Electrical dyssynchrony is postulated to be one of the main factors contributing to non-response ... more Electrical dyssynchrony is postulated to be one of the main factors contributing to non-response of patients to cardiac resynchronization therapy (CRT). We applied inverse epicardial imaging computed from patient-specific geometry and body-surface potential recordings to assess global and regional electrical dyssynchrony. Patients were imaged pre- and post-device implantation, without and with pacing function (P-OFF and P-ON). The reconstructed maps of activation in the dyssynchronous pre-CRT rhythm agree with published contact mapping activation maps with earliest activation starting on the RV free wall and slowly spreading to the LV in a U-shaped pattern. The new ΔQRSi metric captures global pre-CRT dyssynchrony showing negative values (-0.32±0.10) with minimal variability beats (coefficient of variation 10±3.6%) while post-CRT pacing indicates positive values (0.18±0.11). The imaging method is well-suited to study electrical dyssynchrony and potentially guide CRT lead placement.
Clinical and investigative medicine. Medecine clinique et experimentale, 1985
Cardiovascular diseases remain the major cause of death in the adult North American population. M... more Cardiovascular diseases remain the major cause of death in the adult North American population. Most of these deaths are sudden, occurring secondary to ventricular tachycardia/fibrillation (VT/VF). Based on the results of recent clinical trials, it seems likely that many of these deaths could be prevented if reliable means were available to select those patients at highest risk. To date, however, no totally satisfactory means to establish risk has been identified. The purpose of this paper is to review the currently utilized techniques and to draw attention to some new and potentially useful technology involving computer processing of surface recorded electrocardiographic (ECG) signals. ECG monitoring during rest and activity is neither sensitive nor specific. Invasive studies, using programmed ventricular stimulation to reproduce clinical arrhythmias, have proven extremely useful in the management of patients with recurrent VT/VF; this technique allows the selection of effective th...
The objective of this study was to develop and evaluate transformation coefficients for synthesis... more The objective of this study was to develop and evaluate transformation coefficients for synthesis of standard 12-lead electrocardiogram (ECG), 18-lead ECG (with additional leads V7, V8, V9, V3R, V4R, and V5R), and Frank vectocardiogram (VCG) from reduced lead sets using 3 limb electrodes at Mason-Likar sites combined with 2 chest electrodes chosen from V1 to V6 sites. There are 15 such lead-set combinations, and each can be recorded with 6-wire cable. We used a study population from a Dalhousie University (Halifax, Nova Scotia, Canada) database, consisting of 892 individuals: 290 healthy subjects, 497 patients who previously suffered a myocardial infarction, and 105 patients with a history of spontaneous ventricular tachycardia but no evidence of a previous myocardial infarction. For each subject, 120-lead ECG recordings of 15-second duration were aligned and averaged, all samples of the QRST complex for leads of interest were extracted, and these data were used to derive—by regression analysis— coefficients for lead transformations. The coefficients were then used to reconstitute complete 12-lead/18-lead ECG and VCG from 15 predictor sets, and the success of this synthesis was assessed by 2 measures for goodness of fit: similarity coefficient (SC in percentage) and relative error (RE in percentage). Our results show that chest leads V2 and V4 are the best pair for reconstituting the 12-lead ECG (SC = 96.91, RE = 25.53), followed closely by V3 and V5, V2 and V5, V3 and V4, and V1 and V4. The best pair for reconstituting the entire 18-lead set is V1 and V4 (SC = 93.82, RE = 31.93), followed byV1 and V3, V1 and V5, and V1 and V6. The best pair for synthesis of the Frank X, Y, Z leads is V3 and V6 (SC = 96.31, RE = 26.07), followed by V1 and V3, V1 and V4, and V3 and V5. In conclusion, our study demonstrates that good approximation of 12-lead/18-lead ECG andVCG can be achieved by using a lead system using 6-wire cable, provided that electrodes are judiciously placed.
jects for optimum classification of 159 N, 103 AMI, 130 IMI, and 116 LVH subjects. In the first s... more jects for optimum classification of 159 N, 103 AMI, 130 IMI, and 116 LVH subjects. In the first step, multivariate analysis is performed to select measurements for each possible pairwise comparison; in the second step, the selected measurements are pooled together and utilized in a multigroup classification scheme, considering the four groups simultaneously and achieving separation of N, AMI, IMI, and LVH subjects. The results of the classification are compared to those obtained, in a separate study, with the 12-lead ECG in the same population, using the same procedure. 13
High resolution body surface potential maps (BSPM) and magnetic field maps (MFM) for study groups... more High resolution body surface potential maps (BSPM) and magnetic field maps (MFM) for study groups consisting of 11 Q wave and 11 non Q wave myocardial infarct (MI) patients as well as 9 normal subjects, were recorded in a magnetically and electrically shielded room. A control group of 22 normal subjects provided group mean normal time integral maps for selected QRST time intervals. The difference between magnitudes of extrema in each map defined the normal mean data range R for that time interval. The root mean square sum of the differences between the time integral map of a study subject and the normal group-mean map provided an estimate of individual map variability, V. Subsequent calculation of group-mean map variability, V, and group-mean normalized variability, V/R, for specific time intervals of the cardiac cycle, were used to test the abilities of BSPM and MFM techniques to distinguish between the normal and MI study groups. Results indicate that BSPM V/R differences between MI and normal groups are most pronounced during Q wave and Q zone activity; between inferior MI's and normals (p less than 0.05) and between anterior MI's and normal (p less than 0.01). Significant differences in MFM V/R occur during repolarization; between inferior MI's and non Q wave MI's (p less than 0.05), between anterior MI's and normals (p less than 0.05), between non Q wave MI's and normals (p less than 0.05) and between all MI's and normals (p less than 0.01). It is concluded that high resolution BSPM and MFM provide complementary means of discriminating between normal subjects and MI patients.
The aim of this study was to compare general and patient-specific transformations for estimating ... more The aim of this study was to compare general and patient-specific transformations for estimating body surface potential maps (BSPMs) from the standard 12-lead electrocardiogram (ECG). The design set for deriving the general transformation consisted of 120-lead BSPMs of Dalhousie Superset (n = 892); as a test set for comparing patient-specific and general transformations we used 120lead BSPMs from the Dalhousie database of patients (n = 88) who underwent elective percutaneous coronary intervention (PCI). From these two datasets we derived the desired transformations by regression analysis. The estimated BSPMs were assessed by 3 goodness-of-fit measures: similarity coefficient (SC), root-mean-square error, and relative error (RE). Results show that BSPMs can be estimated from the 12-lead ECG by using general transformation with (mean ± SD) SC (%) = 92.4 ± 3.5 and RE (%) = 42.2 ± 9.2; patient-specific transformations yielded significantly better (P < 0.0001) estimates, achieving SC (%) = 96.6 ± 4.3 and RE (%) = 22.4 ± 10.7. Thus, in conclusion, BSPMs of our particular test set could be estimated from the standard 12-lead ECG with a very good accuracy by means of general transformation. With patient-specific transformations, accuracy was further improved. In patient monitoring and some clinical interventional procedures (e.g., elective PCI, catheter ablation), a pre-procedure BSPM recording can be used to derive patient-specific lead transformation that can subsequently enhance utility of the 12-lead ECG during the procedure.
The anisotropic conductivity of cardiac tissue and features of the anatomical architecture of the... more The anisotropic conductivity of cardiac tissue and features of the anatomical architecture of the heart, such as the transmural rotation of fibers from the epicardium to the endocardium or their spiral rotation near the apex [1, 2], have a profound influence on the heart’s propagated excitation and the generation of extracardiac electric potential and magnetic field—as has been substantiated by many experimental findings (e.g.[3, 4]). Therefore it is of great interest to study the propagation phenomena and the associated electromagnetic field in mathematical models that represent realistically the anisotropic heart. We have addressed this problem, and the result of our efforts is a model [5, 6, 7] whose salient features related to the propagation algorithm are highlighted in this paper; a companion paper [8] deals with features related to extracardiac electric and magnetic fields.
We used comprehensive electrophysiological/anatomical digital computer models of atrial excitatio... more We used comprehensive electrophysiological/anatomical digital computer models of atrial excitation and the human torso to study the mechanism of generation of body surface P-waves in normal sinus rhythm, and in middle and lower sinus rhythm. Simulated atrial surface isochrone maps for normal sinus rhythm support the validity of the atrial excitation model. The results suggest that the presence of specialized internodal tracts containing fast-conducting fibers is not essential to account for propagation of excitation in apparent preferential directions from the sinoatrial (SA) node to the atrioventricular node. However, in the absence of fast conducting fibers, a slowly conducting segment in the intercaval region is necessary to achieve proper excitation of the interatrial septum. P-wave notches occur in the absence of specialized fast conducting atrial tracts and anisotropies due to fiber orientation. These notches are due to the atrial geometry and the separate contributions of the...
We studied the evolution of body-surface potential map (BSPM) patterns in 32 patients following f... more We studied the evolution of body-surface potential map (BSPM) patterns in 32 patients following first acute inferior myocardial infarction. Initial BSPMs were obtained at a mean of 79 hours post-infarction; follow-up BSPMs, a mean of eight months post-infarction. Temporal area-of-difference maps, constructed by subtracting initial from follow-up group-mean BSPMs, revealed reciprocal changes over the superior and inferior torso for both Q-zone and ST-segment time-integral distributions. The temporal changes in Q-zone patterns were small but definite: over the inferior torso there was a relative gain in Q-zone values and, over the superior torso, a relative decrease. In contrast, there were marked spatial and quantitative changes of ST-segment distributions during the follow-up period. Over the superior torso, particularly anteriorly, there was a gain in ST-segment values; over the inferior torso, a decrease. With the small temporal changes in Q-zone time-integral distributions, indiv...
The magnetic field produced by a current dipole is made up of two parts: the field from the dipol... more The magnetic field produced by a current dipole is made up of two parts: the field from the dipole element, and from the current generated by the dipole in the volume conductor. It was previously shown for the semi-infinite volume conductor, infinite slab, and the sphere that the volume-current contribution is zero to the component of magnetic field which is normal to the boundary. The volume conductor in the form of the human torso is here investigated by computer simulation. Three different heart-torso models are used. The contribution to the normal field component (Bn) by the volume current (via the boundaries) and by the heart dipoles are computed. For comparison, the boundary contribution to the surface potential (V) is also computed. For Bn the three models yield a ratio of boundary to dipole contribution in the same range, with 0.28 as the average. Simple subtractions can make this ratio negligible. For V the equivalent ratio is somewhat greater. The arrow map, developed prev...
Most studies on diagnostic classification of the electrocardiogram (ECG) deal with only two diagn... more Most studies on diagnostic classification of the electrocardiogram (ECG) deal with only two diagnostic categories at once, for example normals versus anterior myocardial infarction, normals versus inferior myocardial infarction, or normal versus left ventricular hypertrophy. ~-5 Such procedures can be helpful for selecting optimal measurements and providing better insight in diagnostic criteria, and in some important applications, such as monitoring patients with acute myocardial infarction, a normal versus myocardial infarction setting may suffice. Bigroup comparisons, however, are not realistic in clinical practice, where often more than two diagnostic entities must be considered. 6 The multigroup approach was first developed by Pipberger et al. 7 Other investigators have since then applied multivariate statistical techniques for classification of both the vectorcardiogram (VCG) and the ECG in a multigroup setting. 8-1~ The set of measurements to be entered into the multigroup cla...
... 저자, Bohumil Horacek (Department of Mechanical Engineering, University of Maryland, College Pa... more ... 저자, Bohumil Horacek (Department of Mechanical Engineering, University of Maryland, College Park, MD),Jungho Kim (Department of Mechanical Engineering, University of Maryland, College Park, MD)Kenneth T. Kiger (Department of Mechanical Engineering, University of ...
1 Introduction First idealized models describing the normal activation sequence in the human hear... more 1 Introduction First idealized models describing the normal activation sequence in the human heart were reported over two decades ago [1, 2]. Mainly due to computational limitations, the models did not include myocardial anisotropy nor physiological propagation. On the basis of anisotropic bidomain theory [3] and cellular automata theory [4], development of more realistic whole-heart models have become feasible [5]. A ventricular model that produces a correct normal activation sequence is a prerequisite for simulating pathological conditions, such as ischemia, infarction or ventricular arrhythmias. A comprehensive model should feature an anatomically accurate geometry, intramural fibrous structure, and a conduction system. Implementation of the ventricular conduction system is a challenge, since it should be flexible enough to allow " rewiring " of the conduction system for each individual case where endocardial mapping data are available. Advances in computer technology h...
To define and relate the body surface electrocardiographic and left ventricular wall motion patte... more To define and relate the body surface electrocardiographic and left ventricular wall motion patterns in the acute phase of Q-wave infarction, we recorded 120-lead body surface potential maps and radionuclear angiograms in 29 patients on the fifth day of their first infarction. By standard 12-lead electrocardiographic criteria, 17 patients were designated as anterior infarction and 12 as inferior infarction. Body surface map infarct patterns in the anterior group were characterized primarily by abnormal Q-wave, negative Q-zone and positive ST-segment integral patterns over the anterior torso and little reciprocal change. The maps of the inferior patient group were characterized primarily by depolarization and repolarization infarct patterns over the inferior torso and marked reciprocal changes in all integral patterns over the anterior torso. Both groups displayed infarct patterns over a common area of the right anterior-inferior torso. In the anterior group depolarization minima and...
Electrical dyssynchrony is postulated to be one of the main factors contributing to non-response ... more Electrical dyssynchrony is postulated to be one of the main factors contributing to non-response of patients to cardiac resynchronization therapy (CRT). We applied inverse epicardial imaging computed from patient-specific geometry and body-surface potential recordings to assess global and regional electrical dyssynchrony. Patients were imaged pre- and post-device implantation, without and with pacing function (P-OFF and P-ON). The reconstructed maps of activation in the dyssynchronous pre-CRT rhythm agree with published contact mapping activation maps with earliest activation starting on the RV free wall and slowly spreading to the LV in a U-shaped pattern. The new ΔQRSi metric captures global pre-CRT dyssynchrony showing negative values (-0.32±0.10) with minimal variability beats (coefficient of variation 10±3.6%) while post-CRT pacing indicates positive values (0.18±0.11). The imaging method is well-suited to study electrical dyssynchrony and potentially guide CRT lead placement.
Clinical and investigative medicine. Medecine clinique et experimentale, 1985
Cardiovascular diseases remain the major cause of death in the adult North American population. M... more Cardiovascular diseases remain the major cause of death in the adult North American population. Most of these deaths are sudden, occurring secondary to ventricular tachycardia/fibrillation (VT/VF). Based on the results of recent clinical trials, it seems likely that many of these deaths could be prevented if reliable means were available to select those patients at highest risk. To date, however, no totally satisfactory means to establish risk has been identified. The purpose of this paper is to review the currently utilized techniques and to draw attention to some new and potentially useful technology involving computer processing of surface recorded electrocardiographic (ECG) signals. ECG monitoring during rest and activity is neither sensitive nor specific. Invasive studies, using programmed ventricular stimulation to reproduce clinical arrhythmias, have proven extremely useful in the management of patients with recurrent VT/VF; this technique allows the selection of effective th...
The objective of this study was to develop and evaluate transformation coefficients for synthesis... more The objective of this study was to develop and evaluate transformation coefficients for synthesis of standard 12-lead electrocardiogram (ECG), 18-lead ECG (with additional leads V7, V8, V9, V3R, V4R, and V5R), and Frank vectocardiogram (VCG) from reduced lead sets using 3 limb electrodes at Mason-Likar sites combined with 2 chest electrodes chosen from V1 to V6 sites. There are 15 such lead-set combinations, and each can be recorded with 6-wire cable. We used a study population from a Dalhousie University (Halifax, Nova Scotia, Canada) database, consisting of 892 individuals: 290 healthy subjects, 497 patients who previously suffered a myocardial infarction, and 105 patients with a history of spontaneous ventricular tachycardia but no evidence of a previous myocardial infarction. For each subject, 120-lead ECG recordings of 15-second duration were aligned and averaged, all samples of the QRST complex for leads of interest were extracted, and these data were used to derive—by regression analysis— coefficients for lead transformations. The coefficients were then used to reconstitute complete 12-lead/18-lead ECG and VCG from 15 predictor sets, and the success of this synthesis was assessed by 2 measures for goodness of fit: similarity coefficient (SC in percentage) and relative error (RE in percentage). Our results show that chest leads V2 and V4 are the best pair for reconstituting the 12-lead ECG (SC = 96.91, RE = 25.53), followed closely by V3 and V5, V2 and V5, V3 and V4, and V1 and V4. The best pair for reconstituting the entire 18-lead set is V1 and V4 (SC = 93.82, RE = 31.93), followed byV1 and V3, V1 and V5, and V1 and V6. The best pair for synthesis of the Frank X, Y, Z leads is V3 and V6 (SC = 96.31, RE = 26.07), followed by V1 and V3, V1 and V4, and V3 and V5. In conclusion, our study demonstrates that good approximation of 12-lead/18-lead ECG andVCG can be achieved by using a lead system using 6-wire cable, provided that electrodes are judiciously placed.
jects for optimum classification of 159 N, 103 AMI, 130 IMI, and 116 LVH subjects. In the first s... more jects for optimum classification of 159 N, 103 AMI, 130 IMI, and 116 LVH subjects. In the first step, multivariate analysis is performed to select measurements for each possible pairwise comparison; in the second step, the selected measurements are pooled together and utilized in a multigroup classification scheme, considering the four groups simultaneously and achieving separation of N, AMI, IMI, and LVH subjects. The results of the classification are compared to those obtained, in a separate study, with the 12-lead ECG in the same population, using the same procedure. 13
High resolution body surface potential maps (BSPM) and magnetic field maps (MFM) for study groups... more High resolution body surface potential maps (BSPM) and magnetic field maps (MFM) for study groups consisting of 11 Q wave and 11 non Q wave myocardial infarct (MI) patients as well as 9 normal subjects, were recorded in a magnetically and electrically shielded room. A control group of 22 normal subjects provided group mean normal time integral maps for selected QRST time intervals. The difference between magnitudes of extrema in each map defined the normal mean data range R for that time interval. The root mean square sum of the differences between the time integral map of a study subject and the normal group-mean map provided an estimate of individual map variability, V. Subsequent calculation of group-mean map variability, V, and group-mean normalized variability, V/R, for specific time intervals of the cardiac cycle, were used to test the abilities of BSPM and MFM techniques to distinguish between the normal and MI study groups. Results indicate that BSPM V/R differences between MI and normal groups are most pronounced during Q wave and Q zone activity; between inferior MI&amp;amp;amp;amp;#39;s and normals (p less than 0.05) and between anterior MI&amp;amp;amp;amp;#39;s and normal (p less than 0.01). Significant differences in MFM V/R occur during repolarization; between inferior MI&amp;amp;amp;amp;#39;s and non Q wave MI&amp;amp;amp;amp;#39;s (p less than 0.05), between anterior MI&amp;amp;amp;amp;#39;s and normals (p less than 0.05), between non Q wave MI&amp;amp;amp;amp;#39;s and normals (p less than 0.05) and between all MI&amp;amp;amp;amp;#39;s and normals (p less than 0.01). It is concluded that high resolution BSPM and MFM provide complementary means of discriminating between normal subjects and MI patients.
The aim of this study was to compare general and patient-specific transformations for estimating ... more The aim of this study was to compare general and patient-specific transformations for estimating body surface potential maps (BSPMs) from the standard 12-lead electrocardiogram (ECG). The design set for deriving the general transformation consisted of 120-lead BSPMs of Dalhousie Superset (n = 892); as a test set for comparing patient-specific and general transformations we used 120lead BSPMs from the Dalhousie database of patients (n = 88) who underwent elective percutaneous coronary intervention (PCI). From these two datasets we derived the desired transformations by regression analysis. The estimated BSPMs were assessed by 3 goodness-of-fit measures: similarity coefficient (SC), root-mean-square error, and relative error (RE). Results show that BSPMs can be estimated from the 12-lead ECG by using general transformation with (mean ± SD) SC (%) = 92.4 ± 3.5 and RE (%) = 42.2 ± 9.2; patient-specific transformations yielded significantly better (P < 0.0001) estimates, achieving SC (%) = 96.6 ± 4.3 and RE (%) = 22.4 ± 10.7. Thus, in conclusion, BSPMs of our particular test set could be estimated from the standard 12-lead ECG with a very good accuracy by means of general transformation. With patient-specific transformations, accuracy was further improved. In patient monitoring and some clinical interventional procedures (e.g., elective PCI, catheter ablation), a pre-procedure BSPM recording can be used to derive patient-specific lead transformation that can subsequently enhance utility of the 12-lead ECG during the procedure.
The anisotropic conductivity of cardiac tissue and features of the anatomical architecture of the... more The anisotropic conductivity of cardiac tissue and features of the anatomical architecture of the heart, such as the transmural rotation of fibers from the epicardium to the endocardium or their spiral rotation near the apex [1, 2], have a profound influence on the heart’s propagated excitation and the generation of extracardiac electric potential and magnetic field—as has been substantiated by many experimental findings (e.g.[3, 4]). Therefore it is of great interest to study the propagation phenomena and the associated electromagnetic field in mathematical models that represent realistically the anisotropic heart. We have addressed this problem, and the result of our efforts is a model [5, 6, 7] whose salient features related to the propagation algorithm are highlighted in this paper; a companion paper [8] deals with features related to extracardiac electric and magnetic fields.
We used comprehensive electrophysiological/anatomical digital computer models of atrial excitatio... more We used comprehensive electrophysiological/anatomical digital computer models of atrial excitation and the human torso to study the mechanism of generation of body surface P-waves in normal sinus rhythm, and in middle and lower sinus rhythm. Simulated atrial surface isochrone maps for normal sinus rhythm support the validity of the atrial excitation model. The results suggest that the presence of specialized internodal tracts containing fast-conducting fibers is not essential to account for propagation of excitation in apparent preferential directions from the sinoatrial (SA) node to the atrioventricular node. However, in the absence of fast conducting fibers, a slowly conducting segment in the intercaval region is necessary to achieve proper excitation of the interatrial septum. P-wave notches occur in the absence of specialized fast conducting atrial tracts and anisotropies due to fiber orientation. These notches are due to the atrial geometry and the separate contributions of the...
We studied the evolution of body-surface potential map (BSPM) patterns in 32 patients following f... more We studied the evolution of body-surface potential map (BSPM) patterns in 32 patients following first acute inferior myocardial infarction. Initial BSPMs were obtained at a mean of 79 hours post-infarction; follow-up BSPMs, a mean of eight months post-infarction. Temporal area-of-difference maps, constructed by subtracting initial from follow-up group-mean BSPMs, revealed reciprocal changes over the superior and inferior torso for both Q-zone and ST-segment time-integral distributions. The temporal changes in Q-zone patterns were small but definite: over the inferior torso there was a relative gain in Q-zone values and, over the superior torso, a relative decrease. In contrast, there were marked spatial and quantitative changes of ST-segment distributions during the follow-up period. Over the superior torso, particularly anteriorly, there was a gain in ST-segment values; over the inferior torso, a decrease. With the small temporal changes in Q-zone time-integral distributions, indiv...
The magnetic field produced by a current dipole is made up of two parts: the field from the dipol... more The magnetic field produced by a current dipole is made up of two parts: the field from the dipole element, and from the current generated by the dipole in the volume conductor. It was previously shown for the semi-infinite volume conductor, infinite slab, and the sphere that the volume-current contribution is zero to the component of magnetic field which is normal to the boundary. The volume conductor in the form of the human torso is here investigated by computer simulation. Three different heart-torso models are used. The contribution to the normal field component (Bn) by the volume current (via the boundaries) and by the heart dipoles are computed. For comparison, the boundary contribution to the surface potential (V) is also computed. For Bn the three models yield a ratio of boundary to dipole contribution in the same range, with 0.28 as the average. Simple subtractions can make this ratio negligible. For V the equivalent ratio is somewhat greater. The arrow map, developed prev...
Most studies on diagnostic classification of the electrocardiogram (ECG) deal with only two diagn... more Most studies on diagnostic classification of the electrocardiogram (ECG) deal with only two diagnostic categories at once, for example normals versus anterior myocardial infarction, normals versus inferior myocardial infarction, or normal versus left ventricular hypertrophy. ~-5 Such procedures can be helpful for selecting optimal measurements and providing better insight in diagnostic criteria, and in some important applications, such as monitoring patients with acute myocardial infarction, a normal versus myocardial infarction setting may suffice. Bigroup comparisons, however, are not realistic in clinical practice, where often more than two diagnostic entities must be considered. 6 The multigroup approach was first developed by Pipberger et al. 7 Other investigators have since then applied multivariate statistical techniques for classification of both the vectorcardiogram (VCG) and the ECG in a multigroup setting. 8-1~ The set of measurements to be entered into the multigroup cla...
... 저자, Bohumil Horacek (Department of Mechanical Engineering, University of Maryland, College Pa... more ... 저자, Bohumil Horacek (Department of Mechanical Engineering, University of Maryland, College Park, MD),Jungho Kim (Department of Mechanical Engineering, University of Maryland, College Park, MD)Kenneth T. Kiger (Department of Mechanical Engineering, University of ...
1 Introduction First idealized models describing the normal activation sequence in the human hear... more 1 Introduction First idealized models describing the normal activation sequence in the human heart were reported over two decades ago [1, 2]. Mainly due to computational limitations, the models did not include myocardial anisotropy nor physiological propagation. On the basis of anisotropic bidomain theory [3] and cellular automata theory [4], development of more realistic whole-heart models have become feasible [5]. A ventricular model that produces a correct normal activation sequence is a prerequisite for simulating pathological conditions, such as ischemia, infarction or ventricular arrhythmias. A comprehensive model should feature an anatomically accurate geometry, intramural fibrous structure, and a conduction system. Implementation of the ventricular conduction system is a challenge, since it should be flexible enough to allow " rewiring " of the conduction system for each individual case where endocardial mapping data are available. Advances in computer technology h...
To define and relate the body surface electrocardiographic and left ventricular wall motion patte... more To define and relate the body surface electrocardiographic and left ventricular wall motion patterns in the acute phase of Q-wave infarction, we recorded 120-lead body surface potential maps and radionuclear angiograms in 29 patients on the fifth day of their first infarction. By standard 12-lead electrocardiographic criteria, 17 patients were designated as anterior infarction and 12 as inferior infarction. Body surface map infarct patterns in the anterior group were characterized primarily by abnormal Q-wave, negative Q-zone and positive ST-segment integral patterns over the anterior torso and little reciprocal change. The maps of the inferior patient group were characterized primarily by depolarization and repolarization infarct patterns over the inferior torso and marked reciprocal changes in all integral patterns over the anterior torso. Both groups displayed infarct patterns over a common area of the right anterior-inferior torso. In the anterior group depolarization minima and...
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