81 resultados para Gabor Wavelets
Resumo:
Transcatheter aortic valve implantation (TAVI) is an alternative to surgery for high-risk patients with severe aortic valve stenosis. Periprocedural stroke is reported at an incidence up to 10%. Magnetic resonance imaging studies have identified new onset of clinically silent ischaemic cerebral lesions more frequently (68-84%). So far, few data are available about cerebral embolism during TAVI. The aim of this study was to determine the frequency of high-intensity transient signals (HITS) and to explore differences in the HITS pattern between transfemoral and transapical access and between self-expanding (SE) and balloon-expandable (BE) deployment technique.
Resumo:
Objectives The aim of this study was to assess the role of transcatheter aortic valve implantation (TAVI) compared with medical treatment (MT) and surgical aortic valve replacement (SAVR) in patients with severe aortic stenosis (AS) at increased surgical risk. Background Elderly patients with comorbidities are at considerable risk for SAVR. Methods Since July 2007, 442 patients with severe AS (age: 81.7 ± 6.0 years, mean logistic European System for Cardiac Operative Risk Evaluation: 22.3 ± 14.6%) underwent treatment allocation to MT (n = 78), SAVR (n = 107), or TAVI (n = 257) on the basis of a comprehensive evaluation protocol as part of a prospective registry. Results Baseline clinical characteristics were similar among patients allocated to MT and TAVI, whereas patients allocated to SAVR were younger (p < 0.001) and had a lower predicted peri-operative risk (p < 0.001). Unadjusted rates of all-cause mortality at 30 months were lower for SAVR (22.4%) and TAVI (22.6%) compared with MT (61.5%, p < 0.001). Adjusted hazard ratios for death were 0.51 (95% confidence interval: 0.30 to 0.87) for SAVR compared with MT and 0.38 (95% confidence interval: 0.25 to 0.58) for TAVI compared with MT. Medical treatment (<0.001), older age (>80 years, p = 0.01), peripheral vascular disease (<0.001), and atrial fibrillation (p = 0.04) were significantly associated with all-cause mortality at 30 months in the multivariate analysis. At 1 year, more patients undergoing SAVR (92.3%) or TAVI (93.2%) had New York Heart Association functional class I/II as compared with patients with MT (70.8%, p = 0.003). Conclusions Among patients with severe AS with increased surgical risk, SAVR and TAVI improve survival and symptoms compared with MT. Clinical outcomes of TAVI and SAVR seem similar among carefully selected patients with severe symptomatic AS at increased risk.
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The goal of this study was to determine whether advanced age affects mortality and incidence of neurological injury in patients undergoing surgical repair with hypothermic circulatory arrest in acute and chronic thoracic aortic pathology.
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Acute dissection and rupture of aortic aneurysms comprise for 1-2% of all deaths in industrialized countries. Dilation of the aorta is caused by a multitude of mechanisms including inherited connective tissue disorders such as Marfan syndrome (MFS). MFS is one of the most common inherited connective tissue disorders affecting 1 in 5000 individuals. Although the phenotype of MFS can be quite variable, aneurysmal dilation of the aortic root and consecutive acute aortic dissection is the leading cause of death in this patient population. Over the past years it has been shown that a comprehensive understanding of this disorder provides greater understanding of vascular wall biology and identifies pathways relevant to aortic aneurysms and dissection in general. The current review discusses the surgical management of patients with MFS with a special emphasis on indications for surgery in this complex group of patients.
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The progress of wet age-related macular degeneration can now be controlled by intravitreal drug injection. This approach requires repeated injections, which could be avoided by delivering the drug to the retina. Intraocular implants are a promising solution for drug delivery near the retina. Currently, their accurate placement is challenging, and they can only be removed after a vitrectomy. In this paper, we introduce an approach for minimally invasive retinal drug delivery using magnetic intraocular inserts. We briefly discuss the electromagnetic-control system for magnetic implants and then focus on evaluating their ability to move in the vitreous humor. The mobility of magnetic intraocular implants is estimated in vitro with synthesized vitreous humors, and ex vivo with experiments on cadaver porcine eyes. Preliminary results show that with such magnetic implants a vitrectomy can be avoided.
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To investigate the suitability of blood granulocyte and monocyte sensitivity, as measured by the quantity of different agonists required to induce CD62L shedding, for assessment of perioperative immune changes in patients undergoing cardiac surgery with cardiopulmonary bypass.
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In acute traumatic bleeding, permissive arterial hypotension with delayed volume resuscitation is an established lifesaving concept as abridge to surgical control. This study investigated whether preoperatively administered volume also correlated inversely with survival after ruptured abdominal aortic aneurysm (rAAA).
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The aim of the current study was to investigate incidence and causes of surgical interventions in primarily nontreated aortic segments after previous aortic repair in patients with Marfan syndrome.
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In this work, we present a multichannel EEG decomposition model based on an adaptive topographic time-frequency approximation technique. It is an extension of the Matching Pursuit algorithm and called dependency multichannel matching pursuit (DMMP). It takes the physiologically explainable and statistically observable topographic dependencies between the channels into account, namely the spatial smoothness of neighboring electrodes that is implied by the electric leadfield. DMMP decomposes a multichannel signal as a weighted sum of atoms from a given dictionary where the single channels are represented from exactly the same subset of a complete dictionary. The decomposition is illustrated on topographical EEG data during different physiological conditions using a complete Gabor dictionary. Further the extension of the single-channel time-frequency distribution to a multichannel time-frequency distribution is given. This can be used for the visualization of the decomposition structure of multichannel EEG. A clustering procedure applied to the topographies, the vectors of the corresponding contribution of an atom to the signal in each channel produced by DMMP, leads to an extremely sparse topographic decomposition of the EEG.
Resumo:
AIMS: We investigated whether myeloid-related protein 8/14 complex (MRP8/14) expressed by infiltrating monocytes and granulocytes may represent a mediator and early biomarker of acute coronary syndromes (ACS). METHODS AND RESULTS: Immunohistochemistry of coronary thrombi was done in 41 ACS patients. Subsequently, levels of MRP8/14 were assessed systemically in 75 patients with ACS and culprit lesions, with stable coronary artery disease (CAD), or with normal coronary arteries. In a subset of patients, MRP8/14 was measured systemically and at the site of coronary occlusion. Macrophages and granulocytes, but not platelets stained positive for MRP8/14 in 76% of 41 thrombi patients. In ACS, local MRP8/14 levels [22.0 (16.2-41.5) mg/L] were increased when compared with systemic levels [13.4 (8.1-14.7) mg/L, P = 0.03]. Systemic levels of MRP8/14 were markedly elevated [15.1 (12.1-21.8) mg/L, P = 0.001] in ACS when compared with stable CAD [4.6 (3.5-7.1) mg/L] or normals [4.8 (4.0-6.3) mg/L]. Using a cut-off level of 8 mg/L, MRP8/14 but not myoglobin or troponin, identified ACS presenting within 3 h from symptom onset. CONCLUSION: In ACS, MRP8/14 is markedly expressed at the site of coronary occlusion by invading phagocytes. The occurrence of elevated MRP8/14 in the systemic circulation prior to markers of myocardial necrosis makes it a prime candidate for the detection of unstable plaques and management of ACS.