Mitral valve opening in the ovine heart

Area of Science:

• Cardiovascular Physiology
• Cardiac Mechanics
• Biomedical Engineering

Background:

• Understanding the dynamic 3D geometry of the mitral valve is crucial for diagnosing and treating various heart conditions.
• Previous studies have provided limited insights into the complex interplay between the mitral annulus and leaflets during the cardiac cycle.

Purpose of the Study:

• To investigate the three-dimensional size, shape, and motion of the mitral leaflets and annulus in a live animal model.
• To correlate mitral valve dynamics with left ventricular pressure changes.

Main Methods:

• Radiopaque markers were surgically implanted on the mitral annulus and leaflets in seven sheep.
• Three-dimensional marker positions were captured using biplane videofluoroscopy (60 frames/second).
• Computer analysis was employed to reconstruct and analyze marker movement and valve geometry.

Main Results:

• The mitral annulus demonstrated maximal ellipticity in mid-diastole.
• Mitral leaflets initiated descent into the left ventricle (LV) prior to leaflet edge separation, coinciding with a rapid fall in left ventricular pressure (LVP).
• Specific leaflet curvatures were observed during systole and opening, with significant systolic separation of markers at the rough zone border (10 mm).

Conclusions:

• Mitral valve coaptation primarily occurs at the leaflet edges.
• The mitral annulus and leaflets transition towards their open configurations during the rapid decline in LVP.
• Leaflet edge separation, the final event in valve opening, occurs near the point of minimum LVP.