Simultaneous measurement of mitral flow and valve motion showed peak valve excursion precedes peak flow (46 +/- 7 ms after opening), indicating chordal tension drives mid-diastolic closure.
Observational
This physiological study proposes a unifying theory of mitral valve closure where chordal tension is a necessary condition for proper function, challenging the idea that mid-diastolic closing is solely due to flow deceleration or vortices.
To examine the mechanisms of mitral valve motion in mid diastole and at closure, we simultaneously measured mitral flow (electromagnetic), valve motion (echo), and atrioventricular pressures (micromanometer). Peak valve excursion (E point) occurs early 46 +/- 7 ms) after opening and always precedes peak flow; therefore, mid-diastolic closing motion (EF slope) is not due to flow deceleration or vortex formation. Large variations in peak flow are accompanied by small variations in valve excursion (coefficient of variation 41 vs. 12%, respectively). We conclude that the valve overshoots its equilibrium position and that the chordae produce tension on the valve during diastole. This approach is supported by data from papillary muscle rupture, prolonged P-R interval, and mathematical modeling. We offer a valve-closure theory unifying chordal tension, flow deceleration, and vortices, with chordal tension as a necessary condition for the proper function of the other two. Nevertheless, prolonged periods of diastasis and ventricular premature contractions indicate that competent valve closure may occur in the absence of vortices and flow deceleration.
Yellin et al. (1981) conducted an observational in Mitral valve motion. Simultaneous measurement of mitral flow and valve motion showed peak valve excursion precedes peak flow (46 +/- 7 ms after opening), indicating chordal tension drives mid-diastolic closure.