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PubMed1979

Detection of carotid occlusive disease by ultrasonic imaging and pulsed Doppler spectrum analysis.

Ultrasonic imaging of the cervical carotid arteries by ultrasonic arteriography and duplex scanning combined with pulsed Doppler spectrum analysis were investigated in a series of patients undergoing arteriography. By using the ultrasonic image as a guide for precise placement of the pulsed Doppler sample volume, the characteristics of blood flow at points of interest in the carotid arteries could be determined. Audible analysis of the Doppler signal permitted correct diagnosis of 23 of 26 (88%) high-grade stenoses or occlusions with ultrasonic arteriography and 24 of 26 (92%) with duplex scanning. Spectrum analysis of Doppler signals obtained with the duplex scanner detected all of the 22 high-grade stenoses. Spectral abnormalities of a lesser degree also were detected in 18 of 23 vessels (78%) with atherosclerotic plaques which should not have reduced cerebral blood flow. These techniques permit the accurate detection of and the distinction between high-grade stenoses and occlusion, as well as the identification of many plaques which are not large enough to affect intracranial hemodynamics.

Arterial Occlusive Diseases↗

PubMed1979

A comparison of EEG activity in the left and right cerebral hemispheres by power-spectrum analysis during language and non-language tasks.

In 10 female subjects, power-spectrum analysis was performed on the alpha activity elicted during the resting state, 4 right hemispheric tasks, and 3 left hemispheric tasks. The data were treated in 3 ways: approach 1, comparing the right and left hemispheric alpha activity; approach 2, comparing the right and left hemispheric alpha activity adjusted for the resting state; and approach 3, comparing the right and left hemispheric alpha activity adjusted for the previous task. Approaches 1 and 2 revealed few significant differences in the alpha activity of the hemispheres, but approach 3 provided data that better fit the theory of decreased power spectrum of attenuation of activity in the activated hemisphere. Thus, approach 3 may be useful in developing an electroencephalographic test for determining cerebral dominance for language.

Adult↗

PubMed1992

[Modification of the sympatho-vagal interaction in mitral valve prolapse syndrome. Evaluation of heart rate variability by spectrum analysis].

To determine whether clinical manifestations in patients with mitral valve prolapse (MVP) are associated with altered sympatho-vagal tone, 46 patients (mean age 27 +/- 6, range 20-45 years; 18 males and 28 females) were studied by power spectrum analysis of RR variability. Patients were divided in 2 groups, according to echocardiographic criteria: Group A: 11 patients with classical MVP; Group B: 35 patients with non classical MVP. These patients were compared with 30 healthy subjects (Group C) well matched for age, body surface area and heart rate. Our findings indicate that at rest there is a significant difference in the high-frequency component between Group A and Group C. Similarly, during the increase in sympathetic activity induced by 70 degrees head-up tilt all groups showed an increase in the low-frequency component, that was more evident in Group A. The data generated from our laboratory suggest that mitral regurgitation (Group A) is a probable cause of vagal tone increase and that there is an adaptive long-term mechanism towards sympathetic conditions. In addition, probably the normalization, demonstrable by the effect of sympathetic activity in tilt, can mask a dysfunction that may be differently evoked.

Adult↗

PubMed1978

Spectrum analysis of transient phenomena of the left ventricular pressure.

The application of "real time" spectrum analysis to left ventricular pressure during transient phenomena is described. Transient phenomena generated by the injection of drugs (norepinephrine-isoproterenol), anoxia and occlusion of aorta and carotids show sudden changes in the frequency of heart contraction. Propranolol stabilizes the heart rate in similar circumstances.

Animals↗

PubMed1976