The computation of the so-called receiver operator characteristics is simple when based on univariate data. On the contrary, the complexity of computation of multivariate characteristics increases exponentially with the dimension of the data. This study describes a new algorithm for computation of multivariate receiver operator characteristics. The algorithm is based on several concepts which increase its computational efficiency. The most important of them is a pre-sorting of the data in each dimension and the division of each dimension into groups in which the negative cases precede positive ones. The algorithm was tested in a risk stratification study that was aimed at identifying survivors of acute myocardial infarction at risk of early death. A cohort of 539 patients was stratified based on time-domain (3 variables) and spectral turbulence (6 variables) indices of signal averaged electrocardiogram. The computing requirements of this study are presented in the text and the efficiency of the algorithm is discussed in detail.<>
{"title":"Computation of multifactorial receiver operator and predictive accuracy characteristics [ECG analysis]","authors":"K. Hnatkova, J. Poloniecki, A. Camm, M. Malik","doi":"10.1109/CIC.1993.378344","DOIUrl":"https://doi.org/10.1109/CIC.1993.378344","url":null,"abstract":"The computation of the so-called receiver operator characteristics is simple when based on univariate data. On the contrary, the complexity of computation of multivariate characteristics increases exponentially with the dimension of the data. This study describes a new algorithm for computation of multivariate receiver operator characteristics. The algorithm is based on several concepts which increase its computational efficiency. The most important of them is a pre-sorting of the data in each dimension and the division of each dimension into groups in which the negative cases precede positive ones. The algorithm was tested in a risk stratification study that was aimed at identifying survivors of acute myocardial infarction at risk of early death. A cohort of 539 patients was stratified based on time-domain (3 variables) and spectral turbulence (6 variables) indices of signal averaged electrocardiogram. The computing requirements of this study are presented in the text and the efficiency of the algorithm is discussed in detail.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"71 1","pages":"547-550"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76014797","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}
A. Ezekiel, G. Germano, K. V. Van Train, H. Kiat, D. Berman
Reorientation of transaxial SPECT myocardial tomograms into short and vertical long axis tomograms currently requires manual selection of the transaxial reference plane and manual determination of the left ventricle's long axis orientation in that plane. To reduce the time required for this procedure and promote objectivity, an algorithm was developed to automatically determine these parameters, using an approach that models the transaxial section of the myocardium as an ellipse. Automatically determined values for the reference plane and the long axis orientation in 14 normal and 11 abnormal patients in dual isotope, Tl-201 rest and Tc-Sestamibi stress, were compared with those obtained manually, with good correlation (r=0.91, p<0.001 for the axis orientation). The algorithm may eventually allow completely automatic reorientation of myocardial SPECT studies, thereby reducing operator labor and subjectivity.<>
{"title":"Automatic selection of transaxial axis for reorientation of myocardial SPECT tomograms","authors":"A. Ezekiel, G. Germano, K. V. Van Train, H. Kiat, D. Berman","doi":"10.1109/CIC.1993.378318","DOIUrl":"https://doi.org/10.1109/CIC.1993.378318","url":null,"abstract":"Reorientation of transaxial SPECT myocardial tomograms into short and vertical long axis tomograms currently requires manual selection of the transaxial reference plane and manual determination of the left ventricle's long axis orientation in that plane. To reduce the time required for this procedure and promote objectivity, an algorithm was developed to automatically determine these parameters, using an approach that models the transaxial section of the myocardium as an ellipse. Automatically determined values for the reference plane and the long axis orientation in 14 normal and 11 abnormal patients in dual isotope, Tl-201 rest and Tc-Sestamibi stress, were compared with those obtained manually, with good correlation (r=0.91, p<0.001 for the axis orientation). The algorithm may eventually allow completely automatic reorientation of myocardial SPECT studies, thereby reducing operator labor and subjectivity.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"38 1","pages":"651-654"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81037212","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. Vogel, K. Haberl, M. Rudolph, R. Pulter, E. Kreuzer, B. Reichart, G. Steinbeck, R. Haberl
Computer mapping during antitachycardia surgery in patients with ventricular tachycardia offers a new dimension for precise localization of the arrhythmogenic area. However, until now in most mapping systems analysis is restricted to signal processing in the time dimension. Further information might be accessible by treating data as multi-dimensional both in time and space. The authors employed high-resolution frequency-wavenumber spectral estimation on endocardial balloon electrograms to analyze wavefronts of cardiac excitation in space and time. This allowed to determine local activation as a result of a propagating wavefront in the sensor array instead of time domain analysis of only one single channel. The method allows to extract parameters like speed, direction, power and shape of propagating waves present in a set of endocardial signals, thus providing a powerful tool for the analysis of complex activation sequences of cardiac excitation during antitachycardia surgery.<>
{"title":"Time-space analysis of endocardial potentials mapped during antitachycardia surgery in patients with ventricular tachycardia","authors":"J. Vogel, K. Haberl, M. Rudolph, R. Pulter, E. Kreuzer, B. Reichart, G. Steinbeck, R. Haberl","doi":"10.1109/CIC.1993.378486","DOIUrl":"https://doi.org/10.1109/CIC.1993.378486","url":null,"abstract":"Computer mapping during antitachycardia surgery in patients with ventricular tachycardia offers a new dimension for precise localization of the arrhythmogenic area. However, until now in most mapping systems analysis is restricted to signal processing in the time dimension. Further information might be accessible by treating data as multi-dimensional both in time and space. The authors employed high-resolution frequency-wavenumber spectral estimation on endocardial balloon electrograms to analyze wavefronts of cardiac excitation in space and time. This allowed to determine local activation as a result of a propagating wavefront in the sensor array instead of time domain analysis of only one single channel. The method allows to extract parameters like speed, direction, power and shape of propagating waves present in a set of endocardial signals, thus providing a powerful tool for the analysis of complex activation sequences of cardiac excitation during antitachycardia surgery.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"4 1","pages":"133-136"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81847581","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}
ECGs from ischemic animals were analysed using multiresolution wavelets of G.S. Mallat (IEEE Trans. Pattern Anal., Machine Intell., vol. 11, no. 7, p. 674-93, 1989). The authors propose a new way, based on the detail signals D/sub 2j/f, for detecting injury related changes in the ECG. Analyses of experimental data reveal a short-term increase of magnitude in scales corresponding to the medium frequency components during occlusion of coronary vessels.<>
{"title":"Multiresolution wavelet analysis of ECG during ischemia and reperfusion","authors":"N. Thakor, B. Gramatikov, M. Mita","doi":"10.1109/CIC.1993.378295","DOIUrl":"https://doi.org/10.1109/CIC.1993.378295","url":null,"abstract":"ECGs from ischemic animals were analysed using multiresolution wavelets of G.S. Mallat (IEEE Trans. Pattern Anal., Machine Intell., vol. 11, no. 7, p. 674-93, 1989). The authors propose a new way, based on the detail signals D/sub 2j/f, for detecting injury related changes in the ECG. Analyses of experimental data reveal a short-term increase of magnitude in scales corresponding to the medium frequency components during occlusion of coronary vessels.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"4 1","pages":"895-898"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88056272","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}
Although beat-by-beat processing can allow the recovery of transient microvolt signals that are impossible to recover with time-domain averaging, the computational implications can be significant. Frequency-band adaptive filtering is a beat-by-beat technique which illustrates this problem. In particular, the real-time processing required by such approaches may be beyond the capabilities of a single modest DSP processor. Following an investigation of the spectral power and noise characteristics of segmented ECG signals, an optimised multi-frequency-band adaptive filter has been implemented which has reduced the computational demands and is successful in the registration of ventricular late potentials in noisy circumstances on a beat-by-beat basis.<>
{"title":"Optimisation of frequency-band adaptive filtering in real-time beat-by-beat high-gain ECG processing","authors":"W. Wang, M. English","doi":"10.1109/CIC.1993.378414","DOIUrl":"https://doi.org/10.1109/CIC.1993.378414","url":null,"abstract":"Although beat-by-beat processing can allow the recovery of transient microvolt signals that are impossible to recover with time-domain averaging, the computational implications can be significant. Frequency-band adaptive filtering is a beat-by-beat technique which illustrates this problem. In particular, the real-time processing required by such approaches may be beyond the capabilities of a single modest DSP processor. Following an investigation of the spectral power and noise characteristics of segmented ECG signals, an optimised multi-frequency-band adaptive filter has been implemented which has reduced the computational demands and is successful in the registration of ventricular late potentials in noisy circumstances on a beat-by-beat basis.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"15 1","pages":"421-424"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91292754","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}
N. Bruining, R. Krams, H. Passchier, S. Meij, P. D. de Feijter, D. Keane
There is a growing need for (semi) real time measurement of ventricular function which can be quantified by the left ventricular pressure-volume (P-V) relationship. In the catheterization laboratory left ventricular volume is routinely derived from planimetry of contrast ventriculograms. Ventriculography however does not lend itself to repeated assessment as even 40-60 cc of contrast injection can alter baseline ventricular variables. Non-invasive techniques to quantify ventricular volumes combined with electrical pigtail pressure measurement would eliminate these limitations Such real time volume measurements can be achieved by either Doppler flow measurement or planimetry by 2D echo is used. The authors report on a modular system, which enables continuous integration of these rapidly evolving techniques into the existing environment of the catheterization laboratory for on line generation of P-V loops.<>
{"title":"A modular hard and software system for the analysis of cardiac signals: application to real time pressure-volume loops","authors":"N. Bruining, R. Krams, H. Passchier, S. Meij, P. D. de Feijter, D. Keane","doi":"10.1109/CIC.1993.378479","DOIUrl":"https://doi.org/10.1109/CIC.1993.378479","url":null,"abstract":"There is a growing need for (semi) real time measurement of ventricular function which can be quantified by the left ventricular pressure-volume (P-V) relationship. In the catheterization laboratory left ventricular volume is routinely derived from planimetry of contrast ventriculograms. Ventriculography however does not lend itself to repeated assessment as even 40-60 cc of contrast injection can alter baseline ventricular variables. Non-invasive techniques to quantify ventricular volumes combined with electrical pigtail pressure measurement would eliminate these limitations Such real time volume measurements can be achieved by either Doppler flow measurement or planimetry by 2D echo is used. The authors report on a modular system, which enables continuous integration of these rapidly evolving techniques into the existing environment of the catheterization laboratory for on line generation of P-V loops.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"159 ","pages":"161-164"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91520204","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}
U. Renneisen, M. Lang, M. Haude, R. Brennecke, R. Erbel, J. Meyer
To evaluate the functional effect of a coronary artery stenosis on the dependent myocardium, digitized coronary angiograms (DCAs) were recorded. The DCAs, acquired during heart catheterization, provide information about myocardial perfusion and coronary flow reserve of areas supplied by this coronary artery. For each analysis the myocardium is separated into different regions of interest (ROIs); 16 ROIs in the distribution of the LCA and 8 ROIs for the RCA. In addition to that, the ROIs of the diseased vessels are divided into ROIs which are proximal, within and distal to the stenosis. Using a semiautomatic procedure, densograms are constructed from which the parameter rise time is calculated.<>
{"title":"Determination of myocardial perfusion and coronary flow reserve by densitometric measurements: a selective classification of regions of interest","authors":"U. Renneisen, M. Lang, M. Haude, R. Brennecke, R. Erbel, J. Meyer","doi":"10.1109/CIC.1993.378320","DOIUrl":"https://doi.org/10.1109/CIC.1993.378320","url":null,"abstract":"To evaluate the functional effect of a coronary artery stenosis on the dependent myocardium, digitized coronary angiograms (DCAs) were recorded. The DCAs, acquired during heart catheterization, provide information about myocardial perfusion and coronary flow reserve of areas supplied by this coronary artery. For each analysis the myocardium is separated into different regions of interest (ROIs); 16 ROIs in the distribution of the LCA and 8 ROIs for the RCA. In addition to that, the ROIs of the diseased vessels are divided into ROIs which are proximal, within and distal to the stenosis. Using a semiautomatic procedure, densograms are constructed from which the parameter rise time is calculated.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"55 1","pages":"643-645"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91013409","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 paper presents the utility of spectral analysis of heart rate variability for sinoatrial node dysfunction (SAND) diagnosing, which is characterized by the presence of sudden, unexpected heart period fluctuations. In 40 patients (pts) with SAND and in 40 control subjects (sbs) RR interval oscillations during spontaneous breathing in recumbent position were analysed by means of FFT spectral analysis after. SAND pts showed longer mean sinus cycle length (BCL), higher SD-RR and greater relative power at suprarespiratory band (0.35-0.5 Hz). SAND pts were characterized by the lack: of HRV variables dependencies on age and BCL. Discriminative analysis, based on 7 variables showed that BCL duration and relative power spectrum at suprarespiratory band were sufficient for distinction of sinoatrial node function, since 88.75% correct classifications existed when this discriminative model was applied. We state that spectral HRV analysis should be introduced for routine SAND screening SAND.<>
{"title":"Spectral analysis of heart rate variability in patients with sinoatrial node dysfunction-diagnostic implications","authors":"T. Petelenz, M. Sosnowski, Z. Czyz̊, J. Leski","doi":"10.1109/CIC.1993.378405","DOIUrl":"https://doi.org/10.1109/CIC.1993.378405","url":null,"abstract":"The paper presents the utility of spectral analysis of heart rate variability for sinoatrial node dysfunction (SAND) diagnosing, which is characterized by the presence of sudden, unexpected heart period fluctuations. In 40 patients (pts) with SAND and in 40 control subjects (sbs) RR interval oscillations during spontaneous breathing in recumbent position were analysed by means of FFT spectral analysis after. SAND pts showed longer mean sinus cycle length (BCL), higher SD-RR and greater relative power at suprarespiratory band (0.35-0.5 Hz). SAND pts were characterized by the lack: of HRV variables dependencies on age and BCL. Discriminative analysis, based on 7 variables showed that BCL duration and relative power spectrum at suprarespiratory band were sufficient for distinction of sinoatrial node function, since 88.75% correct classifications existed when this discriminative model was applied. We state that spectral HRV analysis should be introduced for routine SAND screening SAND.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"152 1","pages":"455-458"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77389214","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}
Densitometric measurement of coronary artery narrowing requires a correction for the nonarterial contributions to the density ("background"). Two correction methods were studied. The first samples background in two strips of pixel parallel to the artery edges, and excludes nearby arteries. The second method measures density on a morphologically filtered image with no additional background correction. Measurements of % narrowing are consistent, reproducible and well correlated between the two methods. The first method corrects completely for background, the second less so. Using a set of routine arteriograms, densitometric % narrowing correlates with the visual estimate. Both methods underestimate lesion severity. Morphological filtering was less variable when comparing values measured on different views of same lesion.<>
{"title":"Densitometric arterial lesion size using morphologically filtered images","authors":"E. Byrom, B. Alexander, T. Frohlich, D. Hueter","doi":"10.1109/CIC.1993.378333","DOIUrl":"https://doi.org/10.1109/CIC.1993.378333","url":null,"abstract":"Densitometric measurement of coronary artery narrowing requires a correction for the nonarterial contributions to the density (\"background\"). Two correction methods were studied. The first samples background in two strips of pixel parallel to the artery edges, and excludes nearby arteries. The second method measures density on a morphologically filtered image with no additional background correction. Measurements of % narrowing are consistent, reproducible and well correlated between the two methods. The first method corrects completely for background, the second less so. Using a set of routine arteriograms, densitometric % narrowing correlates with the visual estimate. Both methods underestimate lesion severity. Morphological filtering was less variable when comparing values measured on different views of same lesion.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"9 1","pages":"591-594"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82580165","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}
A. Baharav, L. Kesselbrenner, O. Oz, T. Lehrman-Sagie, S. Akselrod
Spectral analysis of heart rate fluctuations was used to investigate the role of the autonomic nervous system in the pathogenesis of vasovagal syncope. Patients with recurrent episodes of unexplained syncope and normal controls were studied in supine and in 60/spl deg/ head-up tilt position applied as a test of the propensity to reflex neurocardiogenic syncope. Heart rate variability was analyzed in the context of physiological changes in mean heart rate, systolic and diastolic blood pressure and pulse pressure. In order to study nonstationary periods during the experiment a time dependent analysis was developed and applied in some cases. The results are consistent with a lower sympathetic reserve in patients. The authors concluded also that prolonged orthostatic stress may induce reflex fainting in normal young subjects.<>
{"title":"The autonomic control in vasovagal syncope investigated by spectral and time-dependent analysis of heart rate fluctuations","authors":"A. Baharav, L. Kesselbrenner, O. Oz, T. Lehrman-Sagie, S. Akselrod","doi":"10.1109/CIC.1993.378452","DOIUrl":"https://doi.org/10.1109/CIC.1993.378452","url":null,"abstract":"Spectral analysis of heart rate fluctuations was used to investigate the role of the autonomic nervous system in the pathogenesis of vasovagal syncope. Patients with recurrent episodes of unexplained syncope and normal controls were studied in supine and in 60/spl deg/ head-up tilt position applied as a test of the propensity to reflex neurocardiogenic syncope. Heart rate variability was analyzed in the context of physiological changes in mean heart rate, systolic and diastolic blood pressure and pulse pressure. In order to study nonstationary periods during the experiment a time dependent analysis was developed and applied in some cases. The results are consistent with a lower sympathetic reserve in patients. The authors concluded also that prolonged orthostatic stress may induce reflex fainting in normal young subjects.<<ETX>>","PeriodicalId":20445,"journal":{"name":"Proceedings of Computers in Cardiology Conference","volume":"65 1","pages":"269-272"},"PeriodicalIF":0.0,"publicationDate":"1993-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82599777","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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