Table 1.

Terms used to describe the aortic root components.

Name	Meaning
Ventricular–arterial junction	The term ventricular–arterial junction describes the border between the ventricular myocardium and the fibroelastic structure of the aortic root. Contrary to the right AV junction, where the pulmonary root is entirely supported by the muscular infundibulum, only the left and the right coronary sinuses are partially supported by the myocardium (see text), being the remaining extent of the aortic root supported by fibrous tissue (MS = membranous septum; see text and references [12,13]).
Cusps, leaflets	The term “cusps” refers to the moving parts of the aortic root. When seen in closed position from the ventricular perspective, this component is similar to the surface of a molar tooth (called cusp). The term is used to describe the structure of the valve (i.e., unicuspidal, bicuspid, and tri-cuspid). Literally the term indicates a pointed end where two curves meet. In the aortic root, it indicates an intact interleaflet triangle with its apex reaching the sinutubular junction. The term leaflet means “small leaf”, which describes a thin, pliable layer. This term perfectly fits the leaflet aspect. N = non-coronary, L = left coronary, R = right coronary leaflets/cusps.
Commissures	In the anatomy of the aortic root this term refers to the most distal area where the insertions of the leaflets on the aortic wall join each other.
Aortic annulus	The aortic annulus is the three-dimensional line that follows the hinge line of the leaflets on the aortic wall. This line of dense connective tissue has a crown-shaped appearance (white dotted line).
Virtual or “echocardiographic” annulus	This term refers to a circumference that joins the lowest points of the leaflet insertion. Although neither anatomically or histologically recognizable, this term has become relevant in the TAVI era. Measurements of this virtual basal plane are used for the sizing of the valve in tricuspid valves. This virtual annuls does not have an anatomic counterpart.
Surgical annulus	Surgeons fix the prosthetic valves on a circular area lying between the nadirs of the sinuses and midway to the commissures (the aortic prostheses have a flat sewing ring). The term “surgical annulus” refers to this “ring area” and provides a precise reference point when the prosthesis is sutured on “supra” annular position.