LAUSR

Dear Editor, The centrally located aortic root is wedged among the remainder cardiac elements, with which it establishes important anatomical relationships. These relationships must be presented in a simple and concomitantly coherent, comprehensive manner while also taking into account the anatomically correct orientation of the human heart (Mori, Spicer, & Anderson, 2016; Mori, Tretter, Spicer, Bolender, & Anderson, 2019) and not least, to be applicable in congenital cardiac malformations and other diseases of the heart. The concept of the aortic root hexagon as proposed and presented by Almoosawy and colleagues in Clinical Anatomy (Almoosawy, Lucka, Cummine, & Buchan, 2020) represents an important step forward in understanding the complex anatomical relationships of the aortic root and a quick guide in orienting the cardiologist and surgeon in diagnostic interrogation and during operative procedures, respectively. However, there are some points that ask for further comments and critics. The orientation of the heart specimens is not the correct one (Anderson & Loukas, 2009). The most posterior and median heart chamber is the left atrium. All images, including the schematic hexagon must be rotated counterclockwise with about 30 , in such a way that the right aortic sinus will become anterior (and in Figure 1, the Point # 3 will be replaced by # 4). The nomenclature of the aortic and pulmonary sinuses, leaflets, and corresponding commissures is cumbersome and even difficult to articulate. The Leiden convention (Gittenberger-de Groot, Sauer, Oppneheimer-Dekker, & Quagebeur, 1983) facilitates this communication and is also applicable in congenital heart disease. Consequently leaflets and sinuses can be labeled as: R = “right” (or #1), L = “left” (or # 2), and NF = “nonfacing” or “nonadjacent” (avoiding the confusion between the “noncoronary sinus” and the “coronary sinus,” i.e., the venous collector of the heart). Commissures can be consequently easily labeled (and verbalized): R–L/L–NF/R–NF. Generally speaking the pig heart offers a fairly good substitute for the human heart, but some differences can misguide the surgeon. The more extensive muscular portion of the pig's aortic root, the aortic tilt angle (Berdajs, Lajos, & Turina, 2002; Lansac et al., 2005) as well as the extension of the outlet septum represents important examples. The drawing in Figure 8 has some flaws as the pulmonary valve leaflets are incorrectly labeled as left, right, and posterior, as these actually are left, right, and anterior (or nonadjacent). The pulmonary and aortic roots appear depicted as parallel; instead they cross almost perpendicularly (Muresian, 2006). The alleged deeper, two-bite suture placement between the nadirs of the right pulmonary and right aortic leaflets has no correspondence in the human heart just like the extent of the fibrous portion in the human aortic root. The location of the atrioventricular node and fascicle is not precisely demonstrated by the authors in the hexagonal scheme. As cardiac surgeons know, the location and the extent of the membranous septum is variable asking for intraoperative identification and sometimes the placement of sutures does not follow a precise flat, planar disposition around the basal ring of the aorta. Another important detail regards the relationship between the mitral valve and the aortic root. In the hexagonal scheme, it would have been better to define and localize the left and right fibrous trigones of the heart, in correspondence with Points 2 and 6. The path of the needles as illustrated by the authors is actually misleading: the nadir of the left aortic leaflet corresponds to the left trigone and not to the anterolateral commissure of the mitral valve. In a similar way (see figure), the nadir of the nonfacing leaflet corresponds to the right fibrous trigone and not to the posteromedial commissure