Apical Loop and Interventricular Septum
In the continuity of the RS of the BL there is a 180° turn, forming the
central fold that divides both loops, being the point of change of
direction of the myocardial fibers in a descending direction. The
subendocardial fibers in the segment reaching the apex overlap helically
to form the ”vortex cordis” described by Richard lower in the
17th-century6. Then they change direction and the
subepicardial forms the AS ending in the insertion of the left fibrous
trigone at the base of the left ventricle. (Figure 1:
Asterik, 5)
The previous configuration leaves two lateral segments (LS, RS) with
predominantly transverse fibers covering or ”embracing” the (AL)
containing two muscular segments with subendocardial (DS) and
subepicardial (AS) direction, interposing each other at an angle of 90°,
called septal segments. The 180° central fold dividing both loops
preserves the continuity of endo-epicardial directions and the
longitudinal axial continuity of the adjacent segments in the unfolded
band.
The two large muscle segments are distinguishable by macroscopical
anatomical dissection7, can be observed by
tractography8, defined as an interseptal hyperechoic
line in echocardiography9, and identified as the path
of dissection of some hematomas, participating in the formation of
septal intramyocardial dissecting agents10.
The BL helix embracing the base of the heart, the 180° central fold, and
the helical twist that superimposes AL subendocardium on subepicardial
that generates the vortex cordis and the interventricular septum, form
the fractal principle of self-similarity and its global
three-dimensional structure a non-orientable geometric surface of triple
torsion like a Moebius strip.