Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166822
L. Gamero, R. Armentano, J. Levenson
The aim of this study was to evaluate and characterize arterial diameter and arterial wall viscoelastic variability. An animal study was performed on seven sheep instrumented in the brachycephalic artery. ECG, arterial diameter and pressure waveforms were simultaneously measured. Four different hemodynamic conditions were considered: 1) under anesthesia, 2) conscious steady state, 3) vascular smooth muscle (VSM) activation and 4) VSM relaxation. A system modeling identification approach was applied in order to estimate viscoelastic indexes. The linear autoregressive with exogenous input model (ARX) was applied to the single beat pressure-diameter data to assess the arterial system dynamics. The elastic and viscous indexes were derived from the identified ARX model. Arterial pressure and diameter, heart rate and viscoelastic indexes variability analysis were performed in the time and frequency domains. While systolic pressure and arterial diameter oscillation show a similar pattern to heart rate at all frequency bands in control condition, wall viscosity variability does not match with these parameters (p<0.05). Compared with control condition, arterial diameter variability was lower during anesthesia and higher during VSM relaxation (p<0.05). The elastic index variability was lower during anesthesia and VSM relaxation and higher during VSM activation. The different behavior of arterial wall viscoelasticity suggests that intrinsic mechanisms related with vascular tone and vasomotion might be involved in the oscillatory pattern of the arterial wall.
{"title":"Arterial wall diameter and viscoelasticity variability","authors":"L. Gamero, R. Armentano, J. Levenson","doi":"10.1109/CIC.2002.1166822","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166822","url":null,"abstract":"The aim of this study was to evaluate and characterize arterial diameter and arterial wall viscoelastic variability. An animal study was performed on seven sheep instrumented in the brachycephalic artery. ECG, arterial diameter and pressure waveforms were simultaneously measured. Four different hemodynamic conditions were considered: 1) under anesthesia, 2) conscious steady state, 3) vascular smooth muscle (VSM) activation and 4) VSM relaxation. A system modeling identification approach was applied in order to estimate viscoelastic indexes. The linear autoregressive with exogenous input model (ARX) was applied to the single beat pressure-diameter data to assess the arterial system dynamics. The elastic and viscous indexes were derived from the identified ARX model. Arterial pressure and diameter, heart rate and viscoelastic indexes variability analysis were performed in the time and frequency domains. While systolic pressure and arterial diameter oscillation show a similar pattern to heart rate at all frequency bands in control condition, wall viscosity variability does not match with these parameters (p<0.05). Compared with control condition, arterial diameter variability was lower during anesthesia and higher during VSM relaxation (p<0.05). The elastic index variability was lower during anesthesia and VSM relaxation and higher during VSM activation. The different behavior of arterial wall viscoelasticity suggests that intrinsic mechanisms related with vascular tone and vasomotion might be involved in the oscillatory pattern of the arterial wall.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"513-516"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166822","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62181607","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166835
E. Pueyo, P. Smetana, K. Hnatkova, P. Laguna, M. Malik
A new method is proposed to evaluate, in continuous 24-hour recordings, the influence on QT of changes in heart rate occurred during some previous minutes. The method is based on considering averages of the RR intervals preceding the ith beat (R~R~i) using window lengths of up to 10 minutes. The averages are performed using several forgetting strategies, with the exponential weighted average turning out to be the best in modeling the QT dependence on previous RR intervals. For each patient, the regression model (selected from a defined set) and the window length leading to the optimum fit of the [QT/sub i/, R~R~i] relationship are selected RR variations in the past 4 minutes, on average, are shown to be required to accurately model the QT response to changes infrequency. A measure of the optimum fit residuum (ORR) is then calculated, showing a remarkable discriminative power to identify post-myocardial infarction patients at high risk of arrhythmic death after treatment with amiodarone.
{"title":"Time for QT adaptation to RR changes and relation to arrhythmic mortality reduction in amiodarone-treated patients","authors":"E. Pueyo, P. Smetana, K. Hnatkova, P. Laguna, M. Malik","doi":"10.1109/CIC.2002.1166835","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166835","url":null,"abstract":"A new method is proposed to evaluate, in continuous 24-hour recordings, the influence on QT of changes in heart rate occurred during some previous minutes. The method is based on considering averages of the RR intervals preceding the ith beat (R~R~i) using window lengths of up to 10 minutes. The averages are performed using several forgetting strategies, with the exponential weighted average turning out to be the best in modeling the QT dependence on previous RR intervals. For each patient, the regression model (selected from a defined set) and the window length leading to the optimum fit of the [QT/sub i/, R~R~i] relationship are selected RR variations in the past 4 minutes, on average, are shown to be required to accurately model the QT response to changes infrequency. A measure of the optimum fit residuum (ORR) is then calculated, showing a remarkable discriminative power to identify post-myocardial infarction patients at high risk of arrhythmic death after treatment with amiodarone.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"565-568"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166835","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62181859","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166866
S. Olmos, J.P. Martinez, L. Sornmo
We propose a multichannel signal model based on linear expansions to analyze cardiac repolarization. Our hypothesis is that a joint spatiotemporal signal description which takes into account both temporal and spatial features provides a more compact signal representation, i.e. the signal energy is packed into a smaller number of coefficients. We also deal with the problem of estimating optimal basis functions in two different situations: when no information of the noise source is available and when the noise statistics is known or estimated from specific signals or intervals, like the TP segment.
{"title":"Spatio-temporal linear expansions for repolarization analysis","authors":"S. Olmos, J.P. Martinez, L. Sornmo","doi":"10.1109/CIC.2002.1166866","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166866","url":null,"abstract":"We propose a multichannel signal model based on linear expansions to analyze cardiac repolarization. Our hypothesis is that a joint spatiotemporal signal description which takes into account both temporal and spatial features provides a more compact signal representation, i.e. the signal energy is packed into a smaller number of coefficients. We also deal with the problem of estimating optimal basis functions in two different situations: when no information of the noise source is available and when the noise statistics is known or estimated from specific signals or intervals, like the TP segment.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"689-692"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166866","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62182492","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166867
C. Zoltani, S. Baskin
An important clinical marker of organophosphate (OP) caused cardiac toxicity is long-QT syndrome (LQTS), elongation of the repolarization period in the ventricles, as measured in an electrocardiogram (ECG). The primary membrane currents responsible for this condition are two potassium currents, k/spl dot/r and i/spl dot//sub Ks/. This computer simulation investigated the effect of modulation of the cardiac membrane currents on the action potential in a two-dimensional slab of tissue affected by OP. We have shown that modulation of the sodium current and reduction of the potassium currents mimic the experimentally observed change in slope of depolarization in the presence of organophosphates as well as the prolongation and shape of repolarization, a precursor to the onset of Torsade de Pointes (TdP) and ventricular fibrillation (VF).
{"title":"Organophosphate-modulated cardiac membrane currents: computer study of the genesis of LQTS","authors":"C. Zoltani, S. Baskin","doi":"10.1109/CIC.2002.1166867","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166867","url":null,"abstract":"An important clinical marker of organophosphate (OP) caused cardiac toxicity is long-QT syndrome (LQTS), elongation of the repolarization period in the ventricles, as measured in an electrocardiogram (ECG). The primary membrane currents responsible for this condition are two potassium currents, k/spl dot/r and i/spl dot//sub Ks/. This computer simulation investigated the effect of modulation of the cardiac membrane currents on the action potential in a two-dimensional slab of tissue affected by OP. We have shown that modulation of the sodium current and reduction of the potassium currents mimic the experimentally observed change in slope of depolarization in the presence of organophosphates as well as the prolongation and shape of repolarization, a precursor to the onset of Torsade de Pointes (TdP) and ventricular fibrillation (VF).","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"693-696"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166867","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62182507","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166868
K. Hnatkova, M. Malik
Drug investigation studies require similar patterns of T/U waves to be measured at the same fiducial points. However, such a systematic measurement is difficult to achieve with manual measurement as compulsory for regulatory review. A new system was developed that adjusts manually measured QT intervals in sets of ECGs obtained from the same drug study. For a given threshold w, the system organizes all the repolarisation patterns in groups of ECG leads that correlate each with each other with abs(r)>w. Within these groups, the system assigns a shift of the measured T wave end in each ECG lead to synchronise the patterns of the manual measurements. The same approach is used to align the QRS onset measurements. The system was used in a drug-study of 4090 ECGs obtained in healthy volunteers off- and on-treatment with an investigational drug. The difference between manual measurements and the measurements adjusted by the new software was characterised by calculating the regression residua between QT and RR intervals and by comparing the QT dispersion. After applying the system, the regression residua were reduced from 15.06 to 14.32 ms (p<0.002). The QT dispersion values were reduced from 38.3 (SD=172) to 30.2 (SD=15.4) ms (p<10/sup -200/). Automatic adjustment of manual measurements of QT intervals in electronically recorded ECGs improves the precision of QT interval assessment in electrocardiographic drug studies.
药物调查研究需要在相同的基准点上测量相似的T/U波模式。然而，这种系统的测量很难实现，因为人工测量是监管审查的强制性要求。开发了一种新的系统，用于调整同一药物研究中获得的心电图组中手动测量的QT间期。对于给定的阈值w，系统将所有的重极化模式组织成ECG导联组，这些导联与abs(r)>w相互关联。在这些组中，系统在每个ECG导联中分配测量的T波端移位，以同步手动测量的模式。使用相同的方法来对齐QRS起始测量值。该系统用于一项药物研究，该研究收集了4090名健康志愿者的心电图，这些志愿者正在接受一种研究药物的治疗。通过计算QT间隔和RR间隔之间的回归残差以及比较QT离散度来表征人工测量与新软件调整后的测量之间的差异。应用该系统后，回归残差由15.06 ms降至14.32 ms (p<0.002)。QT离散度值从38.3 (SD=172)降至30.2 (SD=15.4) ms (p<10/sup -200/)。电子记录心电图中QT间期人工测量的自动调整提高了心电图药物研究中QT间期评估的精度。
{"title":"Automatic adjustment of manually measured QT intervals in digital electrocardiograms improves precision of electrocardiographic drug studies","authors":"K. Hnatkova, M. Malik","doi":"10.1109/CIC.2002.1166868","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166868","url":null,"abstract":"Drug investigation studies require similar patterns of T/U waves to be measured at the same fiducial points. However, such a systematic measurement is difficult to achieve with manual measurement as compulsory for regulatory review. A new system was developed that adjusts manually measured QT intervals in sets of ECGs obtained from the same drug study. For a given threshold w, the system organizes all the repolarisation patterns in groups of ECG leads that correlate each with each other with abs(r)>w. Within these groups, the system assigns a shift of the measured T wave end in each ECG lead to synchronise the patterns of the manual measurements. The same approach is used to align the QRS onset measurements. The system was used in a drug-study of 4090 ECGs obtained in healthy volunteers off- and on-treatment with an investigational drug. The difference between manual measurements and the measurements adjusted by the new software was characterised by calculating the regression residua between QT and RR intervals and by comparing the QT dispersion. After applying the system, the regression residua were reduced from 15.06 to 14.32 ms (p<0.002). The QT dispersion values were reduced from 38.3 (SD=172) to 30.2 (SD=15.4) ms (p<10/sup -200/). Automatic adjustment of manual measurements of QT intervals in electronically recorded ECGs improves the precision of QT interval assessment in electrocardiographic drug studies.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"697-700"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166868","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62182565","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166703
M.C. Melgers, C. A. Swenne, H. van de Vooren, E. E. van der Wall
Stressors intensify sympathetic outflow, thus increasing heart rate and arterial blood pressure. The significance of the arterial baroreflex is to be found in reducing such rate and pressure changes. For a better understanding of the interaction between a hypertensive stressor and the arterial baroreflex we have developed a mathematical simulation model, consisting of a hemodynamic section, a baroreceptor section, and a baroreflex section. Physiological or pathological resting conditions are simulated by specific settings of the autonomic tone parameters and cardiac stroke volume. Also the vagal and sympathetic baroreflex gains can be set. A stressor is introduced by adding extra sympathetic outflow to the heart and peripheral resistance. The responses in heart rate and blood pressure help to understand how the arterial baroreflex protects the heart and circulation.
{"title":"Interaction between the arterial baroreflex and a hypertensive stressor: a mathematical model","authors":"M.C. Melgers, C. A. Swenne, H. van de Vooren, E. E. van der Wall","doi":"10.1109/CIC.2002.1166703","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166703","url":null,"abstract":"Stressors intensify sympathetic outflow, thus increasing heart rate and arterial blood pressure. The significance of the arterial baroreflex is to be found in reducing such rate and pressure changes. For a better understanding of the interaction between a hypertensive stressor and the arterial baroreflex we have developed a mathematical simulation model, consisting of a hemodynamic section, a baroreceptor section, and a baroreflex section. Physiological or pathological resting conditions are simulated by specific settings of the autonomic tone parameters and cardiac stroke volume. Also the vagal and sympathetic baroreflex gains can be set. A stressor is introduced by adding extra sympathetic outflow to the heart and peripheral resistance. The responses in heart rate and blood pressure help to understand how the arterial baroreflex protects the heart and circulation.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"45-48"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166703","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62179702","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166704
G. Baselli, A. Porta
Simulations are performed in order to analyze the tendency of oscillating peripheral vascular districts (PVDs) to maintain equal phases thus inducing low frequency (LF) waves in systemic arterial pressure (AP). A PVD model regulating the local flow by means of a delayed non-linear feedback displayed spontaneous oscillations with a 12 sec period in the pressure range (40-150 mmHg) of active flow compensation. Two identical PVDs loading the same windkessel compartment could oscillate in phase inducing significant (10% of mean) AP waves: however, this behavior was unstable. On the contrary, phase opposition (without AP waves) was stable and corresponded to an energetic minimum (-9 % compared to the unstable solution). The introduction of either baroreflex mechanisms or a central drive was able to steadily align the PVD phases. Vasomotion synchronization can be a powerful modulation mechanism of LF waves in systemic AP.
{"title":"Simulating the interactions among vasomotion waves of peripheral vascular districts","authors":"G. Baselli, A. Porta","doi":"10.1109/CIC.2002.1166704","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166704","url":null,"abstract":"Simulations are performed in order to analyze the tendency of oscillating peripheral vascular districts (PVDs) to maintain equal phases thus inducing low frequency (LF) waves in systemic arterial pressure (AP). A PVD model regulating the local flow by means of a delayed non-linear feedback displayed spontaneous oscillations with a 12 sec period in the pressure range (40-150 mmHg) of active flow compensation. Two identical PVDs loading the same windkessel compartment could oscillate in phase inducing significant (10% of mean) AP waves: however, this behavior was unstable. On the contrary, phase opposition (without AP waves) was stable and corresponded to an energetic minimum (-9 % compared to the unstable solution). The introduction of either baroreflex mechanisms or a central drive was able to steadily align the PVD phases. Vasomotion synchronization can be a powerful modulation mechanism of LF waves in systemic AP.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"49-52"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166704","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62179763","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166733
P. Augustyniak
This paper compares two methods of non-uniform ECG sampling: the variable depth decimation (VDD) and the continuous non-uniform sampling (CNU). The VDD algorithm uses the wavelet-based time-scale decomposition of the segmented ECG in which the high frequency scales representation is eliminated for the signal sections of narrower bandwidth (e.g. T-P segment). In result, the signal is locally decimated down to the level depending on the expected bandwidth. The CNU algorithm uses a soft estimation of the length for each subsequent sampling interval on a basis of expected local bandwidth of the signal. For ECG records from the CSE Multilead Database the average efficiency of the VDD algorithm is significantly higher (4.26) than the efficiency computed for the CNU method (3.01). Unfortunately, the global reconstruction error (PRD) is also higher for the VDD (0.40%) than for the CNU algorithm (0.22%).
{"title":"Adaptive discrete ECG representation - comparing variable depth decimation and continuous non-uniform sampling","authors":"P. Augustyniak","doi":"10.1109/CIC.2002.1166733","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166733","url":null,"abstract":"This paper compares two methods of non-uniform ECG sampling: the variable depth decimation (VDD) and the continuous non-uniform sampling (CNU). The VDD algorithm uses the wavelet-based time-scale decomposition of the segmented ECG in which the high frequency scales representation is eliminated for the signal sections of narrower bandwidth (e.g. T-P segment). In result, the signal is locally decimated down to the level depending on the expected bandwidth. The CNU algorithm uses a soft estimation of the length for each subsequent sampling interval on a basis of expected local bandwidth of the signal. For ECG records from the CSE Multilead Database the average efficiency of the VDD algorithm is significantly higher (4.26) than the efficiency computed for the CNU method (3.01). Unfortunately, the global reconstruction error (PRD) is also higher for the VDD (0.40%) than for the CNU algorithm (0.22%).","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"165-168"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166733","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62180385","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166738
O. Grebe, M. Lehn, H. Neumann, F. Schwenker, J. Wohrle, M. Hoher, V. Hombach, H. Kestler
23 healthy subjects and 23 patients with isolated diastolic dysfunction were examined with cine magnetic resonance imaging to find new markers for the diastolic heart function. A single mid-ventricular short axis slice in the true cardiac axis was used and endo- and epicardial borders were hand drawn. Five features were applied to characterize isolated diastolic function: Irregularity marker of contraction calculated as the sum of the standard deviations of corresponding points across all frames (IRREG); slope of a linear fit to the diastolic area change (SLOPE); slope of the minimal and mean wall thickness (MINWTH/MEANWTH); shift parameter of the least-squares fit of the sigmoid Fermi-Junction (SHIFT). The parameters were corrected for through-plane motion. MINWTH, MEANWTH, and SHIFT differed significantly in both groups. These features represent promising objective parameters to discriminate patients with diastolic dysfunction from healthy subjects.
{"title":"Parameters for characterizing diastolic function with cardiac magnetic resonance imaging","authors":"O. Grebe, M. Lehn, H. Neumann, F. Schwenker, J. Wohrle, M. Hoher, V. Hombach, H. Kestler","doi":"10.1109/CIC.2002.1166738","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166738","url":null,"abstract":"23 healthy subjects and 23 patients with isolated diastolic dysfunction were examined with cine magnetic resonance imaging to find new markers for the diastolic heart function. A single mid-ventricular short axis slice in the true cardiac axis was used and endo- and epicardial borders were hand drawn. Five features were applied to characterize isolated diastolic function: Irregularity marker of contraction calculated as the sum of the standard deviations of corresponding points across all frames (IRREG); slope of a linear fit to the diastolic area change (SLOPE); slope of the minimal and mean wall thickness (MINWTH/MEANWTH); shift parameter of the least-squares fit of the sigmoid Fermi-Junction (SHIFT). The parameters were corrected for through-plane motion. MINWTH, MEANWTH, and SHIFT differed significantly in both groups. These features represent promising objective parameters to discriminate patients with diastolic dysfunction from healthy subjects.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"185-188"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166738","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62180585","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}
Pub Date : 2002-09-22DOI: 10.1109/CIC.2002.1166798
P. Castiglioni, M. Rienzo, H. Yosh
A new algorithm is proposed for the online Fourier analysis of unevenly sampled data. The method is based on the theoretical evaluation of the Fourier Transform of a function linearly interpolating the data, and does not require actual interpolation and re-sampling. The method is particularly suitable for the running evaluation of power spectra. In fact, when a new sample is available, the spectrum can be updated simply by performing calculations on the last sample, without the need to calculate the Fourier Transform again over the whole data record. Applications with simulated and real data show the capability of the algorithm to efficiently estimate the Fourier transform of unevenly sampled cardiovascular data, beat after beat.
{"title":"A computationally efficient algorithm for online spectral analysis of beat-to-beat signals","authors":"P. Castiglioni, M. Rienzo, H. Yosh","doi":"10.1109/CIC.2002.1166798","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166798","url":null,"abstract":"A new algorithm is proposed for the online Fourier analysis of unevenly sampled data. The method is based on the theoretical evaluation of the Fourier Transform of a function linearly interpolating the data, and does not require actual interpolation and re-sampling. The method is particularly suitable for the running evaluation of power spectra. In fact, when a new sample is available, the spectrum can be updated simply by performing calculations on the last sample, without the need to calculate the Fourier Transform again over the whole data record. Applications with simulated and real data show the capability of the algorithm to efficiently estimate the Fourier transform of unevenly sampled cardiovascular data, beat after beat.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"417-420"},"PeriodicalIF":0.0,"publicationDate":"2002-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166798","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62181426","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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