**Congenital Anomalies of the Aortic Valve**

266 Aortic Valve

Zheng, Y., John, M., Liao, R., Boese, J., Kirschstein, U., Georgescu, B., Zhou, S. K., Kempfert, J.,

DOI 10.1007/978-3-642-15705-9\_46

Walther, T., Brockmann, G. & Comaniciu, D. (2010). Automatic Aorta Segmentation and Valve Landmark Detection in C-arm CT: Application to Aortic Valve Implantation. *Med Image Comput Comput Assist Interv*, Vol. 13, No. Pt 1, pp. 476-83,

**14** 

*USA* 

**Unicuspid Aortic Valve** 

Venkata Thota and Farouk Mookadam *Mayo Clinic College of Medicine, Scottsdale, AZ* 

Unicuspid aortic valve was first described more than half a century ago (Edwards, 1958). Although reported infrequently, the natural history of unicuspid aortic valve is poorly understood. Developmental abnormalities of aortic valve cusps in decreasing order of frequency include bicuspid (0.9%-1.3%), unicuspid (0.02%), quadricuspid (0.008%- 0.043%), and pentacupsid aortic valves (Cemri, 2000). Decreasing cusp number in the congenitally abnormal aortic valve has shown increasing male predilection, earlier valve failure and aggressive pathological changes compared to normal tricuspid aortic valve (Collins MJ, 2008).

The normal aortic valve consists of three valve cusps, sinuses and coaptations (Angelini, 1989). During the embryological development, the bulbous cordis elongates and forms the proximal conus and distal truncus arteriosus. This initial single channel bifurcates into two separate trunks, namely, the aortic and pulmonary trunks by two spiral truncoconal ridges, derived from neural crest mesoderm. Simultaneous to this, cardiac mesoderm and cranial neural crest derivatives grow into the two separate lumens forming 3 leaflets for each trunk. These three leaflet structures will constitute the future aortic and pulmonary valves (Carlson, 1999). Abnormalities in the growth of this mesoderm into the lumen to form leaflets are believed to result congenital aortic valvular abnormalities. During the same time, out of the many buds which arise from the coronary sinuses of the aorta, generally only two buds establish a connection with the epicardial tree to form future coronary arteries. These developmental spatial associations can explain the frequent concurrence of abnormalities

Two sub-types of UAV have been described. One is the pinhole shaped acommissural UAV and the second being the slit shaped unicommissural UAV. While the pinhole-shaped UAV presents early in infancy with severe aortic stenosis, the slit-shaped UAV presents relatively later in adults with a less aggressive course. Theoretically, if the leaflet mesoderm grows in circumferentially from annulus it results in pin-hole shaped UAV and if it grows in with

The association of UAV with various coronary artery anomalies, patent ductus arteriosus, aortic aneurysms and coarctation of aorta suggests a common abnormal embryological development. Temporal association of the aortic leaflet evolution with coronary artery

two coaptation points, it results in the slit-shaped unicommisural UAV. (Fig. 1)

development from sinuses of valsalva implies similar embryological derangements.

**1. Introduction** 

**2. Embryology** 

between the aortic valve and coronary arteries.
