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Biomedical subjects

C Brohet

Publications and source records attributed to C Brohet.

30 records · Page 2Linked to original sources
PubMed1984

Factors influencing postoperative survival in aortic regurgitation. Analysis by Cox regression model.

From 1965 to 1981, 114 patients underwent aortic valve replacement for severe aortic regurgitation in our institution. Catheterization was performed preoperatively in 103 patients. Follow-up was possible in 98% of the survivors. Long-term survival was significantly different between patients in preoperative Functional Class I-II and those in Class III-IV (p less than 0.03); those with a preoperative cardiothoracic ratio less than 0.64 versus greater than or equal to 0.64 (p less than 0.001); and those with a preoperative ejection fraction greater than 0.50 versus less than or equal to 0.50 (p less than 0.03). A multifactorial analysis was used to identify the dominant preoperative prognostic variables affecting survival. Three of the 13 parameters examined simultaneously were found to independently influence survival rates: cardiothoracic ratio (p = 0.001), strain pattern on the electrocardiogram (p = 0.072), and left ventricular end-systolic pressure (p = 0.127). After stratification of the population into two groups according to preoperative functional class, the predictive variables were cardiothoracic ratio (p = 0.014), strain pattern (p = 0.050), and acute/chronic form of aortic regurgitation (p = 0.034). This statistical analysis enabled us to derive a mathematical equation for predicting an individual patient's probability of survival. We found a close fit between the survival rate predicted by the mathematical model and the observed survival rate.

Adolescent↗
PubMed1980

Computer-assisted interpretation of electro- and vectorcardiograms. Chapter IV. Achievements in the field of computer-assisted interpretation of electrocardiograms.

The most important advantage of computer-assisted ECG/VCG interpretation in our center is the enhancement of the diagnostic accuracy of ECG interpretation, as compared to that reported in the literature for the visual analysis of ECGs and VCGs. Favourable side effects are also obtained from the optimization of various functions involved n ECG data processing, like data handling, editing, reporting, storage and retrieval. Improvement of the arrhythmia program and creation of a new pediatric VCG program are currently in progress in our laboratory. Computerized electrocardiography has made us aware of the limitations of conventional, visual reading of electrocardiograms. Thanks to the current efforts towards standardization of the quantitative analysis of ECGs and VCGs and towards optimization of diagnostic criteria, computerized electrocardiography will undoubtedly lead to a generalized improved accuracy of ECG interpretation.

Belgium↗
PubMed1976

Computer processing of oxygen dissociation curves.

Oxygen dissociation curves (ODC) plotted by a semi-automatic analyzer are subsequently processed by a digital computer. This computer processing provides a complete determination of the ODC, hence offering more information than the single P50 generally used. The programs consist of three successive modules each with a higher degree of sophistication in the processing. The mass handling of the curves is also described.

Computers↗
PubMedDate not supplied

Data compression for storage of resting ECGs digitized at 500 samples/second.

Data compression of resting electrocardiograms (ECGs) digitized at 500 samples per second (sps) is presented. Tradeoffs between the fidelity of reconstructed data and the overall compression are examined. Data of the median (average) complexes are retained at 500 sps and full resolution and encoded only to reduce redundancy. The raw data for rhythm analysis are evaluated for lowpass filtering and down-sampling (decimation) and requantization. After subtracting the medians from the raw data, the resulting residue signal is examined in detail for data reduction and encoding. Various options for compression of the residue signal are presented. Specific issues examined are the acceptable decimation and requantization of the residue signal. Another important aspect evaluated is the bimodal decimation of the QRS and the rest of the cardiac complex. Here, the QRS complexes are kept at 500 sps and the rest of the data decimated to lower sampling rates. This novel approach reduces data distortion while achieving significant compression. Details of the compression scheme and its evaluation on uncompressed 500-sps ECGs from the European Common Standards for Electrocardiography (CSE) database (128 ECGs with normal sinus rhythm, atrioventricular blocks, atrial fibrillation and flutter, ventricular arrhythmias, and excessive noise) are elucidated. Performance indexes [root mean square (RMS) error, percent RMS difference, normalized RMS difference, maximum peak error, and compression ratio] are computed. To validate the compression method, qualitative evaluation was performed by two physicians overreading the ECGs by comparing the reconstructed waveforms with the original uncompressed data. The median data are retained at 500 sps and full precision. For rhythm data, the bimodal decimation of the residue signal to 125 sps at 10 microvolts resolution preserved the fidelity of the ECG signals well, while giving good data compression. Abnormal atrial activity was well preserved and the QRS was retained without distortion. The average size of a 10-sec compressed ECG with the medians is around 4.5 kilobytes.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Early surgery for severe aortic regurgitation.

One hundred and fourteen consecutive patients who underwent aortic valve replacement (AVR) for isolated aortic regurgitation (AR) from 1965 to 1981 are presented. Sixty eight (60%) were preoperatively in NYHA class I-II and 46 (40%) were in NYHA class III-IV. Eighty-two patients had left and right heart catheterization prior to the operation and the severity of regurgitation was assessed angiographically in 93% of those in functional class (FC) I-II. Left ventricular (LV) end-diastolic volume index and end-systolic volume index were elevated even in the mildly symptomatic patients (156.1 and 61.0 ml/m2 respectively). The ratio of LV end-systolic pressure to LV end systolic volume index was diminished in the FC I-II patients. Two patients in FC III died in hospital (operative mortality: 1.7%) and there were 21 late deaths with a 5-year survival of 82.7%. Late survival differed significantly between patients who were preoperatively in FC I and II or III and IV (P less than 0.03). These data suggest that severe AR with altered LV function is an indication for early operation regardless of the presence of absence of symptoms.

Adolescent↗