Functional Relations to the Right Ventricle.
The RV is formed in its free wall by the circumferential sheath of transverse fibers that make up the RS, however, the septum of this cavity is formed by the continuity of the AS of the AL, (Figure 1: 5) until its insertion in the fibrous trigone and the recently described cardiac fulcrum17,50 the failure of this ventricle is related to septal lesions such as interdependence related to pulmonary hypertension, pulmonary thromboembolism, or occlusion of posterior septal branches of the right coronary artery51,52 so it is must take into account the difference between transverse fibers that form an envelope and helical ones.
The dynamics behind TAPSE (tricuspid annular plane systolic excursion) is the longitudinal translation of the shortening that causes the contraction of the subendocardial DS, this extension and speed of base-apex shortening so that both cavities are interconnected by a muscular unit the only one that during its torsion explains TAPSE in the RV and MAPSE in the LV. In cases of increased afterload, as in pulmonary hypertension, the force to be overcome would be increasing the torsion phenomenon of the DS. Saleh et al. describe that in the RV the helical fibers of the septum determine the highest ejection fraction; in situations where there is septal damage, therefore, a deterioration in torsion, the ejection fraction is compensated by the circumferential constriction caused by the free wall of the RV with fibers of BL, recognizing how septal dysfunction can be the cause of RV failure, this phenomenon does not cause catastrophic LV dysfunction due to the presence of compensation to a greater area of subendocardial fibers, however, in the RV its free wall is predominantly transversal generating low pressure before a high resistance circuit. (Figure 4: Observe the participation of the septal subepicardial velocity vectors, which belong to the AS and therefore to the RV septum).