LVS apex
The apex of the LVS is located superiorly towards the left coronary arterial ostium. It begins at the left coronary artery’s bifurcation to the left circumflex coronary artery and left anterior descending artery. The nearest neighboring structure to the LVS apex is the aortic root, covered by a large fibrous structure—the aorto-ventricular membrane [9] (Figure 2A). The aortic root is the continuation of the left ventricle outflow tract. It occupies a central position within the heart, located to the right and posteriorly, relative to the subpulmonary infundibulum [7]. The apex into the deep of the myocardium correlates with the left aortic sinus of Valsalva, septal summit to the right and aortic–mitral continuity to the left (Figure 1). The epicardial adipose tissue and pulmonary trunk cover the LVS apex (Figure 2A). The mean distance from the LVS apex to the aortic sinus origin of the left coronary artery is approximately 10 mm, but may even reach 21 mm [15,16]. In approximately 10% of hearts, the left coronary artery trifurcates. Its third branch, the ramus intermedius, penetrates the LVS area, trespassing in the midsection over the accessible and inaccessible areas. In almost 2% of cases, the apex of the LVS cannot be defined because of the absence of the circumflex branch of the left coronary artery since it originates directly from the left sinus of Valsalva. In patients with bicuspid aortic valves, variants are even more commonly observed [16].