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Three-dimensional dynamic geometry of the normal canine mitral annulus and papillary muscles
M Komeda1, J R Glasson, A F Bolger
1Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, CA 94305-5247, USA.
Background:
Despite an incomplete knowledge of the geometry and dynamics of the mitral annulus (MA), papillary muscle (PM), and the chordae tendineac, chordal-sparing MVR is popular.
Methods And Results:
The systolic reduction in three-dimensional distance between each PM tip and eight MA sites (DT-A) was measured in nine normal closed-chest dogs by use of surgically implanted radiopaque markers. Three loci (tip, junction, and base) on each PM were also projected onto the MA plane at end diastole and end systole to assess PM dynamics. The anterior PM tip showed significant shortening of DT-A toward the opposite side of the MA or the midanterior MA region (P < .005 or P < .05, respectively, versus same MA side [MANOVA]); conversely, the posterior PM tip DT-A shortened toward the opposite side of the MA near the anterior commissure or the area between the anterior commissure and midposterior MA (P < .005 versus same MA side). Annular projection revealed three-dimensional motion (relative to the MA) of the anterior PM tip, junction, and base toward the right trigone, while posterior PM motion was oriented toward the opposite side of the MA.
Conclusions:
Both PMs in normal canine hearts demonstrated systolic relative motion in a direction compatible with the "oblique" chordal configuration, ie, from the anterior PM to the anterior MA near the right trigone and from the posterior PM to the opposite side of the posterior MA. These observations warrant further investigation of three-dimensional PM-MA dynamics with various methods of chorda preservation during MVR to assess their impact on left ventricular systolic and diastolic function.
Insights
Papillary muscles (PM) move towards the mitral annulus (MA) during systole in dogs, supporting oblique chordal configurations. Understanding this 3D PM-MA dynamics is crucial for mitral valve repair (MVR) techniques.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Surgical Anatomy
Background:
- Chordal-sparing mitral valve repair (MVR) is common despite limited understanding of mitral annulus (MA), papillary muscle (PM), and chordae tendineae geometry and dynamics.
- Accurate knowledge of the three-dimensional (3D) relationships between the PMs and the MA is essential for optimizing MVR strategies.
Purpose of the Study:
- To investigate the 3D systolic motion of papillary muscles (PMs) relative to the mitral annulus (MA) in a canine model.
- To assess the dynamic relationship between PMs and the MA during the cardiac cycle to inform chordal-sparing mitral valve repair techniques.
Main Methods:
- Surgically implanted radiopaque markers were used to measure the 3D distance between PM tips and eight MA sites (DT-A) in nine normal dogs.
- Three loci (tip, junction, base) on each PM were projected onto the MA plane at end diastole and end systole to analyze PM dynamics.
- Statistical analysis (MANOVA) was employed to determine significant directional changes in PM-MA distances.
Main Results:
- The anterior PM tip showed significant systolic shortening of DT-A towards the opposite MA side or midanterior MA region.
- The posterior PM tip exhibited significant systolic DT-A shortening towards the opposite MA side near the anterior commissure.
- Annular projection revealed 3D motion of the anterior PM (tip, junction, base) towards the right trigone, and posterior PM motion towards the opposite MA side.
Conclusions:
- Canine PMs demonstrate systolic relative motion consistent with an oblique chordal configuration, moving from the PM towards specific MA regions.
- These findings highlight the importance of understanding 3D PM-MA dynamics for preserving chordal function during MVR.
- Further research into 3D PM-MA dynamics with various chordal preservation methods is warranted to evaluate their impact on left ventricular function.