3 resultados para Endometrial ablation

em QSpace: Queen's University - Canada


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Laser micromachining is an important material processing technique used in industry and medicine to produce parts with high precision. Control of the material removal process is imperative to obtain the desired part with minimal thermal damage to the surrounding material. Longer pulsed lasers, with pulse durations of milli- and microseconds, are used primarily for laser through-cutting and welding. In this work, a two-pulse sequence using microsecond pulse durations is demonstrated to achieve consistent material removal during percussion drilling when the delay between the pulses is properly defined. The light-matter interaction moves from a regime of surface morphology changes to melt and vapour ejection. Inline coherent imaging (ICI), a broadband, spatially-coherent imaging technique, is used to monitor the ablation process. The pulse parameter space is explored and the key regimes are determined. Material removal is observed when the pulse delay is on the order of the pulse duration. ICI is also used to directly observe the ablation process. Melt dynamics are characterized by monitoring surface changes during and after laser processing at several positions in and around the interaction region. Ablation is enhanced when the melt has time to flow back into the hole before the interaction with the second pulse begins. A phenomenological model is developed to understand the relationship between material removal and pulse delay. Based on melt refilling the interaction region, described by logistic growth, and heat loss, described by exponential decay, the model is fit to several datasets. The fit parameters reflect the pulse energies and durations used in the ablation experiments. For pulse durations of 50 us with pulse energies of 7.32 mJ +/- 0.09 mJ, the logisitic growth component of the model reaches half maximum after 8.3 us +/- 1.1 us and the exponential decays with a rate of 64 us +/- 15 us. The phenomenological model offers an interpretation of the material removal process.

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Atrial fibrillation (AF) is a major global health issue as it is the most prevalent sustained supraventricular arrhythmia. Catheter-based ablation of some parts of the atria is considered an effective treatment of AF. The main objective of this research is to analyze atrial intracardiac electrograms (IEGMs) and extract insightful information for the ablation therapy. Throughout this thesis we propose several computationally efficient algorithms that take streams of IEGMs from different atrial sites as the input signals, sequentially analyze them in various domains (e.g., time and frequency), and create color-coded three-dimensional map of the atria to be used in the ablation therapy.

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Endometriosis affects 5-10% of women and is characterized by the growth of endometrial tissue outside of the uterus. Treatment for endometriosis primarily focuses on symptom relief, is short term with severe side effects and often leads to recurrence of the condition. Establishing new blood supply is a fundamental requirement for endometriosis lesions growth. This has led to the idea that antiangiogenic therapy may be a successful approach for inhibiting endometriosis. Recent evidence indicates that endothelial progenitor cells (EPCs) contribute to neoangiogenesis of endometriotic lesions. These EPCs are recruited to the lesion site by stromal cell-derived factor-1 (SDF-1). We hypothesize that SDF-1 is central to the neoangiogenesis and survival of endometriotic lesions and that administration of SDF-1 blocking antibody will inhibit lesion growth by inhibiting angiogenesis in a murine model of endometriosis. Immunohistochemistry for SDF-1 and CD34 was performed on human endometriosis and normal endometrial samples. Quantification of SDF-1 and EPCs was performed in the blood of endometriosis patients and controls using ELISA and flow cytometry, respectively. A new mouse model of endometriosis was developed using BALB/c-Rag2-/-/IL2rg-/- mice to investigate role of SDF-1 in neoangiogenesis. Either SDF-1 blocking antibody or an isotype control was administered on a weekly basis for four weeks. Weekly samples of peripheral blood from mice were analyzed for SDF-1, other cytokines of interest and EPCs. Mice were euthanized at seven weeks to observe lesion growth and blood vessel development. Our results indicate overabundance of SDF-1 and CD34+ progenitor cells in human endometriotic lesions compared to eutopic endometrium. In the mouse model, SDF-1 and circulating EPC levels decreased from pre-treatment levels after one week, and remained constant over the course of the treatment in both SDF-1 blocking antibody and isotype control groups. In the SDF-1 blocking group, reduced vascularity of lesions, identified by immunofluorescence staining for CD31, was revealed compared to isotype controls. These findings suggest that SDF-1 may be responsible for CD34+ progenitor cell recruitment to the neoangiogenic sites in endometriosis. Blocking of SDF-1 reduces neovascularization of human endometriotic lesions in a mouse model. Further studies on blocking SDF-1 in combination with other antiangiogenic agents are needed.