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PubMed1994

Remodeling in myocardial infarction and body surface potential maps.

This study deals with the capabilities of body surface integral and departure maps to evaluate the chronic stage of myocardial infarction based on dividing the left ventricle into 12 segments. The effects of ventricular remodeling on electrocardiographic potential distributions are considered. A 61-year-old male patient was examined five times by body surface potential mapping during a period of 9 months after acute myocardial infarction. Integral maps were calculated for 60 ms after QRS onset and compared with mean data from a control group using departure maps. Integral maps showed a continual reduction of negative potentials in the lower half of the torso with time. The negative area covered the lower torso in the departure maps during the whole study, but its form and value changed. According to the location of the departure area, the surface projection of the scar moved from a position corresponding to inferior segments to a position corresponding to posterior segments. Its size also decreased. Echocardiographic examinations showed progressive enlargement of both ventricles with time. Therefore, the authors postulate that the changing pattern of body surface potential maps was mainly influenced by ventricular remodeling after myocardial infarction.

Electrocardiography↗
PubMed1991

Evaluation of arrhythmic causes of syncope: correlation between Holter monitoring, electrophysiologic testing, and body surface potential mapping.

Holter monitoring, electrocardiographic (ECG) signal-averaging, body surface potential mapping (BSPM) for PQRST isoarea maps, and electrophysiologic study (EPS) were performed in 100 patients with syncope. Coronary artery disease (CAD) was found in 46 patients and other heart disease was found in 19. EPS was diagnostic in 44 patients, while Holter monitoring suggested a diagnosis in only 21 patients. Abnormal BSPM was frequently seen (56%), especially in CAD (70%), or with inducible ventricular tachycardia (VT) (87%). Late potentials were recorded in 13 patients with CAD; five had inducible VT. In seven other patients with VT, they were either absent or bundle branch block (BBB) was found. Thirteen deaths (three sudden) occurred in our series. EPS-guided therapy resulted in a low rate of total cardiac death. In conclusion, EPS had a higher diagnostic yield than Holter monitoring regardless of cardiac pathology. ECG signal-averaging was useful in predicting VT only in patients with CAD without BBB. BSPM was abnormal in most patients with cardiac disease, but poorly predicted VT.

Arrhythmias, Cardiac↗
PubMed1987

Qualitative and quantitative analysis of characteristic body surface potential map features in anterior and inferior myocardial infarction.

Body surface potential maps were recorded from 120 electrode sites in 236 normal subjects and 258 patients with initial evidence of either anterior myocardial infarction (MI) or inferior MI to identify characteristic map patterns in both groups. After time normalization, averaged map distributions were displayed at 18 equal time intervals during both QRS and ST-T waveforms from the normal, anterior MI and inferior MI groups. At each time instant, the 120-point averaged normal map was subtracted in turn from the corresponding anterior and inferior MI maps; the resulting differences at each electrode site were divided by the pooled standard deviation and the obtained values (discriminant indexes), plotted as contour lines with 1 standard deviation increments, producing discriminant maps for each bi-group comparison. The most consistent discriminant patterns in 114 patients with anterior MI were observed in early QRS in the upper left anterior chest where abnormal negative voltages reflected loss of electric potentials while reciprocal changes were noticed in the lower back; by mid-QRS, both distributions had moved jointly and vertically, the former in the lower torso on the midsternal line, the latter in the upper back. In 144 patients with inferior MI, abnormal positive distributions were observed in early QRS in the upper back, followed later by excessive negative voltages in the inferior right anterior chest; at mid-QRS, both distributions had migrated horizontally, the former proceeding toward the upper anterior torso, the latter to the lower left dorsal area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

Electrocardiographic body surface potential maps of the QRS of normal children.

Electrocardiographic body surface potential maps (BSPM), utilizing 180 active dry electrodes imbedded in an inflatable vest, were obtained in 40 normal children, ages 8 to 18. The potential levels of the maps are displayed as different colors. A qualitative analysis indicated that the onset of right ventricular breakthrough could always be recognized in the upstroke of the QRS by a pseudopod from a right shoulder minimum extending into an anterior maximum, at an average of 24.4 +/- 4.2 msec., for an average QRS duration of 75.0 +/- 7.1 msec. However there was considerable normal variation, particularly in the mid and late QRS. At the time of depolarization of the free walls of the ventricles, the maximum often remained anterior, with an extension posterior, even through the Frank system vectorcardiogram invariably was posterior. Most remarkable was the terminal QRS of the BSPM, where the terminal maximum may be right superior anterior, anterior superior, or right posterior, presumably reflecting the right ventricular outflow tract, the superior septum, or the posterior basal left ventricle.

Adolescent↗
PubMed1990

Multicategory classification of body surface potential maps.

A statistical classification method is suggested for body surface potential maps (BSPM). The initial data reduction utilizes the Fourier expansion and time integration, resulting in physiological-oriented features. Based on Fischer's criterion, optimal discriminant vectors are used to map the features to an optimal subdomain. Experimental criteria determine the dimensionality of the subdomain and the number of features to be mapped into it. Classification is performed in two steps. In the first, a k-nearest neighbor (k-NN) rule is used for every two-category problem, the results of which are fed into a voting rule for final classification. The method is tested with 123 patients divided into four categories: normal (NR), ischemia (IS), myocardial infarction (MI), and left bundle branch block (LB) patients. The success is between 88% (for IS) and 100% (for LB) for QRS segment integration. Departure maps were used to explain the misclassified patterns.

Algorithms↗
PubMed1995

Interpolation of body surface potential maps.

The performance of four methods for interpolation of body surface potential maps (BSPMs) for different electrode grid densities was assessed. This study is part of a research project on the influence of the variability of 12-lead electrocardiograms on computer interpretation due to small electrode position changes. Interpolated BSPMs can be used to simulate this variability. The set of BSPMs studied, derived from a 117-electrode grid with relatively many electrodes on the left precordial part of the thorax, consisted of 232 cases without abnormalities, 277 with infarction, and 237 with left ventricular hypertrophy. The interpolation methods used were fast Fourier transforms, Chebyshev polynomials, linear functions, and cubic splines (CS). In the horizontal plane, a reference signal was first interpolated and, thereafter, resampled using 11 different sets of electrodes with the number of electrodes ranging from 18 down to 8. In the vertical direction, five grids with electrodes only on the front of the thorax and nine grids with electrodes on the front and back were examined. As a performance measure for interpolation, mean absolute error (MAE) was used: the absolute differences between the reference signal and the interpolated signal, averaged over the QRS on all maps. All methods showed deteriorating performance for decreasing grid density. In the horizontal direction, CS proved to be slightly superior to other methods for the left precordial electrodes for all but the densest grid (e.g., MAE = 22.8 microV vs MAE > 24.8 microV for a 12-electrode grid). For electrodes not in that area, CS performed the best as well (MAE = 16.1 microV for the same grid), with differences with the other methods being small (MAE > 16.4 microV). In the vertical direction, CS showed the best results on the front, both for the dense nonperiodic (MAE = 19.1 microV vs MAE > 26.6 microV for a 6-electrode grid) and periodic grids (MAE = 25.1 microV vs MAE > 26.6 microV for a 12-electrode grid). Linear functions performed best for sparse nonperiodic grids and sparse periodic grids for electrodes on the back, with the difference with CS for the last case being small. The method CS performed best overall, and is recommended for interpolating BSPMs.

Algorithms↗
PubMed1993

Body surface potential maps in patients with familial amyloid polyneuropathy.

The purpose of this study was to evaluate the characteristics of body surface potential maps in patients with cardiac amyloidosis. The study population consisted of 30 patients with familial amyloid polyneuropathy and 50 age-matched normal volunteers. The patients were classified into one of the following three stages: stage I, peripheral neuropathy limited to the lower limbs; stage II, neuropathy involving both the lower and upper limbs; and stage III, bedridden because of extensive progressive neuropathy. Electrodes for the body surface potential maps were placed at 87 points (59 anterior and 28 posterior) on the chest. To analyze these body surface electrocardiograms, isopotential maps, isochrone maps, and isointegral maps were used. The mean values of the positive potential were significantly lower in the advanced stage (1.9 +/- 0.2 mV in stage I, 1.0 +/- 0.2 mV in stage II, and 0.7 +/- 0.2 mV in stage III). Prolongation of ventricular activation time was observed on the anterior and lateral chest. The mean QRST isointegral maps of the patients in the advanced stage of cardiac amyloidosis showed a large negative area over the anterior and left lateral chest, the positive areas were small and their potentials were very low. In addition, 18 (60%) of the 30 patients had a multipolar pattern in the QRST isointegral maps. The changes of the body surface potential maps correlated with clinical staging and echocardiographic findings.

Adult↗
PubMed1995

Comparison of body surface potential maps simulated with isotropic and anisotropic computer heart models.

Simulated body surface potential maps (SBSPM) with isotropic and anisotropic heart models were compared to investigate the effect of myocardial anisotropy on body surface electrocardiograms at a whole heart level. Rotative fiber orientations of total 90 degrees was incorporated into an isotropic heart model. The anisotropy of conduction velocity and intracellular electric conductivity was included in the simulation. SBSPM based on epicardial, intramural, and endocardial stimulation show high correlation with fiber orientations. On the other hand, the anisotropy cannot be distinguished from the SBSPM in the simulation of normal heart model.

Anisotropy↗
PubMed1993

Body surface potential mapping of ST-segment shift in patients undergoing percutaneous transluminal coronary angioplasty. Correlations with the ECG and vectorcardiogram.

The purpose of this study was to investigate the thoracic patterns of ST-segment shift induced by the occlusion of different coronary arteries during percutaneous transluminal coronary angioplasty. Body surface potential maps were recorded with 63 leads during sinus rhythm before, during, and after balloon inflation in 20 patients. Two patients underwent dilatation of both the right and circumflex coronary arteries. A 12-lead scalar electrocardiogram and a Frank vectorcardiogram with orthogonal leads X, Y, and Z were obtained with the body surface potential maps. The body surface potential maps at 40 ms during the ST-segment showed patterns that were specific to the dilated vessel. The left anterior descending coronary artery (n = 10) was associated with the largest ST-segment shifts with a precordial maximum and negative potentials over the back; for the right coronary artery (n = 7), negative potentials covered the upper left torso with a left mid-axillary minimum and positive potentials over the rest of the torso; for the left circumflex coronary artery (n = 5), negative potentials covered the anterior torso with a precordial minimum and positive potentials over the back. These changes dissipated rapidly after balloon deflation. ST levels measured on orthogonal leads showed values greater than standard electrocardiographic leads for circumflex and right coronary arteries. In conclusion, body surface potential mapping provides a comprehensive approach for the evaluation of electrocardiographic changes and the development of optimal leads for the detection of acute occlusion of a coronary artery.

Adult↗
PubMed1988

Diagnostic value of body surface potential mapping in old anterior non-Q myocardial infarction.

Body surface potential maps (BSM) were recorded from 140 chest leads in 30 healthy control subjects (C) and in 20 patients who had had an acute non-Q wave myocardial infarction (MI) 1-82 months before the study, to identify reliable indices of necrosis. In 12 MI patients the QRS complex was within normal limits on standard 12-lead ECG (group A), and in 8 patients no pathologic Q waves were present but the R waves were small and did not normally increase from V1 to V4 (group B). In each subject instantaneous potential distributions throughout the QRS interval were examined. Moreover, the potential--time integrals relating to three intervals (first 40 msec, mid-third, and last third of QRS) were calculated at each lead point and displayed as integral (I) maps. For each time interval, deviation index maps (DI), indicating the standardized differences from normal values, were calculated. An area where the integral values differed at least 2 SD from normal mean was considered abnormal. In most group A patients the inspection of instantaneous potential maps did not reveal definitively abnormal patterns. In group B patients a greater variety of patterns was found and in four cases the characteristic features of the anterior Q wave MI were observed. The DI maps of the first 40 msec of QRS provided the best diagnostic accuracy: areas of negative values 2 SD lower than normal were present in all group B patients (100%), in 8 group A patients (67%), and in 4 group C subjects (13%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Data base for body surface potential maps of normal populations--normal data base by the Japanese Circulation Society Task Force Committee on Criteria for Body Surface Mapping].

In order to evaluate the normal ranges of the body surface potential maps, data from normal healthy subjects were compiled by the Japanese Circulation Society Task Force Committee on Criteria for Body Surface Mapping (Chairman: Shoji Yasui, Nagoya National Hospital). The subjects met all the following criteria; (1) normal physical findings; (2) no heart or lung diseases; (3) no hypertension (160/90 mmHg); (4) normal 12-lead electrocardiogram; (5) normal chest roentgenogram (may be omitted in children); (6) normal findings in exercise test in subjects 40 years of age or older; and (7) no major morbidity. Body surface mapping data were recorded by use of 87-lead mapping systems, HPM-5100, HPM-6500, and VCM-3000 (Fukuda Denshi, and Chunichi Denshi), or 128-lead mapping systems Cardiovision (Tokyo Technological University-Teijin), and Cardiomap (Gakken). To construct the database, each original set of body surface mapping data was copied to an MS-DOS file. Data recorded by a 128-lead mapping system was transformed into an 87-lead system data. Next, each individual data was transformed into a file of common format with a header containing clinical information, and the onset and offset of each electrocardiographic waves. From these secondary files, mean and standard deviation of each electrocardiographic lead were calculated for instantaneous voltages of P wave, QRS wave, and ST-T; time integrals of P, QRS, and QRST; and ventricular activation time, to subgroups divided age and gender. All these data were stored in a optical disk, and also mean and standard deviation for subgroups were stored in a set of floppy disks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1981

Redundancy reduction for improved display and analysis of body surface potential maps. II. Temporal compression.

This paper describes use of the Karhunen-Loeve expansion to identify and reduce temporal redundancy in electrocardiographic body surface potential maps (192 body surface leads recorded simultaneously at 1 kHz/channel for approximately 600 msec). Temporal data compression of about 20 to 1 was obtained with accurate representation of the original data. Use of separate sets of orthonormal basis functions for QRS and ST-T provided a more accurate representation than the basis derived from QRST. Combined with the spatial compression described in the preceding paper, overall map data compression of about 320 to 1 was obtained without significant loss of accuracy of representation or map appearance. With both spatial and temporal compression the 100,000 numbers which typically comprise a single cardiac complex were accurately represented by 216 coefficients. Using basis functions derived from a single cardiac complex were accurately represented by 216 coefficients. Using basis functions derived from a training set of 221 maps, the estimated average rms error of representation was 60 microV during the ST-T. For 34 test maps which were not part of the training set, measured average errors were 64 microV during the QRS and 23 microV during the ST-T. This technique provides a basis for quantification of the diagnostic content of maps and automated classification of maps.

Adult↗
PubMed1995

[Usefulness of body surface potential maps to determine ablation site in patients with WPW syndrome].

We studied body surface potential maps (BSPM) in patients with WPW syndrome before surgical ablation. These BSPM were compared with computerized epicardial mapping using sock and snap electrode. In most patients the location of minima in the early delta wave was a simple and accurate index of the site of accessory pathway. In 4 patients BSPM was useful for the diagnosis of presence of bilateral accessory pathways. We conclude that BSPM may be also useful to determine ablation site of radiofrequency catheter ablation.

Body Surface Potential Mapping↗
PubMed1981

Redundancy reduction for improved display and analysis of body surface potential maps. I. Spatial compression.

The Karhunen-Loeve technique of random process representation was investigated as a method of quantitatively characterizing body surface potential maps. One hundred ninety-two lead body surface potential maps from 124 normal subjects and 97 patients with independently documented heart disease were used in the study. Each map frame in QRS and ST-T of 34 maps in a test set was represented as a linear sum of orthonormal distributions derived from the covariance matrix estimated from all QRS frames in the 221 training maps. A 16:1 reduction in spatial data of the test set was achieved with rms errors of 45 and 21 microV in QRS and ST-T, respectively. Results suggest that 12 independent waveforms, derived from the 192 measured ECGs, may be used in place of those 192 ECGs. In addition to providing a convenient and familiar method of display for map data, the technique puts the data in an appropriate form for quantitative statistical analysis.

Cardiomegaly↗
PubMed1996

Body surface potential mapping of a patient with Wolff-Parkinson-White syndrome with two accessory pathways and two atrial pacemaker complexes.

As part of an ongoing research protocol, a patient with Wolff-Parkinson-White syndrome underwent body surface potential mapping and electrophysiologic studies before radiofrequency ablation therapy. Careful analysis of the body surface potential mapping data made it possible to distinguish four different map sequences representing four different cardiac complexes. Analysis of these maps is consistent with two accessory pathways, with the additional pathology of two distinct atrial pacemaker sites. A right anterosuperior pathway was found to conduct continuously. The second pathway is consistent with a right inferior pathway conducting intermittently. The analysis demonstrates the type of information that can be extracted from body surface potential maps, even in the presence of complex pathologies.

Adult↗
PubMed1998

Nonfluoroscopic localization of an amagnetic catheter in a realistic torso phantom by magnetocardiographic and body surface potential mapping.

This study was performed to evaluate the accuracy of multichannel magnetocardiographic (MCG) and body surface potential mapping (BSPM) in localizing three-dimensionally the tip of an amagnetic catheter for electrophysiology without fluoroscopy. An amagnetic catheter (AC), specially designed to produce dipolar sources of different geometry without magnetic disturbances, was placed inside a physical thorax phantom at two different depths, 38 mm and 88 mm below the frontal surface of the phantom. Sixty-seven MCG and 123 BSPM signals generated by the 10 mA current stimuli fed into the catheter were then recorded in a magnetically shielded room. Non-invasive localization of the tip of the catheter was computed from measured MCG and BSPM data using an equivalent current dipole source in a phantom-specific boundary element torso model. The mean 3-dimensional error of the MCG localization at the closer level was 2 +/- 1 mm. The corresponding error calculated from the BSPM measurements was 4 +/- 1 mm. At the deeper level, the mean localization errors of MCG and BSPM were 7 +/- 4 mm and 10 +/- 2 mm, respectively. The results showed that MCG and BSPM localization of the tip of the AC is accurate and reproducible provided that the signal-to-noise ratio is sufficiently high. In our study, the MCG method was found to be more accurate than BSPM. This suggests that both methods could be developed towards a useful clinical tool for nonfluoroscopic 3-dimensional electroanatomical imaging during electrophysiological studies, thus minimizing radiation exposure to patients and operators.

Body Surface Potential Mapping↗
PubMed1981

The determination of the human ventricular gradient from body surface potential map data.

We have analyzed the Wilson ventricular gradient in terms of body surface potential maps and of the reduction of such surface patterns to equivalent dipoles or vectors. While the ventricular gradient traditionally was treated as first a scalar, then a vector concept, we found that the three entities (QRS area, T area, QRST area) did not reduce to vectors with a common location. However, conventional vector addition (QRST area = QRS area + T area) did precisely apply. Further we found considerable more-than-vector or extra-dipolar information remaining for all three entities after removal of the dipole effect. This suggests that maps of these entities should be considered the boundaries of complex electrical fields rather than simple surface effects of vectors.

Adult↗