Biomedical subjects

C Derwael

Publications and source records attributed to C Derwael.

5 recordsLinked to original sources

PubMed1990

Methodology of ECG interpretation in the Louvain program.

The Louvain program performs the analysis and interpretation of the vectorcardiogram (VCG) to increase the clinical utility of ECG analysis. Among its original features, there are (1) a high-resolution vector-loop display for visual analysis, (2) quantitative analysis of the spatial VCG using age-sex stratified limits, (3) separate software for adult and pediatric series and (4) complementary deterministic and statistical methods of diagnostic classification. Using objective, ECG-independent evidence as a reference standard, the Louvain program has shown satisfactory levels of diagnostic accuracy in most basic categories. However, its usefulness is especially marked in "borderline" or "complex" situations, where the 12-lead ECG cannot provide a clear answer. It corresponds to the concept of "computer-assisted ECG interpretation" as opposed to "computer ECG analysis".

Adult↗

PubMed1987

Implementation of the Louvain program for exercise ECG analysis on a microprocessor system.

Several years ago we developed a computer system for the processing of exercise ECGs: the Louvain program for exercise ECG analysis which runs on a minicomputer "Modcomp Classic" and processes XYZ data remotely collected on digital cartridge at the exercise room. This off-line batch procedure is time consuming for the technician (reading of cartridge), but theoretically could be fast. Our experience shows that the results of the exercise test are provided to the referring physician from one day to one week after the procedure because of delays at different levels. The implementation of the programs in a stand-alone unit can produce the results one minute after the end of the test. This solution obviously is more satisfactory for routine clinical testing.

Computers↗

PubMed1986

The normal pediatric Frank orthogonal electrocardiogram: variations according to age and sex.

Quantitative computerized analysis of QRS and ST-T parameters of the Frank orthogonal electrocardiogram and vectorcardiogram was undertaken in a large series of 1317 normal infants, children and adolescents stratified according to age and sex. This study confirms the influence of these two constitutional variables, age and sex, over the normal VCG in the whole time span between birth and late adolescence. As children mature, the mid-portion of the spatial QRS loop shifts leftward and posteriorly with relatively little change in the initial and terminal vectors. The spatial T loop shifts anteriorly but at a different rate in males and in females. Unidirectional changes in many amplitude parameters are observed until age 19 in males whereas in females these changes stop earlier or even show a reverse trend around puberty, leading to more important differences between adolescent males and females. Sex-related differences are the most marked for parameters representing the repolarization process. Infants under six months of age form a distinct group with larger dispersions and more disparate variations in the values of vectorcardiographic parameters than in older children. In the newborn period larger sample size might be necessary in order to reduce the normal ranges of vectorcardiographic parameters.

Adolescent↗

PubMed1986

The normal pediatric Frank orthogonal electrocardiogram: influence of weight, height and chest circumference.

The influence of body weight, height and chest circumference on the pediatric Frank vectorcardiogram (VCG) was investigated in a population of 1317 normal infants, children and adolescents. Simple linear regression analysis showed that 94, 96 and 57 VCG variables were significantly correlated with weight, height and chest circumference, respectively. These numbers were reduced to 10, 18 and 6 VCG variables after a stepwise multiple correlation analysis. The relationship between the VCG and the somatic variables was also studied in ten different age/sex subgroups. Simple regression analysis showed a residual significant correlation between the VCG and all three somatic variables in each group. The multiple correlation analysis allowed us to define a minimum set of VCG variables, from one to six, which could explain all the variation produced by the somatic variables. The coefficient of multiple correlation between VCG and weight was the highest in babies 0 to 6 months old (R = 0.73). For height, the strongest correlation was found in females two to five years old (R = 0.76). In subjects older than two years of age, the correlation between chest circumference and VCG (R = 0.30 to 0.69) was weaker than between VCG and pediatric VCG after stratification for age and sex, especially in the youngest groups.

Adolescent↗

PubMed1984

Computer interpretation of pediatric orthogonal electrocardiograms: statistical and deterministic classification methods.

Statistical multivariate and conventional deterministic methods of computerized interpretation of the electrocardiogram (ECG) were compared in the analysis of 1711 pediatric orthogonal ECGs validated by nonelectrocardiographic criteria on the basis of clinical and anatomic diagnoses. Among 642 children catheterized for the evaluation of congenital heart disease, there were 140 patients with left ventricular hypertrophy, 299 with right ventricular hypertrophy, and 203 with biventricular hypertrophy. A group of 1069 obviously healthy school children was studied as a control. The overall accuracy of multigroup ECG diagnosis was 85% and 79% for the statistical and deterministic methods, respectively. The diagnostic performances of both methods expressed in terms of sensitivity and predictive value were the highest for normal children and those with right ventricular hypertrophy and lowest for children with biventricular hypertrophy. The statistical method was more sensitive in the diagnosis of left ventricular hypertrophy (74% vs 64%), right ventricular hypertrophy (86% vs 83%), and biventricular hypertrophy (62% vs 50%). Mutual agreement for a correct diagnosis by the two methods was 83% for normal children and 82% for those with right ventricular hypertrophy but only 61% for children with left ventricular hypertrophy and 39% for those with biventricular hypertrophy. In conclusion, better classification results are obtained with statistical multivariate techniques as compared with conventional deterministic analysis, but both methods of ECG interpretation are complementary and their combination in the same electrocardiographic computer program can improve diagnostic accuracy.

Adolescent↗