Spectral analysis of heart rate variability (HRV) has been tauted as a noninvasive means of assessing cardiac autonomic tone. Little agreement exists on optimal measures (i.e., peak vs. area absolute value vs. ratio, RR intervals vs. differences in successive RR intervals). The authors compared analyses of the first and last 128 beats of a 5 minute EKG acquisition in 81 healthy adults (age 21-65). It is concluded that: 1) most spectral indices of HRV are independent of resting heart rate; 2) the percent change between first and last segments showed no significant differences between any of the indices measured; 3) large short term changes in measures of HRV may limit their use for assessing changes in autonomic tone in individual subjects in response to physiologic stimuli such as tilt or standing.<>
{"title":"Short term reproducibility of indices of heart rate variability","authors":"M. Meaddens, T. Boyko, T. Vybiral, R. Bryg","doi":"10.1109/CIC.1993.378399","DOIUrl":"https://doi.org/10.1109/CIC.1993.378399","url":null,"abstract":"Spectral analysis of heart rate variability (HRV) has been tauted as a noninvasive means of assessing cardiac autonomic tone. Little agreement exists on optimal measures (i.e., peak vs. area absolute value vs. ratio, RR intervals vs. differences in successive RR intervals). The authors compared analyses of the first and last 128 beats of a 5 minute EKG acquisition in 81 healthy adults (age 21-65). It is concluded that: 1) most spectral indices of HRV are independent of resting heart rate; 2) the percent change between first and last segments showed no significant differences between any of the indices measured; 3) large short term changes in measures of HRV may limit their use for assessing changes in autonomic tone in individual subjects in response to physiologic stimuli such as tilt or standing.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"76 1","pages":"479-482"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86101869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors have developed an optical micromapping system which consists of two individual setups with one common laser as excitation light source. One setup is designed to monitor excitation spread in cardiac tissue preparations in the mm-range, the other one is capable to monitor excitation phenomena in single cardiomyocytes. The time resolutions achieved are about 100 /spl mu/s for the tissue setup (256 pixels, spatial resolution down to 84 /spl mu/m), and about 20 /spl mu/s for the cell setup (24 pixels, spatial resolution down to 14 /spl mu/m). The green line of an argon ion laser (514 nm, up to 2 W) was used to excite fluorescence of various cardiac preparations of rats and guinea pigs which were stained with the potential sensitive dye di-4-ANEPPS. The authors' measurements revealed discontinuous propagation occurring in microscopic areas in cardiac tissues as well as complex excitation phenomena in single cardiomyocytes when stimulated by extracellular electrical fields.<>
{"title":"Optical micromapping in cardiac tissues and cells","authors":"H. Windisch, W. Muller, H. Ahammer, P. Schaffer","doi":"10.1109/CIC.1993.378485","DOIUrl":"https://doi.org/10.1109/CIC.1993.378485","url":null,"abstract":"The authors have developed an optical micromapping system which consists of two individual setups with one common laser as excitation light source. One setup is designed to monitor excitation spread in cardiac tissue preparations in the mm-range, the other one is capable to monitor excitation phenomena in single cardiomyocytes. The time resolutions achieved are about 100 /spl mu/s for the tissue setup (256 pixels, spatial resolution down to 84 /spl mu/m), and about 20 /spl mu/s for the cell setup (24 pixels, spatial resolution down to 14 /spl mu/m). The green line of an argon ion laser (514 nm, up to 2 W) was used to excite fluorescence of various cardiac preparations of rats and guinea pigs which were stained with the potential sensitive dye di-4-ANEPPS. The authors' measurements revealed discontinuous propagation occurring in microscopic areas in cardiac tissues as well as complex excitation phenomena in single cardiomyocytes when stimulated by extracellular electrical fields.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"11 1","pages":"137-140"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89723317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Varanini, A. Taddei, R. Balocchi, M. Macerata, F. Conforti, M. Emdin, C. Carpeggiani, C. Marchesi
The authors propose a method for artifact detection based on linear modelling of biological time series. An artifact, coming from a different "source", generally does not fit in the model and can be detected. Biological time series are not stationary, so that adaptive filtering is used for model estimation. Real time constraints warrant the use of predictive models only past input values are used to predict the current sample values. A set of thresholds or the prediction errors is used to detect artifacts. The authors model each time series by means of an adaptive prediction filter and, when a priori knowledge or the relation between two measurements, is available, they model this specific cross-channel relation with an adaptive filter. They applied this method to sequences of cardiovascular measurements from ICU and from Holter monitoring. The results obtained are fully satisfactory.<>
{"title":"Adaptive modelling of biological time series for artifact detection","authors":"M. Varanini, A. Taddei, R. Balocchi, M. Macerata, F. Conforti, M. Emdin, C. Carpeggiani, C. Marchesi","doi":"10.1109/CIC.1993.378307","DOIUrl":"https://doi.org/10.1109/CIC.1993.378307","url":null,"abstract":"The authors propose a method for artifact detection based on linear modelling of biological time series. An artifact, coming from a different \"source\", generally does not fit in the model and can be detected. Biological time series are not stationary, so that adaptive filtering is used for model estimation. Real time constraints warrant the use of predictive models only past input values are used to predict the current sample values. A set of thresholds or the prediction errors is used to detect artifacts. The authors model each time series by means of an adaptive prediction filter and, when a priori knowledge or the relation between two measurements, is available, they model this specific cross-channel relation with an adaptive filter. They applied this method to sequences of cardiovascular measurements from ICU and from Holter monitoring. The results obtained are fully satisfactory.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"74 1","pages":"695-698"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86317199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Karson, S. Chandra, A. Morehead, S. Nissen, J.D. Thomas
The degree of information loss by compression of echocardiographic images utilizing the Joint Photographic Experts Group (JPEG) baseline system was evaluated using objective fidelity criteria. Standard echocardiograms were acquired digitally in real-time and stored on optical disk. 180 still frame images were processed in software using 5 preset quantization tables yielding average compression ratios of 7:1, 10:1, 17:1, 30:1 and 36:1. Objective parameters evaluated include the root mean square error (RMSE), signal-to-noise ratio (SNR), difference image mean and maximal pixel value shift. The mean pixel values and standard deviations of all images over all levels of compression were very similar. Even for ratios as high as 35:1, no significant bias was introduced in the pixel intensity values. Average RMSE ranged from 1.27 to 7.89 while average SNR ranged from 38.81 to 22.93. The data shows that JPEG compression at high ratios does not significantly alter objective image content and is a potential solution for reducing digital storage requirements.<>
{"title":"Digital compression of echocardiographic images: is it viable?","authors":"T. Karson, S. Chandra, A. Morehead, S. Nissen, J.D. Thomas","doi":"10.1109/CIC.1993.378356","DOIUrl":"https://doi.org/10.1109/CIC.1993.378356","url":null,"abstract":"The degree of information loss by compression of echocardiographic images utilizing the Joint Photographic Experts Group (JPEG) baseline system was evaluated using objective fidelity criteria. Standard echocardiograms were acquired digitally in real-time and stored on optical disk. 180 still frame images were processed in software using 5 preset quantization tables yielding average compression ratios of 7:1, 10:1, 17:1, 30:1 and 36:1. Objective parameters evaluated include the root mean square error (RMSE), signal-to-noise ratio (SNR), difference image mean and maximal pixel value shift. The mean pixel values and standard deviations of all images over all levels of compression were very similar. Even for ratios as high as 35:1, no significant bias was introduced in the pixel intensity values. Average RMSE ranged from 1.27 to 7.89 while average SNR ranged from 38.81 to 22.93. The data shows that JPEG compression at high ratios does not significantly alter objective image content and is a potential solution for reducing digital storage requirements.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"8 1","pages":"831-834"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82226928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Describes a method to trace the coronary arterial boundaries with branches automatically from X-ray angiograms. The edge points are fixed by a function based on smoothing differential operator for the gray values on the searching line defined from the edge points fixed previously. Thus the boundary points along the artery are detected automatically. The branch positions are detected automatically and the branch of the artery is searched by the same algorithm. In the edge detection process, the required user interaction is only the manual pointing of the initial data such as the starting point the direction and the range for search. This method is tested and verified its usefulness through computer generated images with different stenoses and actual angiograms.<>
{"title":"Automatic detection of the coronary arterial contours with sub-branches from an X-ray angiogram","authors":"S. Lu, S. Eiho","doi":"10.1109/CIC.1993.378337","DOIUrl":"https://doi.org/10.1109/CIC.1993.378337","url":null,"abstract":"Describes a method to trace the coronary arterial boundaries with branches automatically from X-ray angiograms. The edge points are fixed by a function based on smoothing differential operator for the gray values on the searching line defined from the edge points fixed previously. Thus the boundary points along the artery are detected automatically. The branch positions are detected automatically and the branch of the artery is searched by the same algorithm. In the edge detection process, the required user interaction is only the manual pointing of the initial data such as the starting point the direction and the range for search. This method is tested and verified its usefulness through computer generated images with different stenoses and actual angiograms.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"92 1","pages":"575-578"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80551952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Bollacker, E. V. Simpson, R. Hillsley, S. M. Blanchard, W.M. Smith, R. Ideker
Cardiac activation sequences are normally determined by the detection and timing of local activations in cardiac electrograms, but assigning of a unique activation time, especially during ventricular fibrillation (VF), is often difficult. Even if distinct activations can be derived, it is difficult to group activations into wavefronts. A method was developed for automating the identification and analysis of distinct wavefronts of electrical activity that eliminates the inconsistencies of manual analysis and the ambiguities of isochronal mapping. After individual wavefronts have been identified, analysis of their characteristics became a simple task that was also automated. This automated method shows promise as an accurate and powerful tool for quantitative analysis of VF.<>
{"title":"Automatic identification and analysis of activation wavefronts in a 2-D electrogram array","authors":"K. Bollacker, E. V. Simpson, R. Hillsley, S. M. Blanchard, W.M. Smith, R. Ideker","doi":"10.1109/CIC.1993.378472","DOIUrl":"https://doi.org/10.1109/CIC.1993.378472","url":null,"abstract":"Cardiac activation sequences are normally determined by the detection and timing of local activations in cardiac electrograms, but assigning of a unique activation time, especially during ventricular fibrillation (VF), is often difficult. Even if distinct activations can be derived, it is difficult to group activations into wavefronts. A method was developed for automating the identification and analysis of distinct wavefronts of electrical activity that eliminates the inconsistencies of manual analysis and the ambiguities of isochronal mapping. After individual wavefronts have been identified, analysis of their characteristics became a simple task that was also automated. This automated method shows promise as an accurate and powerful tool for quantitative analysis of VF.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"138 1","pages":"189-192"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89926045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Existing methods for automatically finding arteries in coronary angiograms rely on preprocessing (digital subtraction or edge enhancement). Structure recognition in unprocessed images will enable the analysis of a wider range clinical images (of varying quality). The authors have previously reported on a prototype which works on such unsubtracted and unprocessed digital angiograms. They now present a system designed to process image pairs and thereby perform recognition in three dimensions. This approach, the "Deformable Template Matcher" (DTM), combines a-priori knowledge of the arterial tree (encoded as mathematical "templates") with a stochastic deformation process described by a hidden Markov model. An introduction so the technique is presented along with examples of its application to bi-plane images and a discussion of the computational implications.<>
{"title":"Three dimensional structure recognition in digital angiograms using Gauss-Markov methods","authors":"R. Petrocelli, K. Manbeck, J. Elion","doi":"10.1109/CIC.1993.378494","DOIUrl":"https://doi.org/10.1109/CIC.1993.378494","url":null,"abstract":"Existing methods for automatically finding arteries in coronary angiograms rely on preprocessing (digital subtraction or edge enhancement). Structure recognition in unprocessed images will enable the analysis of a wider range clinical images (of varying quality). The authors have previously reported on a prototype which works on such unsubtracted and unprocessed digital angiograms. They now present a system designed to process image pairs and thereby perform recognition in three dimensions. This approach, the \"Deformable Template Matcher\" (DTM), combines a-priori knowledge of the arterial tree (encoded as mathematical \"templates\") with a stochastic deformation process described by a hidden Markov model. An introduction so the technique is presented along with examples of its application to bi-plane images and a discussion of the computational implications.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"53 1","pages":"101-104"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90256091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetic resonance images of the heart provide a wide variety of cardiac anatomical and physiological data. In this study an almost fully automatic process, that extracts the endocardial and epicardial boundaries and provides numerical values of the main cardiac functional parameters, is presented. The contour extraction algorithm performs well in more than 60% of the inspected images for variable quality images. Its performance improves markedly when only reasonable quality images are considered. The values obtained for cardiac parameters seem to be within the normal range.<>
{"title":"Evaluation of cardiac function from short-axis cardiac magnetic resonance images using automatic boundary extraction","authors":"Y. Zimmer, Solange Akselrod","doi":"10.1109/CIC.1993.378378","DOIUrl":"https://doi.org/10.1109/CIC.1993.378378","url":null,"abstract":"Magnetic resonance images of the heart provide a wide variety of cardiac anatomical and physiological data. In this study an almost fully automatic process, that extracts the endocardial and epicardial boundaries and provides numerical values of the main cardiac functional parameters, is presented. The contour extraction algorithm performs well in more than 60% of the inspected images for variable quality images. Its performance improves markedly when only reasonable quality images are considered. The values obtained for cardiac parameters seem to be within the normal range.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"3 1","pages":"743-746"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90304282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J.J. Chungath, A. Ramanathan, M. Kienzle, G. Myers
Heart rate variability (HRV) is primarily due to instability oscillations of homeostatic feedback loops. Each loop tends to oscillate at a frequency characteristic of the time required to traverse that loop. Discarding all segments with ectopy is impractical in a clinical setting, since the number of ectopy-free segments is low even in patients with moderate ectopy. Investigators are extending spectra into lower frequency ranges, which requires longer data segments, and further reduces the number of ectopy-free segments. A method is proposed to determine the level of ectopy above which data segments should be discarded. By enforcing an effective ectopy cutoff, the mean distance among the spectra making up the average periodogram is reduced, increasing the confidence in these spectra. This technique allows for "quality control" of the data upon which HRV spectral analysis is based.<>
{"title":"Improving the quality of heart rate variability spectra by imposing a constraint on the amount of ectopy in each data segment","authors":"J.J. Chungath, A. Ramanathan, M. Kienzle, G. Myers","doi":"10.1109/CIC.1993.378381","DOIUrl":"https://doi.org/10.1109/CIC.1993.378381","url":null,"abstract":"Heart rate variability (HRV) is primarily due to instability oscillations of homeostatic feedback loops. Each loop tends to oscillate at a frequency characteristic of the time required to traverse that loop. Discarding all segments with ectopy is impractical in a clinical setting, since the number of ectopy-free segments is low even in patients with moderate ectopy. Investigators are extending spectra into lower frequency ranges, which requires longer data segments, and further reduces the number of ectopy-free segments. A method is proposed to determine the level of ectopy above which data segments should be discarded. By enforcing an effective ectopy cutoff, the mean distance among the spectra making up the average periodogram is reduced, increasing the confidence in these spectra. This technique allows for \"quality control\" of the data upon which HRV spectral analysis is based.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"22 1","pages":"727-729"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72985717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wigner Ville distribution has many of the desirable features for the spectral analysis of cardiovascular series during the transients of the autonomic tests, but the presence of the artefacts makes power measurements from the spectra often unreliable. This work proposes new approaches for rejecting artefacts, besides the well known spectral averaging. In particular, an appropriate preprocessing and a segment-regression based smoothing are considered and compared with the classical approach, taking into account both the different characteristics of the considered autonomic tests.<>
{"title":"Artefact rejection from Wigner Ville spectra of cardiovascular series in autonomic tests","authors":"S. Pola, M. Emdin, A. Macerata, C. Marchesi","doi":"10.1109/CIC.1993.378361","DOIUrl":"https://doi.org/10.1109/CIC.1993.378361","url":null,"abstract":"Wigner Ville distribution has many of the desirable features for the spectral analysis of cardiovascular series during the transients of the autonomic tests, but the presence of the artefacts makes power measurements from the spectra often unreliable. This work proposes new approaches for rejecting artefacts, besides the well known spectral averaging. In particular, an appropriate preprocessing and a segment-regression based smoothing are considered and compared with the classical approach, taking into account both the different characteristics of the considered autonomic tests.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"5 1","pages":"811-814"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78626907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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