Multivariate analysis of body surface potential maps in left ventricular hypertrophy

Discriminant analysis was performed on ECG data simultaneously recorded using 120 leads for 250 normal subjects and 214 patients with left ventricular hypertrophy (LVH). Instantaneous voltages on time-normalized P, PR, QRS, and ST-T waveforms as well as the durations of these waveforms were used as features. A total of six features from five 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, in mid QRS, and slightly before the peak of the T wave. The optimal sites for LVH diagnosis were in general outside the conventional ECG lead locations. In comparison, multivariate analysis on the standard 12 leads correctly classified 86% of pure LVH patients and 83% of complicated LVH cases at specificity rates of 94% and 93%, respectively.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Multigroup diagnosis of body surface potential maps

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Diagnostic body surface potential map patterns in left ventricular hypertrophy during PQRST

Body surface potential maps were recorded from 117 thoracic sites and 3 limb electrodes in 173 normal subjects older than 30 years of age and 122 patients with clinically "pure" left ventricular (LV) hypertrophy. Typical LV hypertrophy map patterns were identified at successive instants during the PQRST waveform by removing from sequential LV hypertrophy maps the corresponding normal variability range at each electrode site. The presence in individual patients of 1 or more patterns typical in time and location of LV hypertrophy allowed retrospective assignment to the LV hypertrophy group. The most consistent discriminant patterns were excessive negative voltages in the anterior torso with reciprocal excess of positive voltages in the upper right chest during the second half of the P wave, excessive negative voltages in the lower right anterior torso at mid-QRS and excessive negative voltages in the left precordium with reciprocal excess of positive voltages in the upper right chest throughout ST-T. Best classification results were achieved with ST-T features, followed by features from the P wave, the QRS waveform and the PR segment. Cumulative use of ST-T and P features yielded a specificity of 94% with a sensitivity of 88%. Little improvement was obtained by the addition of QRS and PR information. The discriminant map criteria were applied to body surface potential maps from 169 new subjects (77 normal subjects ages 20 to 30 years and 92 patients with complicated LV hypertrophy). Little modification in specificity (93%) and sensitivity (90%) was observed. The performance of commonly used standard lead criteria was also tested. The Sokoloff-Lyon criterion and the Romhilt-Estes point score produced specificities of 82 and 97%, respectively, with sensitivities of 55 and 64%. The recently described Cornell voltage criteria achieved a specificity of 83% and a sensitivity of 72%. © 1989.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Identification of best electrocardiographic leads for diagnosing anterior and inferior myocardial infarction by statistical analysis of body surface potential maps

In view of the increasing interest in quantifying and modifying the size of myocardial infarction (MI), it is important to look for clinically practical subsets of electrocardiographic leads that allow the earliest and most accurate diagnosis of the presence and electrocardiographic type of MI. A practical approach is described, taking advantage of the increased information content of body surface potential maps over standard electrocardiographic techniques for facilitating clinical use of body surface potential maps for such a purpose. Multivariate analysis was performed on 120-lead electrocardiographic data, simultaneously recorded in 236 normal subjects, 114 patients with anterior MI and 144 patients with inferior MI, using as features instantaneous voltages on time-normalized QRS and ST-T waveforms. Leads and features for optimal separation of normal subjects from, respectively, anterior MI and inferior MI patients were selected. Features measured on leads originating from the upper left precordial area, lower midthoracic region and the back correctly identified 97% of anterior MI patients, with a specificity of 95%; in patients with inferior MI, features obtained from leads located in the lower left back, left leg, right subclavicular area, upper dorsal region and lower right chest correctly classified 94% of the group, with specificity kept at 95%. Most features were measured in early and mid-QRS, although very potent discriminators were found in the late portion of the T wave. Repeatability of the results was investigated by separating the study population in training and testing sets; no deterioration was observed when the discriminant functions computed on the training sets were run on the testing sets. In comparison, at the same level of specificity and with the same number of features (n = 6), the standard 12-lead electrocardiogram correctly diagnosed 89% of anterior MI and 85% of inferior MI patients. Thus, diagnosis of anterior and inferior MI can be substantially improved by appropriate selection of electrocardiographic leads and features. © 1986.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

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 bigroup 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 Ml, 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. Abnormal negative voltages were seen in the precordial region during ST in the inferior MI group, moving toward the lower left flank where they stayed throughout T; in the anterior MI group abnormal negativities appeared in the precordial area at the beginning of T and remained there until the end of repolarization. Intragroup variability was investigated by producing scattergrams of extrema and of abnormal peak discriminant indexes (≥2 standard deviations) derived from individual patients within each population. The presence of electrocardiographic subgroups was suggested for both classes of infarction: anterior MI with or without apical involvement in the anterior group and inferior-posterior MI with or without right ventricular involvement and with or without apical extension in the inferior group. Thus, both types of infarction share a temporally common but spatially discriminating portion of the early QRS. Repolarization patterns in both infarction groups were also spatially discriminant from normal subjects, but temporally heterogeneous one from the other. Retrospective classification of patients based on the presence of one or more patterns typical in time and in location of their respective groups yielded 96% and 93% of correct assignment to the anterior MI and the inferior MI classes, respectively. The specificity was 94% for normal control subjects. © 1987.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Typical body surface potential map patterns in anterior and inferior myocardial infarction

Body surface potential maps were recorded from 120 electrode sites in 236 normals (N), 114 patients with anterior MI (AMI) and 144 patients with inferior MI (IMI). At each time instant, the group-mean N map was subtracted in turn from the corresponding AMI and IMI maps; the resulting differences at each electrode site were standardized, producing discriminant maps for each bi-group comparison. Classification of patients based on the presence of one or more patterns typical in time and in location of their respective groups yielded 96% and 93% of correct assignment to AMI and IMI, respectively. Specificity was 94%.SCOPUS: cp.pinfo:eu-repo/semantics/publishe