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C Abreu-Lima

Publications and source records attributed to C Abreu-Lima.

10 recordsLinked to original sources
PubMed1991

The diagnostic performance of computer programs for the interpretation of electrocardiograms.

BACKGROUND: Computer programs for the interpretation of electrocardiograms (ECGs) are now widely used. However, a systematic assessment of various computer programs for the interpretation of ECGs has not been performed. METHODS: We undertook a large international study to compare the performance of nine electrocardiographic computer programs with that of eight cardiologists in interpreting ECGs in 1220 clinically validated cases of various cardiac disorders. ECGs from the following groups were included in the sample: control patients (n = 382); patients with left ventricular hypertrophy (n = 183), right ventricular hypertrophy (n = 55), or biventricular hypertrophy (n = 53); patients with anterior myocardial infarction (n = 170), inferior myocardial infarction (n = 273), or combined myocardial infarction (n = 73); and patients with combined infarction and hypertrophy (n = 31). The interpretations of the computer programs and the cardiologists were compared with the clinical diagnoses made independently of the ECGs, and the computer interpretations were compared with those of the cardiologists. RESULTS: The percentage of ECGs correctly classified by the computer programs (median, 91.3 percent) was lower than that of the cardiologists (median, 96.0 percent; P less than 0.01). The median sensitivity of the computer programs was also significantly lower than that of the cardiologists in diagnosing left ventricular hypertrophy (56.6 percent vs. 63.9 percent, P less than 0.02), right ventricular hypertrophy (31.8 percent vs. 46.6 percent, P less than 0.01), anterior myocardial infarction (77.1 percent vs. 84.9 percent, P less than 0.001), and inferior myocardial infarction (58.8 percent vs. 71.7 percent, P less than 0.0001). The median total accuracy level (the percentage of correct classifications) was 6.6 percent lower for the computer programs (69.7 percent) than for the cardiologists (76.3 percent; P less than 0.001). However, the performance of the best programs nearly matched that of the most accurate cardiologists. CONCLUSIONS: Our study shows that some but not all computer programs for the interpretation of ECGs perform almost as well as cardiologists in identifying seven major cardiac disorders.

Cardiology↗
PubMed1990

Evaluation of ECG interpretation results obtained by computer and cardiologists.

In an international project investigators from 25 institutes are trying to establish a common reference library and evaluation methods for testing the diagnostic performance of various ECG computer programs and of cardiologists, based on ECG-independent clinical information. A first set of 500 validated ECGs was collected and analyzed by fifteen different computer programs and nine cardiologists, seven of who analysed the ECG and five the VCG. A coding scheme was used to map individual diagnostic statements onto a common set. Combined program and referee results were obtained by weighted averaging. Preliminary results indicate that the classification accuracy of several programs can still be improved. However, it was also apparent that the results of the best 12-lead ECG computer programs proved to be almost as accurate as the best of seven cardiologists in classifying seven main disease categories, i.e., normal, left, right and biventricular hypertrophy, anterior, inferior and combined myocardial infarction. Evaluation of rhythm statements and conduction disturbances was not included in the study. The data collection is still being pursued in order to reach over 1,000 cases. In this way a common diagnostic database is being established for comparative testing of diagnostic computer programs. This should lead to consumer protection and improve the accuracy and reliability of computerized electrocardiography.

Cardiovascular Diseases↗
PubMed1990

Interpretation of short ECGs with a personal computer: the Porto program.

A computer program for ECG analysis and interpretation developed at the University of Porto, Portugal is presented. The program runs on a microcomputer and employs the three-lead Frank VCG. The signals are sampled at 250 Hz with 8-bit precision during 5.5 s. Details on signal conditioning and wave recognition and measurement techniques are given. The diagnostic part of the program uses decision-tree logic. The decision rules are mainly derived from the Washington Code. The diagnostic accuracy of four classes (normal, left and right ventricular hypertrophies and myocardial infarction), evaluated in a sample of 1,075 pediatric and adult patients and classified by ECG-independent means was 76%. The program is currently being evaluated on the CSE database.

Adolescent↗
PubMed1988

Frontal-plane QRS axis revisited: accuracy of current approximations and reappraisal of their merit in the diagnosis of right ventricular hypertrophy.

The frontal-plane mean QRS vector orientation (AQRSxy)--the so-called electrical axis--is an ECG feature commonly used for the diagnosis of right ventricular hypertrophy and is correctly measured by calculating the areas subtended by QRS deflections in two different leads. To overcome the drawbacks of doing this by hand, two alleged approximations of AQRSxy have become popular and are in current use: one is based on the measurement of QRS component wave peak amplitudes and the other on the estimation of the half-area vector of the frontal plane loop. The values obtained with the correct and the two more practical methods are compared and their diagnostic efficiency is assessed by means of a procedure for ECG criteria optimization based on the receiver operating characteristics (ROC) curve analyzed in terms of information theory. The authors conclude that the two more popular methods for AQRSxy determination provide similar values that, although correlated with the true measure of the parameter are statistically different from it. On the other hand, the diagnostic efficiency of AQRSxy alone, regardless of the method by which it is computed, is only as good as, if not bettered by, other much more easily measurable frontal-plane parameters (ie, left to rightward forces amplitude ratio in adults and rightward forces amplitude in pediatric patients).

Adolescent↗
PubMed1988

Effect of combining electrocardiographic interpretation results on diagnostic accuracy.

In order to test the diagnostic performance of various ECG computer programs a reference library of ECGs is being established and evaluation methods are being developed in an international co-operative project. A pilot study was undertaken in which 250 validated electrocardiograms (ECG) and vectorcardiograms (VCG) comprising seven diagnostic groups i.e., normal, left, right and bi-ventricular hypertrophy, anterior, inferior and combined infarction have been analysed independently by 11 different computer programs as well as by six cardiologists. A coding scheme was applied to assign individual diagnostic statements to a common set and to obtain combined program and cardiologist interpretation results. Preliminary results indicate that the accuracy of classification by different programs varies widely. Total accuracy varied between 57.2% and 75.8% (median 69.4%). The cardiologists had a higher accuracy (median 74.3%) than the majority of programs, at least when using the standard ECG. As it is considered premature to stress individual program results, in view of the current sample size, the enhancement in diagnostic accuracy obtained by combining interpretation results is highlighted. Indeed combined cardiologist and program results demonstrated the highest accuracy i.e., respectively 78.7% and 76.1%, higher than the result of any individual reader or program. The combined result of the five most accurate programs was 78.4%, that of the six least accurate was 71.5%, which is again higher than the respective individual components. These findings demonstrate that the combination of expert knowledge of computer programs can, similar to panel review and group analysis in clinical practice, enhance diagnostic accuracy.

Diagnosis, Computer-Assisted↗
PubMed1987

Testing the performance of ECG computer programs: the CSE diagnostic pilot study.

In an international project investigators from 21 institutes are trying to establish a common reference library and evaluation methods for testing the diagnostic performance of various ECG computer programs using ECG independent clinical information. Preliminary results indicate that the classification accuracy of different programs varies widely.

Electrocardiography↗
PubMed1986

A new ECG classifier based on linear prediction techniques.

A longstanding tradition in automatic ECG classification has been the use of conventional features (amplitudes, duration, etc.) as waveform descriptors for pattern discrimination purposes. This paper presents an alternative approach in statistical ECG classification. It is based on the use of linear prediction coefficients, a sort of "abstract" features which, as waveform descriptors, enjoy the desirable property of whole-signal dependency, being rather insensitive to high-frequency noise. Experimental results obtained on 400 ECGs distributed by four clinical groups according to clinicopathological data (normal, myocardial infarction, right and left hypertrophies) show interesting potentialities of this new method, namely a classification error for equal class prevalences (30%) significantly lower than by using conventional features. Classification and cluster separability results are presented and discussed as well as the viability of the new method in a clinical environment.

Adolescent↗
PubMed1985

A double-blind trial comparing mianserin and maprotiline in depressed inpatients.

The antidepressant effects and side effects of mianserin and maprotiline were assessed in a double-blind trial in 62 inpatients (34 men and 28 women; mean age, 43.6 years) with primary depressive illness. For the first week of the trial, 32 patients received 30 mg/day of mianserin and 30 patients received 75 mg/day of maprotiline; for the next three weeks, the dosage of each drug was doubled. According to scores on the Hamilton Psychiatric Rating Scale for Depression, administered on days 0, 7, 14, 21, and 28, the antidepressant effects of the two drugs were virtually identical. Results of electrocardiographic and vectorcardiographic recordings and other measurements indicated that by day 28 the QRS duration was significantly longer (P less than 0.05) in the maprotiline group. On days 14 and 28, mean systolic blood pressure was significantly higher (P less than 0.05) in the maprotiline group. By day 28, the incidence of anticholinergic side effects--constipation and dry mouth--was significantly higher (P less than 0.05) in the maprotiline group. Although maprotiline's effects on heart functions never reached clinical significance, its anticholinergic side effects could be bothersome, especially to older patients.

Adolescent↗