In Vivo Dynamic Strains of the Mitral Valve Annulus

The mitral valve apparatus is a complex structure with multiple components that require seamless, integrated operation for normal valve function. One of these components is the annulus, a fibrous ring of tissue that defines the boundary between the mitral valve leaflets and the surrounding superstructure of the heart. During the cardiac cycle the annulus undergoes large deformations and dramatic shape changes. Moreover, the annulus motion represents a key boundary condition for mitral valve leaflet deformation. Yet, to date our knowledge of the subtle deformations this structure undergoes during the cardiac cycle remains very limited. In the present study, an array of 1 mm diameter piezoelectric sonocrystals was implanted in 5 sheep to quantify annular deformation over the complete cardiac cycle. These crystals act as fiducial markers for the mitral annulus with a temporal resolution of ∼1ms and a special resolution of .01mm in a calibrated three dimensional space. A quintic order generalized 3D spline was developed to reconstruct the annular geometry.