[Clinical utility of body surface potential mapping and its new direction of research].
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Body Surface Potential Mapping↗
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Additional data on body surface potential maps of ventricular repolarization in normal adults.
To date most published studies on normal basic data of the potential distribution of cardiac activity have been restricted to ventricular depolarization. Only a few papers have dealt with ventricular repolarization in normal subjects. This is an attempt to establish the basic data of the body surface potential maps (BSPM) of ventricular repolarization in normal adults. BSPM of ventricular repolarization utilizing 87 electrodes through the heart potential map system designed by Toyama et al. were studied in 50 normal Chinese male adults. The following information on BSPMs was obtained: (1) In the initial phase of ventricular repolarization, the potential maximum was located on the precordial area and the potential minimum appeared on the right-superior portion of the back; (2) The movement of potentials was counterclockwise and stable during the later portion of the T loop; (3) The magnitudes of the potentials changed in a spindle pattern with the drifting of ventricular repolarization. They first increased and then decreased with the largest value being around the peak period of the T wave; (4) The absolute value was greater in the potential maximum than the potential minimum throughout ventricular repolarization. There was no "reversal" potential distribution pattern. This parameter may be of importance clinically; (5) There were usually multiple potential maxima and multiple potential minima during the ST segment and early phase of the T wave; (6) The largest potential maximum and potential minimum were 0.93 +/- 0.28 mV and 0.35 +/- 0.19 mV, respectively. The potential maximum and potential minimum at the peak T wave were 0.91 +/- 0.23 mV and 0.35 +/- 0.17 mV, respectively. Obviously, this study offers valuable basic data on the BSPM in normal adults and will be helpful to our understanding of the BSPM in various heart diseases.
Adult↗
Recovery time dispersion measured from 87-lead body surface potential mapping as a predictor of sustained ventricular tachycardia in patients with idiopathic dilated cardiomyopathy.
INTRODUCTION: The clinical usefulness of QT dispersion in 12-lead ECG has been controversial in identifying subjects at risk for sustained ventricular tachycardia (VT) in patients with idiopathic dilated cardiomyopathy (DCM). We hypothesized that increasing the spatial resolution of the ECG improves the accuracy of risk stratification. The purpose of this study was to test the ability of recovery time dispersion measured from 87-lead body surface potential mapping (BSPM) to identify patients at risk for sustained VT in idiopathic DCM. METHODS AND RESULTS: We obtained 87-lead BSPM and 12-lead ECG in 33 patients with idiopathic DCM (15 patients with a history of sustained VT [VT(+) group] and 18 patients without a history of sustained VT [VT(-) group]) and in 20 normal control subjects. We measured the corrected QT dispersion and corrected recovery time dispersion from 12-lead ECG (QTc-12 dispersion and RTc-12 dispersion, respectively) and 87-lead BSPM (QTc-87 dispersion and RTc-87 dispersion, respectively). Signal-averaged ECG also was recorded in 25 patients. Neither the QTc-12 nor QTc-87 dispersion discriminated between the VT(+) and VT(-) groups patients. The VT(+) group patients had a larger but insignificant RTc-12 dispersion than the VT(-) group patients. In contrast, the RTc-87 dispersion was significantly larger in the VT(+) group patients than in the VT(-) group patients (236 +/- 39 msec vs 184 +/- 28 msec, P < 0.001). Receiver operating curve analysis indicated that the RTc-87 dispersion was as good as late potentials in predicting susceptibility to sustained VT; its sensitivity, specificity, and negative predictive value were 73%, 76%, and 76%, respectively (cutoff value 200 msec). RTc-87 dispersion >200 msec combined with positive late potentials provide high sensitivity (92%) and high negative predictive value (88%) for sustained VT. CONCLUSION: The RTc-87 dispersion is a useful tool to identify subjects at risk for sustained VT in patients with idiopathic DCM.
Body Surface Potential Mapping↗
Improved prediction of left ventricular mass by regression analysis of body surface potential maps.
Electrocardiographic left ventricular (LV) hypertrophy involving ST-T abnormalities, in addition to high QRS voltages, is associated with increased risk of cardiovascular disease mortality. Unfortunately, conventional electrocardiographic criteria have limited utility in the quantitative assessment of LV hypertrophy. Body surface potential maps, which contain diagnostic information not present in commonly used lead systems, were recorded from 117 thoracic sites and 3 limb electrodes in 72 normal subjects and 84 patients with LV hypertrophy. Multiple regression analysis was performed separately for 54 women and 102 men on 120-lead data, using as features instantaneous voltages on time-normalized P, PR, QRS and ST-T waveforms. Leads and features for optimal prediction of echocardiographically determined LV mass were selected. A total of 6 features from 3 torso sites in men, and from the same 3 sites plus 2 others in women, yielded correlations between echocardiographic and electrocardiographic estimates of LV mass of 0.89 and 0.88, respectively. The standard errors of the estimate (SEE), or average errors in predicting LV mass from the regression equations, were 31 and 22 g, respectively. The single most potent predictor in both sexes was a mid-QRS voltage measured on a lead positioned 10 cm below V1; QRS duration, late QRS and early-to-mid T-wave amplitudes recorded in the lower left flank contributed significantly to the performance of both regression models. The optimal electrode sites for electrocardiographic prediction of LV mass were outside the conventional lead locations.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Comparative study of QRST values from body surface potential mapping, 12-lead ECGs, VCGs in detecting inferior myocardial infarction, and evaluating the severity of left ventricular wall motion abnormalities in simulated left bundle branch block.
The authors compared the ability of QRST time-integral values (QRST values) from body surface potential maps (BSPM), 12-lead electrocardiograms (ECGs), and Frank lead vectorcardiograms (VCGs) in diagnosing a prior inferior myocardial infarction (MI) in simulated left bundle branch block (LBBB). The study included 32 patients whose digitized ECGs were recorded simultaneously for BSPM, ECGs, and VCGs during normal sinus rhythm and during right ventricular pacing simulating LBBB (18 with and 14 without an inferior MI). QRST values were calculated in each lead point of ECGs. Data on 608 normal subjects were used as controls; mean +/- 2 SD was regarded as the normal range. The following parameters were derived: sigma DM, sigma DE, sigma DV, the sum of the differences between the normal mean QRST value, and the QRST value of a given patient in leads where the QRST value was less than the normal range ("-2 SD area") in BSPM, ECGs, and VCGs (Y lead). The correlation coefficients for sigma DM, sigma DE, and sigma DV between the two activation sequences were highly significant. Sensitivity and specificity were as follows: 89% and 93% for sigma DM > 100 mV.ms, 89% and 93% for sigma DE > 50 mV.ms, and 56% and 100% for sigma DV > 10 mV.ms, respectively. Although sigma DM, sigma DE, and sigma DV were significantly (P < .01) correlated with the asynergy index calculated from left ventriculograms, sigma DM showed the best correlation. QRST values from BSPM, ECGs, and VCGs provide information that is useful in detecting an inferior MI and in estimating the severity of left ventricular wall motion abnormalities in the setting of LBBB. Of the three parameters, BSPM showed the best correlation with the severity of left ventricular wall motion abnormalities.
Aged↗
ECG body surface potential mapping many years after successful surgery for coarctation of the aorta.
Patients with coarctation of the aorta (CoA) who previously underwent successful surgery are often diagnosed on standard electrocardiograms as having partial right bundle branch block. After surgery 24 patients with CoA had body surface potential mapping (BSPM) with the Case Western Reserve University 180 electrode system; of these 7 had additional aortic stenosis and none had ever had intracardiac communication. The average age at the initial surgery for CoA was 4.0 +/- 3.3 years and at the time of the BSPM it was 12.7 +/- 5.9 years. For the 17 patients with CoA without aortic stenosis the average age at the initial surgery was 5.0 +/- 3.4 years and at the time of the BSPM it was 14.2 +/- 6.0 years. In 11 of the 24 patients, a cardiac catheterization was performed, and each patient demonstrated normal pulmonary artery and right ventricular systolic pressure except for one child with 40 mmHg systolic. In the others all indications were that right ventricular pressure was normal. In 11 of the 24 patients, congestive heart failure had been present in infancy. All 24 cases had evidence for epicardial right ventricular breakthrough on the BSPM, a finding believed to indicate right ventricular activation from endocardium to epicardium via the normal Purkinje system. There were no findings on the BSPM suggesting that right bundle branch block was present. Right ventricular hypertrophy with or without terminal right conduction delay was present on the BSPM in 19 of the 24 patients (9 with additional left ventricular hypertrophy--left ventricular hypertrophy alone in 5). Right ventricular hypertrophy could be considered in 6 of 19 patients in the electrocardiogram, and in 11 of 19 in the vectorcardiogram. The mechanism for the persistent electrocardiographic right ventricular hypertrophy is postulated to involve right ventricular hyperplasia in utero or in early neonatal life, which never disappears.
Adolescent↗
Electrocardiographic body surface potential mapping in the Wolff-Parkinson-White syndrome. Noninvasive determination of the ventricular insertion sites of accessory atrioventricular connections.
BACKGROUND: A reliable, noninvasive procedure to determine the location of accessory atrioventricular connections in patients with Wolff-Parkinson-White syndrome would add an important diagnostic tool to the clinical armamentarium. METHODS AND RESULTS: Body surface potential mapping (BSPM) using 180 electrodes in various-sized vests and displayed as a calibrated color map was used to determine the ventricular insertion site of the accessory atrioventricular (AV) connections in 34 patients with Wolff-Parkinson-White syndrome. Attempts were made to determine the 17 ventricular insertion sites described by Guiraudon et al. All 34 patients had an electrophysiologic study (EPS) at cardiac catheterization, and 18 had surgery so the ventricular insertion sites could be accurately located using EPS at surgery. A number of physiologic observations were also made with BSPM. CONCLUSIONS: The following conclusions were drawn: 1) BSPM using QRS analysis accurately predicts the ventricular insertion site of accessory AV connections in the presence of a delta wave in the electrocardiogram; 2) the ventricular insertion sites of accessory AV connections determined by BSPM and by EPS at surgery were identical or within one mapping site (1.5 cm or less) in all but four of 18 cases; three of the four exceptions had more than one accessory AV connection, and the other had a very broad ventricular insertion; 3) BSPM and EPS locations of the accessory AV connections correlated very well in the 34 cases despite the fact that BSPM determines the ventricular insertion site and EPS determines the atrial insertion site of the accessory AV connection; 4) as suggested by the three cases of multiple accessory AV connections, EPS and BSPM may be complementary since BSPM identified one pathway and EPS identified the other (in the case with a broad ventricular insertion, BSPM and EPS demonstrated different proportions of that insertion); 5) BSPM using ST-T analysis is very much less accurate in predicting the ventricular insertion site of accessory AV connections unless there is marked preexcitation; 6) standard electrocardiography using the Gallagher grid methodology (but with no attempt at stimulating maximal preexcitation) was not as accurate as QRS analysis of BSPM in predicting the ventricular insertion site of the accessory AV connection; however, exact comparison is hampered by the different number and size of the Gallagher and Guiraudon insertion sites; 7) BSPM using QRS analysis appears to be very accurate in predicting right ventricular versus left ventricular posteroseptal accessory AV connections; 8) typical epicardial right ventricular breakthrough, indicative of conduction via the specialized AV conduction system, occurs in all patients with left ventricular free wall accessory AV connections; 9) epicardial right ventricular breakthrough was not observed in cases with right ventricular free wall or anteroseptal accessory AV connections; 10) epicardial right ventricular breakthrough can occur in the presence of posteroseptal accessory AV connections, whether right or left ventricular; and 11) the delay in epicardial right ventricular breakthrough in cases with left ventricular insertion may provide a marker to estimate the degree of ventricular preexcitation.
Adult↗
Identification of best electrocardiographic leads for diagnosing left ventricular hypertrophy by statistical analysis of body surface potential maps.
In view of the increased risk of cardiovascular mortality associated with left ventricular (LV) hypertrophy, early recognition and quantitation of LV hypertrophy are important clinical goals. The standard 12-lead electrocardiogram is the easiest and most widely used noninvasive method for the diagnosis of LV hypertrophy; unfortunately, the diagnostic accuracy of commonly used electrocardiographic criteria remains unsatisfactory. Body surface potential maps contain diagnostic information not present in conventional lead systems. The present investigation combines the increased information content of surface maps with the power of multivariate statistical techniques in order to identify practical subsets of electrocardiographic leads that would allow improved diagnosis of LV hypertrophy. Discriminant analysis was performed on 120-lead data simultaneously recorded in 250 normal subjects and 214 patients with LV hypertrophy using as features instantaneous voltages on time-normalized P, PR, QRS and ST-T waveforms as well as the duration of these waveforms. Leads and features for optimal separation of 173 normal subjects aged greater than or equal to 30 years from 122 patients with pure LV hypertrophy were selected. A total of 6 features from 5 torso sites accounted for a specificity of 97% and a sensitivity of 94%. The single most potent discriminator was the duration of the P wave; voltages were measured in mid and late P on leads located in the lower left parasternal area, the left precordial region and the upper right back, in mid-QRS on a lead positioned 10 cm below V1 and slightly before the peak of the T wave on a lead in the lower left flank.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Identification of first acute Q wave and non-Q wave myocardial infarction by multivariate analysis of body surface potential maps.
BACKGROUND: Patients with acute non-Q wave myocardial infarction (NQMI) appear to have more jeopardized residual myocardium at high risk for subsequent angina, reinfarction, or malignant arrhythmias than patients with acute Q wave myocardial infarction (QMI). Unfortunately, conventional electrocardiographic (ECG) criteria have limited utility in recognizing NQMI. METHODS AND RESULTS: The present study combines the increased information content of body surface potential maps (BSPM) over the 12-lead ECG with the power of multivariate statistical procedures to identify a practical subset of leads that would allow improved diagnosis of NQMI. Discriminant analysis was performed on 120-lead data recorded simultaneously in 159 normal subjects and 308 patients with various types of myocardial infarction (MI) by using instantaneous voltages on time-normalized P, PR, QRS, and ST-T waveforms as well as the duration of these waveforms as features. Leads and features for optimal separation of 159 normals from 183 patients with recent or old QMI (group A) were selected. A total of six features from six torso sites accounted for a specificity of 96% and a sensitivity of 94%. All lead positions were outside the conventional electrode sites and selected features were voltages at mid-P, early and mid-QRS, and before and after the peak of the T wave. The discriminant function was then tested on 57 patients with acute NQMI (group B) and 68 patients with acute QMI (group C): Rates of correct classification were 91% and 93%, respectively. Because of the possible deterioration of the results caused by ST-T abnormalities also present in other clinical entities, a second classification model including an independent group of 116 patients with left ventricular hypertrophy (LVH) but without MI was developed. Two additional measurements were required, namely, P wave duration and a mid-QRS voltage on a lead located 10 cm below V1. Testing the model on both acute MI groups produced correct classification rates of 88% for acute NQMI and 93% for acute QMI. Group mean BSPM were plotted for the three MI groups at successive instants throughout the PQRST waveform. Typical patterns for each MI group were identified during PQRST by removing the corresponding normal variability at each electrode site from sequential MI maps. These standardized maps or discriminant maps provided information on the capability of each measurement at each electrode site and at each instant to separate each class of MI from the normal group (N). Striking similarities were observed between the three MI groups, particularly at mid-QRS and throughout ST-T. The closest resemblance was between acute NQMI and old QMI. Discriminant analysis was also performed on the 12-lead ECG: The first classification model (N versus MI) produced correct classification rates of 85% for acute QMI and 70% for NQMI. With the second model (MI versus N or LVH), correct rates were 81% and 65%, respectively. CONCLUSIONS: Diagnosis of acute NQMI and QMI (also in the presence of LVH) can be improved substantially by appropriate selection of ECG leads and features. Comparison of discriminant maps from groups A, B, and C does not support the concept of acute NQMI as a distinct ECG entity but rather as a group with infarcts of smaller size. However, pathophysiological and clinical differences between acute NQMI and acute QMI influence long-term risks and may define different therapeutic approaches.
Adult↗
Fine detail in body surface potential maps: accuracy of maps using a limited lead array and spatial and temporal data representation.
In order to evaluate the accuracy with which a limited lead array can be used to estimate fine details of the thoracic distribution of cardiac potentials, we compared 192-lead body surface maps and those constructed using a subset of 32 leads. We also evaluated preservation of detail in body surface maps reconstructed following spatial and temporal data representation, a method proposed for quantitative comparison of maps. Maps were analyzed with respect to four previously reported normal map features recorded with extensive lead arrays. The maps constructed from 32 leads accurately reproduced all map features with 92% or greater accuracy. Maps constructed after spatial and temporal data representation had a reproduction accuracy of 93% and 98% respectively for two map features more than 100 microV in amplitude but accuracy with respect to the two map features less than 100 microV in amplitude was 86% and 59% respectively. The study demonstrates that a selected limited lead array permits accurate estimation of the body surface distribution of cardiac potentials even when potentials are low level or occur in regions not directly sampled by a recording electrode. To represent potentials of less than 100 microV, more coefficients would be required to permit accurate spatial and temporal representation.
Electrocardiography↗
Diagnostic features of body surface potential maps in patients with myocardial ischemia and normal resting 12-lead electrocardiograms.
Body surface maps recorded from 35 ischemic patients with normal resting 12-lead electrocardiograms were compared with those obtained from 36 age- and sex-matched normal subjects. From instantaneous maps of each subject 187 variables were derived relating to the configuration (80 variables) and magnitude (104 variables) of the potential distribution and duration of the electrocardiographic intervals (3 variables). By using stepwise discriminant analysis we selected 3 variables whose linear combination enabled us to correctly allocate 91% of the study population (jacknife procedure; specificity 92%, sensitivity 91%). To substantiate the validity of the results the discriminant function was tested on a new independent population consisting of 27 ischemic patients and 54 normal subjects from another laboratory. A proper allocation was obtained in 86% of the cases (specificity 87%, sensitivity 85%). The large number of correctly classified ischemic patients and the repeatability of the results indicate that the adopted criteria are good markers of ischemic heart disease.
Adult↗
Body surface potential mapping: historical background, present possibilities, diagnostic challenges.
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Animals↗
Sample size and dimensionality in multivariate classification: implications for body surface potential mapping.
This paper presents empirically determined guidelines for specifying the number of features appropriate for multivariate classification studies for given sample sizes. Sample size was considered adequate if the mean distance between two sample sets, taken from the same continuous multivariate distribution and projected onto the best separating direction, remained below a prescribed level. To quantitate the sample size requirement, homogeneity of sample set pairs of equal size. N, taken from the same continuous multivariate distribution was studied as a function of dimensionality. M. Homogeneity was characterized by the maximum absolute distances (Dmax) between the corresponding pairs of empirical cumulative probability distributions on the best separating projection. Computer generated data sets were used to estimate the cumulative probability distribution, P(D)M.N, for sample sizes, N, ranging from 5 to 100 and the dimensionality, M, ranging from 1 to 4. An empirical relationship between the estimated step-polygons and the Kolmogorov type one dimensional limiting distribution L(z) has been established. Based on the sample size data of 34 key papers on clinical body surface potential mapping (BSPM) it is noted that in 30% of the cases only one, and in 6% of the cases only two parameters could be used for statistical group representation to ensure a reasonable reliability (Dmax less than 0.2). In 56% of the published cases the sample sizes could not guarantee this reliability even for one feature or parameter.
Computer Simulation↗
Extraction of intrinsic timing features of cardiac activation from body surface potential maps.
According to previous modeling studies--propagation of depolarizing wave fronts--consists of subintervals, each characterized by a smooth progression of waves through the myocardium. At the onset and end of these intervals, abrupt changes occur in the 3D pattern of activation waves (e.g. at the time of the collision of activation waves with other waves, obstacles or unexcitable myocardium and epicardial breakthrough), which manifest themselves in the surface ECG as "jumps" (high frequency notches and slurs). The timing of jumps provides diagnostic information on bioelectrical tissue properties of the heart. Findings of this study validated previous simulation results. Furthermore, essential signal processing requirements were formulated for a high-resolution body surface potential mapping technology.
Action Potentials↗
Body surface potential mapping of ST segment changes in acute myocardial infarction. Implications for ECG enrollment criteria for thrombolytic therapy.
BACKGROUND: Several large, randomized clinical trials have shown that early thrombolytic therapy substantially reduces early mortality after acute myocardial infarction (MI). In most trials, eligibility criteria include typical chest pain and diagnostic ST segment elevation in two or more contiguous leads of the standard 12-lead ECG. Unfortunately, large areas of the thoracic surface are left unexplored by the standard electrode positions. As a consequence, acute MI patients with ST elevation in regions not interrogated by the conventional electrodes may not receive reperfusion therapy and its attendant benefits. METHODS AND RESULTS: The present study compares 120-lead body surface potential map (BSPM) data from 131 patients with acute MI and 159 normal control subjects (N). The MI population was stratified according to the location of ventricular wall motion abnormalities evidenced by radionuclide imaging into 76 patients with anterior MI (AMI), 32 patients with inferior MI (IMI), and 23 patients with posterior MI (PMI). BSPM were recorded within 24 hours of admission. Group mean BSPM of the ST segment were obtained for N, AMI, IMI, and PMI by sampling the time-normalized ST-T waveform at 18 equal intervals and averaging the voltages at each electrode site over the first five of these 18 ST-T time instants. Corresponding discriminant maps were also computed for each pairwise comparison (AMI versus N, IMI versus N, and PMI versus N) by subtracting the normal group mean voltages from each MI group mean voltages and by further dividing each resulting difference by the composite standard deviation calculated from the pooled groups. Discriminant analysis for each bigroup classification was also performed using as measurements the ST magnitudes in 120 electrode sites from each individual. Finally, the number of patients in each MI group with ST changes outside the 95% normal range was calculated for each electrode position. The following results were obtained: 1) In each MI group, ST depression departs more significantly from normal values than ST elevation. 2) The most significant ST changes (both ST elevation and ST depression) are observed in IMI, the least significant in AMI. 3) For each pairwise comparison, measurements from two lead sites are entered into the stepwise discriminant procedure: the first measurement is ST depression, the second ST elevation. Classification rates are 82% for AMI, 93% for PMI, and 100% for IMI at a specificity level of 95%. 4) From the six leads selected for optimal classification of the three MI groups, five are outside the area sampled by the conventional precordial electrodes. 5) The use of site-dependent thresholds for ST measurements based on 95% normal range yields the best compromise between sensitivity and specificity. A fixed threshold of 1 mm for ST elevation or ST depression produces increased sensitivity in AMI at the cost of marked loss in specificity and reduces sensitivity in both IMI and PMI with no benefit in specificity. CONCLUSIONS: Analysis of BSPM identifies areas on the torso where the most significant ST changes most frequently occur in acute MI. Two leads from areas with the most abnormal ST changes achieve optimal classification in each MI class. Of these six leads, five are outside the standard precordial lead positions. ST depression is the most potent discriminator for each MI group and contains information independent from ST elevation. Quantitative analysis of ST magnitude at each electrode site allows determination of best thresholds for ECG criteria. Appropriate selection of ECG leads may help remove inconsistencies in current ECG selection criteria and improve comparability of treatment results.
Adult↗
Usefulness of body surface potential mapping for clinical diagnosis and research.
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Body Surface Area↗
Body surface potential mapping improves detection of ST segment alteration during percutaneous coronary intervention.
BACKGROUND: The 12-lead electrocardiogram underestimates ST segment alteration in acute coronary syndromes compared with multi-lead body surface mapping. We assessed whether 80-lead mapping would improve detection of ST alteration during percutaneous coronary intervention. METHODS: Simultaneous maps and 12-lead electrocardiograms were recorded pre-procedure, during balloon inflation and post-procedure from patients undergoing elective intervention to native coronary arteries. Recordings were obtained from 39 inflations (19 patients). All arteries were successfully stented. RESULTS: Mean 'lead specific' ST alteration (the difference in ST elevation/depression between pre-procedure and inflation recordings in the lead showing maximal ST alteration) was greater on the map than on electrocardiogram, both for ST elevation (0.16+/-0.02 vs. 0.06+/-0.01 mV; p<0.001) and ST depression (0.11+/-0.017 vs. -0.03+/-0.006 mV; p<0.001). During first inflations (n=19), mean lead specific ST elevation and depression on map were greater than on electrocardiogram (0.20+/-0.034 vs. 0.07+/-0.015 mV; p<0.001 and 0.11+/-0.029 vs. 0.03+/-0.009 mV; p=0.001, respectively). Mapping detected greater summated ST elevation and depression during inflation than electrocardiogram (0.04+/-0.005 vs. 0.021+/-0.003 mV; p<0.001 and 0.026+/-0.004 vs. 0.011+/-0.002 mV; p<0.001, respectively). Qualitative analysis of maps and electrocardiograms showed that 21/39 (53.8%) maps recorded during inflation met criteria for myocardial ischaemia compared with 7/39 (17.9%) electrocardiograms (p<0.001). CONCLUSION: Body surface mapping compared with the 12-lead electrocardiogram improves detection of myocardial ischaemia during intervention.
Angioplasty, Balloon, Coronary↗
Body surface potential mapping in ischemic patients with normal resting ECG.
Patients with ischemic heart disease frequently have a normal 12-lead electrocardiogram. We recorded body surface maps from 14 ischemic patients with normal (group A) and 5 with abnormal (group B) resting electrocardiograms. ST-T map data were compared with those of 36 normal subjects. In ischemic patients the following abnormalities were found: an anomalous location and/or trajectory of the potential minimum (lowest potential) on the chest in some; in others the instantaneous values of the time functions: Mxi (highest potential on the chest), delta Vi (highest potential difference) and integral of s/Vi/dS (integral of the absolute value of the potential function extended to the entire chest surface) were lower. In some ischemic patients, both abnormalities were observed. All changes were detectable during the first 200 msec of ST-T. The anomalous potential patterns were similar in group A and B patients, suggesting an ischemic origin of group A abnormalities. By submitting 10 properly selected variables, obtained from body surface maps, to Fisher's discriminant analysis, we succeeded in correctly classifying more than 90% of the cases. The efficacy of the method was validated by using one third of the cases as a test set, with correct allocation in 80.9% of the cases. We conclude that body surface maps at rest can reveal an altered cardiac electrogenesis induced by myocardial ischemia, not apparent in the 12-lead electrocardiogram.
Action Potentials↗