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For end-stage renal disease patients undergoing hemodialysis, thrombosis caused by stenosis hinders the long-term use of vascular access. However, traditional spectral bruit analysis techniques for detecting the severity of vascular access stenosis are not robust. Accordingly, the present study proposes an automated method for mimicking a trained practitioner in performing the auscultation process. In the proposed approach, the bruit obtained using a standard phonoangiographic method is transformed into the time-frequency domain, and two spectro-temporal features, namely the auditory spectrum flux and the auditory spectral centroid, are then extracted. The distributions of the two features are analyzed using a multivariate Gaussian distribution (MGD) model. Finally, the distribution parameters of the MGD model are used to detect the presence (or otherwise) of vascular access stenosis. The validity of the proposed approach is investigated using the phonoangiography signals obtained from 16 hemodialysis patients with straight arteriovenous grafts over the upper arm region. The results show that the MGD covariance matrix coefficient of the auditory spectral centroid feature yields an accuracy of 83.87 % in detecting significant vascular access stenosis. Thus, the proposed method has significant potential for the applications of vascular access stenosis detection. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 16-year-old boy who was admitted to an emergency department because of chest pain with back radiation. Findings of chest X-ray and emergency chest computed tomography revealed whiteout of the left thorax and a ruptured aortic arch aneurysm, respectively. The patient underwent emergency surgery for the reconstruction of hybrid aortic arch, but died after prolonged shock.

To detect the early developmental stages of arteriovenous access (AVA) stenosis in hemodialysis patients, this study explored a stenosis detector based on the Burg method and the fractional-order chaos system (FOCS). The bruit developed by the blood flowing through AVA can be a viable noninvasive strategy for monitoring AVA functions. We used the Burg method of the autoregressive model to estimate the frequency spectra of phonographic signals recorded by an electronic stethoscope in patients' AVAs and to identify the spectral peaks in the region of 25-800 Hz. The frequency spectra differed significantly between normal and stenosis statuses in AVA. We found that the frequency and amplitude in power spectra analysis varied in accordance with the severity of AVA stenosis. However, the correlation of these parameters for classifying the degree of stenosis is limited when only using the Burg method. Therefore, we used an FOCS to monitor the differing frequency spectra between the normal condition and AVA stenosis. The variances of these two conditions were dynamic errors that were the coupling variables that tracked the responses between the master system and the slave system. A total of 42 patients who had received percutaneous transluminal angioplasty (PTA) for their failing AVAs was recruited for this study. In this study, the dynamic error, Index Ψ, was used to calculate the frequency spectrum redistribution in patients undergoing PTA. In addition, ΔImp was the index used to evaluate improvements in the luminal diameter between pre- and post-PTA. Therefore, we used linear regression to model the relationship between ΔImp and Index Ψ. The findings indicate that the proposed method has enhanced efficiency, especially in the venous anastomosis (V-site). The FOCS is a novel and simple algorithm for analyzing the residual AVA stenosis of PTA treatment. [ABSTRACT FROM AUTHOR]

Background: Computed tomography (CT) is the modality of choice in the diagnosis of mycotic aneurysms. The present study aimed to classify the CT findings of mycotic aneurysms, and to assess their predictive value based on the correlation of a CT-based grading system with prognostic factors and outcomes. Methods: Over the past 21 years, 40 consecutive patients underwent open surgery for mycotic aneurysms of the abdominal aorta and iliac arteries in our hospital. The CT appearances of mycotic aneurysms were categorized into four grades: grade 1, periarterial changes without destruction of the arterial wall; grade 2, presence of saccular outpouching; grade 3, extensive retroperitoneal infection; and grade 4, massive perianeurysmal hemorrhage. Clinical data were recorded for analysis. Results: The surgical mortality and overall aneurysm-related mortality rates were 17.5 and 25 %, respectively. The poor prognostic predictors were shock, rupture, and concomitant gastrointestinal procedures. The increasing proportions of shock and rupture status corresponded to mycotic aneurysms of higher grades in the CT-based grading. In addition, one patient in grades 1 and 2, versus five in grades 3 and 4 ( P = 0.02), required concomitant gastrointestinal procedures. The CT-based grading exhibited a strong association with surgical mortality (Cramer's V coefficient = 0.65; P = 0.002) and a relatively strong association with overall aneurysm-related mortality (Cramer's V coefficient = 0.53; P = 0.01). Conclusions: For patients surgically treated for abdominal mycotic aneurysms, the CT-based grading is correlated with clinical severity, surgical complexity, and outcomes, and thus it may serve as a simple scale for risk classification. [ABSTRACT FROM AUTHOR]