Torsion-Elongation-Detorsion Interdependence as the Genesis of Diastolic Dysfunction.
During the evaluation of diastolic dysfunction, emphasis should be placed on the moment of detorsion, which occurs with the elevation of the BL, which stopped contracting during ejection; however, in the period that coincides with isovolumetric relaxation, the AS is contracting to perpetuate a turn counterclockwise against the base clockwise, likewise in experimental studies, it has been documented that at the end of the isovolumetric relaxation phase the AS has stopped to give step to its reconstitution by the release of accumulated kinetic energy during torsion, it is clear that its contribution is important to untwist, elongate and reconstitute the myocardium. Recoil does not start until torque ends. (Figure 3) The recoil process causes the predominance of ventricular filling due to the genesis of negative pressure during the so-called isovolumic relaxation phase due to contraction of the AS, and elevation of the base, the recoil ends during rapid ventricular filling and is due to the elastic recoil of the AS. An increase in torque will delay the onset of recoil and de-torque, therefore a late and short recoil will restrict suction.
The time interval between the end of DS contraction (end of ejection) and the end of AS contraction (end of isovolumetric relaxation) is the central time interval for understanding the mechanical actions responsible for diastolic dysfunction (Figure 3: yellow and green shade) . Buckberg et al. have shown in multiple studies and reviews the importance of the interdependence between DS and AS. In an experimental study, he shows25 the correlation between the start of DS contraction, which corresponds to the QRS, and when the dP/dt curve is positive, however once the QRS has finished and when the maximum peak of the dP/dt reaches the AS starts its contraction, the ejection is finished and when the dP/dt starts its negative change the DS ends its contraction, the records show that the subepicardial AS still continues to contract, and it is at this point where the controversial isovolumetric relaxation phase begins, the AS ends its contraction at the end of the isovolumetric phase and when dP/dt returns to baseline, something very interesting to analyze is that AS contraction coincides with the T wave, because it does not reflect repolarization and another meaning must be depicted, as Manel Ballester does, attributing it to the electromagnetic field associated with the mechanical activity of the myocardium and the movement of blood, an effect called magnetohydrodynamic53. Considering diastolic dysfunction as impaired ventricular relaxation, the concept should be reviewed: Aortic stenosis, hypertrophic cardiomyopathy, transmural ischemia can prolong torsion compromising unwinding, aortic valve replacement in stenosis allows hypertrophic LV regression, improving torsion and recoil, post-ischemic diastolic dysfunction is reversed when sodium and hydrogen ion inhibitors limit calcium accumulation within the internal helix54, 55.