Mechanisms of mitral valve motion during diastole

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Abstract
To examine the mechanisms of mitral valve motion in mid diastole and at closure, mitral flow (electromagnetic), valve motion (echo) and atrioventricular pressures (micromanometer) were simultaneously measured. 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). Evidently, the valve overshoots its equilibrium position and 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. A valve-closure theory is offered unifying chordal tension, flow deceleration and vortices, with chordal tension as a necessary condition for the proper function of the other 2. Prolonged periods of diastasis and ventricular premature contractions indicate that competent valve closure may occur in the absence of vortices and flow deceleration.