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Author Notes:

Ajit P. Yoganathan, 387 Technology Circle NW, Suite 200, Atlanta, GA 30313, Ph. (404)894-2849, Fax. (404)894-4243, ajit.yoganathan@bme.gatech.edu


Research Funding:

Partially supported by a fellowship from the National Science Foundation (DGE-1148903: ELP) and by the National Heart, Lung and Blood Institute (HL113216).

This work was partially supported by a fellowship from the National Science Foundation (DGE-1148903: ELP) and by the National Heart, Lung and Blood Institute (HL113216).


  • Science & Technology
  • Life Sciences & Biomedicine
  • Cardiac & Cardiovascular Systems
  • Respiratory System
  • Surgery
  • Cardiovascular System & Cardiology

How Local Annular Force and Collagen Density Govern Mitral Annuloplasty Ring Dehiscence Risk

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Journal Title:

Annals of Thoracic Surgery


Volume 102, Number 2


, Pages 518-526

Type of Work:

Article | Post-print: After Peer Review


Background Annuloplasty ring dehiscence is a well described mode of mitral valve repair failure. Defining the mechanisms underlying dehiscence may facilitate its prevention. Methods: Factors that govern suture dehiscence were examined with an ovine model. After undersized ring annuloplasty in live animals (n = 5), cyclic force (F C ) that acts on sutures during cardiac contraction was measured with custom transducers. F C was measured at ten suture positions, throughout cardiac cycles with peak left ventricular pressure (LVP max ) of 100, 125, and 150 mm Hg. Suture pullout testing was conducted on explanted mitral annuli (n = 12) to determine suture holding strength at each position. Finally, relative collagen density differences at suture sites around the annulus were assessed by two-photon excitation fluoroscopy. Results: Anterior F C exceeded posterior F C at each LVP max (eg, 2.8 ± 1.3 N versus 1.8 ± 1.2 N at LVP max = 125 mm Hg, p < 0.01). Anterior holding strength exceeded posterior holding strength (6.4 ± 3.6 N versus 3.9 ± 1.6 N, p < 0.0001). On the basis of F C at LVP max of 150 mm Hg, margin of safety before suture pullout was vastly higher between the trigones (exclusive) versus elsewhere (4.8 ± 0.9 N versus 1.9 ± 0.5 N, p < 0.001). Margin of safety exhibited strong correlation to collagen density (R 2 = 0.947). Conclusions: Despite lower cyclic loading on posterior sutures, the weaker posterior mitral annular tissue creates higher risk of dehiscence, apparently because of reduced collagen content. Sutures placed atop the trigones are less secure than predicted, because of a combination of reduced collagen and higher overall rigidity in this region. These findings highlight the inter-trigonal tissue as the superior anchor and have implications on the design and implantation techniques for next-generation mitral prostheses.

Copyright information:

© 2016 The Society of Thoracic Surgeons

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