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Biomedical subjects

R H Selvester

Publications and source records attributed to R H Selvester.

At least 37 records · Page 2Linked to original sources
PubMed1995

Estimates of myocardium at risk and collateral flow in acute myocardial infarction using electrocardiographic indexes with comparison to radionuclide and angiographic measures.

OBJECTIVES: This study sought to determine the accuracy of the initial 12-lead electrocardiogram (ECG) in predicting final infarct size after direct coronary angioplasty for myocardial infarction and to examine which physiologic variables known to be determinants of outcome the ST segment changes most closely reflect. BACKGROUND: Myocardium at risk, collateral flow and time to reperfusion have been shown to be independent physiologic predictors of infarct size in animal and clinical models. However, such measurements may be difficult to perform on a routine basis in patients with myocardial infarction. The standard 12-lead ECG is inexpensive and readily available. METHODS: Sixty-seven patients with acute myocardial infarction, ST segment elevation and duration of chest pain < 12 h had an initial injection of technetium-99m sestamibi. Tomographic imaging was performed 1 to 8 h later (after direct coronary angioplasty), and the images were quantified to measure perfusion defect size (myocardium at risk) and severity (a measure of collateral flow). Contrast agent injection and tomographic acquisition were repeated at hospital discharge to measure infarct size. The ST segment elevation score was calculated for each patient according to infarct location and using previously described formulas. RESULTS: ST segment elevation score correlated closest with the radionuclide measure of collateral flow (r = -0.44, p < or = 0.0001), as well as an angiographic measure of collateral flow (r = -0.38, p = 0.05). Although ST segment elevation score correlated weakly with the magnitude of myocardium at risk by technetium-99m sestamibi, it was not as strong as infarct location alone in predicting myocardium at risk ([mean +/- SD] anterior 51 +/- 13% left ventricle vs. inferior 17 +/- 10% left ventricle, p < 0.0001). ST segment elevation score was weakly associated with final infarct size (r = 0.34, p = 0.005). A multivariate ECG model was constructed with infarct location as a surrogate for myocardium at risk, ST segment elevation score as a surrogate for estimated collateral flow, and elapsed time to reperfusion from onset of chest pain. All three variables were independently associated with infarct size. CONCLUSIONS: The initial standard 12-lead ECG can provide insight into myocardium at risk and, to a greater extent, collateral flow and can consequently provide some estimate of subsequent infarct size. However, the confidence limits for such predictors are wide.

Adult↗
PubMed1995

T wave amplitudes in normal populations. Variation with ECG lead, sex, and age.

Consideration of increased T wave amplitude (tall T waves), either alone or in association with other electrocardiographic (ECG) parameters, may be beneficial for the early detection of acute transmural ischemia, and quantification of the increase might be used in quantifying the ischemic area. The primary purpose of this study was to quantify normal T wave amplitude limits according to ECG lead, sex, and age. One thousand nine hundred thirty-five subjects in two normal populations were analyzed, and the 98th percentile of the positive T wave amplitude for each ECG lead (including -aVR) was considered the upper limit of normal. Normal T wave amplitude was two times greater in the precordial than in the limb leads, and it was approximately 25% greater in men than in women in all leads. There was approximately a 10% decrease in normal T wave amplitude between 18-39- and 40-59-year-old patients and a 15% decrease between 40-59- and 60-79-year-old patients. The upper limit of normal T wave amplitudes identified in this study confirm those developed by Lepeschkin for use as means for each lead when age and sex are not considered. These limits might be incorporated into both normograms and automated ECG analysis systems to determine the presence or absence of tall T waves in patients presenting with symptoms of acute transmural ischemia.

Adolescent↗
PubMed1995

Evolution of electrocardiographic and echocardiographic abnormalities during the 4 years following first acute myocardial infarction.

Therapies aimed at salvaging jeopardized myocardium in patients with acute myocardial infarction (MI) are now routine. The success of these therapies must often be estimated by non-invasive tests, such as the 12-lead electrocardiogram (ECG) or two-dimensional echocardiography. To monitor QRS changes and left ventricular (LV) function over time in patients who have received therapies aimed at myocardial salvage, it is important to know the 'spontaneous' evolution of these estimates. Consecutive MI survivors admitted in the pre-thrombolytic era with their first MI were re-studied at 4 years. Patients were excluded if they had experienced reinfarction, coronary revascularization or bundle branch block in the acute or follow-up period. A standard ECG and a two-dimensional echocardiogram were obtained prior to discharge and at follow-up. The quantitative ECG analysis was performed according to the Selvester QRS scoring method. During the two-dimensional echocardiogram each of the 20 segments of the LV were assessed to provide a wall motion score. Eighty patients with a median age of 64 years (range 40-79) were included in the study. Thirty-two had anterior and 48 inferior MI. A significant decrement in median QRS score-estimated AMI size occurred between pre-discharge and follow-up ECGs in the entire group (18.3% vs 10.5%; P<0.0001). This difference occurred in both anterior (21.6% vs 10.5%; P<0.0001) and inferior-posterior (16.5 vs 10.5%; P<0.0001) MI locations. In the anterior MI group ther was a trend towards a greater total decrease of QRS points than in the inferior-posterior MI group (42% vs 27%; P=0.10). Within the anterior MI group, more QRS points awarded in the anteroseptal leads (V1-V3) remained follow-up than in the anterosuperior and apical leads (I, aVL and V4-V6), (80% vs 49%; P=0,03).

Adult↗
PubMed1994

Panoramic display of the orderly sequenced 12-lead ECG.

The standard 12-lead electrocardiogram (ECG) has been developed over many years. The ECG has had a long and successful history of providing diagnostic information in clinical medicine. Cardiac arrhythmias have been elucidated by deductive reasoning from continuous ECG recordings with confirmation from electrophysiologic studies. Recently, there has been renewed interest in the morphology of the QRS complex, ST-segment, and T wave, which raises the important question of considering whether the usual method of display provides maximal diagnostic capabilities. The conventional display provides a logical visualization of precordial lead recordings representing the horizontal plane, but does not provide a logical visualization of the limb lead recordings representing the frontal plane. Many clinical problems require the consideration of serial ECGs necessitating the comparison of separate pages. An alternate format presenting serial recordings on a single page would be advantageous. Some automated ECG analysis systems already include the capability for multiple display formats, but these have not yet been widely used in clinical practice. This point of view paper introduces a new display format for the standard 12-lead ECG that includes: (1) a presentation of an orderly sequence of leads to facilitate scanning through different points in space and (2) a presentation of recordings of 12-lead sequences to facilitate scanning through different points in time. This display format could either replace or supplement the conventional ECG format.

Arrhythmias, Cardiac↗
PubMed1994

ECG myocardial infarct size: a gender-, age-, race-insensitive 12-segment multiple regression model. I: Retrospective learning set of 100 pathoanatomic infarcts and 229 normal control subjects.

In this early study of ongoing work with multiple regression modeling for mapping myocardial infarct (MI) into 12 left ventricular (LV) segments, promising results have been presented using electrocardiographic (ECG) QRS variables that are gender, age, and race insensitive (GARI), the GARI-QRS 12-segment multiple regression model. These include Q, R, and S duration, expressed as percentage total QRS duration, and R/Q duration, R/Q amplitude, R/S duration, and R/S amplitude variables. For version I, building 12 regression models using 68 single and 32 multiple MIs, the GARI-QRS variables correlated with pathoanatomic MI in each of 12 segments with r values ranging from .67 to .88. In version II of the model, using all MIs and 229 normal subjects, r = .73-.91. Version II predictions of MI in 12 LV segments for each subject were used to calculate the predicted total percentage LV infarct, which correlated well with that found at autopsy. The r values found were .81 for all single MIs, .73 for multiple MIs, and .80 for all MIs taken together. With refinements of the input ECG variables to include (1) improvement in the GARI-QRS variables, (2) adding a significant number of subjects with hypertrophies and conduction defects with and without MI to an expanded learning set, and (3) applying the enhanced 12-LV-segment regression models to a similar test set, it is to be expected that these regression models can be improved even further in such a way as to be applicable to general clinical populations using routine computerized ECG analysis programs.

Adult↗
PubMed1994

QRST changes during and after percutaneous transluminal coronary angioplasty.

This study reports preliminary results on 45 patients who underwent percutaneous transluminal coronary angioplasty (PTCA); 120-lead data (including the 12-lead standard electrocardiogram [ECG]) were recorded before, during, and after balloon inflation. Twenty-one patients underwent PTCA for left anterior descending coronary disease, 13 for right coronary artery disease, and 10 for left circumflex; 1 patient had combined left anterior descending and right coronary artery disease. In each patient, voltage data recorded during the various phases of the procedure were compared with the patient's own baseline data. In 18 patients, 120 leads were also recorded 24 hours after PTCA. In this study, the usefulness of the standard 12-lead ECG was investigated in locating the coronary artery being occluded, in elucidating the mechanisms of the QRS changes, and in identifying changes occurring 24 hours after completion of the procedure. Results indicate that the observation of ST elevation in the 12-lead ECG may lead to ambiguous interpretation. Also, limiting observation to ST-T patterns alone instead of including QRS changes further hampers correct identification of the involved vessel. QRS modifications during inflation are interpreted as conduction disturbances, although other mechanisms are evoked: study of surface maps may contribute to the understanding of these mechanisms. Changes present 24 hours later are visible in the standard leads, but again, in the absence of the thoracic potential distribution, these are difficult to interpret. These changes were different from those observed after cessation of inflation at the end of the procedure. It is hypothesized that next-day changes may reflect reperfusion injury and/or represent myocardial stunning. Presence of injury and reversibility of changes require further investigation. Also, biochemical markers such as creatine kinase-MB mass, creatine kinase-MB activity, myoglobin, and troponin-T may help elucidate the significance of these findings.

Angioplasty, Balloon, Coronary↗
PubMed1993

The 12-lead ECG and the initiation of thrombolytic therapy for acute myocardial infarction.

Previous work has shown that the ST-segment of acute myocardial infarction (MI) on the admitting electrocardiogram (or vectorcardiogram) is predictive of the final predischarge QRS score (or loss of QRS spatial vector magnitude), in terms of MI size, ejection fraction, acute MI mortality, and prognosis. Patients in the GISSI I randomized multicenter trial were risk stratified by the ECG. The relative risk (RR) of mortality in the group treated with thrombolytic therapy compared to control subjects was as follows: anterior, 0.75; inferior, 0.94; multiple, 0.61; lateral, 1.22; and prior MI 1.03, thus, indicating subsets with no benefit from thrombolysis (RR > or = 1). The RR was also 1.00 in an overlapping group of 3,539 out of 11,712 patients (30%) with ST elevation limited to two or three leads, indicating a final MI size < 10% of the left ventricle. A similar RR was demonstrated in the European Cooperative Group trial of recombinant tissue-type plasminogen activator. This study examines published data from two randomized control trials, ISIS II (n = 17,187) and GISSI II (n = 12,490), for evidence of a similar relationship. The known distribution of MI size, right ventricular infarction, and mortality data in each electrocardiographic trial subset was used to develop a risk predictive model for RR as a function of the initial ST-segment predicted MI size in each location. This further subsetting of the data revealed that 37%, that is, over 10,000 patients, in these two large trials, who did not have a prior MI or evidence of right ventricular infarction, had small MIs.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗
PubMed1992

Correlation of the complete version of the Selvester QRS scoring system with quantitative anatomic findings for multiple left ventricular myocardial infarcts.

The correlation between myocardial infarct size estimated by the complete version of the Selvester QRS scoring system and that documented by pathoanatomic studies has been reported for single anterior, inferior and posterolateral infarcts. Although previous studies described electrocardiographic changes in patients with multiple infarcts, no quantitative documentation of the ability of such changes to estimate the total amount of left ventricular infarction has been reported. This study of 32 patients with anatomically documented multiple infarcts shows a significant correlation between QRS-estimated and anatomically documented sizes (r = 0.44; p = 0.01), which is less than that previously reported for single infarcts in the anterior, inferior and posterolateral locations. Several of the 54 electrocardiographic criteria were never satisfied. Criteria for posterior infarction were seldom present, suggesting "cancellation effect" of coexisting anterior infarction. These results will be the basis for future modification of QRS criteria for estimating myocardial infarct size.

Adult↗
PubMed1992

Evaluation of changes in standard electrocardiographic QRS waveforms recorded from activity-compatible proximal limb lead positions.

Proximal limb lead positions are currently used for activity-compatible electrocardiographic monitoring of myocardial ischemia. Two previously described systems for alternate limb lead placement were studied in patients with and without QRS evidence of healed anterior or inferior myocardial infarction. An innovative method was used to simultaneously record 6 standard and 6 modified limb leads, and 3 standard and 3 modified precordial leads on a standard digital electrocardiograph. Both alternate lead placement systems showed rightward frontal plane axis shift and diminished Q-wave durations in lead aVF compared with those of their simultaneous standard controls. Furthermore, potential differences between the standard distal limb lead sites and 5 more proximal sites were explored along each limb. Differences along the left arm were accentuated relative to those along the right arm owing to differences in proximity of the arms to the myocardium. Along the lower limb, and anterior site showed less deviation from standard than did a more lateral site. It is imperative that recordings from alternate sites be labeled accordingly so that their output cannot be confused with that obtained from standard sites.

Arm↗
PubMed1992

Evaluation of a QRS scoring system for estimating myocardial infarct size. VIII. Specificity in a control group with left ventricular hypertrophy and proposal of a new scoring system for use with this confounding factor.

Electrocardiographic differentiation between left ventricular hypertrophy (LVH) and myocardial infarction (MI) is often difficult because both diagnoses are based primarily on QRS changes on the electrocardiogram (ECG). The specific goal of this study was the development of ECG criteria that could be used with the complete Selvester QRS scoring system for MI size in patients with LVH. A study population of 127 patients had significant aortic valve disease verified by cardiac catheterization. Inclusion in the study required no significant coronary artery disease, no focal contraction abnormality on the left ventriculogram, and no documented MI. Quantitative criteria for LVH developed by Bonner (IBM) and also those developed by the Cornell group were used to determine the ECG evidence for LVH in each patient. One or both sets of criteria were met in 110 (87%) of the 127 patients. This group was compared to a previously evaluated control population of 500 normal subjects. The complete 54-criteria, 32-point QRS MI size scoring system was applied to the 12-lead ECG of both groups. The score was 98% specific in the normal controls and 73% specific in the LVH group using a score of greater than 3 points as diagnostic for MI. Of the 54 individual QRS criteria, 16 failed to achieve 95% specificity in the LVH population: 13 were for anterior (and apical), 2 for inferior, and 1 for posterior locations. Of these 16, minor modifications to 11 were sufficient to achieve the 95% specificity standard.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomegaly↗
PubMed1992

Discriminant analysis of the standard 12-lead ECG for diagnosing non-Q wave myocardial infarction.

Discriminant analysis was performed on 12 standard lead data from 159 normal subjects (N) and 304 patients with first myocardial infarction (MI): the latter group consisted of 543 patients with acute non-Q wave MI (NQMI-group A), 68 patients with acute Q wave MI (QMI-group B) and 183 patients (group C) with recent (29) or old (154) QMI. A discriminant function was computed to separate optimally the larger group of QMI patients (group C) from N. A total of 7 features accounted for a specificity of 92% and a sensitivity of 89%. The classification model was then tested on patients with acute MI, regardless of the presence of Q waves (groups A and B); rates of correct classification were 72% for acute NQMI and 85% for acute QMI. The best measurements were voltages in the late portion of the T wave in aVR, V1 and V5, in early and late QRS in V2, at mid-QRS in lead II and in the second half of the P wave in V1. A weighted combination of these features with the coefficients of the discriminant function produced individual discriminant scores for each subject. Group-mean scores were 1.82 for N, -1.27 for acute QMI, -1.14 for old QMI and -.44 for acute NQMI, indicating that acute NQMI was "closer" to N than both acute and old QMI. QRS measurements from the 12-lead ECG were also used to derive the 45 criteria/33 point Selvester score in 53 patients with NQMI: 32% of NQMI were classified as MI with a score of 3 points or more (corresponding to a posterior probability greater than .50). These results were compared with those achieved by multivariate analysis using only QRS measurements: 56% of NQMI were classified as MI with a posterior probability threshold greater than .50. Associating a point score greater than or equal to 1 with criteria for ST-T abnormalities yielded a sensitivity of 72% at a specificity level of 95%. The results emphasize the presence of diagnostic information outside the initial part of QRS, the power of multivariate statistical procedures applied on continuous measurements and the potential benefit of discriminant scores for quantitative assessment of myocardial infarction.

Discriminant Analysis↗
PubMed1992

16-lead ECG changes with coronary angioplasty. Location of ST-T changes with balloon occlusion of five arterial perfusion beds.

Percutaneous transluminal coronary angioplasty (PTCA) occlusion in five individual coronary artery distributions produced significant ST elevation ("current of injury") in 48/50 PTCAs in 46 patients. Four patients had PTCA of two separate coronary arteries. Two patients had no significant ischemic ST changes in the 16 simultaneous lead ECG and no chest pain with PTCA. The six limb leads were recorded from Mason-Likar locations modified by moving them centrally on the anterior torso; the V leads were recorded in standard locations, except V1 was moved to V3R. Four extra leads were placed as follows: (1) left axilla, (2) left subcostal margin, (3) V8, and (4) midback at the level of V4-V8. The left axillary and back leads discriminated diagonal and left circumflex (LCX) PTCAs from the others and from each other. V6 showed ST elevation in all LCX PTCAs and in only 10% of left anterior descending occlusions. V3R showed ST elevation in 82% of right coronary PTCAs. In 48/50 (96%) of PTCA occlusions the ST elevation was localized to the torso locations defined in Forward Model Simulations as specific for the arterial perfusion bed involved. These data strongly support the hypothesis that additional resolution and sensitivity to ischemic change is to be expected with a broader array of ECG leads.

Angioplasty, Balloon, Coronary↗