Effect of cutting second-order chordae on in-vivo anterior mitral leaflet compound curvature

Filiberto Rodriguez, Frank Langer, Katherine B. Harrington, Frederick A. Tibayan, Mary K. Zasio, David Liang, George T. Daughters, Neil B. Ingels, D. Craig Miller

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    Abstract

    Background and aim of the study: Leaflet curvature determines leaflet stress. In order to assess the influence of second-order chordae (2°CT) on anterior mitral valve leaflet (AMVL) geometry, AMVL curvature was measured before (Baseline) and after (CUT) cutting the 2°CT. Methods: Miniature radiopaque markers were sutured onto the AMVL in eight sheep: four along the central-meridian from mid-septal annulus to the free-margin; and one each at the 2°CT insertion. Biplane videofluoroscopic data were acquired (open-chest) before and after CUT. Marker-triplet 3-D coordinates were used to calculate radii-of-curvature at LVPmax along the central-meridian (ROCm) and across the AMVL belly (commissure-commissure axis, ROCc-c). Results: CUT did not change LVPmax (111 ± 12 versus 106 ± 11 mmHg; p = 0.19). At baseline, the AMVL central-meridian had compound curvature: Convex to the left ventricle near the annulus (-ROCm) and concave near the free-margin (+ROCm). After CUT, the AMVL flattened: ROCm increased near the annulus (from -1.37 ± 0.52 to -12.58 ± 29.04 cm; p = 0.02), but did not change near the edge. In the commissure-commissure axis, ROCc-c was concave to the left ventricle at baseline and increased after CUT in all eight animals. In five sheep, ROCc-c was increased (from 1.93 ± 1.01 to 2.80 ± 1.36 cm; p = 0.03), but in three sheep ROCc-c was increased and inverted (from 3.65 ± 2.17 to -1.72: ± 0.53 cm; p = 0.03), becoming convex to the left ventricle. Conclusion: Compound curvature along the AMVL central-meridian appears to be an intrinsic leaflet property that persists even without support from second-order chordae, whereas concave curvature in the commissure-commissure axis is more dependent on intact second-order chordae. Leaflet compound curvature must be incorporated into future finite element models to characterize leaflet stresses accurately. The importance of second-order chordae in maintaining leaflet shape must be considered during mitral repair. A larger ROC increases leaflet stresses, while reversal of ROC changes tensile stress to compressive stress; this might trigger deleterious leaflet remodeling after chordal cutting.

    Original languageEnglish (US)
    Pages (from-to)592-602
    Number of pages11
    JournalJournal of Heart Valve Disease
    Volume14
    Issue number5
    StatePublished - Sep 1 2005

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    ASJC Scopus subject areas

    • Cardiology and Cardiovascular Medicine

    Cite this

    Rodriguez, F., Langer, F., Harrington, K. B., Tibayan, F. A., Zasio, M. K., Liang, D., Daughters, G. T., Ingels, N. B., & Miller, D. C. (2005). Effect of cutting second-order chordae on in-vivo anterior mitral leaflet compound curvature. Journal of Heart Valve Disease, 14(5), 592-602.