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At least 109 records · Page 6Linked to original sources
PubMed1991

Validity of catheter-tip Doppler technique in assessment of coronary flow velocity and application of spectrum analysis method.

Measurement of coronary flow velocity in clinical cases contributes to understanding the pathophysiology of coronary circulation. To determine absolute coronary flow velocity, coronary blood flow was assessed with an end-mounted Doppler catheter (3Fr, 20 MHz), which was combined with a custom-designed fast-Fourier transformation analysis system. In vitro study using model circuit, actual flow velocity (8 to 96 cm/s) was well correlated with that determined by this catheter system (y = 1.01 X +1.5, r = 0.988). In a clinical study of 12 patients with normal coronary arteriograms, the Doppler catheter was positioned at the proximal left anterior descending artery. Clear flow velocity patterns, which consisted of predominant diastolic components and preceding small systolic components, were obtained in all cases. The peak flow velocity was 17 +/- 8 cm/s (mean +/- standard deviation) during systole and 44 +/- 12 cm/s during diastole in this portion. In 5 patients, the great cardiac vein flow, which reflects the left anterior descending artery flow, was simultaneously measured during rapid atrial pacing. During pacing, percent increases in flow velocity were well correlated with those in great cardiac vein flow (y = 0.90 x +6.4, r = 0.935). These results indicate that catheter-tip Doppler technique with fast-Fourier transformation analysis may be useful in quantitatively determining coronary flow velocity in clinical cases.

Aged↗
PubMedDate not supplied

[Detection and quantification of carotid atheroma. Respective value of vascular ultrasonography, spectrum analysis and digital intravenous angiography].

This retrospective study involved 37 subjects who were examined by means of intravenous digitalised angiography, vascular ultrasonography and spectral analysis of the Doppler signal. The last two examinations were found to give the most precise images and functional information. The concordances between angiography and ultrasonography on the one hand and spectral analysis on the other were 82 and 90 per cent. The authors have established a protocol in order to limit and systematize these examinations during screening for carotid atheroma: the risk factors are weighted; a score is obtained by summation; depending on the value of this score and the patient's age, the investigation procedure is pursued or not. The sequence always consists of ultrasonography followed by spectral analysis when plaque is detected and by angiography when the plaque is stenotic or ulcerated. In symptomatic patients, ultrasonography and digitalised angiography are performed routinely.

Arteriosclerosis↗
PubMedDate not supplied

Regression of uveal malignant melanomas following cobalt-60 plaque. Correlates between acoustic spectrum analysis and tumor regression.

Parameters derived from computer analysis of digital radio-frequency (rf) ultrasound scan data of untreated uveal malignant melanomas were examined for correlations with tumor regression following cobalt-60 plaque. Parameters included tumor height, normalized power spectrum and acoustic tissue type (ATT). Acoustic tissue type was based upon discriminant analysis of tumor power spectra, with spectra of tumors of known pathology serving as a model. Results showed ATT to be correlated with tumor regression during the first 18 months following treatment. Tumors with ATT associated with spindle cell malignant melanoma showed over twice the percentage reduction in height as those with ATT associated with mixed/epithelioid melanomas. Pre-treatment height was only weakly correlated with regression. Additionally, significant spectral changes were observed following treatment. Ultrasonic spectrum analysis thus provides a noninvasive tool for classification, prediction and monitoring of tumor response to cobalt-60 plaque.

Cobalt Radioisotopes↗
PubMed1989

[Spectrum analysis of blood pressure and cardiac rate in the conscious rat].

Intrafemoral pulsatile blood pressure of conscious rats was computed to generate evenly spaced signals (systolic, diastolic, mean blood pressure, heart rate) at 200 ms intervals. This equidistant sampling allowed a direct spectral analysis using a Fast Fourier Transform algorithm. Systolic blood pressure and heart rate exhibited low frequency oscillations (Mayer waves, 20-605 mHz) and a high frequency peak related to respiration (1,765 mHz). The diastolic blood pressure and the mean blood pressure only exhibited low frequency oscillations. This procedure could be useful to analyze the various components of blood pressure variability.

Analysis of Variance↗