Biodegradable polymeric microspheres can be used to deliver drugs through controlled rate and targeted processes. The drug is released from the particles by drug leaching or degradation of the polymeric matrix. Crystallinity can play a very important role in the degradation of polymeric matrixes; it can affect the drug-release rate, especially in chemoembolization. Most commercial embolic agents have a low degree of crystallinity, and the correlation between the drug-delivery rate and the degree of crystallinity is not fully understood. This study presents the appropriated synthesis conditions for the preparation of highly crystalline poly(vinyl alcohol) and poly(vinyl alcohol)/poly(vinyl acetate) microspheres and physicochemical characterizations by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and cross-polarization/magic angle spinning nuclear magnetic resonance.
The results of the histopathological analyses after the implantation of highly crystalline PVA microspheres in subcutaneous tissues of Wistar rats are here in reported. Three different groups of PVA microparticles were systematically studied: highly crystalline, amorphous, and commercial ones. In addition to these experiments, complementary analyses of architectural complexity were performed using fractal dimension (FD), and Shannon's entropy (SE) concepts. The highly crystalline microspheres induced inflammatory reactions similar to the ones observed for the commercial ones, while the inflammatory reactions caused by the amorphous ones were less intense. Statistical analyses of the subcutaneous tissues of Wistar rats implanted with the highly crystalline microspheres resulted in FD and SE values significantly higher than the statistical parameters observed for the amorphous ones. The FD and SE parameters obtained for the subcutaneous tissues of Wistar rats implanted with crystalline and commercial microparticles were statistically similar. Briefly, the results indicated that the new highly crystalline microspheres had biocompatible behavior comparable to the commercial ones. In addition, statistical tools such as FD and SE analyses when combined with histopathological analyses can be useful tools to investigate the architectural complexity tissues caused by complex inflammatory reactions.
Background:The 6 minute walk test (6-MWT) has been established as an important tool for functional assessment in heart failure patients. However, its prognostic impact on outcome in a mitral regurgitation population undergoing transcatheter mitral valve repair is unknown. Purpose: The present study assessed the 1-year outcome of patients after MitraClip implantation depending on the result of the pre-procedural 6-MWT. Methods: This present work represents a sub-analysis of the German, prospective, multicenter, transcatheter mitral valve interventions (TRAMI) registry. Of the main study cohort (n=828) 326 patients underwent a 6-MWT prior to their procedure. Patients were assigned to 2 groups depending on the pre-procedural 6-MWT distance using the median (<200m [group 1] vs. ≥200m [group 2]). Results: A total of 153 patients in group 1 and 173 patients in group 2 were available for the analysis. Among other differences in baseline characteristics patients in group 1 were older (77±8 years vs. 73±9 years; p<0.001) and had more severe multimorbidity as indicated by the STS score (12±8% vs. 8±6%; p=0.026). No differences regarding technical success defined as the absence of conversion to open heart surgery and residual mitral regurgitation ≤2+ (3% vs. 4%; p=0.71) and hospital MACCE (2% vs. 2%; p=0.88) were observed between the groups. With regard to 1-year outcome, patients with a distance in 6-MWT <200m had higher all-cause mortality (26% vs. 14%; p=0.013) as compared to those with a 6-MWT distance ≥200m. After adjustment for baseline risk factors, 6-MWT distance <200m still showed a strong trend towards increased 1-year all-cause mortality (HR 1.62, 95% confidence interval 0.95-2.74; p=0.075).
Conclusion:In the present study pre-procedural 6-MWT distance <200m was associated with significantly higher 1-year all-cause mortality in patients undergoing MitraClip implantation. Based on these results, the 6-MWT can be used as additional prognostic tool in this patient cohort. Background: Cardiac valve diseases cause damage to health, leading to detriment of the quality of life of the patient. Among these diseases, the main ones are aortic stenosis, mitral insufficiency and degeneration of bioprostheses previously implanted. The gold standard in the treatment is surgical intervention, with replacement of the valve by a new bioprosthesis, being classified as a procedure of high surgical risk. However, traditional treatment is not indicated for people with advanced age and associated comorbidities. The development of expandable transcatheter valves presented as an alternative treatment and brought an option to inoperable patients. Purpose: Presentation of the clinical indications of the transcatheter treatment and evaluation of patients submitted to transapical transcatheter valve implantation in the aortic (stenosis and valve-in-valve) and mitral (valve-in-valve) positions. Methods: Transapical procedures were performed to implant the Brazilian transcatheter valve in patients with contraindications to the surgical gold s...
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