Aortic Valve Atresia - Types, Causes, Symptoms, Diagnosis, Treatment, and Prognosis

Introduction:

Aortic valve atresia is one of the rare anomalies of the heart present at birth due to the fusion or closure of the aortic valvular cusps, which compromises the blood flow from the left ventricle into the aorta. It is a common cause of fatality in neonates with heart problems. It is also a commonly occurring feature in hypoplastic left heart syndrome.

What Is Hypoplastic Left Heart Syndrome?

• It is a rare congenital heart condition that is associated with an underdeveloped left heart and its parts.

• It is a complex condition associated with several other heart defects, including aortic valve atresia.

• This defect affects the normal blood flow within the heart.

• The right side of the heart manages this defect by performing the functions of the left heart, such as pumping the blood into the lungs and supplying it to the entire body.

What Is Atresia?

Atresia is a condition in which normal openings of the parts of the body are closed or absent due to underdevelopment. It is a congenital (present at birth) defect and can affect any organ in the body.

What Is Aortic Valve Atresia?

• Aortic valve atresia is a condition in which the cusps (a triangular flap of tissue that opens and closes the heart valves to promote blood flow in and out of the heart) of the aortic valve become thick or appear fused, causing the narrowing of the valves, which prevents the blood flow from the heart.

• The aortic valve has three cusps, namely, the left coronary cusp, right coronary cusp, and non-coronary cusp.

What Are the Types of Atresia?

Depending upon the site at which the defect is seen, it is classified as;

• Sub valvular (occurring below the valve).

• Valvular.

• Supra valvular (occurring above the valve).

What Are the Features of Aortic Valve Atresia?

The aortic valve atresia presents with different features depending upon the defects involved. Commonly occurring feature includes;

• In aortic valve atresia, there is an abnormal connection between the left and the right sides of the heart, which is absent otherwise.

• Also, the right ventricle, which is usually thick, is dilated. And the left ventricle appears thickened and very small compared to the right ventricle.

• The mitral valve appears relatively small and sometimes shows atresia as well.

What Happens in Aortic Valve Atresia?

• Oxygenated (pure) blood comes back after purification from the lungs into the heart's left side, which leaks abnormally into the right side due to the abnormal connection between the left and right sides of the heart.

• In the right ventricle, the oxygenated blood gets mixed with deoxygenated (impure) blood and creates pressure within the right side of the heart.

• Resulting in the delivery of mixed blood to the systemic supply, leading to systemic complications.

What Are the Symptoms of Aortic Valve Atresia?

• Cyanosis (bluish discoloration of the body).

• Pulmonary edema (fluid accumulation in the lungs).

• Hepatomegaly (enlargement of the liver).

• Heart failure.

• Dyspnea (shortness of breath).

• The precordium bulge is not a reliable feature but is still noted in a few cases. (the skin over the heart called the precordium shows a bulge on palpation).

• Palpable spleen.

• Low blood pressure.

• Scanty pulse.

What Are the Causes of Aortic Valve Atresia?

• The cause of aortic atresia is unknown. But some cases have shown a genetic link to this condition due to mutations in the genes.

• It occurs predominantly in males than females.

How Is Aortic Valve Atresia Diagnosed?

Evaluation of this condition starts in the prenatal period. The investigations that are done to rule out atrial valve atresia include;

• Echocardiogram using color doppler.

• Chest radiography.

How Is Aortic Valve Atresia Treated?

• The treatment for aortic valve atresia is complex and requires a multidisciplinary approach (intervention of doctors from various specialties) for its management.

• A team of cardiologists, pediatric surgeons, and pediatricians decide this condition's management depends upon the associated defects.

• Surgery is the only management for this condition. Various surgical procedures are performed that vary with the type of underlying defect.

• In some cases, follow-up surgeries are indicated as well.

What Is the Prognosis of Aortic Valve Atresia?

The prognosis of the aortic valve atresia with and without intervention does not show much variation. It accounts for the majority of deaths in children with heart diseases. If aortic valve atresia is suspected in neonates, they should be initiated with prostaglandins E1 (naturally available prostaglandin used to treat heart diseases in children).

What Are the Complications Associated With Aortic Valve Atresia?

Complications could occur during surgery. Post-surgical complications in neonates include;

1. Risk of bronchitis (inflammation of the bronchial tubes that carry air from and into the lungs).

2. Pulmonary arteriovenous malformations (abnormal communications between the pulmonary arteries that carry the impure blood from the heart to lungs and the pulmonary vein that carries blood from the lungs to the heart).

3. Protein-losing enteropathy (leakage of proteins from the blood into the intestines).

4. Surgical site infection.

5. Hypoxia (lack of oxygen supply in the body).

What Is the Differential Diagnosis of Aortic Valve Atresia?

The rare congenital disabilities in the heart that could be mistaken for aortic valve atresia include;

• Tetralogy of Fallot (a rare condition associated with four heart defects).

• Hypoplastic left heart syndrome (underdeveloped left heart).

• Tricuspid valve atresia.

• Pulmonic valve atresia. (difficulty in the blood flow from the heart to the lungs).

• Ebstein anomaly (abnormal positioning of the tricuspid valve with defects in its cusps).

What Are the Prevention Protocols for Aortic Valve Atresia?

Though there is no prevention for this condition, pregnant women should be advised to take utmost care, take vitamins and mineral supplements as prescribed, and not miss any monthly follow-up appointments.

Conclusion:

Aortic valve atresia is a rare, serious heart defect with no accurate information on the cause and prevention. Yet, the survival period seems to have slightly improved with surgical management.