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PubMed1996

Signal-averaged electrocardiography and echocardiography in the evaluation of myocardial involvement in progressive systemic sclerosis.

To assess the myocardial involvement in progressive systemic sclerosis we evaluated the presence of late potentials by signal-averaged electrocardiography (signal-averaged ECG) and the left ventricular function by M-mode, two dimensional and Doppler echocardiography. Fifteen outpatients, 7 with diffuse progressive systemic sclerosis and 8 with CREST syndrome variant, without clinical or electrocardiographic evidence of cardiac disease were studied and compared with 18 normal subjects. Late potentials occurred in 5 out of 15 progressive systemic sclerosis patients (33%) with a significant difference versus controls (P < 0.05) and were present only in the patients with diffuse progressive systemic sclerosis (P < or = 0.001 vs. controls). All progressive systemic sclerosis patients showed a normal left ventricular systolic function. Abnormal left ventricular filling was found in 9 progressive systemic sclerosis patients (5 with diffuse progressive systemic sclerosis and 4 with CREST). A more severe impairment of the mean values of diastolic function indexes was found in diffuse progressive systemic sclerosis than in CREST. In all diffuse progressive systemic sclerosis patients at least one method showed altered results, whereas half the CREST patients showed no pathological findings with both techniques. These results confirm a lower myocardial involvement in the CREST syndrome than in diffuse progressive systemic sclerosis and consequently this is probably related to a better prognosis.

Adult↗
PubMed1992

Does the heart electric activation split upon the infarcted area? An attempt at its detection by high-resolution electrocardiography.

Based on the presumption of the activation front splitting, the authors present their own proposal for the estimation of the myocardial electric activation course and for the detection of micropotentials 'hidden' within QRS complexes by the method of high-resolution electrocardiography. After filtration of QRS complex the values of delta RMS and those of cumulative amplitudes are calculated from the initial and from the terminal parts of QRS complexes. The presence of late potentials is reflected in a slowing down of the termination of activation course. As compared with healthy subjects, a slower rise of activation was observed in patients with myocardial infarction of the anterior wall. The curves of cumulative amplitudes rose very slowly during the first 70 ms of heart ventricle activation, explained according to the hypothesis of authors as being due to splitting of the activation front at the infarction focus. The usefulness of the proposed method was checked in patients with arterial hypertension and left ventricular hypertrophy, and in a group of patients with myocardial infarction. By the construction of cumulative amplitude curves from the onset of filtered QRS complexes, myocardial foci not reflected by 'classic' late potentials can be detected. The partial cumulative amplitudes of the QRS complex are suitable for comparative studies.

Adolescent↗
PubMed1981

Dynamic electrocardiography. III. The "imaginary cardiac vector" hypothesis: theoretical basis.

The "imaginary cardiac vector" hypothesis states that the "cardiac vector" is not a "real" vector entity. The hypothesis arises from the fact that voltage is not a vector but a scalar quantity. Nevertheless, in classical electrocardiographic analysis and teaching, the ECG voltage is treated as a vector. These voltages are used as "vector" components--first, to calculate a "resultant manifest potential difference", represented by the "cardiac vector" arrow in electrocardiography, and second, to draw the "cardiac vector" loop in vectorcardiography. The resultant "cardiac vector" is usually considered to be a "real" vector quantity describing the electrical activity of the heart. It is also widely believed that this "vector" was first described by Einthoven in 1913. To evaluate the hypothesis, we have utilised the actual values and methods presented by Einthoven, and demonstrated that the theoretical basis of the "cardiac vector" is false. It appears that Einthoven followed scalar and not vector procedures and that he did not describe a vector.

Electrocardiography↗
PubMed1989

Significance of signal-averaged electrocardiography in relation to endomyocardial biopsy and ventricular stimulation studies in patients with ventricular tachycardia without clinically apparent heart disease.

Signal-averaged electrocardiography (ECG) was performed in 38 patients (mean age 38 years, range 15 to 70) with ventricular tachycardia who had no clinical evidence of structural heart disease. Spontaneous ventricular tachycardia was nonsustained in 23 patients and sustained in 15. None of the patients had symptoms of heart failure or ischemic heart disease, and at cardiac catheterization none had significant coronary artery disease or left ventricular wall motion abnormalities. In addition, all patients underwent left and right ventricular endomyocardial biopsy and ventricular stimulation studies. Signal-averaged ECG was performed and late QRS potentials were defined with use of Simson's method. Late QRS potentials were detected in a minority (18%) of patients including 2 of 23 with nonsustained and 5 of 15 with sustained (p = NS) ventricular tachycardia. Fifteen patients (40%) had abnormal endomyocardial biopsy results and these findings were more common in patients with sustained than in those with nonsustained ventricular tachycardia (9 of 15 versus 6 of 23, p less than 0.05). Late potentials were associated with abnormal endomyocardial biopsy findings (6 of 15 versus 1 of 23, p less than 0.01). An increase in fibrous tissue was the most frequent histopathologic abnormality; this increase was quantified by morphometric methods and compared with biopsy findings in normal control subjects. In the control group the proportion of collagen in relation to myocytes was less than 10%. All patients with both late potentials and abnormal biopsy findings had a greater than 15% ratio of collagen to myocytes in at least one specimen and the biopsies revealed marked interstitial fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Cardiac arrhythmias on 24-h ambulatory electrocardiography in older women and men: the Cardiovascular Health Study.

OBJECTIVES: This study describes the prevalence and correlates of cardiac arrhythmias in older persons. BACKGROUND: Cardiac arrhythmias are frequent in selected samples of elderly persons, but their prevalence and association with cardiovascular disease and its risk factors have not been examined in a large population-based sample. METHODS: In 1,372 participants in the Cardiovascular Health Study, a population-based study of cardiovascular disease risk factors, 24-h ambulatory electrocardiography was performed. RESULTS: Serious arrhythmias, such as sustained ventricular tachycardia and complete atrioventricular block, were uncommon, but brief episodes of ventricular tachycardia (> or = 3 consecutive ventricular depolarizations) were detected in 4.3% of women and 10.3% of men. Ventricular arrhythmias as a group (excluding ectopic beats < 15/h) were more common in men than in women but were not significantly associated with age. The same patterns were true for bradycardia/conduction blocks. Supraventricular arrhythmias as a group (excluding ectopic beats < 15/h), in contrast, did not differ by gender but were strongly associated with increased age. Multivariate analyses showed associations with arrhythmias to differ by gender, with only one association (increased age and supraventricular arrhythmias) present in both women and men. Ventricular arrhythmias, particularly in men, were associated with a higher prevalence of cardiovascular disease and its risk factors and with subclinical disease, as measured by increased left ventricular mass and impaired left ventricular function. CONCLUSIONS: Arrhythmias are common in the elderly, and their association with cardiovascular disease differs by gender. Although risk related to arrhythmias can only be determined by prospective study, such studies should have adequate power to examine potential gender differences in associations.

Aged↗
PubMed1994

How accurate is dobutamine stress electrocardiography for detection of coronary artery disease? Comparison with two-dimensional echocardiography and technetium-99m methoxyl isobutyl isonitrile (mibi) perfusion scintigraphy.

OBJECTIVES: This study was designed to establish the appropriate diagnostic criteria for positive dobutamine electrocardiographic (ECG) stress test results and to compare their accuracy with those of dobutamine two-dimensional echocardiography and perfusion scintigraphy. BACKGROUND: Conventional criteria for positive findings on ECG exercise testing may not be appropriate for use with dobutamine ECG stress testing. METHODS: One hundred twenty-nine consecutive patients with an interpretable ECG and without previous myocardial infarction were prospectively studied at the time of coronary arteriography. All completed a standard dobutamine protocol (5 to 40 micrograms/kg body weight per min in 3-min dose increments) without side effects. Significant coronary artery disease, defined as > 50% lumen diameter stenosis of a major epicardial coronary artery on coronary angiography, was present in 83 patients. Empiric receiver operating curves were generated for various ECG criteria derived from computer-averaged signals. RESULTS: The best ECG criterion, with a sensitivity of 42% and a specificity of 83%, was an ST segment shift, relative to baseline, of 0.5 mm 80 ms after the J point. The sensitivity of this criterion was greater than that of the conventional criterion of 1-mm ST segment depression 60 (23%) or 80 (18%) ms after the J point, was comparable to that of chest pain occurring during the test (44%, p = NS) but remained inferior to the sensitivities of technetium-99m methoxyl isobutyl isonitrile (mibi) perfusion (76%) or stress echocardiography (76%, p < 0.001, for both). The specificity of this criterion was not significantly different from that of technetium-99m mibi perfusion tomography (65%) or stress echocardiography (89%) but was superior to that of chest pain (59%, p < 0.025). CONCLUSIONS: We conclude that this new criterion for dobutamine electrocardiography is specific but that an imaging technique is still required to accurately predict coronary artery disease.

Adult↗
PubMed1992

Three-dimensional electrocardiography in the rat.

Three-dimensional electrocardiography with computerized analysis provides a means to rapidly collect and quantitatively analyze electrocardiographic data from rats. Electrical activity at each point in time can be expressed quantitatively as a vector with magnitude and direction. Rats are fitted with plate and needle electrodes in three mutually perpendicular axes: X (right to left), Y (rostral to caudal), and Z (ventral to dorsal). Electrocardiographic signals are recorded on paper and also collected at 1000/sec using an IBM-compatible computer equipped with a fast A/D convertor. Signals are analyzed using an interactive program written in Turbo PASCAL which transforms data into an array consisting of vector magnitude and direction at each time point. The data are further used to produce both a tabular report and graphic output. This method retains simplicity while extending the accuracy of electrocardiographic (ECG) measurement. It literally adds another dimension of information to the three-lead ECG most commonly measured in rats.

Animals↗
PubMed2005

Role of electrocardiography in identifying right ventricular dysfunction in acute pulmonary embolism.

The role of electrocardiography in identifying right ventricular (RV) dysfunction in acute pulmonary embolism (APE) was evaluated in 81 patients with APE. The electrocardiographic markers studied were T-wave inversion in leads V1 to V3, the S1Q3T3 pattern, right bundle branch block, and sinus tachycardia. T-wave inversion in leads V1 to V3 had the greatest sensitivity and diagnostic accuracy for identifying RV dysfunction in patients with APE. The S1Q3T3 pattern and right bundle branch block had good specificity but moderate accuracy.

Acute Disease↗
PubMed2005

Comparison of prognostic value of stress echocardiography versus stress electrocardiography in patients with suspected coronary artery disease.

Stress electrocardiographic (ECG) ST-segment depression is a prognostic marker of adverse cardiac outcomes in coronary artery disease. However, use of concurrent stress echocardiography (ECHO) has lead to concordant and discordant findings on stress electrocardiogram during stress studies. The prognostic value of stress ECHO in the setting of these stress ECG findings has not been previously evaluated. Outcomes of 1,268 patients (60 +/- 12 years old, 48% women) who had normal electrocardiograms and underwent stress ECHO were analyzed. ST-segment depression > or =1.5 mm in 2 contiguous leads on stress electrocardiogram and a wall motion score index of >1 on peak stress echocardiogram were considered abnormal. Events of nonfatal myocardial infarction (n = 18) and cardiac death (n = 32) were analyzed during follow-up (2.8 +/- 0.9 years). In 91 patients (7%) who had abnormal findings on stress electrocardiogram, 38 (41%) had an abnormal finding on stress echocardiogram and 4 had cardiac events (0.6% per year), and all who had a normal finding on stress echocardiogram had no events (n = 53, 59%, p = 0.01). Among 46 events (92%) with a normal finding on stress electrocardiogram, 30 (60%) showed a discordantly abnormal finding on stress echocardiogram (3.2% per year, p <0.01). Overall, the cohort that had normal findings on stress echocardiogram showed a lower event rate (72%, 16 events, 1.1% per year) compared with the cohort that had abnormal findings on stress echocardiogram (28%, 34 events, 3.6% per year, p <0.001), independent of stress ECG response. Peak wall motion score index (hazard ratio 2.55, p <0.001) and left ventricular ejection fraction (hazard ratio 0.99, p <0.001) were independent and incremental (global chi-square, p <0.001) prognostic markers by stress ECHO. In conclusion, a normal finding on stress echocardiogram confers a benign prognosis independent of the type of stress ECG response during stress studies. In addition, peak wall motion score index and ejection fraction by ECHO are stronger prognostic markers over stress electrocardiography in patients who are evaluated for coronary artery disease.

Adult↗
PubMed2006

Pitfalls and artifacts in electrocardiography.

The standard 12-lead ECG is a common diagnostic test that provides a wealth of diagnostic information of value for clinical decision making. Its value, however, depends upon the accuracy of its recording. This article presents common errors in clinical electrocardiography including inaccurate lead placement, inappropriate serial comparisons using different lead sets, lead wire reversals, inappropriate filter settings, and excessively noisy signals. Practical information is provided to prevent errors and to improve the quality and utility of ECGs.

Artifacts↗
PubMed2006

Is electrocardiography still useful in the diagnosis of cardiac chamber hypertrophy and dilatation?

The echocardiogram undoubtedly is part of the cardiologist's armamentarium in the diagnosis and elucidation of cardiac abnormalities, but the ECG still continues to be the most frequently recorded noninvasive test in medicine. For many patients, particularly those who have newly diagnosed hypertension, a 12-lead ECG recording may be the only test that is required as a baseline measure. For those who have possible heart failure, an ECG and B-type natriuretic peptide measurement may be sufficient to obviate the need for an echocardiogram. Electrocardiography and echocardiography will continue to live side-by-side for the foreseeable future.

Cardiomegaly↗
PubMed2004

How reliable is electrocardiography in differentiating transmural from non-transmural myocardial infarction? A study with contrast magnetic resonance imaging as gold standard.

Cardiovascular magnetic resonance (CMR) using contrast enhancement allows exact determination of the site and transmural extent of myocardial infarction (MI). We evaluated whether 12-lead electrocardiography can differentiate transmural from non-transmural MI or determine the site of MI by comparing the findings with those of contrast-enhanced CMR. A total of 27 patients (59.5+/-12.9 years) with a history of MI (6.4+/-2.9 months) underwent CMR (Magnetom, Siemens, Erlangen, Germany). Cine images were acquired in the horizontal and vertical long axes and short axis by TrueFISP. Contrast-enhanced CMR images were acquired in the same axes by segmented FLASH 15 min after administration of gadolinium-DTPA (0.15 mmol/kg). This showed the MI to be transmural in 11 patients and non-transmural in 16. An electrocardiogram (ECG) was recorded in all patients before CMR. T-wave alterations, descending ST-depression, pathological Q-waves and absent R waves were more frequent in non-transmural MI than transmural MI, as defined by contrast-enhanced CMR (p> or =0.618). However, none of the differences were statistically significant. R-wave reduction, q waves and horizontal ST-depression were more frequent in transmural than in non-transmural MI (p> or =0.157). Again, the differences were not significant. The sensitivity of the ECG for MI localization was highest in inferior infarctions (85.71%), the specificity was highest in anterior infarctions (100%), the best positive predictive value (80%) was achieved for anterolateral infarctions, and the best negative predictive value for lateral infarctions (95.83%). Transmural and non-transmural MI cannot be differentiated by ECG. The ECG is most accurate in detecting anterolateral MI.

Contrast Media↗
PubMed2007

Electrocardiography and Wells scoring in predicting the anatomic severity of pulmonary embolism.

Pulmonary embolism (PE) is a major health problem associated with a significant morbidity and mortality. Immediate recognition of submassive and massive cases is extremely important in order to commencement of early and appropriate therapy that could be life saving. The aim of this study was to assess the ability of two scoring systems, electrocardiography (ECG) and simplified Wells (sWells) clinical scorings in predicting anatomic severity of PE. Hence, ECG and sWells scorings were combined in order to test the hypothesis if this new scoring does enhance the prediction of severity. Fifty six patients with proven PE with high (50 patients) and moderate (six patients)-probability of ventilation/perfusion (V/Q) scan were retrospectively studied. Baseline ECGs were analysed by two independent observers in order to constitute ECG scorings. Baseline sWells scores were also calculated. Anatomic severity of PE was calculated by scintigraphically and categorized into mild (<50% perfusion defect) (group 1), and severe (50% perfusion defect) (group 2) diseases. The mean of ECG scores, sWells scores and the combined scores were 5.23+/-3.42 and 5.85+/-3.82; 6.60+/-1.88 and 7.03+/-2.40; and 10.73+/-3.60 and 11.60+/-4.32 in groups 1 and 2, respectively (p>0.05). An ECG score of 6.5 predicted severe disease (perfusion defect 50%) with a sensitivity of 41.7% and a specificity of 82%). sWells and combined scores did not provide better sensitivity or specificity values based on ROC curve analysis. Our results indicated that ECG scoring could be valuable test in predicting anatomic severity of PE, adding sWells scoring to ECG scoring did not provide any beneficial effect.

Adult↗
PubMed1977

His bundle electrocardiography in manifest and concealed right bundle branch extrasystoles.

His bundle electrocardiography was helpful in the diagnosis of impulse formation in the right bundle branch. Ten patients with narrow QRS complexes had ectopic beats with an "incomplete" left bundle branch pattern and almost simultaneous activation of His bundle and ventricles. Both QRS morphology and H- - V intervals depended on the more proximal or distal location of the ectopic focus. In four patients with "complete" right bundle branch block the morphology of ectopic ventricular complexes and H- - V intervals also depeneded on the presence or absence of retrograde block and differential degrees of forward and/or retrograde conduction delays. Nine patients with "complete" right bundle branch block and four with "complete" left bundle branch block had premature beats which could have originated in the proximal right bundle branch, proximal left bundle branch, or distal His bundle. In one patient with "complete" left bundle branch block, "concealed" His bundle depolarizations (probably originating in an ectopic focus located in the right bundle branch) produced pseudo Type II (Mobitz) A-V block. Although lidocaine appeared to have been more effective in patients with bundle branch block than in those with narrow QRS complexes, further studies are necessary to corroborate this impression.

Adult↗
PubMed1996

Twenty-four-hour ambulatory electrocardiography in elderly subjects: prevalence of various arrhythmias and prognostic implications (report from the Bronx Longitudinal Aging Study).

Functional, ambulatory, community-dwelling subjects (n = 423, aged 75 to 85 years) underwent baseline 24-hour ambulatory electrocardiography (ECG) examinations as part of the Bronx Aging Study, a 10-year prospective cohort study designed to identify risk factors and disease markers for cardiovascular, cerebrovascular, and dementia illnesses in old people. Premature ventricular contractions were the most commonly observed arrhythmia noted (93% of subjects), with a low prevalence of nonsustained ventricular tachycardia (5%), paroxysmal atrial tachycardia (13%), atrial fibrillation (4%), and atrioventricular blocks (4%). A 24-hour sinus rate of < 60 beats/min was noted in 13% of subjects, and 11% of subjects were noted to have transient episodes of severe bradycardia (< 40 beats/min). In a multivariate analysis, nonsustained ventricular tachycardia was an independent predictor of death (p = 0.015; relative risk [RR] 2.8; 95% confidence interval [CI] 1.4 to 5.8) and myocardial infarction (p = 0.031; RR 3.2; CI 1.2 to 9.4). Transient atrioventricular block was an independent predictor of stroke (p - 0.0006; RR 9.7; CI 3.3 to 28.9), as was sinus bradycardia over a 24-hour period (p = 0.033; RR 2.7; CI 1.2 to 6.4). Ventricular tachycardia approached significance as an independent predictor of multiinfarct dementia (p = 0.052; RR 6.3; CI 1.4 to 28.7). Episodes of paroxysmal atrial fibrillation, a trial tachycardia, and severe bradycardia were not associated with adverse outcomes. Some arrhythmias found on the ambulatory ECG in very old subjects can predict an increased risk for subsequent death, myocardial infarction, stroke, and multiinfarct dementia.

Aged↗
PubMed2000

Detection of coronary restenosis by exercise electrocardiography thallium-201 perfusion imaging and coronary angiography in asymptomatic patients after percutaneous transluminal coronary angioplasty.

Noninvasive detection of restenosis in patients remaining asymptomatic after percutaneous transluminal coronary angioplasty (PTCA) remains a major clinical problem. The value of exercise electrocardiography (ECG) and exercise-redistribution thallium-201 single-photon emission computed tomography (SPECT) in detecting restenosis in such patients remains uncertain. Discordances between these tests and coronary angiography is a common situation. We studied 179 consecutive patients remaining asymptomatic after successful PTCA (208 vessels), who underwent 6 +/- 2 months of exercise ECG, SPECT, and coronary angiography. We sought to assess the diagnostic value of the noninvasive tests compared with coronary angiography, and identify the determinants of discordances between the tests. Restenosis (diameter stenosis >50%) was detected in 39% of patients and in 37% of vessels. The overall sensitivity, specificity, and accuracy for exercise ECG and SPECT in detecting restenosis in individual vessels were, respectively, 53% versus 63% (p = 0.06), 59% versus 77% (p = 0.0001), and 57% versus 72% (p = 0. 0001). On multivariate analysis, positive exercise ECG was associated with higher heart rate response (p = 0.02), incomplete revascularization (p = 0.004), and angiographic restenosis (p = 0. 03), whereas positive SPECT was associated with incomplete revascularization (p = 0.02), infarct-related artery PTCA (p = 0.01), and angiographic restenosis (p = 0.0001). Accuracies of the 2 tests were not significantly different in patients with incomplete revascularization or PTCA of an infarct-related vessel. Overall, SPECT is more accurate than exercise ECG in detecting asymptomatic restenosis. Nevertheless, incomplete revascularization and PTCA of an infarct-related artery could cause reversible perfusion defects regardless of restenosis, reducing the diagnostic value of SPECT in such patients.

Angioplasty, Balloon, Coronary↗
PubMed1996

Accurate detection of coronary artery disease by integrated analysis of the ST-segment depression/heart rate patterns during the exercise and recovery phases of the exercise electrocardiography test.

In this comparative cross-sectional study, we evaluated whether a novel computerized diagnostic variable, ST-segment depression/heart rate ST/HR analysis during both the exercise and postexercise recovery phases of the exercise electrocardiography (ECG) test, can detect coronary artery disease more accurately than methods using either exercise or recovery phase alone. The study population comprised 347 clinical patients referred for a routine bicycle exercise ECG test at Tampere University Hospital, Finland. Of these, 127 had angiographically proven coronary artery disease, whereas 13 had no coronary artery disease according to angiography, 18 had no perfusion defect according to technetium-99m sestamibi single-photon emission computed tomography, and 189 were clinically normal with respect to cardiac diseases. For each patient, the maximum values of the ST/HR hysteresis, ST/HR index, end-exercise ST depression, and recovery ST depression were determined from the Mason-Likar modification of the standard 12-lead exercise electrocardiogram [aVL, aVR, and V1 excluded]. The diagnostic performance of these continuous diagnostic variables was compared by means of receiver-operating characteristic analysis. The area under the receiver-operating characteristic curve of the ST/HR hysteresis was 89%, which was significantly larger than that of the end-exercise ST depression (76%, p < or = 0.0001), recovery ST depression (84%, p = 0.0063), or ST/HR index (83%, p = 0.0023), indicating superior diagnostic performance of the ST/HR hysteresis independent of the partition value selection. In conclusion, computerized analysis of the HR-adjusted ST depression pattern during the exercise phase, integrated with the HR-adjusted ST depression pattern during the recovery phase after exercise, can significantly improve the diagnostic performance and clinical utility of the exercise ECG test for the detection of coronary artery disease.

Adult↗