Reinterpreting Isovolumetric Relaxation: Decompression Phase.
As a consequence of the shortening of the DS during ejection, lengthening of the AS occurs, beginning its intervention in this phase with its contraction, it shortening during the criticized phase of isovolumetric relaxation30. At this moment the overall result of its shortening causes a clockwise reversal after ejection since it reverses its ejection-conditioned movement which is counterclockwise, (Figure 2: 2A-B) as a result, the LV elongates from the straightening of the AS just when the DS has stopped contracting but maintains rigidity and tension33(Figure 4: 2A-C) together with the recently reported osteochondroid tissue, the fulcrum or support point of the myocardium is obtained17 for the AS straightening, base elevation as it continues to contract unopposed for approximately 90 ms more. The AS according to experimental studies begins to contract approximately 60 ms later than the DS, followed by a time interval of 90 ms that marks the difference between the end of the DS contraction, followed by the shortening of the AS31, 32. (Figure 3: Transition from color yellow to green)
With an apical 5-chamber echocardiographic window, during the closure of the aortic valve a longitudinal elongation of the ventricles is observed, as well as a subsequent widening of the cavities. This simultaneous elevation and straightening are due to the shortening of the AS, its activity as already mentioned, is delayed until the interval of the isovolumic relaxation when its current contraction is not accompanied by that of the DS, observed as a positive deflection of the longitudinal strain of the AS (28) and a velocity vector directed upwards (the base rises and separates from the apex.)[7] (Figure 4: 2 A-C observe the change of direction of the subepicardial vectors undertakes a direction towards the base which is manifested at the end of the isovolumetric relaxation.) also occurs the widening of both cavities without flowometric exchange related to the retreat of the circumferential muscle that has stopped contracting, particularly in the RV, different characteristics have been experimentally reported, defining a phase of longer ejection divided into early and late and the absence of a phase of isovolumic relaxation34. This detorsion of the LV generated by the contraction of the AS produces the elongation that creates a negative pressure and a vacuum generating the suction of blood during rapid filling35. (Figure 4: 2C)