RESUMEN
Transcatheter Mitral Valve Replacement (TMVR) is currently under clinical investigation as a viable treatment option for mitral regurgitation (MR). Therefore, it is important to outline the key functional requirements of a TMVR prosthesis in order to provide an overall approach to assessing mitral valve replacement devices utilizing a combination of in vitro and preclinical methods. This article provides a review of the mitral valve disease as well as general considerations and guidance for developing a TMVR device based on International Industry Standards. Specific details pertaining to the mitral valve apparatus, morphology of mitral valve disease, assessment of specific patient population as well as hazard analysis to evaluate and develop a TMVR device to treat a specific patient population have been included. The details contained within this report are not all inclusive or explicate for every technology being developed but rather thought of as a general guide on how a TMVR technology could be developed in alignment with International Industry Standards. Key learnings from the Transcatheter Aortic Valve Replacement (TAVR) experience has also been considered and taken into account when outlining this general guidance for TMVR. Key learning points from the TAVR development experience included the following: quantification of acceptable levels of paravalvular leak, valve migration potential using various anchoring methods and overall implant frame failure modes when treating the native aortic valve. It should be noted that TAVR is over a decade further along in development and clinical experience compared to TMVR. These key learnings from the early experience with TAVR should be considered with all transcatheter development projects.
Asunto(s)
Cateterismo Cardíaco/instrumentación , Implantación de Prótesis de Válvulas Cardíacas/instrumentación , Prótesis Valvulares Cardíacas , Ensayo de Materiales/métodos , Insuficiencia de la Válvula Mitral/cirugía , Válvula Mitral/cirugía , Animales , Cateterismo Cardíaco/efectos adversos , Cateterismo Cardíaco/normas , Prótesis Valvulares Cardíacas/normas , Implantación de Prótesis de Válvulas Cardíacas/efectos adversos , Implantación de Prótesis de Válvulas Cardíacas/normas , Humanos , Ensayo de Materiales/normas , Válvula Mitral/fisiopatología , Insuficiencia de la Válvula Mitral/fisiopatología , Modelos Anatómicos , Modelos Animales , Modelos Cardiovasculares , Diseño de PrótesisRESUMEN
OBJECTIVES: This study sought to describe the pre-clinical evaluation of transapical mitral implantation of the Tiara (Neovasc Inc, Vancouver, British Columbia, Canada) valve in preparation for first-in-man implantation. BACKGROUND: The Tiara is a transcatheter self-expanding mitral bioprosthesis, specifically designed for the complex anatomic configuration of the mitral apparatus. METHODS: Tiara valves were implanted in a short-term porcine model, in a long-term ovine model, and in human cadavers. RESULTS: Short-term and long-term evaluation demonstrated excellent function and alignment of the valves, with no left ventricular outflow tract obstruction, coronary artery obstruction, or transvalvular gradients. Long-term evaluation of 7 sheep demonstrated clinically stable animals. A mild degree of prosthetic valve regurgitation was seen in 2 of the 7 sheep. A mild-to-moderate degree of paravalvular leak, which was attributed to this animal model, was observed in 6 of these animals. Cardioscopy and macroscopic evaluation demonstrated stable and secure positioning of the Tiara valve with no evidence of injury to the ventricular or atrial walls. Pericardial leaflets were free and mobile without calcifications. Implantation of the Tiara valves in human cadaver hearts demonstrated, upon visual inspection, proper anatomic alignment and seating of the valve, both at the atrial and at the ventricular aspects of the native mitral apparatus. CONCLUSIONS: In preparation for the first-in-man transcatheter mitral valve implantation, we report the successful pre-clinical evaluation of the Tiara transcatheter self-expanding mitral bioprosthetic valve. In porcine and ovine models without mitral regurgitation, transapical mitral implantation of the Tiara valve is technically feasible and safe, and results in a stable and well-functioning mitral bioprosthesis.
Asunto(s)
Bioprótesis , Cateterismo Cardíaco/instrumentación , Implantación de Prótesis de Válvulas Cardíacas/instrumentación , Implantación de Prótesis de Válvulas Cardíacas/métodos , Prótesis Valvulares Cardíacas , Válvula Mitral , Anciano , Anciano de 80 o más Años , Animales , Cadáver , Cateterismo Cardíaco/efectos adversos , Angiografía Coronaria , Ecocardiografía Tridimensional , Femenino , Implantación de Prótesis de Válvulas Cardíacas/efectos adversos , Humanos , Masculino , Persona de Mediana Edad , Válvula Mitral/diagnóstico por imagen , Válvula Mitral/fisiopatología , Insuficiencia de la Válvula Mitral/etiología , Insuficiencia de la Válvula Mitral/fisiopatología , Modelos Animales , Diseño de Prótesis , Ovinos , Porcinos , Factores de TiempoRESUMEN
Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) is used to find the structural differences between cancerous breast cells (MCF-7 line) and normal breast cells (MCF-12F line). Gold nanoparticles were prepared and the hydrodynamic diameter of the gold nanoparticles found to be 38.45 nm. The Gold nanoparticles were exposed to both MCF-7 and MCF-12F cells from lower to higher concentrations. Spectroscopic studies founds nanoparticles were within the cells, and increasing the nanoparticles concentration inside the cells also resulted in sharper IR peaks as a result of localized surface Plasmon resonance. Asymmetric and symmetric stretching and bending vibrations between phosphate, COO-, CH2 groups were found to give negative shifts in wavenumbers and a decrease in peak intensities when going from noncancerous to cancerous cells. Cellular proteins produced peak assignments at the 1542 and 1644 cm(-1) wavenumbers which were attributed to the amide I and amide II bands of the polypeptide bond of proteins. Significant changes were found in the peak intensities between the cell lines in the spectrum range from 2854-2956 cm(-1). Results show that the concentration range of gold nanoparticles used in this research showed no significant changes in cell viability in either cell line. Therefore, we believe ATR-FTIR and gold nanotechnology can be at the forefront of cancer diagnosis for some time to come.