Publications by authors named "Wai-Ki Yiu"

Endovascular treatment of femoropopliteal occlusive disease is challenging and often limited by its unique anatomic, hemodynamic and biomechanical constraints. Despite technical improvement, percutaneous transluminal angioplasty alone is not adequate to provide satisfactory long-term patency. Several randomized controlled trials have shown that primary nitinol stenting can provide a better short-term radiological patency in intermediate lesion, but the results were often limited by intrinsic stent complications, particularly in-stent restenosis.

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Background: The long-term results of treating chronic aortic dissections and aneurysms in association with dissections with thoracic endovascular aortic repair (TEVAR) are unknown, and the timing for intervention is uncertain. We evaluated the morphology of stent graft and aorta remodeling and the volumetric changes in these patients after successful TEVAR.

Methods: Serial computed tomography scans of 32 patients who underwent TEVAR for uncomplicated chronic dissections (group A, n = 17) and chronic dissections with aneurysms (group B, n = 15) were analyzed at 1, 6, 12, and 36 months.

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Purpose: To investigate the effects of supercooling, a phase whereby cells are below 0 degrees C but still in a liquid state, and freezing, the phase when cells become solid, of vascular cells in culture.

Materials And Methods: Bovine aortic endothelial cells and smooth muscle cells were supercooled to -10 degrees C with or without freezing for 3, 30, or 60 seconds and then rewarmed to 37 degrees C for 24 hours. Viability was assessed by means of trypan blue exclusion, and apoptosis was assessed with the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay.

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Purpose: Cryoplasty combines mechanical dilation with supercooling of the vessel and has shown encouraging preliminary results in the management of atherosclerotic lesions. However, the mechanisms of action and the optimum inflation regimen are still not well established. This study investigates the effects of single and dual supercooling and rewarming cycles on the survival responses of smooth muscle cells (SMCs) and endothelial cells (ECs).

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Background: Cryoplasty combines mechanical dilatation with the delivery of hypothermia to atherosclerotic plaques. The response of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) to supercooling and subsequent rewarming is still not clear. This study investigated the differential effects of vascular cell survival and proliferation in an in vitro model simulating cryoplasty.

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Cryosurgery dates back to the 19th century, with the description of the benefits of local application of cooling for conditions such as pain control. Once commercial liquefied gases became available, more progress was made in the use of cryotherapy for localized lesions. As understanding of disease response to freezing increased, safer techniques for performing freezing procedures helped prepare its clinical application in different clinical situations, such as prostate disease and bronchial cancers.

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Purpose: The underlying mechanisms for the reduction in restenosis caused by cryoplasty for peripheral atherosclerotic lesions are not well understood. Because vascular smooth muscle cells (SMCs) are known to play a critical role in restenosis and neointimal hyperplasia, the aim of this study was to determine SMC survival under conditions of "supercooling" and/or rewarming.

Materials And Methods: Bovine aortic SMCs were supercooled to -10 degrees C for 0, 60, or 120 seconds with a custom-designed conduction cooling stage and then rewarmed to 37 degrees C in an incubator for 0, 12, or 24 hours.

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