The anterior interventricular groove with the adjacent structures—the left anterior descending artery and anterior interventricular vein—determines the septal (or superior) boundary of the LVS [8,17,18]. The relationship between those two vessels in the majority (54.4%) of cases presents a profound intersection of the anterior interventricular vein to the left anterior descending artery [19]. Along the artery and vein, the left coronary cardiac nerve forms the left coronary subplexus that contributes to the autonomic innervation of the left ventricle [20]. The septal margin corresponds with the pulmonary trunk. Nevertheless, a few millimeters of the septal summit, or the septal aspect of LVS, are present between the anterior part of the interventricular groove and the pulmonary trunk. The distance from the left coronary artery bifurcation to the first dominant septal perforator denotes the length of the septal margin of the LVS [8]. The annulus of the pulmonary valve and pulmonary trunk is present above the LVS septal margin. These structures are overlying the LVS in the most superior aspect. The right ventricular outflow tract correlates with the lower portion of the septal margin, and various amounts of epicardial adipose tissue are present between those structures (Figure 2C). From the septal margin of LVS, the first or sometimes second diagonal branch enters the LVS region while septal perforators penetrate the ventricular septum. Rarely, the right-sided branches occur, creating preconal ring anastomosis—arterial ring of Vieussens [21]. The anterior interventricular vein enters from the anterior aspect of the interventricular groove into the LVS.