Percutaneous Transvenous Melody Valve-in-Ring Procedure for Mitral Valve Replacement

ObjectivesThe purpose of this study was to demonstrate the feasibility of percutaneous transvenous mitral valve-in-ring (VIR) implantation using the Melody valve in an ovine model.BackgroundThe recurrence of mitral regurgitation following surgical mitral valve (MV) repair in both adult and pediatric patients remains a significant clinical problem. Mitral annuloplasty rings are commonly used in MV repair procedures and may serve as secure landing zones for percutaneous valves.MethodsFive sheep underwent surgical MV annuloplasty (24 mm, n = 2; 26 mm, n = 2; 28 mm, n = 1). Animals underwent cardiac catheterization with VIR implantation via a transfemoral venous, transatrial septal approach 1 week following surgery. Hemodynamic, angiographic, and echocardiographic data were recorded before and after VIR.ResultsVIR was technically successful and required <1 h of procedure time in all animals. Fluoroscopy demonstrated securely positioned Melody valves within the annuloplasty ring in all animals. Angiography revealed no significant MV regurgitation in 4 and moderate central MV regurgitation in the animal with the 28-mm annuloplasty. All animals demonstrated vigorous left ventricular function, no outflow tract obstruction, and no aortic valve insufficiency.ConclusionsThis study demonstrated the feasibility of a purely percutaneous approach to MV replacement in patients with preexisting annuloplasty rings. This novel approach may be of particular benefit to patients with failed repair of ischemic mitral regurgitation and in pediatric patients with complex structural heart disease

Reduction of Ischemia/Reperfusion Injury With Bendavia, a Mitochondria-Targeting Cytoprotective Peptide

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Integration of microstructural architecture of the mitral valve into an anatomically accurate finite element mesh

Although mitral valve (MV) repair initially restores normal leaflets coaptation and stops MV regurgitation, in long term it can also dramatically change the leaflet geometry and stress distribution that may be in part responsible for limited repair durability. As shown for other collagenous tissues, such changes in geometry and loading reorganize the fiber architecture. In addition, MV interstitial cells respond to the altered stress by undergoing alterations in biosynthetic function, which would affect the load-bearing capabilities of MV and its long-term durability. Thus, investigating the repair-induced MV stress and the concomitant microstructural alterations is a key step in assessing the repaired valve durability. Finite element models have been widely used for stress analysis of the mitral valve [1–3]. Most of these models, however, have employed only basic constitutive models and utilized simplified valve geometry. Above all, they have ignored the complex microstructure of the MV, which is the critical physical link between organ level stresses and cellular function. Thus, in this work we developed an initial method to develop an accurate geometrical model of the ovine MV and map the fiber structure for the purposes of developing high fidelity computational meshes of the MV.</jats:p

Injectable hydrogel properties influence infarct expansion and extent of postinfarction left ventricular remodeling in an ovine model

A recent trend has emerged that involves myocardial injection of biomaterials, containing cells or acellular, following myocardial infarction (MI) to influence the remodeling response through both biological and mechanical effects. Despite the number of different materials injected in these approaches, there has been little investigation into the importance of material properties on therapeutic outcomes. This work focuses on the investigation of injectable hyaluronic acid (MeHA) hydrogels that have tunable mechanics and gelation behavior. Specifically, two MeHA formulations that exhibit similar degradation and tissue distribution upon injection but have differential moduli (~8 versus ~43 kPa) were injected into a clinically relevant ovine MI model to evaluate the associated salutary effect of intramyocardial hydrogel injection on the remodeling response based on hydrogel mechanics. Treatment with both hydrogels significantly increased the wall thickness in the apex and basilar infarct regions compared with the control infarct. However, only the higher-modulus (MeHA High) treatment group had a statistically smaller infarct area compared with the control infarct group. Moreover, reductions in normalized end-diastolic and end-systolic volumes were observed for the MeHA High group. This group also tended to have better functional outcomes (cardiac output and ejection fraction) than the low-modulus (MeHA Low) and control infarct groups. This study provides fundamental information that can be used in the rational design of therapeutic materials for treatment of MI