Anatomical considerations
Anatomically, the PV is formed by three semilunar cusps attached to connective tissue of the annulus, a ring-shaped structure, with a mean diameter of 20 mm, that delimits the right ventricle chamber at the junction with the pulmonary arterial trunk. PV consists of three cusps: anterior, left, and right, separated by a commissure with an overlap area between cusps called the lunula. On the superior border of the PV, there is a pocket formed by the valve cusp and adjacent arterial wall, called the sinus of Valsalva [17]. The left cusp is the closest to the aortic root, the aortic valve, and the epicardial aspect of basal left ventricle, being these structures located posteriorly to it (Fig. 1). Normally, left cusp is close to the left main coronary artery and to the proximal part of anterior interventricular descending branch, before it approaches the commissure between the left and anterior cusp and the medial side of it [18]. This close proximity has been exploited to ablate, from the left pulmonic cusp, arrhythmias originating from the left ventricular summit [19]. The remaining part of the anterior cusp and the right cusp are considered non-septal ones because they lie above anterolateral free wall, in contact with the right atrial appendage. In normal hearts, the right coronary artery originates from the right sinus of Valsalva beside the right ventricle at a level that is far below the valve, and separates from RVOT as it then goes down through the atrioventricular groove. An important aspect to keep in mind when dealing with PV reconstruction is that the valve lies on an oblique transverse plan, with the left cusp tilted more downward compared to the other cusps [20]. Furthermore, although the semilunar valves are approximately on the same level, the pulmonary valve is oriented on a perpendicular plane with respect to the aortic valve. This explains why the aortic valve is displayed on face during intracardiac echo visualization (2D), while the pulmonary valve is seen on edge, and vice-versa [21]. Both short- and long-axis views need to be visualized for an optimal SOUND reconstruction of the annular plane, the cusps, and the sinus of Valsalva.