Cerebral blood supply with aging: Normal, stenotic and recanalized☆
Introduction
It is well known, that cerebral circulation during aging is endangered by the development of atherosclerosis and by a decreasing driving force due to disturbances of cardiac output. To compensate for this lifelong gradual degradation of cerebral supply the resistance vessels in the brain gradually diminish their vasomotor tonus and thus preserve a relatively constant perfusion. Nevertheless the vasomotor reserve capacity is being gradually exhausted and the brain is less effectively protected against acute fluctuations in cardiovascular parameters.
One of the most important parameters of cerebral blood supply is the easy to access blood flow velocity in cervical arteries. To deepen our knowledge of its behavior in simple aging, in stenotic carotid processes and after recanalization by means of endarterectomy or stenting we have carried out Doppler ultrasonographic measurements in 3 groups of patients.
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Subjects and methods
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To study blood flow velocities in healthy aging we have collected data of 199 patients for analysis of carotid arteries (mean age 58.15 years, range 21–92, 83 males) and data of 200 persons for analysis of vertebral arteries (mean age 62.32, range 20–85 years, 101 males). Excluded were patients with any stenotic changes, malformations or conspicuous alterations in the vascular wall. Diffuse discrete atherosclerotic signs like slightly increased intimomedial thickness or minute calcified plaques
CCA velocities
The average PSV 0.62 m/s comes from a broad spectrum of individual values, ranging between 0.17 and 1.39 m/s. The mean EDV 0.13 m/s ranges in individual persons between 0 and 0.38 m/s. Zero end diastolic velocities have been found on each side in less than 3% of the patients.
ICA velocities
The PSV is in average 0.73 m/s ranging between 0.23 and 1.49 m/s. EDV of 0.24 m/s in average ranges between 0 and 0.55 m/s. The zero EDV values were encountered only in 2% of all instances.
ECA velocities
The average PSV 0.79 m/s ranges
Discussion
Our bilateral blood flow velocity measurements in several segments of the carotid system on the neck have brought quite consistent results in 3 different cohorts of patients. The 3 studies disregard observations in individual persons, which would be of course much different in particular haemodynamic arrangements. Our averaged data in the cohorts allow to describe rather general tendencies in driving forces of the blood flow.
We were attracted by the proportion of blood flow velocities in the
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This paper has been supported by a research project grant no. 0021620816 of the Czech Ministry of Education.