology
During fetal circulation, the ductus arteriosus provides blood to the distal extremities of the fetus and the upper part of the body receives its blood supply from the left ventricle to the aorta. After birth, the pulmonary vascular resistance decreases, promoting the closure of the ductus arteriosus. This leads to the inability of the heart to provide blood to the distal part of the body and produces respiratory distress and cyanosis, leading to cardiogenic shock and death if the necessary measures are not instated in time.
Signs and symptoms
Signs and symptoms of poor perfusion, heart failure or shock may develop when the ductus arteriosus begins to close, usually within the first day or two of life. They include:
- fatigue
- poor feeding
- rapid breathing
- fast heart rate
- parlor
- mottled skin
- poor perfusion and coolness in lower half of the body
- reduced urine output and less wet nappies low oxygen levels and poor pulses particularly when measured in the legs and feet.
- Shock when condition worsens
- weak pulse and difference in pulse findings in the brachial and femoral region,
- Signs of ischaemia to organ system can be seen due to IAA and poor organ perfusion. These include signs of kidney injury (creatine levels) , liver injury (elevated Ast /SGOT, LDH levels , intestinal injury (Necrotizing Enterocolitis, NEC)
Diagnosis
Diagnosis of interrupted aortic arch may be suspected based on the symptoms the infant has on presentation. It is then confirmed by echocardiography. Further investigations may be requested as with other CHDs
Management of IAA
Stabilization: Immediate treatment includes the administration of a prostaglandin infusion. Prostaglandin is a medication that is administered intravenously (IV) and keeps the ductus arteriosus open. This allows blood flow to the lower body until surgery is done to re-establish continuity of the aortic arch. Goals of treatment are aimed at stabilizing and supporting the infant until surgical intervention. Such treatment may include:
– Intubation (Endotracheal or “breathing tube” placed in the airway) and mechanical ventilation.
– Administration of inotropic medications (to help improve the pumping action of the heart)
– Monitoring and correction of abnormal blood gases (carbon dioxide and oxygen levels in the blood) and electrolytes (potassium and calcium levels in the blood)
– Administration of nutrition via enteral means, usually by nasogastric tube, called NG tubes.
Open-heart surgery will be done to connect the two separate portions of the aorta, close the ventricular septal defect and tie off (ligate) the patent ductus arteriosus depending on child’s case. Surgery is typically performed urgently but after the infant is stabilized (usually in the first few days of life).
Prognosis
Failure to treat the condition yields a mortality rate of 90% at a median age of 4 days. 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.
