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.