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Ricardo Armentano

Universidad de la República (Uruguay), “Predictive and Preventive Cardiovascular Engineering Working Group”, Faculty Member

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Prof. Ricardo Armentano is a member of Member of EMBS IEEE Technical Committee on Cardiopulmonary Systems and Physiology-based Engineering. In 2019, he was conferred the IEEE R9 Eminent Engineer Award. He has served as EMBS Distinguished Lecturer, AdCom 2015 EMBS IEEE Latin America representative, and chaired the 32nd International Conference EMBC - IEEE Buenos Aires 2010. Prof. Armentano has acquired international recognition in the field of cardiovascular hemodynamics and arterial hypertension. He has 350 publications including books, book chapters and peer-reviewed articles, and is on the editorial and reviewer boards of 15 journals in the field of cardiovascular engineering.Recently, he was also selected as a Fellow of the International Academy of Medical and Biological Engineering (IAMBE). Prof. Armentano has carried out extensive academic, professional, and administrative tasks in the Americas and Europe as an educator and scientist. In his role as educator, he has designed, launched and managed 3 undergraduate and one postgraduate degree courses in Biomedical Engineering, along with a doctoral degree in signal and image processing that has been qualified with the highest categorizations in Argentina and Uruguay. For 20 years, he has served the university in several administrative posts like director of the research and development council, dean of the Faculty of Engineering, Exact and Natural Sciences, Executive Scientific Academic Director of the Favaloro University and Dr. Rene Favaloro Foundation. In his extensive academic trajectory, Prof Armentano has designed various transdisciplinary research groups, involving scientists, physicians, engineers, students and pioneered new research lines. Currently he is the Director of the UNDP Project URU/06/004 “Predictive and Preventive Cardiovascular Engineering Working Group

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Papers by Ricardo Armentano

Carotid wall viscosity decrease is related to intima-media thinning in hypertensive patients after treatment with ace inhibitor

American Journal of Hypertension, 1999

Deformable Surface Model for the Evaluation of Abdominal Aortic Aneurysms Treated with an Endovascular Sealing System

Annals of biomedical engineering, Jan 8, 2015

Rupture of abdominal aortic aneurysms (AAA) is responsible for 1-3% of all deaths among the elder... more Rupture of abdominal aortic aneurysms (AAA) is responsible for 1-3% of all deaths among the elderly population in developed countries. A novel endograft proposes an endovascular aneurysm sealing (EVAS) system that isolates the aneurysm wall from blood flow using a polymer-filled endobag that surrounds two balloon-expandable stents. The volume of injected polymer is determined by monitoring the endobag pressure but the final AAA expansion remains unknown. We conceived and developed a fully deformable surface model for the comparison of pre-operative sac lumen size and final endobag size (measured using a follow-up scan) with the volume of injected polymer. Computed tomography images were acquired for eight patients. Aneurysms were manually and automatically segmented twice by the same observer. The injected polymer volume resulted 9% higher than the aneurysm pre-operative lumen size (p < 0.05), and 11% lower than the final follow-up endobag volume (p < 0.01). The automated meth...

VELOCIDAD DE LA ONDA DE PULSO: RELEVANCIA DE LA EDAD EN NORMOTENSION, HIPERTENSION LIMITROFE E HIPERTENSION ESENCIALes

Revista argentina de cardiología

$Research paper thumbnail of Coronary arterial stiffness is related with a loss of fractal complexity in the aortic pressure$

Coronary arterial stiffness is related with a loss of fractal complexity in the aortic pressure

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012

Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pu... more Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pulsatility is associated with various common diseases of aging and hypertension. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. Arterial pressure and diameter time series were evaluated in order to assess the relationship between arterial stiffness and FD. Three Corriedale male sheep were operated. Left anterior descending artery (LAD) was dissected and the external arterial diameter was measured trough sonomicrometry. Similarly, a pressure microtransducer was positioned in the upper third of the ascending aorta. Simultaneous pressure and diameter were measured in normal state and under smooth muscle activation. Each time series FD were assessed by the application of Higuchi&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s method while arterial wall elastic modulus was evaluated by means of the pressure-strain relationship. Coronary stiffness was increased from normal state to phenylephrine state (47.32%, 21.12%, 10.87%) while aortic pressure FD was decreased (2.11%, 2.57%, 6.85%), respectively. Acute hypertension induced by phenylephrine produces an increase in the coronary wall elastic modulus with a concomitant decrease in the fractal nature of the aortic pressure, suggesting that coronary stiffening is associated with an unwrinkled aortic pressure.

Flow behavior and applicability of models for different hemodynamic states

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010

Arterial behavior analysis requires an accurate and dynamic knowledge of the stimuli and reaction... more Arterial behavior analysis requires an accurate and dynamic knowledge of the stimuli and reactions involved. Belonging parameters quantification is performed by a data acquisition process and the application of existing models. However, it turns essentially to analyze the adjustment degree of the aforementioned models in terms of the arterial tree. Blood flow behavior as well as wall shear rate and the arterial compliance are anatomic location dependent. The main objective of the present work is to analyze the existing functional relationships between arterial wall and blood flow, in a particular place (brachial artery), in order to asses the specific model applicability, in cases such Poiseuille or Womersley models. In addition, due to the characteristic of the study, gender differential dynamic responses will be evaluated.

Arterial pressure and diameter waveforms analysis by means of wavelet transform: Application to artery de-endothelization

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010

... JM Gaspoz , S. Molliex , A. Antoniadis, T. Busso , Roche F, Wavelet transform to quantify he... more

Conceptual model of arterial tree based on solitons by compartments

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014

Models define a simplification of reality, which help to understand function. The arterial system... more Models define a simplification of reality, which help to understand function. The arterial system has been modeled in many ways: lumped models, tube models and anatomically based distributed models. In this work, arterial segments were modeled as thin nonlinear elastic tubes filled with an incompressible fluid, whose governing dynamics were denoted by the Korteweg and DeVries equation. In order characterize the pressure pulse propagation, a discrete multi-segmented conduit was proposed. Arterial wall mechanical parameters were obtained from existing literature and assigned to each individual segment. The numerical model was developed starting in the aortic arch, and ending at the femoral artery. The main idea of this article was to perform a computational simulation of pressure wave propagation, considered as a solitons combination, along several segments of the arterial tree.

Pulse Wave Velocity as Marker of Preclinical Arterial Disease: Reference Levels in a Uruguayan Population Considering Wave Detection Algorithms, Path Lengths, Aging, and Blood Pressure

International Journal of Hypertension, 2012

Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evalu... more Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness; absence of standardized methodologies of study and lack of normal and reference values have limited a wider clinical implementation. This work was carried out in a Uruguayan (South American) population in order to characterize normal, reference, and threshold levels of PWV considering normal age-related changes in PWV and the prevailing blood pressure level during the study. A conservative approach was used, and we excluded symptomatic subjects; subjects with history of cardiovascular (CV) disease, diabetes mellitus or renal failure; subjects with traditional CV risk factors (other than age and gender); asymptomatic subjects with atherosclerotic plaques in carotid arteries; patients taking anti-hypertensives or lipid-lowering medications. The included subjects (n=429) were categorized according to the age decade and the blood pressure levels (at study time). Al...

Integrated Evaluation of Age-Related Changes in Structural and Functional Vascular Parameters Used to Assess Arterial Aging, Subclinical Atherosclerosis, and Cardiovascular Risk in Uruguayan Adults: CUiiDARTE Project

International Journal of Hypertension, 2011

This work was carried out in a Uruguayan (South American) population to characterize aging-associ... more This work was carried out in a Uruguayan (South American) population to characterize aging-associated physiological arterial changes. Parameters markers of subclinical atherosclerosis and that associate age-related changes were evaluated in healthy people. A conservative approach was used and people with nonphysiological and pathological conditions were excluded. Then, we excluded subjects with (a) cardiovascular (CV) symptoms, (b) CV disease, (c) diabetes mellitus or renal failure, and (d) traditional CV risk factors (other than age and gender). Subjects (n=388) were submitted to non-invasive vascular studies (gold-standard techniques), to evaluate (1) common (CCA), internal, and external carotid plaque prevalence, (2) CCA intima-media thickness and diameter, (3) CCA stiffness (percentual pulsatility, compliance, distensibility, and stiffness index), (4) aortic stiffness (carotid-femoral pulse wave velocity), and (5) peripheral and central pressure wave-derived parameters. Age grou...

Disipación energética latido a latido endotelio-dependiente en la pared arterial

Revista Brasileira de Engenharia Biomédica, 2009

Frequency Dependance of Arterial Wall Young Modulus After De-Endothelization

The aim of the present study was to determine if endothelial function could influence the complex... more The aim of the present study was to determine if endothelial function could influence the complex elastic modulus of the arterial wall. Seven ovine brachiocephalic arteries were studied in-vitro, under pulsatile flow conditions. Complex Viscoelastic Modulus (E') and Phase Angle of E' (φ) were calculated before and after de-endothelization (DE) in three frequency (f) levels within the physiological range. Values

Carotid-radial pulse wave velocity as a discriminator of intrinsic wall alterations during evaluation of endothelial function by flow-mediated dilatation

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2011

Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial f... more Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial function. However, it has been show a great inter-subject variability limiting its clinical use. Carotid-radial pulse wave velocity (PWVcr) was proposed as an alternative tool for the evaluation of endothelial function. At the present, there is no doubt that PWVcr reduces its values in response to reactive hyperemia test (RHT) in healthy subjects. a) to determine simultaneously the temporal profile of FMD, PWVcr and shear rate in response to RHT and b) to describe and analyze how subjects &quot;FMD responders&quot; or &quot;non-responders&quot; behave regards to PWVcr changes. 34 Healthy young subjects were included. The PWVcr (strain gauge mechanotransducers), brachial diameter (B-Mode ultrasound and blood flow velocity (Doppler ultrasound) were measured before (baseline) the cuff was inflated and after its deflation (5 minutes). 10(th) percentiles FMD and PWVcr changes in the population were used for the definition of the subjects (&quot;responders and non-responders&quot;). Changes in PWVcr, brachial arterial diameter and shear rate were evidenced after the cuff release (p&lt;0.05). There were differences in the PWV and FMD temporal profiles. Within &quot;FMD responders&quot; there were &quot;PWV responders and non-responders&quot;. Assessing RHT-related changes in PWVcr in the context of a FMD evaluation, could be useful as a discriminator of intrinsic wall alterations giving additional information of vascular dynamics.

Aging-related changes and reference values for the carotid intima-media thickness in a Uruguayan Population

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012

Carotid intima-media thickness (CIMT) is a well-established subclinical marker of atherosclerosis... more Carotid intima-media thickness (CIMT) is a well-established subclinical marker of atherosclerosis. Non-invasive vascular evaluation has emerged as a useful tool to aid in individual cardiovascular (CV) risk stratification and diagnose. The use of CIMT in CV risk stratification requires knowing the expected reference values for the population studied. Our aim were: a) to evaluate the relationship between aging and CIMT, b) to analyze gender and side (right vs left) related-differences in CIMT and c) to determine the CIMT reference values for an Uruguayan population taking into account aging-related CIMT changes. 367 asymptomatic subjects without known CV disease or risk factors were included in the study. Subjects were divided into six age groups. High-resolution B-mode ultrasound images of both (right and left) common carotid arteries were obtained based on the techniques and recommendations described in international consensus. No significant age-related differences in CIMT between men and women were observed. The mean left CIMT was thicker compared with right CIMT in groups 4, 5 and 6. However, there were no significant differences in those groups. The nomogram model was constructed from data base, in which the 95% confidence interval was considered. Diagnosis thresholds were determined as well. We define reference values of CIMT for our population using gold standard techniques which contributes to standard techniques which contributes to an improved insight into clinical practice and can be used routinely for evaluation.

Identifying the Principal Modes of Variation in Human Thoracic Aorta Morphology

Journal of Thoracic Imaging, 2014

$Research paper thumbnail of Arterial pressure fractality is highly dependent on wave reflection$

Arterial pressure fractality is highly dependent on wave reflection

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013

Wave reflection is an important factor that influences pressure wave morphology and becomes more ... more Wave reflection is an important factor that influences pressure wave morphology and becomes more significant with aging, when cardiovascular risk increases. A pressure wave, measured at any location in the arterial tree, can be decomposed into its forward and backward components and depends on the corresponding amplitude and shifting time delays. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. The aim of this study was to evaluate the arterial pressure and diameter time series in order to assess the relationship between wave reflection and arterial pressure fractal dimension (FD). Simultaneous aortic pressure and diameter were measured in 14 conscious dogs. A pair of ultrasonic crystals, a pressure microtransducer and a pneumatic cuff occluder were positioned in the upper third of the descending aorta. Total reflection induced by the occlusion maneuver decreased FD concomitant to the aortic stiffening. Arterial pressure fractality is highly dependent on wave reflection.

Evaluación mecánica de arterias sistémicas: análisis del rol del desacople mecánico en la génesis de vasculopatías obstructivas; Mechanical evaluation of systemic …

Prensa méd. …, 2005

Wall Viscosity of the Stented Arteries * Response

Stroke, 2004

Fractal dimension as an index of left ventricular ischaemia: a pilot study

Physiological Measurement, 2012

Myocardial perfusion is performed by the left and the right coronary arteries, which deliver bloo... more Myocardial perfusion is performed by the left and the right coronary arteries, which deliver blood to the left and right ventricles, respectively. The impairment of arterial flow supply to the cardiac muscle by disease denotes a phenomenon known as ischaemia. Previous studies have demonstrated the ability of fractal dimension (FD) value of a physiological parameter in differentiating healthy/pathological behaviours. The aim of this study consisted in quantifying the loss of ventricular thickness fractal complexity in order to determine if FD is an intrinsic marker of acute coronary ischaemia. Five mongrel dogs weighing 18.8-26.5 kg (24.4 ± 3.3, mean ± SD) were submitted to this studio. A left ventricular pressure transducer and a fluid-filled catheter for later calibration of the pressure transducer were introduced through a stab wound near the apex. Two pairs of ultrasonic microcrystals (5 MHz) for continuous wall thickness measurements were implanted at the anterior and posterior walls of the left ventricle following a previously described technique. During coronary occlusion, the ischemic wall started to thin at the very onset of relaxation (showing abnormal motility), while the normoperfused wall displayed postejective thickening. Concomitantly, posterior ventricular wall thickness and anterior wall ventricular thickness showed a significant decrease in its FD value (P &lt;0.05). In conclusion, loss of time series fractal complexity (waveform fine structure diminution or &#39;unwrinkling&#39;) constitutes a marker of the presence of an ischemic process. As a result, a single scalar value is sufficient to characterize the entire behaviour of the time series. This value manifested a similar trend compared to the most well-known clinical indices of myocardial ischaemia.

Construction of a 3D coronary map to assess geometrical information in-vivo from coronary patients

Journal of Physics: Conference Series, 2011

Stiffness Indices and Fractal Dimension relationship in Arterial Pressure and Diameter Time Series in-Vitro

Journal of Physics: Conference Series, 2011

Carotid wall viscosity decrease is related to intima-media thinning in hypertensive patients after treatment with ace inhibitor

American Journal of Hypertension, 1999

Deformable Surface Model for the Evaluation of Abdominal Aortic Aneurysms Treated with an Endovascular Sealing System

Annals of biomedical engineering, Jan 8, 2015

Rupture of abdominal aortic aneurysms (AAA) is responsible for 1-3% of all deaths among the elder... more Rupture of abdominal aortic aneurysms (AAA) is responsible for 1-3% of all deaths among the elderly population in developed countries. A novel endograft proposes an endovascular aneurysm sealing (EVAS) system that isolates the aneurysm wall from blood flow using a polymer-filled endobag that surrounds two balloon-expandable stents. The volume of injected polymer is determined by monitoring the endobag pressure but the final AAA expansion remains unknown. We conceived and developed a fully deformable surface model for the comparison of pre-operative sac lumen size and final endobag size (measured using a follow-up scan) with the volume of injected polymer. Computed tomography images were acquired for eight patients. Aneurysms were manually and automatically segmented twice by the same observer. The injected polymer volume resulted 9% higher than the aneurysm pre-operative lumen size (p < 0.05), and 11% lower than the final follow-up endobag volume (p < 0.01). The automated meth...

VELOCIDAD DE LA ONDA DE PULSO: RELEVANCIA DE LA EDAD EN NORMOTENSION, HIPERTENSION LIMITROFE E HIPERTENSION ESENCIALes

Revista argentina de cardiología

$Research paper thumbnail of Coronary arterial stiffness is related with a loss of fractal complexity in the aortic pressure$

Coronary arterial stiffness is related with a loss of fractal complexity in the aortic pressure

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012

Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pu... more Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pulsatility is associated with various common diseases of aging and hypertension. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. Arterial pressure and diameter time series were evaluated in order to assess the relationship between arterial stiffness and FD. Three Corriedale male sheep were operated. Left anterior descending artery (LAD) was dissected and the external arterial diameter was measured trough sonomicrometry. Similarly, a pressure microtransducer was positioned in the upper third of the ascending aorta. Simultaneous pressure and diameter were measured in normal state and under smooth muscle activation. Each time series FD were assessed by the application of Higuchi&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s method while arterial wall elastic modulus was evaluated by means of the pressure-strain relationship. Coronary stiffness was increased from normal state to phenylephrine state (47.32%, 21.12%, 10.87%) while aortic pressure FD was decreased (2.11%, 2.57%, 6.85%), respectively. Acute hypertension induced by phenylephrine produces an increase in the coronary wall elastic modulus with a concomitant decrease in the fractal nature of the aortic pressure, suggesting that coronary stiffening is associated with an unwrinkled aortic pressure.

Flow behavior and applicability of models for different hemodynamic states

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010

Arterial behavior analysis requires an accurate and dynamic knowledge of the stimuli and reaction... more Arterial behavior analysis requires an accurate and dynamic knowledge of the stimuli and reactions involved. Belonging parameters quantification is performed by a data acquisition process and the application of existing models. However, it turns essentially to analyze the adjustment degree of the aforementioned models in terms of the arterial tree. Blood flow behavior as well as wall shear rate and the arterial compliance are anatomic location dependent. The main objective of the present work is to analyze the existing functional relationships between arterial wall and blood flow, in a particular place (brachial artery), in order to asses the specific model applicability, in cases such Poiseuille or Womersley models. In addition, due to the characteristic of the study, gender differential dynamic responses will be evaluated.

Arterial pressure and diameter waveforms analysis by means of wavelet transform: Application to artery de-endothelization

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010

... JM Gaspoz , S. Molliex , A. Antoniadis, T. Busso , Roche F, Wavelet transform to quantify he... more

Conceptual model of arterial tree based on solitons by compartments

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014

Models define a simplification of reality, which help to understand function. The arterial system... more Models define a simplification of reality, which help to understand function. The arterial system has been modeled in many ways: lumped models, tube models and anatomically based distributed models. In this work, arterial segments were modeled as thin nonlinear elastic tubes filled with an incompressible fluid, whose governing dynamics were denoted by the Korteweg and DeVries equation. In order characterize the pressure pulse propagation, a discrete multi-segmented conduit was proposed. Arterial wall mechanical parameters were obtained from existing literature and assigned to each individual segment. The numerical model was developed starting in the aortic arch, and ending at the femoral artery. The main idea of this article was to perform a computational simulation of pressure wave propagation, considered as a solitons combination, along several segments of the arterial tree.

Pulse Wave Velocity as Marker of Preclinical Arterial Disease: Reference Levels in a Uruguayan Population Considering Wave Detection Algorithms, Path Lengths, Aging, and Blood Pressure

International Journal of Hypertension, 2012

Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evalu... more Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness; absence of standardized methodologies of study and lack of normal and reference values have limited a wider clinical implementation. This work was carried out in a Uruguayan (South American) population in order to characterize normal, reference, and threshold levels of PWV considering normal age-related changes in PWV and the prevailing blood pressure level during the study. A conservative approach was used, and we excluded symptomatic subjects; subjects with history of cardiovascular (CV) disease, diabetes mellitus or renal failure; subjects with traditional CV risk factors (other than age and gender); asymptomatic subjects with atherosclerotic plaques in carotid arteries; patients taking anti-hypertensives or lipid-lowering medications. The included subjects (n=429) were categorized according to the age decade and the blood pressure levels (at study time). Al...

Integrated Evaluation of Age-Related Changes in Structural and Functional Vascular Parameters Used to Assess Arterial Aging, Subclinical Atherosclerosis, and Cardiovascular Risk in Uruguayan Adults: CUiiDARTE Project

International Journal of Hypertension, 2011

This work was carried out in a Uruguayan (South American) population to characterize aging-associ... more This work was carried out in a Uruguayan (South American) population to characterize aging-associated physiological arterial changes. Parameters markers of subclinical atherosclerosis and that associate age-related changes were evaluated in healthy people. A conservative approach was used and people with nonphysiological and pathological conditions were excluded. Then, we excluded subjects with (a) cardiovascular (CV) symptoms, (b) CV disease, (c) diabetes mellitus or renal failure, and (d) traditional CV risk factors (other than age and gender). Subjects (n=388) were submitted to non-invasive vascular studies (gold-standard techniques), to evaluate (1) common (CCA), internal, and external carotid plaque prevalence, (2) CCA intima-media thickness and diameter, (3) CCA stiffness (percentual pulsatility, compliance, distensibility, and stiffness index), (4) aortic stiffness (carotid-femoral pulse wave velocity), and (5) peripheral and central pressure wave-derived parameters. Age grou...

Disipación energética latido a latido endotelio-dependiente en la pared arterial

Revista Brasileira de Engenharia Biomédica, 2009

Frequency Dependance of Arterial Wall Young Modulus After De-Endothelization

The aim of the present study was to determine if endothelial function could influence the complex... more The aim of the present study was to determine if endothelial function could influence the complex elastic modulus of the arterial wall. Seven ovine brachiocephalic arteries were studied in-vitro, under pulsatile flow conditions. Complex Viscoelastic Modulus (E') and Phase Angle of E' (φ) were calculated before and after de-endothelization (DE) in three frequency (f) levels within the physiological range. Values

Carotid-radial pulse wave velocity as a discriminator of intrinsic wall alterations during evaluation of endothelial function by flow-mediated dilatation

2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2011

Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial f... more Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial function. However, it has been show a great inter-subject variability limiting its clinical use. Carotid-radial pulse wave velocity (PWVcr) was proposed as an alternative tool for the evaluation of endothelial function. At the present, there is no doubt that PWVcr reduces its values in response to reactive hyperemia test (RHT) in healthy subjects. a) to determine simultaneously the temporal profile of FMD, PWVcr and shear rate in response to RHT and b) to describe and analyze how subjects &quot;FMD responders&quot; or &quot;non-responders&quot; behave regards to PWVcr changes. 34 Healthy young subjects were included. The PWVcr (strain gauge mechanotransducers), brachial diameter (B-Mode ultrasound and blood flow velocity (Doppler ultrasound) were measured before (baseline) the cuff was inflated and after its deflation (5 minutes). 10(th) percentiles FMD and PWVcr changes in the population were used for the definition of the subjects (&quot;responders and non-responders&quot;). Changes in PWVcr, brachial arterial diameter and shear rate were evidenced after the cuff release (p&lt;0.05). There were differences in the PWV and FMD temporal profiles. Within &quot;FMD responders&quot; there were &quot;PWV responders and non-responders&quot;. Assessing RHT-related changes in PWVcr in the context of a FMD evaluation, could be useful as a discriminator of intrinsic wall alterations giving additional information of vascular dynamics.

Aging-related changes and reference values for the carotid intima-media thickness in a Uruguayan Population

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012

Carotid intima-media thickness (CIMT) is a well-established subclinical marker of atherosclerosis... more Carotid intima-media thickness (CIMT) is a well-established subclinical marker of atherosclerosis. Non-invasive vascular evaluation has emerged as a useful tool to aid in individual cardiovascular (CV) risk stratification and diagnose. The use of CIMT in CV risk stratification requires knowing the expected reference values for the population studied. Our aim were: a) to evaluate the relationship between aging and CIMT, b) to analyze gender and side (right vs left) related-differences in CIMT and c) to determine the CIMT reference values for an Uruguayan population taking into account aging-related CIMT changes. 367 asymptomatic subjects without known CV disease or risk factors were included in the study. Subjects were divided into six age groups. High-resolution B-mode ultrasound images of both (right and left) common carotid arteries were obtained based on the techniques and recommendations described in international consensus. No significant age-related differences in CIMT between men and women were observed. The mean left CIMT was thicker compared with right CIMT in groups 4, 5 and 6. However, there were no significant differences in those groups. The nomogram model was constructed from data base, in which the 95% confidence interval was considered. Diagnosis thresholds were determined as well. We define reference values of CIMT for our population using gold standard techniques which contributes to standard techniques which contributes to an improved insight into clinical practice and can be used routinely for evaluation.

Identifying the Principal Modes of Variation in Human Thoracic Aorta Morphology

Journal of Thoracic Imaging, 2014

$Research paper thumbnail of Arterial pressure fractality is highly dependent on wave reflection$

Arterial pressure fractality is highly dependent on wave reflection

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013

Wave reflection is an important factor that influences pressure wave morphology and becomes more ... more Wave reflection is an important factor that influences pressure wave morphology and becomes more significant with aging, when cardiovascular risk increases. A pressure wave, measured at any location in the arterial tree, can be decomposed into its forward and backward components and depends on the corresponding amplitude and shifting time delays. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. The aim of this study was to evaluate the arterial pressure and diameter time series in order to assess the relationship between wave reflection and arterial pressure fractal dimension (FD). Simultaneous aortic pressure and diameter were measured in 14 conscious dogs. A pair of ultrasonic crystals, a pressure microtransducer and a pneumatic cuff occluder were positioned in the upper third of the descending aorta. Total reflection induced by the occlusion maneuver decreased FD concomitant to the aortic stiffening. Arterial pressure fractality is highly dependent on wave reflection.

Evaluación mecánica de arterias sistémicas: análisis del rol del desacople mecánico en la génesis de vasculopatías obstructivas; Mechanical evaluation of systemic …

Prensa méd. …, 2005

Wall Viscosity of the Stented Arteries * Response

Stroke, 2004

Fractal dimension as an index of left ventricular ischaemia: a pilot study

Physiological Measurement, 2012

Myocardial perfusion is performed by the left and the right coronary arteries, which deliver bloo... more Myocardial perfusion is performed by the left and the right coronary arteries, which deliver blood to the left and right ventricles, respectively. The impairment of arterial flow supply to the cardiac muscle by disease denotes a phenomenon known as ischaemia. Previous studies have demonstrated the ability of fractal dimension (FD) value of a physiological parameter in differentiating healthy/pathological behaviours. The aim of this study consisted in quantifying the loss of ventricular thickness fractal complexity in order to determine if FD is an intrinsic marker of acute coronary ischaemia. Five mongrel dogs weighing 18.8-26.5 kg (24.4 ± 3.3, mean ± SD) were submitted to this studio. A left ventricular pressure transducer and a fluid-filled catheter for later calibration of the pressure transducer were introduced through a stab wound near the apex. Two pairs of ultrasonic microcrystals (5 MHz) for continuous wall thickness measurements were implanted at the anterior and posterior walls of the left ventricle following a previously described technique. During coronary occlusion, the ischemic wall started to thin at the very onset of relaxation (showing abnormal motility), while the normoperfused wall displayed postejective thickening. Concomitantly, posterior ventricular wall thickness and anterior wall ventricular thickness showed a significant decrease in its FD value (P &lt;0.05). In conclusion, loss of time series fractal complexity (waveform fine structure diminution or &#39;unwrinkling&#39;) constitutes a marker of the presence of an ischemic process. As a result, a single scalar value is sufficient to characterize the entire behaviour of the time series. This value manifested a similar trend compared to the most well-known clinical indices of myocardial ischaemia.

Construction of a 3D coronary map to assess geometrical information in-vivo from coronary patients

Journal of Physics: Conference Series, 2011

Stiffness Indices and Fractal Dimension relationship in Arterial Pressure and Diameter Time Series in-Vitro

Journal of Physics: Conference Series, 2011