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.