DynaRing: A Patient-Specific Mitral Annuloplasty Ring With Selective Stiffness Segments

Samuel Frishman; Ali Kight; Ileana Pirozzi; Sainiteesh Maddineni; Annabel M Imbrie-Moore; Zulekha Karachiwalla; Michael J Paulsen; Alexander D Kaiser; Y Joseph Woo; Mark R Cutkosky

doi:10.1115/1.4054445

DynaRing: A Patient-Specific Mitral Annuloplasty Ring With Selective Stiffness Segments

J Med Device. 2022 Sep 1;16(3):031009. doi: 10.1115/1.4054445. Epub 2022 May 18.

Affiliations

¹ Department of Mechanical Engineering, Stanford University, Stanford, CA 94305.
² Department of Bioengineering, Stanford University, Stanford, CA 94305.
³ Department of Computer Engineering, University of Maryland, Baltimore, MD 21250.
⁴ Department of Cardiothoracic Surgery, Stanford University, Stanford, CA 94305.
⁵ ICME and Department of Pediatrics, Stanford University, Stanford, CA 94305.

^# Contributed equally.

Abstract

Annuloplasty ring choice and design are critical to the long-term efficacy of mitral valve (MV) repair. DynaRing is a selectively compliant annuloplasty ring composed of varying stiffness elastomer segments, a shape-set nitinol core, and a cross diameter filament. The ring provides sufficient stiffness to stabilize a diseased annulus while allowing physiological annular dynamics. Moreover, adjusting elastomer properties provides a mechanism for effectively tuning key MV metrics to specific patients. We evaluate the ring embedded in porcine valves with an ex-vivo left heart simulator and perform a 150 million cycle fatigue test via a custom oscillatory system. We present a patient-specific design approach for determining ring parameters using a finite element model optimization and patient MRI data. Ex-vivo experiment results demonstrate that motion of DynaRing closely matches literature values for healthy annuli. Findings from the patient-specific optimization establish DynaRing's ability to adjust the anterior-posterior and intercommissural diameters and saddle height by up to 8.8%, 5.6%, 19.8%, respectively, and match a wide range of patient data.