Pub Date : 2008-01-01DOI: 10.1109/CIC.2008.4749126
Lh Lehman, M Saeed, Gb Moody, Rg Mark
We present a similarity-based searching and pattern matching algorithm that identifies time series data with similar temporal dynamics in large-scale, multi-parameter databases. We represent time series segments by feature vectors that reflect the dynamical patterns of single and multi-dimensional physiological time series. Features include regression slopes at varying time scales, maximum transient changes, auto-correlation coefficients of individual signals, and cross correlations among multiple signals. We model the dynamical patterns with a Gaussian mixture model (GMM) learned with the Expectation Maximization algorithm, and compute similarity between segments as Mahalanobis distances. We evaluate the use of our algorithm in three applications: search-by-example based data retrieval, event classification, and forecasting, using synthetic and real physiologic time series from a variety of sources.
{"title":"Similarity-Based Searching in Multi-Parameter Time Series Databases.","authors":"Lh Lehman, M Saeed, Gb Moody, Rg Mark","doi":"10.1109/CIC.2008.4749126","DOIUrl":"https://doi.org/10.1109/CIC.2008.4749126","url":null,"abstract":"<p><p>We present a similarity-based searching and pattern matching algorithm that identifies time series data with similar temporal dynamics in large-scale, multi-parameter databases. We represent time series segments by feature vectors that reflect the dynamical patterns of single and multi-dimensional physiological time series. Features include regression slopes at varying time scales, maximum transient changes, auto-correlation coefficients of individual signals, and cross correlations among multiple signals. We model the dynamical patterns with a Gaussian mixture model (GMM) learned with the Expectation Maximization algorithm, and compute similarity between segments as Mahalanobis distances. We evaluate the use of our algorithm in three applications: search-by-example based data retrieval, event classification, and forecasting, using synthetic and real physiologic time series from a variety of sources.</p>","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"35 4749126","pages":"653-656"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2008.4749126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29554231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Novel methods need to be developed to detect electrical instability in children. The dynamical properties of action potential restitution play an important role in the development of instability leading to arrhythmias. A new method, the Restitution Portrait (RP), was developed to visualize and quantify these properties at the action potential level. Here, we apply the RP method using the activation-recovery interval (ARI) from the ECG to detect, in vitro, repolarization abnormalities in neonatal and preadolescent rabbit myocardium with drug-induced Long QT Syndrome (LQTS Type 1 or Type 2). The ECG was recorded during programmed endocardial pacing to record the RP. The ECG RP demonstrated significant changes in dynamical restitution components during drug-induced LQTS compared to baseline. This study shows that the ECG RP may be an important noninvasive diagnostic tool for detecting electrical instability in the young.
{"title":"The Electrocardiogram Restitution Portrait Quantifying Dynamical Electrical Instability in Young Myocardium.","authors":"Ja Bell, Nc Rouze, W Krassowska, Sf Idriss","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Novel methods need to be developed to detect electrical instability in children. The dynamical properties of action potential restitution play an important role in the development of instability leading to arrhythmias. A new method, the Restitution Portrait (RP), was developed to visualize and quantify these properties at the action potential level. Here, we apply the RP method using the activation-recovery interval (ARI) from the ECG to detect, in vitro, repolarization abnormalities in neonatal and preadolescent rabbit myocardium with drug-induced Long QT Syndrome (LQTS Type 1 or Type 2). The ECG was recorded during programmed endocardial pacing to record the RP. The ECG RP demonstrated significant changes in dynamical restitution components during drug-induced LQTS compared to baseline. This study shows that the ECG RP may be an important noninvasive diagnostic tool for detecting electrical instability in the young.</p>","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"34 ","pages":"789-792"},"PeriodicalIF":0.0,"publicationDate":"2007-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2597806/pdf/nihms55282.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"27896680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jg Stinstra, Sf Roberts, Jb Pormann, Rs Macleod, Cs Henriquez
A model was developed of a bundle of cardiac fibers embedded in an extracellular space. In contrast to the classical bidomain approach, the model is constructed such that the intracellular and extracellular spaces are spatially distinct. The model was used to test the hypothesis that the distribution of the extracellular fluid in the tissue can affect the conduction velocity. The preliminary results suggest that under nominally normal conditions, the propagation speed depends on the fraction of extracellular space and less on the actual distribution of extracellular space within the bundle.
{"title":"A Model of 3D Propagation in Discrete Cardiac Tissue.","authors":"Jg Stinstra, Sf Roberts, Jb Pormann, Rs Macleod, Cs Henriquez","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A model was developed of a bundle of cardiac fibers embedded in an extracellular space. In contrast to the classical bidomain approach, the model is constructed such that the intracellular and extracellular spaces are spatially distinct. The model was used to test the hypothesis that the distribution of the extracellular fluid in the tissue can affect the conduction velocity. The preliminary results suggest that under nominally normal conditions, the propagation speed depends on the fraction of extracellular space and less on the actual distribution of extracellular space within the bundle.</p>","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"33 ","pages":"41-44"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1847422/pdf/nihms15658.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26241109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.1109/CIC.2002.1166716
V. John, M. Neuman, A. Talati, H. Bada
To understand the effects of in utero cocaine exposure on the developing fetus, we studied the heart rate and the heart rate variability (HRV) in near and full term cocaine-exposed infants during quiet sleep supine and following orthostatic stress. 21 cocaine-exposed and 23 control infants were studied within 120 hours of birth. 30-minute segments of the electrocardiogram (ECG) were recorded with the infant, horizontal followed by the infant in a 25/spl deg/ head-up tilt. The cocaine-exposed group, as compared with the control group, had a trend toward an increase in heart rate in the horizontal position and a significant increase in heart rate following the tilt. The frequency components of the heart rate were lower in the horizontal position and increased following the orthostatic stress. These results are consistent with the known pharmacological actions of cocaine and demonstrate the possible adverse neonatal effects of cocaine abuse during pregnancy.
{"title":"The effects of in utero cocaine-exposure on the heart rate and heart rate variability of near and full term infants following orthostatic stress","authors":"V. John, M. Neuman, A. Talati, H. Bada","doi":"10.1109/CIC.2002.1166716","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166716","url":null,"abstract":"To understand the effects of in utero cocaine exposure on the developing fetus, we studied the heart rate and the heart rate variability (HRV) in near and full term cocaine-exposed infants during quiet sleep supine and following orthostatic stress. 21 cocaine-exposed and 23 control infants were studied within 120 hours of birth. 30-minute segments of the electrocardiogram (ECG) were recorded with the infant, horizontal followed by the infant in a 25/spl deg/ head-up tilt. The cocaine-exposed group, as compared with the control group, had a trend toward an increase in heart rate in the horizontal position and a significant increase in heart rate following the tilt. The frequency components of the heart rate were lower in the horizontal position and increased following the orthostatic stress. These results are consistent with the known pharmacological actions of cocaine and demonstrate the possible adverse neonatal effects of cocaine abuse during pregnancy.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"97-99"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166716","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62179807","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166763
N. Maglaveras, G. Gogou, I. Chouvarda, V. Koutkias, I. Lekka, D. Adamidis, C. Karvounis, G. Louridas, E. Balas
The Citizen Health System (CHS) is a European Commission (CEC) funded project in the field of IST for Health. Its main goal is to develop a generic contact center which in its pilot stage can be used in the monitoring, treatment and management of chronically ill patients at home such as congestive heart failure (CHF) patients. Such contact centers, which can use any type of communication and telematics technology, and can provide timely and preventive prompting to the patients are envisaged in the future to evolve into well-being contact centers providing services to all citizens. In this paper, we present the structure of such a generic contact center focusing on the telecommunication infrastructure, the communication protocols and procedures related to the vital parameters and signals, and finally the educational modules that are integrated into this contact center. We present examples of the communication means between the medical professionals using this contact center and the congestive heart failure patients, and elaborate on the telemedicine and educational issues involved.
{"title":"Using contact centers in tele-management and home care of congestive heart failure patients: The CHS experience","authors":"N. Maglaveras, G. Gogou, I. Chouvarda, V. Koutkias, I. Lekka, D. Adamidis, C. Karvounis, G. Louridas, E. Balas","doi":"10.1109/CIC.2002.1166763","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166763","url":null,"abstract":"The Citizen Health System (CHS) is a European Commission (CEC) funded project in the field of IST for Health. Its main goal is to develop a generic contact center which in its pilot stage can be used in the monitoring, treatment and management of chronically ill patients at home such as congestive heart failure (CHF) patients. Such contact centers, which can use any type of communication and telematics technology, and can provide timely and preventive prompting to the patients are envisaged in the future to evolve into well-being contact centers providing services to all citizens. In this paper, we present the structure of such a generic contact center focusing on the telecommunication infrastructure, the communication protocols and procedures related to the vital parameters and signals, and finally the educational modules that are integrated into this contact center. We present examples of the communication means between the medical professionals using this contact center and the congestive heart failure patients, and elaborate on the telemedicine and educational issues involved.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"281-284"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166763","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62180375","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166839
A. Porta, N. Montano, M. Pagani, A. Malliani, P. van de Borne, V. Somers
Low dose of atropine increases heart period and respiratory sinus arrhythmia, while at high doses the peripheral parasympathetic blockade becomes appreciable. The mechanisms underlying this phenomenon are investigated in a set of 10 healthy young humans by means of a linear causal open loop model. This model allows us to contemporaneously and non invasively derive an estimate of the sinus node transfer function and of the baroreflex gain. Neither the dynamic properties of the sinus node nor the baroreflex gain appear to be modified by the low dose administration of atropine. These results support the conclusion that the increase of respiratory sinus arrhythmia does not depend on either a modification of the transduction properties at the sinus node level or an increased responsiveness of the baroreflex but may have a central origin.
{"title":"The increase of respiratory sinus arrhythmia during low dose atropine is not due to changes of the sinus node transfer function or baroreflex","authors":"A. Porta, N. Montano, M. Pagani, A. Malliani, P. van de Borne, V. Somers","doi":"10.1109/CIC.2002.1166839","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166839","url":null,"abstract":"Low dose of atropine increases heart period and respiratory sinus arrhythmia, while at high doses the peripheral parasympathetic blockade becomes appreciable. The mechanisms underlying this phenomenon are investigated in a set of 10 healthy young humans by means of a linear causal open loop model. This model allows us to contemporaneously and non invasively derive an estimate of the sinus node transfer function and of the baroreflex gain. Neither the dynamic properties of the sinus node nor the baroreflex gain appear to be modified by the low dose administration of atropine. These results support the conclusion that the increase of respiratory sinus arrhythmia does not depend on either a modification of the transduction properties at the sinus node level or an increased responsiveness of the baroreflex but may have a central origin.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"581-584"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166839","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62182205","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166861
P. Stein, D. Yanez, P. Domitrovich, J. Gottdiener, P. Chaves, R. Kronmal, P. Rautaharju
Decreased heart rate variability (HRV) predicts adverse outcomes. HRV can be elevated by episodes of significant non-respiratory sinus arrhythmia (i.e., a highly erratic sinus rhythm with normal p-waves, ESR). This elevated HRV could confound risk stratification by increasing HRV in high-risk patients. HRV was determined from tapes recorded at baseline in the Cardiovascular Health Study, a population study of older adults. Twenty-four hour time, frequency and non-linear domain HRV was compared between ESR+ and ESR$subjects, with (CVD+) and without (CVD-) cardiovascular disease. ESR+ was associated with higher HRV in the time and frequency domains and with decreased short-term fractal scaling exponent and increased ratios of the dimensions of the Poincare plot fitted ellipse. (ESR+ and CVD+) subjects with had the highest HRV for virtually all indices, while (ESR- and CVD+) had the lowest HRV. Since decreased HRV is associated with adverse outcomes, ESR is likely to dilute the predictive power of HRV.
{"title":"Heart rate variability is confounded by the presence of erratic sinus rhythm","authors":"P. Stein, D. Yanez, P. Domitrovich, J. Gottdiener, P. Chaves, R. Kronmal, P. Rautaharju","doi":"10.1109/CIC.2002.1166861","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166861","url":null,"abstract":"Decreased heart rate variability (HRV) predicts adverse outcomes. HRV can be elevated by episodes of significant non-respiratory sinus arrhythmia (i.e., a highly erratic sinus rhythm with normal p-waves, ESR). This elevated HRV could confound risk stratification by increasing HRV in high-risk patients. HRV was determined from tapes recorded at baseline in the Cardiovascular Health Study, a population study of older adults. Twenty-four hour time, frequency and non-linear domain HRV was compared between ESR+ and ESR$subjects, with (CVD+) and without (CVD-) cardiovascular disease. ESR+ was associated with higher HRV in the time and frequency domains and with decreased short-term fractal scaling exponent and increased ratios of the dimensions of the Poincare plot fitted ellipse. (ESR+ and CVD+) subjects with had the highest HRV for virtually all indices, while (ESR- and CVD+) had the lowest HRV. Since decreased HRV is associated with adverse outcomes, ESR is likely to dilute the predictive power of HRV.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"669-672"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166861","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62182283","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166724
Gari D Clifford, P. McSharry, L. Tarassenko
The authors present an investigation into the incidences of ectopy and artefact as a function of time of day, heart rate and state changes for 19 normal subjects. State changes are defined to be a statistically significant change in mean or variance over a window of a few minutes. Artefact incidence is shown to be significantly correlated with state change and heart rate in normal humans, whereas ectopy exhibits no significant relationship. Artefact is therefore shown to be a source of information which can aid identification of activity or state changes and facilitate abnormality detection inpatient populations. Timing thresholds are proposed which differentiate between artefact, ectopy and sinus beats. A classification system based upon the frequency of artefact occurrences in relation to state changes is presented which correctly separates 78% of the the real (normal) and artificial RR interval time series in event 2 of the CinC Challenge 2002 (entry number 38).
{"title":"Characterizing artefact in the normal human 24-hour RR time series to aid identification and artificial replication of circadian variations in human beat to beat heart rate using a simple threshold","authors":"Gari D Clifford, P. McSharry, L. Tarassenko","doi":"10.1109/CIC.2002.1166724","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166724","url":null,"abstract":"The authors present an investigation into the incidences of ectopy and artefact as a function of time of day, heart rate and state changes for 19 normal subjects. State changes are defined to be a statistically significant change in mean or variance over a window of a few minutes. Artefact incidence is shown to be significantly correlated with state change and heart rate in normal humans, whereas ectopy exhibits no significant relationship. Artefact is therefore shown to be a source of information which can aid identification of activity or state changes and facilitate abnormality detection inpatient populations. Timing thresholds are proposed which differentiate between artefact, ectopy and sinus beats. A classification system based upon the frequency of artefact occurrences in relation to state changes is presented which correctly separates 78% of the the real (normal) and artificial RR interval time series in event 2 of the CinC Challenge 2002 (entry number 38).","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"4 2 1","pages":"129-132"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166724","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62180092","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166693
D. Moratal-Pérez, M. Brummer, C. Hong, R. Pettigrew, J. Millet-Roig, W. T. Dixon
A novel cardiac magnetic resonance imaging (MRI) acceleration strategy called "NoQuist" is presented. Using this new technique, a more sparsely sampled dynamic image sequence is correctly reconstructed without the Nyquist foldover artifact by reductions in the size of the Fourier model of k-space data for the dynamic image. It does not rely on substitution or interpolation to arrive at a data set sufficient for reconstruction of the dynamic sequence. The proposed "NoQuist" method allows reduction of acquisition time in dynamic MRI scans by eliminating the data redundancy that is associated with the presence of static regions in the dynamic scene. A reduction of acquisition time can be achieved by omitting acquisition of a strategically selected subset of phase encoding views from a conventional equidistant Cartesian acquisition grid.
{"title":"A novel reduced field-of-view technique for cardiac MRI: NoQuist","authors":"D. Moratal-Pérez, M. Brummer, C. Hong, R. Pettigrew, J. Millet-Roig, W. T. Dixon","doi":"10.1109/CIC.2002.1166693","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166693","url":null,"abstract":"A novel cardiac magnetic resonance imaging (MRI) acceleration strategy called \"NoQuist\" is presented. Using this new technique, a more sparsely sampled dynamic image sequence is correctly reconstructed without the Nyquist foldover artifact by reductions in the size of the Fourier model of k-space data for the dynamic image. It does not rely on substitution or interpolation to arrive at a data set sufficient for reconstruction of the dynamic sequence. The proposed \"NoQuist\" method allows reduction of acquisition time in dynamic MRI scans by eliminating the data redundancy that is associated with the presence of static regions in the dynamic scene. A reduction of acquisition time can be achieved by omitting acquisition of a strategically selected subset of phase encoding views from a conventional equidistant Cartesian acquisition grid.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"5-8"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166693","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62179389","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 : 2002-12-01DOI: 10.1109/CIC.2002.1166754
S. Marak, A. de Jongh
Previous studies have shown that administration of angiotensin II (Ang II) causes atrial and ventricular fibrosis in rats, as is found in patients with chronic heart failure. We hypothesize that fibrosis creates a substrate that promotes the induction of ventricular fibrillation (VF). Fourteen, eight-week old, Sprague-Dawley rats were studied. Eleven received a four-week treatment of Ang II (9 /spl mu/g/hr) from an implanted mini-pump. After treatment, the chest was opened, and 50 Hz stimulation at a strength of three times the pacing threshold was applied across the atria and ventricles for 2.5, 5, and 10 s. VF was more inducible in treated rats (6 of 11) than untreated rats (0 of 3, P < 0.05). Three of 12 VF episodes were sustained (> 10 s) while the remaining VF episodes were nonsustained (> 30 ms and < 10 s) after stimulation ended. Our results suggest that cardiac fibrosis induced by Ang II treatment creates a substrate for sustained VF.
{"title":"Ventricular fibrillation in rats with cardiac fibrosis","authors":"S. Marak, A. de Jongh","doi":"10.1109/CIC.2002.1166754","DOIUrl":"https://doi.org/10.1109/CIC.2002.1166754","url":null,"abstract":"Previous studies have shown that administration of angiotensin II (Ang II) causes atrial and ventricular fibrosis in rats, as is found in patients with chronic heart failure. We hypothesize that fibrosis creates a substrate that promotes the induction of ventricular fibrillation (VF). Fourteen, eight-week old, Sprague-Dawley rats were studied. Eleven received a four-week treatment of Ang II (9 /spl mu/g/hr) from an implanted mini-pump. After treatment, the chest was opened, and 50 Hz stimulation at a strength of three times the pacing threshold was applied across the atria and ventricles for 2.5, 5, and 10 s. VF was more inducible in treated rats (6 of 11) than untreated rats (0 of 3, P < 0.05). Three of 12 VF episodes were sustained (> 10 s) while the remaining VF episodes were nonsustained (> 30 ms and < 10 s) after stimulation ended. Our results suggest that cardiac fibrosis induced by Ang II treatment creates a substrate for sustained VF.","PeriodicalId":80984,"journal":{"name":"Computers in cardiology","volume":"1 1","pages":"249-250"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/CIC.2002.1166754","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62180627","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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