Prof. Dr. Aristotle G. Koutsiaris
Faculty of Medicine, University of Thessaly, Larissa, Greece
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Academic Career Length
29Years (1998-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications1 September 2007 in Biorheology
Journal Article
Aristotle G. KoutsiarisSTSophia V. Tachmitzi
Sophia V. Tachmitzi
NBNick Batis
Nick Batis
MKMaria G. Kotoula
Maria G. Kotoula
CKConstantinos H. Karabatsas
Constantinos H. Karabatsas
DCDimitrios Z. Chatzoulis
Dimitrios Z. Chatzoulis
+1
Understanding the mathematical relationships of volume blood flow and wall shear stress with respect to microvessel diameter is necessary for the study of vascular design. Here, for the first time, volume flow and wall shear stress were quantified from axial red blood cell velocity measurements in 104 conjunctival microvessels of 17 normal human volunteers. Measurements were taken with a slit lamp based imaging system from the post capillary side of the bulbar conjunctiva in microvessel diameters ranging from 4 to 24 micrometers. The variation of the velocity profile with diameter was taken into account by using a profile factor function. Volume flow ranged from 5 to 462 pl/s with a mean value of 102 pl/s and gave a second power law best fitting line (r=0.97) deviating significantly from the third power law relation with diameter. The estimated wall shear stress declined hyperbolically (r=0.93) from a maximum of 9.55 N/m 2 at the smallest capillaries, down to a minimum of 0.28 N/m 2 at the higher diameter post capillary venules. The mean wall shear stress value for all microvessels was 1.54 N/m 2 .
1 January 2013 in Microvascular Research
Journal Article
Aristotle G. KoutsiarisSTSophia V. Tachmitzi
Sophia V. Tachmitzi
NBNick Batis
Nick Batis
1 September 2010 in Microvascular Research
Journal Article
Aristotle G. KoutsiarisSTSophia V. Tachmitzi
Sophia V. Tachmitzi
PPPeriklis Papavasileiou
Periklis Papavasileiou
NBNick Batis
Nick Batis
MKMaria G. Kotoula
Maria G. Kotoula
ETEvagelia Tsironi
Evagelia Tsironi
+1
30 September 1999 in Measurement Science and Technology
Journal Article
Aristotle G. KoutsiarisDMDimitris S Mathioulakis
Dimitris S Mathioulakis
STSokrates Tsangaris
Sokrates Tsangaris
25 September 2015 in Clinical Hemorheology and Microcirculation
Journal Article
Aristotle G. KoutsiarisWall shear stress (WSS) is a very important hemodynamic parameter implicated in many physiological and pathological phenomena. In order to study these phenomena, it is more convenient to use in vitro models before testing on animals and humans. Dynamic in vitro cerebrovascular models are considered capable of simulating the in vivo hemodynamic conditions, but only few of them seem to meet the criteria for this task. It is now clear that in the human eye microcirculation a significant pulsation exists at the pre-capillary arterioles with average WSS values more than twice those in the venular side, for the same diameters. WSS heterogeneity is in support of segmental heterogeneity i.e. the endothelial phenotypic and functional difference among arterioles, capillaries and venules. In this review paper, the importance of WSS is described in detail and two more microvascular segments are proposed: a pre-capillary arteriolar and a post-capillary venular segment. The accurate hemodynamic simulation in all microvascular segments seems to be a prerequisite step in the development of dynamic in vitro blood brain barrier (BBB) models and microfluidic platforms on chip. Endothelial cells in the cardiovascular system seem to have sophisticated role acting like cardiovascular processing sensors (CPSs).
7 November 2003 in Physiological Measurement
Journal Article
Aristotle G. KoutsiarisAPAphroditi Pogiatzi
Aphroditi Pogiatzi
The axial red blood cell velocity pulse was quantified throughout its period by a high-speed video microscopy method, using images of erythrocytes moving near the microvessel axis. In 10 mesenteric precapillary arterioles (8 to 12 microm in diameter) from six rabbits, axial velocities ranged from 0.46 (the minimum of all the end diastolic values) to 4.8 mm s(-1) (the maximum of all the peak systolic values). With the velocity pulse shape properly quantified, a correct estimation of the average velocity over time can be made and hence, appropriate quantification of blood flow. Average velocity ranged between 1.14 mm s(-1) (8 microm arterioles) and 1.98 mm s(-1) (9 microm arterioles). Also, with the velocity pulse shape known, an estimation of the magnitude of the pulsation can be made by introducing Pourcelot's resistive index (RI) in the microvascular haemodynamics (diameter less than 15 microm). The results of this study reveal that RI in the precapillary arterioles is quite high ranging between 0.56 (8 microm arterioles) and 0.74 (12 microm arterioles). Observing the velocity pulse diagrams in different diameters, quantitative information is obtained for the first time on how the velocity pulse shape flattens as it proceeds to the capillary bed.
About Me
Dr. Aristotle G. Koutsiaris is currently a member of the Academic Staff of the Faculty of Medicine of the University of Thessaly, Greece. He has a Diploma (Dipl. Eng.) in Electrical and Computer Engineering (Aristotle University of Thessaloniki), an M.Sc. (University of Dundee), and a PhD (NTUA & University of Patras) in Biomedical Engineering. He has more than 20 years of post-PhD teaching experience at prominent Greek institutions, including the National Technical University of Athens, the University of Athens Medical School, the Technological Educational Institute (HTEI) of Thessaly, and the University of Thessaly. In addition, he has served for more than 10 years as a member of the General Assembly of various departments and participated in numerous academic elections and institutional committees. His research interests include hemodynamics, microcirculation, biofluid dynamics, hemorheology, blood vessels, biomedical imaging/bio-microscopy (both in vitro and in vivo), biomedical informatics and devices, and artificial intelligence. Aristole G. Koutsiaris has authored more than 30 international peer-reviewed journal papers (introducing 4 equations to model microvascular phenomena), contributed to international scientific books/chapters (plus editing an applied informatics text), and is an active reviewer for more than 30 international scientific journals.