Duplex-scanning of the deep venous drainage in the evaluation of blood flow velocity of the cerebral vascular system in infants

Three dimensional blood flow in a truncated vascular system is investigated numerically using a commercially available finite element analysis and simulation software. The vascular system considered in this study has three levels of symmetric bifurcation. Geometric parameters for daughter vessels, such as their diameters and their angles of bifurcation, are specified according to Murray’s law based on the principle of minimum work. The ratio of blood vessel length to diameter is based upon experimental data found in the literature. An experimentally obtained velocity profile, available in the literature, is used as the inlet boundary condition. An outflow boundary model, consisting of a contraction tube to represent the pressure drop of the small arteries, arterioles, and capillaries that would follow the truncated vascular system, is used to specify the boundary condition at the eight outlets. The results show that although the blood flow velocity experiences a sudden decrease after the bifurcation points due to the higher total cross-sectional area of the daughter vessels as compared to the parent vessel, this decrease in velocity is partially recovered due to the tapering of the blood vessels as they approach the next bifurcation point. The results also show that the secondary flow which is typical after the bifurcation of large arteries does not develop after the bifurcation of small arteries due to the presence of laminar blood flow with very low Reynolds number in the small arteries. The numerical model yields pressure distributions and pressure drops along the vascular system that agree quite well with the physiological data found in the literature. Finally, the results show that, immediately following a bifurcation, the blood flow velocity profile is not symmetrical about the longitudinal axes of blood vessel. However, symmetry is recovered as the blood flow proceeds down the vessel.

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Effects of nicardipine on cerebral vascular responses to hypocapnia and blood flow velocity in the middle cerebral artery.

Stroke ◽

10.1161/01.str.22.9.1170 ◽

1991 ◽

Vol 22 (9) ◽

pp. 1170-1172 ◽

Cited By ~ 20

Author(s):

M Kawaguchi ◽

H Furuya ◽

K Kurehara ◽

M Yamada

Keyword(s):

Blood Flow ◽

Middle Cerebral Artery ◽

Flow Velocity ◽

Cerebral Artery ◽

Blood Flow Velocity ◽

Vascular Responses ◽

Cerebral Vascular

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The principle of adequate blood supply to tissues: one of postulates in the G.A. Ilizarov`s teaching

ZHurnal «Patologicheskaia fiziologiia i eksperimental`naia terapiia» ◽

10.25557/0031-2991.2018.03.44-48 ◽

2018 ◽

pp. 44-48

Author(s):

В.А. Щуров

Keyword(s):

Blood Flow ◽

Flow Velocity ◽

Blood Supply ◽

Blood Flow Velocity ◽

Vascular System ◽

Capillary Blood ◽

Functional Adaptation ◽

Capillary Blood Flow ◽

Locomotor System ◽

Age Related

Цель исследования - расширить существующее представление об адекватности кровоснабжения тканей: оценить соответствие количества притекающей крови энергетическим потребностям тканей, резервы функциональной адаптации сосудистого русла для функциональной устойчивости органов и возможность подстройки интенсивности метаболизма тканей под возможности системы микроциркуляции. Методика. Исследован магистральный и капиллярный кровоток (окклюзионная плетизмография, ультразвуковая допплерография, полярография, лазерная флоуметрия) у здоровых людей (157 чел.) и различных групп больных в возрасте от 5 до 70 лет (620) с травмами костей и ортопедическими заболеваниями голени в процессе лечения по Илизарову. Результаты. Обнаружено, что с увеличением возраста у здоровых и больных обследуемых снижается скорость кровотока по сосудам бедра и по средней мозговой артерии при сохранении функциональных резервов сосудистого русла, выявляемых с помощью ишемических или нагрузочных проб. Заключение. Адекватность кровоснабжения предполагает не только соответствие скорости кровотока потребностям органов, но и сохранение при этом резерва функциональной адаптации сосудистой системы, а также возрастное ограничение функциональных способностей органов движения при снижении возможностей сосудистой системы. The aim of the study was to expand the existing concept on the adequacy of blood supply as an exact correlation of the amount of delivered blood with energy demands of the tissue; to evaluate reserves of functional adaptation of the vasculature for functional stability of organs; and to assess the capability of tissue metabolism for adjusting to potentialities of the microcirculation. Methods. Conduit vessel and capillary blood flow (occlusion plethysmography, Doppler ultrasound, polarography, laser flowmetry) was studied in healthy subjects (n=157) and different groups of patients aged 5-70 years (620) with bone injuries and orthopedic diseases of the lower leg during the treatment according to Ilizarov. Results. Maximum values of blood flow in main limb arteries were not reached at maximum and average values of capillary blood flow, which were different for different groups of patients. With increasing age, the blood flow velocity in femoral blood vessels and middle cerebral artery decreased while the vasculature functional reserve was maintained as evidenced by ischemic or loading tests. Conclusion. The adequacy of blood supply involves not only matching the blood flow velocity to demands of organs but also maintaining the adaptive reserve of vasculature function as well as the age-related limitation of functional capability of the locomotor system when the vascular system function declines.

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State of cerebral circulation in neurosensoral deaf in combination stable voltage stenocardia

Russian otorhinolaryngology ◽

10.18692/1810-4800-2021-6-20-25 ◽

2021 ◽

Vol 20 (6) ◽

pp. 20-25

Author(s):

S. S. Arifov ◽

◽

D. А. Каlandarova ◽

Keyword(s):

Blood Flow ◽

Hearing Loss ◽

Sensorineural Hearing Loss ◽

Flow Velocity ◽

Blood Flow Velocity ◽

Cerebral Circulation ◽

Sensorineural Hearing ◽

Duplex Scanning ◽

Exertional Angina ◽

Antianginal Drugs

The aim of this study was to study the state of cerebral circulation using duplex scanning of extra- and intracranial vessels in sensorineural hearing loss in combination with stable exertional angina. The study included 43 patients with diagnosed sensorineural hearing loss in combination with stable exertional angina at the age of 30 to 63 years, who had not previously received antianginal drugs. With the help of color duplex scanning, cerebral circulation in the extra- and intracranial vessels was studied. 19 people (44,2%) had the first degree, and 16 people (37,2%) had the second degree of hearing loss. In 9,3% of cases, the average air conduction rate in patients did not reach 26 dB. In 9,3% of patients, an increase in thresholds was observed only in the ultra-high-frequency zone (10 000–20 000 Hz). In patients with sensorineural hearing loss in combination with stable exertional angina, there was a change in the linear blood flow velocity in the extra- and intracranial vessels. In the common carotid and vertebral arteries, an increase in the linear blood flow velocity and the Gosling pulsative index was revealed. In the intracranial segment, a decrease in the linear velocity of blood flow in the vertebral and main arteries was found, which in 42% of patients was combined with a decrease in the anatomical reserve of blood vessels due to a disconnected variant of the structure of the circle of Willis and / or the presence of obstructed venous outflow.

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Hemodynamic parameters in the central retinal artery in active retinopathy of prematurity and their relationship with the central retinal vein

Fyodorov journal of ophthalmic surgery ◽

10.25276/0235-4160-2021-4-21-29 ◽

2021 ◽

pp. 21-29

Author(s):

I.G. Trifanenkova ◽

◽

A.V. Tereshchenko ◽

E.V. Erohina ◽

◽

...

Keyword(s):

Blood Flow ◽

Flow Velocity ◽

Retinopathy Of Prematurity ◽

Blood Flow Velocity ◽

Central Retinal Artery ◽

Duplex Scanning ◽

Subsequent Stage ◽

Hemodynamic Parameters ◽

Retinal Artery ◽

Central Retinal Vein

Purpose. To analyze the main hemodynamic parameters in the central retinal artery, as well as their relationship with hemodynamic indicators in the central retinal vein, depending on the stage and type of active ROP with the use of color duplex scanning. Material and methods. The 63 premature babies with various stages of active ROP and no signs of ROP were included in the study. The 55 children with active ROP included in the study were distributed according to the stages and type of disease course. All children were at the same gestational age at the time of examination – 37–38 weeks of postmenstrual age or at 6–11 weeks of life. For all these children were performed color duplex scanning of the vessels of the eye and orbit in the modes of color Doppler mapping and pulsed Doppler. Results. The study of the hemodynamic features of the central retinal artery in premature infants with active ROP showed that the progression of the disease was accompanied by a significant increase in blood flow velocity (Vsyst and Vdiast) with each subsequent stage of ROP. A higher index of peripheral vascular resistance is recorded in comparison with the non-progressive favorable type for children with an unfavorable course of the disease.The analysis of the ratio of the maximum blood flow velocities in the central retinal artery and central retinal vein made it possible to determine in which of the vessels the hemodynamic changes are most pronounced, depending on the stage and form of active ROP. Conclusion. Thus, there are statistically significant changes in such large vessels of the retinal bed as the central retinal artery and central retinal vein during active ROP. Color duplex scanning, having a significant diagnostic potential in assessing hemodynamic parameters, made it possible to obtain reliable information about the linear blood flow velocity and the state of peripheral resistance in the central retinal artery and their relationship with the central retinal vein. This information opens up prospects for improving the accuracy of predicting the nature of the course of the disease, especially i n the early stages. Keywords: color duplex scanning, active retinopathy of prematurity, hemodynamic parameters, central retinal artery, central retinal vein

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DIAGNOSTICS OF THE ELASTIC PROPERTIES OF THE VASCULAR WALL AND BLOOD FLOW VELOCITY BY ACOUSTIC METHODS

Problems of Strength and Plasticity ◽

10.32326/1814-9146-2021-83-4-379-390 ◽

2021 ◽

Vol 83 (4) ◽

pp. 379-390

Author(s):

T.S. Vikulova ◽

I.N. Didenkulov ◽

N.V. Pronchatov-Rubtsov ◽

D.V. Sakharov

Keyword(s):

Blood Flow ◽

Velocity Distribution ◽

Flow Velocity ◽

Cross Section ◽

Blood Flow Velocity ◽

Vessel Wall ◽

Cardiac Cycle ◽

Vascular System ◽

Vascular Wall ◽

Nonlinear Acoustic

The stiffness of the vascular wall and blood flow velocity are the most important characteristics of the vascular system, which largely determine the state of health of the body. For measuring blood flow velocity, the spectral Doppler method has become widespread, which makes it possible to determine the blood velocity in a vessel, including by the shape of the Doppler spectrum – the velocity distribution in the section of large vessels. However, blood particles scattering ultrasound – erythrocytes are strongly deformed in the flow and are unevenly distributed over the cross section of the vessel. More accurate information about the velocity distribution over the cross section can be obtained by the nonlinear Doppler method, which uses microbubbles – contrast agents – as scatterers. The method is based on the generation of difference frequency waves by microbubbles when they are irradiated with two high-frequency waves having different but close frequencies.Theoretical and experimental results are presented that demonstrate the capabilities and advantages of the nonlinear acoustic difference frequency method for measuring blood flow parameters. The method makes it possible to analyze the spatio-temporal dynamics of blood flow in blood vessels during the cardiac cycle: contraction (systole) – relaxation (diastole), which makes it possible to detect violations in the bloodstream. The possibilities of determining the elasticity of the blood vessel wall have been analyzed. The method used in practice is based on measuring the speed of the pulse wave and finding the Young's modulus of the vessel wall using the Moens–Korteweg formula.To assess the stiffness of the wall of blood vessels, it is proposed to combine a nonlinear acoustic method for measuring the distribution of blood flow velocity and scanning a vessel during the cardiac cycle on the basis of a single set of ultrasound transducers. The considered methods make it possible to carry out a comprehensive diagnosis of the state of various vessels and the vascular system as a whole.

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