دانلود رایگان مقاله آنالیز نیرومندی افزایش شدت موج کرونر با تفاضل محدود مرکزی مراتب بالا

Abstract

Background: Coronary Wave Intensity Analysis (cWIA) is a technique capable of separating the effects of proximal arterial haemodynamics from cardiac mechanics. Studies have identified WIA-derived indices that are closely correlated with several disease processes and predictive of functional recovery following myocardial infarction. The cWIA clinical application has, however, been limited by technical challenges including a lack of standardization across different studies and the derived indices’ sensitivity to the processing parameters. Specifically, a critical step in WIA is the noise removal for evaluation of derivatives of the acquired signals, typically performed by applying a SavitzkyeGolay filter, to reduce the high frequency acquisition noise. Methods: The impact of the filter parameter selection on cWIA output, and on the derived clinical metrics (integral areas and peaks of the major waves), is first analysed. The sensitivity analysis is performed either by using the filter as a differentiator to calculate the signals’ time derivative or by applying the filter to smooth the ensemble-averaged waveforms. Furthermore, the power-spectrum of the ensemble-averaged waveforms contains little highfrequency components, which motivated us to propose an alternative approach to compute the time derivatives of the acquired waveforms using a central finite difference scheme. Results and Conclusion: The cWIA output and consequently the derived clinical metrics are significantly affected by the filter parameters, irrespective of its use as a smoothing filter or a differentiator. The proposed approach is parameter-free and, when applied to the 10 invivo human datasets and the 50 in-vivo animal datasets, enhances the cWIA robustness by significantly reducing the outcome variability (by 60%).

Conclusion

In conclusion, if in practice the SeG filter is employed we remark that it is crucial to apply it to smooth the ensembleaveraged waveforms (SG-S approach) and to keep the parameters consistent through the analysis and to publish them. Based on our observations, N Z 4,5 appear to perform most optimally in this case. Moreover, when applying WIA to the coronary arteries, it is important to avoid using the SeG filter as a differentiator with N Z 2. The newly proposed method provides an important advancement for cWIA robustness, towards a standardized clinical analysis. Furthermore, this new method may help to highlight previously overlooked clinical relevance of the FCW and BCW waves confounded by the sensitivity to the processing parameters.