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The Critical Biomechanics of Aortomitral Angle and Systolic Anterior Motion: Engineering Native Ex Vivo Simulation

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Abstract

Systolic anterior motion (SAM) of the mitral valve (MV) is a complex pathological phenomenon often occurring as an iatrogenic effect of surgical and transcatheter intervention. While the aortomitral angle has long been linked to SAM, the mechanistic relationship is not well understood. We developed the first ex vivo heart simulator capable of recreating native aortomitral biomechanics, and to generate models of SAM, we performed anterior leaflet augmentation and sequential undersized annuloplasty procedures on porcine aortomitral junctions (n = 6). Hemodynamics and echocardiograms were recorded, and echocardiographic analysis revealed significantly reduced coaptation-septal distances confirming SAM (p = 0.003) and effective manipulation of the aortomitral angle (p < 0.001). Upon increasing the angle in our pathological models, we recorded significant increases (p < 0.05) in both coaptation-septal distance and multiple hemodynamic metrics, such as aortic peak flow and effective orifice area. These results indicate that an increased aortomitral angle is correlated with more efficient hemodynamic performance of the valvular system, presenting a potential, clinically translatable treatment opportunity for reducing the risk and adverse effects of SAM. As the standard of care shifts towards surgical and transcatheter interventions, it is increasingly important to better understand SAM biomechanics, and our advances represent a significant step towards that goal.

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Abbreviations

SAM:

Systolic anterior motion

MV:

Mitral valve

LVOT:

Left ventricular outflow tract

HCM:

Hypertrophic cardiomyopathy

DOF:

Degree-of-freedom

RMS:

Root mean square

C-Sept:AMA:

Coaptation-septal distance to aortomitral angle ratio

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Acknowledgments

This work was supported by the National Institutes of Health (NIH R01 HL152155, YJW), the National Science Foundation Graduate Research Fellowship Program (DGE-1656518, AMI), the Stanford Graduate Fellowship (AMI), and the Thoracic Surgery Foundation Resident Research Fellowship (YZ). We would also like to thank the generous donation by Donald and Sally O’Neal to support this research effort.

Funding

Dr. Y Joseph Woo: NIH R01 HL152155. Dr. Annabel M Imbrie-Moore: National Science Foundation, DGE-1656518.

Conflict of interest

The authors have nothing to disclose and report no conflicts of interest.

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Authors and Affiliations

  1. Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA

    Matthew H. Park, Annabel M. Imbrie-Moore, Yuanjia Zhu, Robert J. Wilkerson, Hanjay Wang, Grant H. Park, Catherine A. Wu, Pearly K. Pandya, Danielle M. Mullis, Mateo Marin-Cuartas & Y. Joseph Woo

  2. Department of Mechanical Engineering, Stanford University, Stanford, CA, USA

    Matthew H. Park, Annabel M. Imbrie-Moore & Pearly K. Pandya

  3. Department of Bioengineering, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA, 94305-5407, USA

    Yuanjia Zhu & Y. Joseph Woo

  4. University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany

    Mateo Marin-Cuartas

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  1. Matthew H. Park
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Correspondence to Y. Joseph Woo.

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Associate Editor Stefan M. Duma oversaw the review of this article

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Supplementary Information

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Supplementary file1 (MP4 5383 KB)

Video 1 Operation of the aortomitral simulator. Each chamber interfaces with the respective heart anatomy to create a single, enclosed flow-loop driven by a pulsatile linear piston pump. (https://youtu.be/8ov0thE2gf0)

Supplementary file2 (MP4 5451 KB)

Video 2 Echocardiogram video demonstrating representative occurrence of systolic anterior motion in our ex vivo aortomitral simulator. (https://youtu.be/xU4XcknW8Zk)

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Park, M.H., Imbrie-Moore, A.M., Zhu, Y. et al. The Critical Biomechanics of Aortomitral Angle and Systolic Anterior Motion: Engineering Native Ex Vivo Simulation. Ann Biomed Eng 51, 794–805 (2023). https://doi.org/10.1007/s10439-022-03091-z

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