Ejection Phase.
During this phase, the circumferential fibers of the BL accompany the AL
during its shortening, producing a force perpetuating the continuity of
the narrowing during ejection. This will keep the base narrow,
counteracting the vectorial forces generated in opposite directions by
the DS and AS in movements. of torsion and untorsion of the
LV27 (Figure 3: 1A, B, C) at the
moment of ejecting and sucking the blood. (Figure 2)
At this moment, the key piece is the entry into contraction of the DS,
its shortening moving the base towards the apex of the LV, turning the
base clockwise while the apex rotates counterclockwise due to the torque
of torsion of the longest lever radius of the AS. (Figure
3: 1B) The mechanical phenomenon of shortening the LV and consequently
ejecting blood is provided by the shortening of the DS, although the
subepicardial AS is adjacent to it, reports of longitudinal strain at
the level of the AS interventricular septum located in both segments of
the AL show a positive wave deflection showing its elongation not it’s
shortening, the longitudinal strain of the subendocardial DS shows a
negative wave deflection denoting its shortening during the ejection
phase28. This superimposition of segments in the
interventricular septum was documented as an interseptal hyperechoic
line delimiting both segments21 and is demonstrated in
great detail in the anatomical correlations to the
echocardiogram7 (Figure 2 panel 4-3:
3) and tractography8. This difference in directions
in the septum can capture opposite shortenings in the longitudinal
strain. This activation and deformation of the sequential fiber also
coincides with the findings of experimental studies by sonomicrometry
reported by various authors19,20,27(Figure 3) where it is evident how there is a shortening
of the subendocardium (DS) moments before the ejection phase with a
maximum shortening before the traditional isovolumetric relaxation
phase, the maximum shortening of the subepicardial AS is recorded once
the rapid filling has begun, demonstrating that there is a sequential
mechanical activity which follows the segments of the helical pattern
(Figure 3: 1-2) , itself the apical short-axis strain
velocity vectors demonstrate a radial inward direction of the cavity
throughout the endocardium formed by the DS (Figure 2:
1A-B) , in an apical window the strain velocity vectors show an inward
motion of the LV cavity of right, left, and apex during early ejection,
as ejection period temporally progresses downward motion persists
(displacement of base toward apex) during late ejection and now shows
leftward directional shift in basal portion of the septum by rotation
clockwise by the start of shortening of the AS that will give way to the
first diastolic phase (Figure 4: 1A, B, C).
The increased tension in the DS explains its ability to cause shortening
and clockwise twisting of the base of the heart, but the simultaneous
counterclockwise apical twisting is due to AS torsion
(Figure 4: 1 A-C transition of apical vectors in opposite
directions) , (Figure 2 B) . Contracting together with a
greater radius of curvature. This interaction is responsible for
systolic torsion, and recent electrophysiological studies denote a
radial transmural activation in the middle third of the interventricular
septum,17 explaining this phenomenon by coactivation
of the DS and AS simultaneously (Figure 3) . The AS
shortens during co-contraction to compress the cavity, but its effect by
raising the base of the ventricles is counteracted by the dominance of
the SD contraction, which, as we have seen, already contributes a
greater percentage to the ventricular mass17, 29.