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Biomedical subjects

C Brohet

Publications and source records attributed to C Brohet.

42 records · Page 3Linked to original sources
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

[Recommendations for the prevention of cardiovascular diseases in clinical practice. Belgian Working Group on Prevention of Ccardiovascular Diseases].

These recommendations are largely based on the Executive Summary of the "European Guidelines on Cardiovascular Disease Prevention in Clinical Practice" proposed by the "Third Joint Task Force of European and other Societies on Cardiovascular Disease Prevention in Clinical Practice". The model used to assess the overall risk was adapted for Belgium. Otherwise, very few things were changed from the Executive Summary of the European Guidelines.

Cardiovascular Diseases↗
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↗