The Clinical Anatomy of the Aortic Root
The aortic root is the component of the left ventricular outflow tract interposed between the subvalvar left ventricular outlet and the intrapericardial component of the ascending aorta. Its distal boundary is the sinutubular junction. Proximally it is bounded by a virtual plane that is constructed by joining together the nadirs of attachment of the semilunar leaflets of the aortic valve. In this chapter, we provide a detailed account of the structure and relationships of the components of the root. We begin our account, however, by discussing the problems that currently exist in defining these components. This relates to ongoing disagreements regarding the usage of terms such as “cusp” and “annulus”. Because of these disagreements, we avoid the use of “cusp”. Instead, we describe the moving components of the root as the leaflets, and the expanded components that house the leaflets as the valvar sinuses. We then emphasise the presence of fibrous interleaflet triangles that separate the sinuses on their ventricular aspect. We also show how the descent of the semilunar hinges of the leaflets relative to the anatomic ventriculo-arterial junction results in the incorporation of ventricular myocardium at the bases of the two sinuses that give rise to the coronary arteries. Using images prepared by virtual dissection of computed tomographic datasets obtained from individuals undergoing assessment of suspected coronary arterial disease, we demonstrate the advantages of attitudinally appropriate description for the various components. With regard to the so-called “annulus”, we emphasise the difference between the surgical annulus, represented by the semilunar hinges of the valvar leaflets, and the clinical annulus, represented by the virtual plane marking the entrance to the root. We also show the potential problems currently existing in measuring accurately the dimensions of the clinical annulus. We complete out account by summarising the features of the anatomy of greatest significance to the surgeon and the interventionist.
KeywordsValve Sinus Sinutubular junction Annulus Leaflet
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