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PubMed1994

Relationship between diabetic autonomic neuropathy and peripheral neuropathy as assessed by power spectral analysis of heart rate variations and vibratory perception thresholds.

To investigate the relationship between diabetic autonomic and peripheral neuropathies, we carried out power spectral analysis (PSA) of heart rate variations and determined the vibratory perception threshold (VPT) in diabetic subjects (DM). The VPT, measured with a Suzuki-Matsuoka Vibrometer (SMV-5), was greater in diabetic subjects than in controls. The low frequency (LF) component of the PSA which represents sympathetic nervous activity and the high frequency (HF) component of the PSA which indicates parasympathetic nervous activity were significantly decreased in diabetic subjects when compared to values in the controls. In addition, there were significant inverse correlations between the LF and HF components of the PSA of heart rate variations and the VPT. These results suggest that the PSA of heart rate variations and the measurement of VPT are useful tools for evaluating diabetic autonomic and peripheral neuropathies.

Autonomic Nervous System↗
PubMedDate not supplied

[Spectral analysis of normal subjects and cardiac patients in relation to the age (author's transl)].

A statistical study has been performed on E.E.G. spectral analysis of control subjects and cardiac patients. This work has confirmed that the cerebral activity was slightly different in relation to the age. These modifications concern alpha frequencies, and also delta, thêta and bêta energies. In cardiac patients, these changes occurred earlier than in control subjects, but the evolution is different in relation to the pathology.

Adult↗
PubMed1980

Waveform and spectral analysis of crackles.

Crackles were recorded from six patients, four with tuberculosis and two with chronic bronchitis. It was observed by waveform and spectral analysis that most of the frequency components of a crackle were limited within a range of 0.1 to 1 kHz. Characteristically, waveforms of crackles were separable into two segments, initial "starting segments" and subsequent "decay segments." It is suggested that the former represents a shock wave caused by an abrupt opening of the airway and that the latter is a damped sinusoid caused by this shock wave exciting a resonator in the lung. It is speculated that the starting segment is determined by the pressure ratio at the site of the airway opening, and the decay segment by the resonant frequency and the quality factor of the resonator. Because transmission of a crackle is highly directional the waveforms recorded on the chest wall are modified by the positional relationship between the sound source and the microphone.

Bronchitis↗
PubMed1991

Autonomic nervous system and cardiovascular variability in rats: a spectral analysis approach.

Mechanisms underlying systolic (SBP) and diastolic (DBP) blood pressure and heart rate (HR) beat-to-beat variability were investigated using spectral analysis in conscious genetically normotensive (LN) and hypertensive (LH) adult rats from the Lyon strains. In LN rats, basal SBP, DBP, and HR spectra exhibited peaks in low (LF: 0.38-0.45 Hz) and high (HF: 1.04-1.13 Hz) frequencies. The LF peak of SBP, and even more of DBP, could be attributed to the influence of the sympathetic nervous system as it disappeared after destruction of the sympathetic nerves or a combined alpha- and beta-adrenoceptor blockade, whereas it was higher after blockade of the parasympathetic system. The HF peak of HR, linked to the respiratory rate, was abolished by the parasympathetic system blockade, whereas those of SBP and DBP were enhanced. In LH rats, which exhibit a lower sympathetic activity, the LF peaks of SBP and DBP were less distinct compared with LN controls. We conclude that the LF peak of DBP and the HF peak of HR are likely to represent useful estimates of the sympathetic vascular control and of the parasympathetic cardiac control, respectively.

Angiotensin Receptor Antagonists↗
PubMed2002

[Spectral analysis of cardiac rhythm as an indicator of the autonomic cardiovascular regulation].

AIM: To study cardiovascular function at rest and during exercise by spectral analysis of heart rhythm in patients with spinal osteochondrosis and cardialgia, in patients with excessive body weight, and with cardial type neurocirculatory dystonia (NCD). MATERIAL AND METHODS: A total of 223 patients were examined. Spinal osteochondrosis with cardialgia was diagnosed in 80, excessive body weight in 78, and cardial type NCD in 65. Heart rhythm wave structure was evaluated using VKK-12 Ergometer complex before and after bicycle ergometry. RESULTS: Submaximal exercise did not induce changes in the heart rhythm wave structure of normal subjects. In cardial type NCD the intensity of first order slow waves increased during the recovery period, while in patients with spinal osteochondrosis and cardialgia and in those with excessive body weight, heart rhythm centralization index increased.

Adolescent↗
PubMed1986

[Average spectral analysis of the voice. A comparison between the normal voice and the voice altered by various categories of laryngeal pathology].

Long-time spectral analysis shows a highly significant difference between a sample of normal voices, a sample of voices of nodule- and polyp-carriers, and a sample of voices of small malignant lesion-carriers. Schematically, pathologic voices due to lesions of the vocal folds have a relative excess of noise in the high part of the spectrum (6-10 kHz), but, in cases of small malignancy, this high-frequency noise also extends to the region 4-6 kHz. No clear difference appears between spectra of voices from nodule-carriers and voices of polyp-carriers. A standardized, phonetically selected text, seems to improve the discrimination power.

Adult↗
PubMed2005

Comparison of fast Fourier transform and autoregressive spectral analysis for the study of heart rate variability in diabetic patients.

INTRODUCTION: Impaired heart rate variability (HRV) is associated with poor outcome in diabetic patients. The present prospective study compared spectral components of HRV obtained by either fast Fourier transform (FFT) or autoregressive (AR) analyses in diabetic patients. METHODS: Thirty patients (49+/-12 years; 11 F/19 M; 60% with insulin-dependent type 1 diabetes) underwent 24-h ambulatory electrocardiographic recordings which comprised a 10-min resting period at the onset (n=30) and end (n=12) of the monitoring. Spectral analysis was applied to 5-min sequences at rest, and the total power and power spectra integrated over the very low (VLF), low (LF), and high (HF) frequency bands were obtained. RESULTS: Fifteen patients had moderately depressed HRV and two patients had highly depressed HRV (standard deviation of the RR intervals over 24-h<100 ms and <50 ms, respectively). Both raw data and ln-transformed data were significantly different between FFT and AR. All spectra component were obtained in each patient using FFT. Using AR, the LF/HF ratio could not be estimated or was zero in 4 and 11 patients, respectively. The AR results were more sensitive than FFT results to minor changes (+/-5%) in the timing of the onset of analysis. The day-to-day reproducibility of FFT was better than that of AR. Finally, using FFT, the LF/HF ratio, LFnu, and HFnu were essentially redundant (nu=normalized units). CONCLUSIONS: The spectral components of short-term HRV calculated by using the FFT and AR methods were not interchangeable and FFT analysis must be preferred in diabetic patients.

Adult↗
PubMed2005

Spectral analysis of cerebellar activity after acute brain injury in anesthetized rats.

We investigated cerebellar electrocortical activity before and after unilateral brain injury in anesthetized rats. Spectral analysis of cerebellar activity was obtained by Fast Fourier Transformation. There was a dominance of delta frequency range, while the wide gamma range presented no more than 5% of the total mean power spectra of cerebellar activity before brain injury. A few minutes after brain injury and within the first 90 minutes, there was a decrease of total mean power spectra and a relative decrease of delta range power to about 30%, some increase of beta range, and an increase of gamma range to 20-25%. Relative increase of gamma range in the cerebellar mean power spectra was still present 120 min after the brain injury, while other changes started to diminish. We suggest that spectral changes within slow and fast (gamma) frequency ranges of cerebellar activity may be indicators of the brain state after acute injury.

Anesthesia↗
PubMed1993

Spectral analysis and modelling of ACh and NE effects on shark nervus terminalis activity.

We investigated the effects of acetylcholine (ACh) and norepinephrine (NE) on activity in the nervus terminalis (NT) ganglion of the bonnethead shark (Sphyrna tiburo) using an in vitro preparation and whole nerve recordings. Spectral analysis indicated that ACh (10 and 100 microM) had a variable effect on the total spectral power of whole nerve activity but produced a consistent decrease in half power frequency (HPF; the median frequency of the power spectrum). Norepinephrine (10 microM) reduced baseline activity and total spectral power but produced an increase in HPF in all NT preparations. Computer simulations of extracellular recordings suggested a general explanation for these findings. Acetylcholine may have opposite effects on activity in two NT cell populations with axons in the central nerve trunk, increasing activity in cells whose axons have broad spikes (low spectral frequency) and decreasing activity in cells whose axons have narrow spikes (high spectral frequency). The NE effects are consistent with a decrease in activity of cells whose axons have broad spikes (low spectral frequency) and little or no change in cells whose axons have narrow spikes (high spectral frequency). The physiological data, together with the theoretical analysis, suggest that cholinergic and catecholaminergic neurotransmitter systems are active in the bonnethead NT ganglion, and that ACh and NE have different effects on two populations of ganglion cells.

Acetylcholine↗
PubMed1989

Longitudinal EEG spectral analysis in early stage of Alzheimer's disease.

Twenty-four patients with mild to moderate Alzheimer's disease (AD) were studied using quantitative spectral analysis of EEG at the time of the diagnosis and 1 year later. In 50% of the patients EEG spectra from the T6-O2 derivation were either normal or mildly abnormal at baseline and did not change at 1 year. In another half of the patients the mean quantitative EEG variables (the alpha and the delta power and the mean frequency) deteriorated significantly when baseline and 1 year values were compared. The patient groups with deteriorating and stable EEGs did not differ in age, sex, age at onset or duration of the disease or clinical severity at baseline or at 1 year. Dementia also progressed significantly in both subgroups of AD patients. We conclude that even if the mean values of quantitative EEG variables analysed from the T6-O2 derivation showed distinct slowing at the time of the AD diagnosis and further deterioration 1 year later, in 50% of these early AD cases there was no EEG alteration or worsening in 1 year follow-up, suggesting heterogeneity of the disease.

Aged↗
PubMed1991

Slow-wave activity in the spectral analysis of the electroencephalogram is associated with cortical dysfunctions in patients with Alzheimer's disease.

Cortical functions and slow-wave activity in the spectral analysis of the electroencephalogram (EEG) have been studied in 19 patients with Alzheimer's disease (AD), 18 patients with Parkinson's disease with dementia (PD), and 14 control subjects (C) to determine which functions are explained by their relationship of slow-wave activity. Multiple regression analyses revealed that a variance in visual functions, praxia of the hand, automatic speech, speech understanding, and retrieval from semantic memory were explained by their relationship with slow-wave activity in EEG in the AD group but not in the PD or C groups. The PD and AD groups exhibited equal cortical dysfunctions and mean amplitudes of delta activity in EEG. The cholinergic system, disrupted in AD, has been shown to be important in the regulation of neocortical electrical activity and may be associated with the processing of cortical functions.

Aged↗
PubMedDate not supplied

Imaging the carotid bifurcation using continuous-wave Doppler-shift ultrasound and spectral analysis.

A non-invasive method is described for visualizing the carotid bifurcation using a continuous-wave Doppler-shift technique simultaneously with spectral analysis of the blood velocities from all parts of the vessel lumen. The system is directional so that arteries can be visualized in the presence of signals from adjacent veins. The technique uses a transducer which is attached to a position-sensing arm so that the position of the ultrasound beam on the neck, when sensing arterial blood flow-velocities, can be translated onto a storage oscilloscope. By repeated passes of the transducer across the vessel lumen a 2 dimensional image of the carotid bifurcation is formed. As each image point is marked, the full spectrum of blood-velocities corresponding to that position is continuously displayed on a second oscilloscope beside the image scope. Ultrasound images are compared with arteriograms and both continuous-wave and pulsed Doppler ultrasound imaging systems are discussed.

Adult↗
PubMed2005

A spectral analysis of the myoelectric activity of the left colon in patients with schistosomiasis mansoni.

The objective of the present study was to perform a spectral analysis of the electrical activity of the left colon of patients with hepatosplenic schistosomiasis. Thirty patients were studied, divided into 2 groups: group A was composed of 14 patients (9 males and 5 females) with hepatosplenic schistosomiasis and group B was composed of 16 female patients without schistosomiasis mansoni. Three pairs of electrodes were implanted in the left colon at the moment of the surgical treatment. The signals of the electric activity of the colon were captured after postoperative recovery from the ileus and fed into a computer by means of a DATAQ data collection system which identified and captured frequencies between 0.02 and 10 Hz. Data were recorded, stored and analyzed using the WINDAQ 200 software. For electrical analysis, the average voltage of the electrical wave in the three electrodes of all patients, expressed as millivolts (mV), was considered, together with the maximum and minimum values, the root mean square (RMS), the skewness, and the results of the fast Fourier transforms. The average RMS of the schistosomiasis mansoni patients was 284.007 mV. During a long period of contraction, the RMS increased in a statistically significant manner from 127.455 mV during a resting period to 748.959 mV in patients with schistosomiasis mansoni. We conclude that there were no statistically significant differences in RMS values between patients with schistosomiasis mansoni and patients without the disease during the rest period or during a long period of contraction.

Adult↗
PubMed1986

Doppler spectral analysis of the internal carotid before and after endarterectomy.

In 37 randomly selected patients, stenosis of the internal carotid artery was evaluated with Doppler spectral analysis before and 6-10 weeks after endarterectomy. Postoperatively 20 of the vessels were entirely within the normal variation range and four, though not normal, showed significantly lower blood flow velocity, indicating wider vascular lumen. In ten cases there were no significant postoperative change, and in three significant worsening of the Doppler shift was seen without clinical implications. The method is useful for evaluating the endarterectomized carotid noninvasively without use of contrast medium, and when bilateral operation is contemplated the analysis is most valuable for ruling out occlusion in the artery first operated on.

Aged↗
PubMed1976

A real-time software system on the PDP-11 for two-channel EEG spectral analysis during surgery.

Three functions are performed in real time by a stand-alone PDP-11-assembly language program. First two channels of EEG data are acquired by quantization techniques; second spectral analysis of the EEG data is carried out; third the resulting spectra are displayed as time compressed spectral profiles on an X-Y plotter. The method provides EEG time trends during anesthesia, permitting evaluation of brain functions.

Anesthesia, General↗
PubMed1975

Spectral analysis of the abnormal theta rhythm in the EEG of young children.

The abnormal theta rhythm of the EEG of early childhood was investigated by spectral analysis. The pattern in the power spectrum is characterized by a peak in the thetaband. The relative peak intensity (peak ratio = ratio of peak intensity and average intensity of the spectrum within the frequency range of 0--10 Hz) as well as the right-left coherence proved to be good criteria for the description of the abnormal theta rhythms. When the ratio q greater than or equal to 2.0 and the coherence Coh greater than or equal to 0.7 an abnormal theta rhythm can be considered to be present. When this definition is applied, a high correspondence between the mathematical and visual evaluation of the EEG is present. The abnormal theta rhythm must be regarded as a symptom of a functional anomaly which is -- under electroencephalographic aspects -- characterized by generators acting in abnormal synchronism and monofrequency.

Brain Diseases↗
PubMed1995

Assessment of training-induced autonomic adaptations in athletes with spectral analysis of cardiovascular variability signals.

The purpose of this study was to assess the adaptive effects of endurance training on autonomic functions in athletes with spectral analysis of cardiovascular variability signals. Continuous ECG, arterial blood pressure (ABP), and respiratory signals were recorded from 15 athletes (VO2max > 55 ml/(kg.min)) and 15 nonathletes (VO2max < 45 ml/(kg.min)) in the sitting position during controlled respiration (tidal volume 700 ml and 15 cycles/min). The autonomic functions were assessed by the normalized low-frequency power (LF power: 0.06-0.14 Hz) and high-frequency power (HF power: the region of the respiratory frequency based on respiratory spectrum) obtained from the autospectra of the RR interval, systolic arterial pressure (SAP), and diastolic arterial pressure (DAP) variability signals. The spontaneous baroreflex sensitivity (BRS) was evaluated by the moduli, BRSLF and BRSHF, of the transfer function between the RR interval and SAP variability in LF and HF bands. The resting HR in athletes was significantly lower than that in nonathletes. In the case of RR interval spectra, the HF power was significantly higher in athletes than in nonathletes, whereas the LF power was significantly lower in athletes than in nonahtletes. These differences might reflect an alteration of sympathovagal interaction with a predominance of parasympathetic activity. However, there was no significant difference in the LF power of SAP and DAP autospectra, reflecting the sympathetic vascular control. The BRSLF and BRSHF were significantly higher in athletes as compared with nonathletes. These results indicate that endurance training induces autonomic imbalance (i.e., the enhanced vagal activities/the attenuated sympathetic tone), which may in part contribute to the resting bradycardia and an increase in the spontaneous BRS in athletes.

Adaptation, Physiological↗
PubMed1995

A new approach for detecting the position of retinal vessels and calculating their diameter on the basis of dynamic spectral analysis.

Fast adaptive algorithms were used for the detection of retinal vessels and for pre-processing the signals. By using different methods of dynamic spectral analysis, the local frequency of the vessels was determined. On this basis a method of calculating the diameters of the vessels was constructed; it is robust in relation to disturbances in the domain of the edges.

Algorithms↗