Aortic Valvular Atresia

Book
In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.
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Excerpt

Aortic valvular atresia is a congenital condition in which the aortic valvular cusps are fused at birth. It frequently forms as a spectrum of malformations of the left ventricular outflow tract (LVOT). The atresia can be characterized as sub-valvular, valvular, or supra-valvular, depending on the site of the anomaly. Most commonly, the defect presents as aortic stenosis, though in rare cases, it can manifest as complete atresia. When atretic, the valve can be dome-shaped, monocuspid, bicuspid, or even quadricuspid, and the associated leaflets are dysplastic or fused, not permitting flow through the abnormal valve. It is sometimes but not always associated with congenital ventricular hypoplasia, which can be part of hypoplastic left heart syndrome (HLHS). In this condition, there is abnormal or under-development of the left heart as well as aortic structures. In HLHS, there is often underdevelopment of the mitral valve as well, though there is a universal association with aortic valve abnormalities. Isolated aortic valvular atresia is exceedingly rare, and in context, total aortic valvular atresia can be regarded as the most advanced manifestation of hypoplastic left heart syndrome.

In a classic case of aortic valve atresia, there is generally an anatomic connection between the right and left sides of the heart, usually in the form of either a patent foramen ovale, another form of an atrial septal defect, or in cases with a functioning mitral valve, a ventricular septal defect. The right ventricle is generally dilated rather than thickened, and the left ventricle is hypoplastic and thick-walled, being much smaller than the right ventricle. The mitral valve has been noted to usually be small, and in some cases, there is associated mitral valve atresia as well.

No pathological case report in the literature has shown transposition of the great vessels, and the pulmonary trunk arises normally from the right ventricle with appropriate branching. Due to the lack of an aortic valve, the aortic root generally arises from the base of the heart. The coronary arteries arise normally from the aortic root, but the ascending aorta and arch of the aorta are generally hypoplastic. The branches of the aorta are normal in caliber, and all studied cases report a large ductus arteriosus that empties into the descending aorta, providing mixed-oxygenation blood for the fetus.

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