Collective methods of propulsion and steering for untethered microscale nanorobots navigating in the human vascular network

2010 ◽  
Vol 224 (7) ◽  
pp. 1505-1513 ◽  
Author(s):  
S Martel
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Human Body ◽  
Interventional Procedures ◽  
Vascular Network ◽  
Single Type ◽  
Tumour Targeting ◽  
Miniature Robots ◽  
Medical Diagnostic ◽  
Blood Flow Velocities

In the field of medical nanorobotics, nanometre-scale components and phenomena are exploited within the context of robotics to provide new medical diagnostic and interventional procedures, or at least to enhance the existing ones. The best route for such miniature robots to access various regions inside the human body is certainly the vascular network. Such a network is made of nearly 100 000 km of blood vessels varying in diameters from a few millimetres in the arteries down to ∼ 4 μm in the capillaries with respective important variations in blood flow velocities. When injected in the blood circulatory network using existing modern techniques such as catheterization, such robots must travel from larger-diameter vessels before reaching much tinier capillaries. As such, the use of a single type of microscale robots capable of travelling in various environments and conditions related to such different blood vessels while being trackable by an external system seems, at the present time, inconceivable. Therefore, as explained in this article, an approach based on the use of several types of microscale robots with complementary methods of propulsion and steering capable of operating in a collective manner is more likely to achieve better results. This is especially true for interventions such as direct tumour targeting where the tiniest blood vessels such as the ones found in the angiogenesis network must be travelled.

Microfluidics of blood in blood vessels stenosis

2016 ◽  
Vol 11 (2) ◽  
pp. 210-217 ◽  
Author(s):  
A.T. Akhmetov ◽  
A.A. Valiev ◽  
A.A. Rakhimov ◽  
S.P. Sametov ◽  
R.R. Habibullina
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Hydraulic Resistance ◽  
Microfluidic Device ◽  
Human Body ◽  
Vascular System ◽  
Hydrodynamic Conditions ◽  
Microstructure Change ◽  
Healthy Part

It is mentioned in the paper that hydrodynamic conditions of a flow in blood vessels with the stenosis are abnormal in relation to the total hemodynamic conditions of blood flow in a vascular system of a human body. A microfluidic device developed with a stepped narrowing for studying of the blood flow at abnormal conditions allowed to reveal blood structure in microchannels simulating the stenosis. Microstructure change is observed during the flow of both native and diluted blood through the narrowing. The study of hemorheological properties allowed us to determine an increasing contribution of the hydraulic resistance of the healthy part of the vessel during the stenosis formation.

scholarly journals Treatment of Vasculitis: Beyond the Basics

2020 ◽  
Author(s):  
Muhammad Ishaq Ghauri ◽  
Muhammad Shariq Mukarram
Keyword(s):  
Blood Flow ◽  
Mycophenolate Mofetil ◽  
Blood Vessels ◽  
Human Body ◽  
Systemic Vasculitis ◽  
Organ Damage ◽  
Biological Agents ◽  
Cytotoxic Agents ◽  
Is Failure ◽  
Primary Vasculitis

Vasculitis is the inflammation of blood vessels in the human body. It causes changes and remodeling in the walls of the vessels that include thickening, narrowing and scarring. As a result, the blood flow to the organs and tissues gets restricted leading to organ damage. The cause of primary vasculitis is not known; however, most cases are thought to be autoimmune. In the present era, it is getting difficult to treat vasculitis with conventional therapies, which includes cyclophosphamide, methotrexate, azathioprine and mycophenolate mofetil, with increasing rates of relapses. Since ever, corticosteroids and cytotoxic agents or immunosuppressants have been the mainstay for treating systemic vasculitis. However, the introduction of newer biological agents have bring about a revolution in the treatment of relapses and in cases where there is failure to induce and sustain remission.

Geometrical Models of Vertebral Arteries and Numerical Simulations of the Blood Flow Through Them

2008 ◽  
Author(s):  
Krzysztof Jozwik ◽  
Damian Obidowski
Keyword(s):  
Blood Flow ◽  
Numerical Simulations ◽  
Blood Vessels ◽  
Human Body ◽  
Special Kind ◽  
3D Models ◽  
Vertebral Arteries ◽  
The Individual ◽  
Physical Phenomena ◽  
The Brain

Vertebral arteries are a system of two blood vessels through which blood is carried to the rear region of the brain. This region of the human body has to be very well supplied with blood, without any breaks or deficiencies in the blood flow. Blood is delivered to the brain through carotid arteries as well. All these arteries are connected to the circle of Willis, which has to fulfill all demands of the human brain as far as the blood flow is concerned. However, vertebral arteries due to their position and shape are a special kind of blood vessels. They originate at various distances from the aortic ostium, may branch off at different angles, have various length, inner diameter and spatial shape. Three different geometries of vertebral arteries, which most frequently occur in the human body structure, have been chosen, and for each twenty five various combinations of artery inner diameters have been used to generate 3D models of these arteries. For seventy five different models thus created, the numerical simulations have been performed. The results obtained have indicated explicitly that differences in the flow and instantaneous velocity values in vertebral arteries and in the point they join to form the basilar artery do not result from pathological changes in the artery system, but may follow from physical phenomena that occur in arteries as a consequence of the pulsating character of the flow and the unique geometry, which is related to the individual human anatomical structure.

Innervation of endoneurial microvessels in human sural nerve

1992 ◽  
Vol 50 (1) ◽  
pp. 920-921
Author(s):  
John L. Beggs ◽  
Peter C. Johnson ◽  
Astrid G. Olafsen ◽  
C. Jane Watkins
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Blood Supply ◽  
Peripheral Nerves ◽  
Sural Nerve ◽  
Nerve Fibers ◽  
Arterial Supply ◽  
Autonomic Nerve ◽  
Vasa Nervorum ◽  
Endoneurial Blood Flow

The blood supply (vasa nervorum) to peripheral nerves is composed of an interconnected dual circulation. The endoneurium of nerve fascicles is maintained by the intrinsic circulation which is composed of microvessels primarily of capillary caliber. Transperineurial arterioles link the intrinsic circulation with the extrinsic arterial supply located in the epineurium. Blood flow in the vasa nervorum is neurogenically influenced (1,2). Although a recent hypothesis proposes that endoneurial blood flow is controlled by the action of autonomic nerve fibers associated with epineurial arterioles (2), our recent studies (3) show that in addition to epineurial arterioles other segments of the vasa nervorum are also innervated. In this study, we examine blood vessels of the endoneurium for possible innervation.

Patterns of Cerebral Blood Flow and Systemic Hemodynamics During Arithmetic Processing

2008 ◽  
Vol 22 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Natalie Werner ◽  
Neval Kapan ◽  
Gustavo A. Reyes del Paso
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Time Course ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Systemic Hemodynamics ◽  
Heart Period ◽  
Blood Flow Velocities ◽  
Flow Velocities

The present study explored modulations in cerebral blood flow and systemic hemodynamics during the execution of a mental calculation task in 41 healthy subjects. Time course and lateralization of blood flow velocities in the medial cerebral arteries of both hemispheres were assessed using functional transcranial Doppler sonography. Indices of systemic hemodynamics were obtained using continuous blood pressure recordings. Doppler sonography revealed a biphasic left dominant rise in cerebral blood flow velocities during task execution. Systemic blood pressure increased, whereas heart period, heart period variability, and baroreflex sensitivity declined. Blood pressure and heart period proved predictive of the magnitude of the cerebral blood flow response, particularly of its initial component. Various physiological mechanisms may be assumed to be involved in cardiovascular adjustment to cognitive demands. While specific contributions of the sympathetic and parasympathetic systems may account for the observed pattern of systemic hemodynamics, flow metabolism coupling, fast neurogenic vasodilation, and cerebral autoregulation may be involved in mediating cerebral blood flow modulations. Furthermore, during conditions of high cardiovascular reactivity, systemic hemodynamic changes exert a marked influence on cerebral blood perfusion.

COMPARISON OF ANTIHYPERTENSIVE EFFECT OF MOXONIDINE VERSUS CLONIDINE IN RENAL FAILURE PATIENTS.

2018 ◽  
Vol 6 (9) ◽  
Author(s):  
DR.MATHEW GEORGE ◽  
DR.LINCY JOSEPH ◽  
MRS.DEEPTHI MATHEW ◽  
ALISHA MARIA SHAJI ◽  
BIJI JOSEPH ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renal Failure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Blood Vessels ◽  
High Blood Pressure ◽  
Antihypertensive Effect ◽  
The Body ◽  
Ability To Work ◽  
Blood Flows

Blood pressure is the force of blood pushing against blood vessel walls as the heart pumps out blood, and high blood pressure, also called hypertension, is an increase in the amount of force that blood places on blood vessels as it moves through the body. Factors that can increase this force include higher blood volume due to extra fluid in the blood and blood vessels that are narrow, stiff, or clogged(1). High blood pressure can damage blood vessels in the kidneys, reducing their ability to work properly. When the force of blood flow is high, blood vessels stretch so blood flows more easily. Eventually, this stretching scars and weakens blood vessels throughout the body, including those in the kidneys.

scholarly journals Effect of positioning from supine and left lateral positions to left lateral tilt on maternal blood flow velocities and waveforms in full-term parturients

Anaesthesia ◽  
2012 ◽  
Vol 67 (8) ◽  
pp. 936-936 ◽  
Author(s):  
P. Kundra ◽  
J. Velraj ◽  
U. Amirthalingam ◽  
S. Habeebullah ◽  
K. Yuvaraj ◽  
...  
Keyword(s):  
Blood Flow ◽  
Maternal Blood ◽  
Full Term ◽  
Lateral Tilt ◽  
Blood Flow Velocities ◽  
Flow Velocities
Sign in / Sign up

Export Citation Format

Share Document