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Biomedical subjects

S Abboud

Publications and source records attributed to S Abboud.

69 records · Page 4Linked to original sources
PubMed1986

High frequency electrocardiography using an advanced method of signal averaging for non-invasive detection of coronary artery disease in patients with normal conventional electrocardiogram.

The ability to detect coronary artery disease (CAD) in patients with normal, conventional electrocardiograms (ECG) was studied using high frequency electrocardiography and an advanced method of signal averaging in three groups of subjects. Group A consisted of ten healthy subjects under the age of 30; Group B of 15 patients with chest pains and normal coronary arteries; and Group C of 20 patients with chest pains and CAD. Four hundred ECG waveforms from leads V3, V4 and V5 were recorded, and the recorded analog data were digitized. The digitized waveforms were averaged using a cross-correlation function which operates in the frequency domain (fast-Fourier transform algorithm). The signals were filtered with a digital band pass filter with 150 and 250 Hz low and high cut-off frequencies, respectively. Zones of reduced amplitude in the envelope of the filtered QRS complex of at least two precordial leads were found more significantly in patients with CAD (75%) than in patients without CAD (12% for Groups A and B, p less than 0.00003). However, no significant difference was found between the voltage over the high frequency QRS complex and that of its envelope between the three groups. It is concluded that the morphology of the high frequency QRS complex as determined by this advanced method of analysis of the signal averaged ECG may be a useful indicator for the presence of CAD in patients with normal conventional ECG's.

Adult↗
PubMed1986

Sarcoidosis, Hodgkin's disease, and autoimmune hemolytic anemia.

Reported is the unique occurrence of sarcoidosis, Hodgkin's disease, and autoimmune hemolytic anemia in the same patient. Although the diagnosis of sarcoidosis preceded that of Hodgkin's disease by 29 years, massive splenomegaly had been present for 13 years before Hodgkin's disease was diagnosed following splenectomy. The known associations of sarcoidosis and Hodgkin's disease as well as each disease with autoimmune hemolytic anemia are reviewed.

Anemia, Hemolytic, Autoimmune↗
PubMed1985

Cross-correlation technique for arrhythmia detection using PR and PP intervals.

A combined, cross-correlation procedure for computerized arrhythmia detection is presented. It enables the classification of a wide range of arrhythmia and is based upon the determination of both P and QRS waves. The electrocardiogram (ECG) signal is recorded from external leads, digitized (10 bits of resolution) at 1.28 kHz and processed with a CDC 6600 computer. A normal beat is stored as a reference signal and the onsets of the P wave and the QRS complex are measured for determining the PR, PP, and RR intervals. The combined cross-correlation procedure is carried out between the template and each successive ECG waveform over two time intervals, the first of which includes the P wave and the second, the QRS complex. Prior to this correlation procedure each of the ECG waveforms is filtered through a nonrecursive digital bandpass filter (10 and 100 Hz for low and high cutoff frequencies, respectively). The cross-correlation functions are then calculated by means of a cross spectrum and Fast Fourier Transform algorithm. The maximum value of the normalized cross-correlation function and the time shift providing that value are searched for, allowing (1) determination of the similarity between the present beat and the normal reference beat, allowing for the discrimination of abnormal P and QRS shapes; (2) accurate measurement of the RR, PP, and PR intervals of this subsequent waveform. Applying this method enables a reliable detection of a wide variety of arrhythmia.

Arrhythmias, Cardiac↗
PubMed1984

The use of cross-correlation function for the alignment of ECG waveforms and rejection of extrasystoles.

The cross-correlation function for alignment of ECG waveforms and rejection of artifacts was studied. ECG waveforms were recorded and digitized (10-bit resolution) at 1.28 KHz and were processed with a CDC 6600 computer. The cross-correlation function was calculated using the cross spectrum and the fast Fourier transform algorithm. The maximum value of the cross-correlation function and the time location of that value were searched for (a) the similarity between the waveforms (for elimination of extrasystoles), and (b) measuring the relative time delay (for the waveform's alignment in the averaging process) between the ECG waveforms. Prior to the correlation procedure each of the ECG waveforms was filtered through a nonrecursive digital bandpass filter. Experiments with various filters indicated that when low-frequency cutoff at 30 Hz and high-frequency cutoff at 250 Hz were used the maximum value of the cross-correlation function was higher than 0.9 for most of our recorded waveforms and more accurate results were obtained.

Arrhythmias, Cardiac↗
PubMed1984

Non-invasive recording of His bundle activity in patients with Wolff-Parkinson-White syndrome.

Ten patients with Wolff-Parkinson-White syndrome underwent external His bundle recording using an advanced signal-averaging technique. Surface ECG waveforms were recorded and digitized at 1.28 kHz (10 bit resolution) and then averaged with a CDC-6600 computer. A cross-correlation function, operating in the frequency domain (using the Fast Fourier Transform algorithm) was employed to extract fiducial synchronizing marks for the waveform alignment. Using this technique, reliable His bundle activity could be recorded in nine of ten patients. There was a good correlation between the HQ and HV intervals obtained during external and internal His bundle recordings, respectively, in seven patients who underwent both recordings. Administration of ajmaline enabled to obtain the His bundle activity using a digital filter with low frequency cut-off of 30 Hz as compared to the cut-off of 150 Hz which was necessary during control to reduce the electrical activity of the delta wave. We conclude that using a computerized cross-correlation signal-averaging technique enables the external His bundle recording in patients with WPW syndrome.

Adolescent↗
PubMed1983

Non-invasive recording of late ventricular activity using an advanced method in patients with a damaged mass of ventricular tissue.

Late potentials occurring after the QRS complex were detected on the body surface using an advanced signal averaging technique. ECG waveforms were recorded from patients with and without recurrent ventricular tachycardia who had a damaged mass of ventricular tissue (left ventricular aneurysm or right ventricular dysplasia). The recorded analog data were digitized by a 10 bit A/D converter with a sampling rate of 1280 Hz onto digital magnetic tape. The digitized waveforms were averaged with a CDC-6600 computer using an advanced algorithm which employs a cross correlation function to extract fiducial synchronizing marks for the signal averaging. Waveforms were filtered with a digital bandpass filter with 30 Hz and 250 Hz low and high cut-off frequencies, respectively. Late potentials were detected in seven out of ten patients with left ventricular aneurysm (or right ventricular dysplasia) and recurrent ventricular tachycardia and in four out of five patients with left ventricular aneurysm (or right ventricular dysplasia) but without recurrent ventricular tachycardia. The delayed depolarizations, which were recorded, had an amplitude of 3.0-27.0 microV and extended a mean of 90 msec beyond the termination of the QRS complex. In three patients with left ventricular aneurysm the delayed waveforms were abolished by aneurysmectomy. In nine control subjects no late potentials were detected. We conclude that late potentials which represent late depolarization of a damaged mass of ventricular tissue can be detected in patients with and without recurrent ventricular tachycardia.

Adolescent↗
PubMed1983

An advanced non-invasive technique for the recording of His bundle potential in man.

A new method for external recording of the His bundle electrical activity is described. Four hundred standard ECG waveforms were recorded and digitized at 1.28 kHz (8 bit resolution) and averaged with the aid of a CDC 6600 computer to reduce the random noise. A cross correlation function, which operates in the frequency domain using the Fast Fourier Transform algorithm, was employed to extract fiducial synchronizing marks for the waveforms alignment (triggering). Waveforms were filtered with a digital bandpass filter (30 Hz and 250 Hz low and high cut off frequencies respectively). The activity of the His bundle which was thus obtained was present on an isoelectric line, with signal amplitude of 4 to 7 microV. A strong correlation (r = 0.95, n = 10) was found between the HV intervals and the HQ intervals obtained from intracardiac electrograms and the new technique. It was concluded that the new method is convenient, reliable and can be successfully applied for the management of patients with various problems in their cardiac conducting system.

Adolescent↗
PubMedDate not supplied

Modeling of the heart's ventricular conduction system using fractal geometry: spectral analysis of the QRS complex.

Many biological systems having one or more characteristics that remain constant over a wide range of scales may be considered self-similar or fractal. Geometrical and functional overview of the ventricular conduction system of the heart reveals that it shares structures common to a tree with repeatedly bifurcating "branches," decreasing in length with each generation. This system may further simplify by assuming that the bifurcating and decreasing process is the same at any generation, that is, the shortening factor and the angle of bifurcation are the same for each generation. Under these assumptions, the conduction system can be described as a fractal tree. A model of the heart's ventricles which consists of muscle cells and a fractal conduction system is described. The model is activated and the dipole potential generated by adjacent activated and resting cells is calculated to obtain a QRS complex. Analysis of the frequency spectrum of the QRS complex reveals that the simulated waveforms show an enhancement in the high frequency components as generations are added to the conduction system. It was also found that the QRS complex shows a form of an inverse power law, which was predicted by the fractal depolarization hypothesis, with a highly correlated straight line for a log-power versus log frequency plot with a slope of approximately -4. Similar results were obtained using real QRS data from healthy subjects.

Computer Simulation↗
PubMedDate not supplied

Left-right asymmetry of visual evoked potentials in brain-damaged patients: a mathematical model and experimental results.

The left-right asymmetry in the potential amplitude on the scalp was studied in poststroke patients by using flash visual evoked potential (VEP) and a numerical two-dimensional model of the head. The left-right asymmetry of the VEP was measured in three patients after thrombosis, in one after hemorrhage, and in one healthy subject. The numerical model used computed tomography images to define the different compartments of the head. The volume conductor equation for the potential distribution created by a dipole source in the occipital region was solved numerically with use of a finite volume method. Left-right asymmetry was calculated with several values of conductivity of the damaged region. The experimental results revealed a negative asymmetry in the three patients after thrombosis (i.e., the potential amplitude over the ischemic hemisphere was smaller than that over the intact hemisphere), whereas, in the patient after hemorrhage, a positive asymmetry was found. Nonsignificant left-right asymmetry was found in the healthy subject. The numerical model revealed that the electrical conductivity of the damaged tissue has a major effect on the left-right asymmetry. Negative asymmetry, such as that found for patients after thrombosis, was obtained when the conductivity of the damaged region was greater than that of the brain, whereas positive asymmetry (hemorrhage patient) was obtained when that conductivity was smaller than that of the brain. This finding indicates that the left-right asymmetry in the scalp VEP of patients after brain damage may be a result of changes in the conductivity of the volume conductor (the ischemic region) between the source and the electrodes.

Cerebrovascular Disorders↗
PubMedDate not supplied

Stress, social support and well-being of Arab mothers of children with intellectual disability who are served by welfare services in northern Israel.

BACKGROUND: The present study examined the influence of a social support system on the level of stress and the sense of personal well-being of 100 Israeli Arab mothers of young children with special needs. METHODS: Fifty mothers were served by the welfare services in the Nazareth area while 50 did not get help on a regular basis. A comparison was done between educated, urban mothers, and less-educated, rural mothers. RESULTS: The research results point to a relationship between informal support resources, and the marital and economic stress of the mothers: the higher the amount of the informal support resources, the lower the level of stress that was experienced by the mothers. A relationship between the amount of informal support and level of parental stress was not confirmed. A relationship between the amount of support resources and the personal well-being of the mothers was found: the higher the amount of informal support resources, the higher the sense of well-being of the mothers. A relationship between formal support (the welfare services), and level of stress or personal well-being was not found. Education and place of living were not related to level of stress or personal well-being. Educated mothers from urban areas used the formal support (the welfare services) less than less-educated mothers who lived in rural areas. CONCLUSIONS: The findings are interpreted with respect to practice and previous studies.

Adult↗
PubMedDate not supplied

[Multicenter study of children with terminal renal failure in Lebanon].

A retrospective study was conducted in June 1997 concerning all Lebanese children with end stage renal failure. This study was able to recognize 20 children and infants (age less than 15) dialysed regularly in 8 hemodialysis centers. The other 23 centers are not following children. Thirteen children are dialysed on bicarbonate and seven on acetate. Children receive erythropoietin occasionally; 30% of them are polytransfused, 60% of them suffer from anemia. Four children have never received immunization against hepatitis B and three are seropositive for hepatitis C. None of these children has regular school attendance and psychological support for the child and his family do not exist. We conclude that the situation of children on hemodialysis in Lebanon is alarming. Solutions are possible and available; they need to be undertaken urgently.

Adolescent↗