Neochordal Goldilocks: Analyzing the Biomechanics of Neochord Length on Papillary Muscle Forces Suggests Higher Tolerance to Shorter Neochordae. The Journal of thoracic and cardiovascular surgery Park, M. H., van Kampen, A., Zhu, Y., Melnitchouk, S., Levine, R. A., Borger, M. A., Woo, Y. J. 2023


Estimating neochord lengths during mitral valve (MV) repair is challenging, as approximation must be performed largely based on intuition and surgical experience. Little data exist on quantifying the effects of neochord length misestimation. We aimed to evaluate the impact of neochord length on papillary muscle (PM) forces and MV hemodynamics, which is especially pertinent as increased forces have been linked to aberrant MV biomechanics.Porcine MVs (n=8) were mounted in an ex vivo heart simulator, and PMs were fixed to high resolution strain gauges, while hemodynamic data were recorded. We used an adjustable system to modulate neochord lengths. Optimal length was qualitatively verified by a single experienced operator, and neochordae were randomly lengthened or shortened in 1 mm increments up to ±5 mm from the optimal length.Optimal length neochordae resulted in the lowest peak composite PM forces (6.94±0.29 N), significantly different from all lengths >±1 mm. Both longer and shorter neochordae increased forces linearly according to difference from optimal length. Both peak PM forces and MR scaled more aggressively for longer versus shorter neochordae by factors of 1.6 and 6.9, respectively.Leveraging precision ex vivo heart simulation, we found that millimeter-level neochord length differences can result in significant differences in PM forces and MR, thereby altering valvular biomechanics. Differences in lengthened versus shortened neochordae scaling of forces and MR may indicate different levels of biomechanical tolerance towards longer and shorter neochordae. Our findings highlight the need for more thorough biomechanical understanding of neochordal MV repair.

View details for DOI 10.1016/j.jtcvs.2023.04.026

View details for PubMedID 37160219