37 results on '"Cabrera-Fischer E"'
Search Results
2. Adventitia-dependent mechanical properties of brachiocephalic ovine arteries in in vivo and in vitro studies
- Author
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Cabrera Fischer, E. I., Bia, D., Camus, J. M., Zócalo, Y., de Forteza, E., and Armentano, R. L.
- Published
- 2006
3. P6.20: Vascular Accesses for Haemodialysis in the Arm Cause Greater Reduction in the Carotid-Brachial Stiffness Than Those in the Forearm: Study of Gender Differences
- Author
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Bia, D., Cabrera-Fischer, E. I., Zócalo, Y., Galli, C., Graf, S., Valtuille, R., Pérez, H., Saldías, M., Álvarez, I., and Armentano, R. L.
- Published
- 2011
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4. Increased reversal and oscillatory shear stress cause smooth muscle contraction‐dependent changes in sheep aortic dynamics: role in aortic balloon pump circulatory support
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Bia, D., primary, Zócalo, Y., additional, Armentano, R., additional, Camus, J., additional, Forteza, E. de, additional, and Cabrera‐Fischer, E., additional
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- 2007
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5. ISOBARIC PULSE VISCOELASTIC MAPPING REVEALS REGIONAL FUNCTIONAL DIFFERENCES IN MAJOR SYSTEMIC ARTERIES
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Bia, D., primary, Barra, J. G., additional, Craiem, D., additional, Aguirre, I., additional, Zocalo, Y., additional, Devera, L., additional, Cabrera-Fischer, E. I., additional, and Armentano, R. L., additional
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- 2004
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6. Acute increase in reversal blood flow during counterpulsation is associated with vasoconstriction and changes in the aortic mechanics.
- Author
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Bia, D., Zocalo, Y., Armentano, R., de Forteza, E., and Cabrera-Fischer, E.
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- 2007
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7. In vivo angiotensin II receptor blockade and converting enzyme inhibition on canine aortic viscoelasticity
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Barra, J. G., primary, Levenson, J., additional, Armentano, R. L., additional, Cabrera Fischer, E. I., additional, Pichel, R. H., additional, and Simon, A., additional
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- 1997
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8. Paradoxically decreased aortic wall stiffness in response to vitamin D3-induced calcinosis. A biphasic analysis of segmental elastic properties in conscious dogs.
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Cabrera Fischer, E I, primary, Armentano, R L, additional, Levenson, J, additional, Barra, J G, additional, Morales, M C, additional, Breitbart, G J, additional, Pichel, R H, additional, and Simon, A, additional
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- 1991
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9. Inconsistency of the slope and the volume intercept of the end-systolic pressure-volume relationship as individual indexes of inotropic state in conscious dogs: presentation of an index combining both variables.
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Crottogini, A J, primary, Willshaw, P, additional, Barra, J G, additional, Armentano, R, additional, Cabrera Fischer, E I, additional, and Pichel, R H, additional
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- 1987
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10. Assessment of Intra-Aortic Counterpulsation in an Animal Model of Heart Failure and Myocardial Ischemia.
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Wray S, Lascano E, Negroni J, and Cabrera Fischer E
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- Animals, Aorta, Cardiac Output, Disease Models, Animal, Heart Failure etiology, Humans, Intra-Aortic Balloon Pumping instrumentation, Male, Myocardial Ischemia etiology, Sheep, Treatment Outcome, Heart Failure surgery, Intra-Aortic Balloon Pumping methods, Myocardial Ischemia surgery
- Abstract
The effectiveness of intra-aortic balloon pumping (IABP) is currently evaluated using indirect indexes. The diastolic pressure augmentation is quantified using the subendocardial viability ratio (SEVR) and the DABAC/SABAC index (areas beneath the aortic pressure-time signals during the diastolic and systolic periods, respectively). The SEVR requires invasive recordings of left ventricular pressure; the DABAC/SABAC index may represent an alternative, since it only requires an aortic pressure signal. Nonetheless, it has never been used in an animal model of counterpulsated heart failure and ischemia-reperfusion episode. The aims of this work were: (i) to develop an animal model of heart failure, with a myocardial ischemia-reperfusion episode, treated with IABP during the reperfusion period; (ii) to evaluate the effects of the IABP using the SEVR and DABAC/SABAC indices; and (iii) to assess the relationship between both ratios. Cardiovascular parameters were obtained in anesthetized sheep, in which induced heart failure and ischemia-reperfusion episodes were monitored with and without IABP 1:2. Systolic and diastolic blood pressure signals were assessed in the aorta and in the left ventricle. Values of cardiac output and left ventricular wall thickness signals were obtained. Induction of ischemia and heart failure determined decreases in SEVR and DABAC/SABAC indices with respect to their basal stage (0.807 ± 0.118 vs. 0.601 ± 0.107, P < 0.05 and 1.062 ± 0.136 vs. 0.902 ± 0.161, P < 0.05, respectively). Counterpulsated animals whose myocardial reperfusion was accompanied by heart failure showed a significant improvement of wall thickening fraction along time (R
2 = 0.7627, P < 0.001). During counterpulsated heart failure accompanied by myocardial reperfusion, the SEVR was positively correlated with DABAC/SABAC index., (© 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)- Published
- 2019
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11. Reference intervals and percentile curve for left ventricular outflow tract (LVOT), velocity time integral (VTI), and LVOT-VTI-derived hemodynamic parameters in healthy children and adolescents: Analysis of echocardiographic methods association and agreement.
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Díaz A, Zócalo Y, Cabrera-Fischer E, and Bia D
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- Adolescent, Adult, Child, Child, Preschool, Female, Follow-Up Studies, Humans, Male, ROC Curve, Reference Values, Retrospective Studies, Young Adult, Blood Flow Velocity physiology, Cardiac Output physiology, Echocardiography, Doppler, Pulsed methods, Heart Ventricles diagnostic imaging, Ventricular Function, Left physiology
- Abstract
Background: Echocardiographic reference intervals (RIs) for left ventricular outflow tract (LVOT) and velocity time integral (VTI) are scarce in pediatrics., Aims: (a) to generate RIs and percentiles for LVOT, VTI, and hemodynamic variables in healthy children and adolescents from Argentina; (b) to analyze the equivalence between stroke volume (SV), cardiac output (CO), and cardiac index (CI) obtained from two-dimensional echocardiography (2D) and LVOT-VTI analysis with pulsed wave Doppler (PWD); and (c) to analyze the association between subjects' characteristics and VTI and LVOT-VTI-derived parameters., Methods: Two-dimensional and PWD studies were done in 385 subjects (5-24 years). Mean and standard deviation age-related and body surface area (BSA)-related equations were obtained for VTI and LVOT-VTI-derived parameters (parametric regression methods based on fractional polynomials). BSA- and age-specific percentiles were determined., Results: Pulsed wave Doppler- and 2D-derived parameters were positively correlated. However, PWD values were always lower than those from 2D. Specific RIs for PWD and 2D data were necessary. Covariance analysis showed that sex-specific RIs were required for LVOT, but not for VTI, VTI-derived CO and CI. Age-related RIs were obtained for LVOT, LVOT-VTI, and VTI-derived CO and CI. BSA-related RIs for VTI-derived CO and CI were obtained., Conclusions: Stroke volume, CO, and CI data from 2D and PWD are not equivalent. An accurate analysis of LVOT-VTI-derived parameters requires considering age and BSA. In this study, age- and BSA-related RIs and percentiles for LVOT, VTI, and hemodynamic parameters in healthy children and adolescents were determined, discriminating data according to the methodological approach (2D or PWD)., (© 2018 Wiley Periodicals, Inc.)
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- 2018
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12. Reference Intervals of Central Aortic Blood Pressure and Augmentation Index Assessed with an Oscillometric Device in Healthy Children, Adolescents, and Young Adults from Argentina.
- Author
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Diaz A, Zócalo Y, Bia D, and Cabrera Fischer E
- Abstract
Age-related reference intervals (RIs) of central (aortic) systolic blood pressure (cSBP) and augmentation index (cAIx) obtained from large healthy population are lacking in Argentina (South America). Aims. To analyze the existence of associations among cSBP and cAIx with demographic, anthropometric, and hemodynamic parameters and to generate percentile curves and RIs adjusted to each level of age and gender and/or body height. cSBP and cAIx were measured in 1038 healthy children, adolescents, and young adults. First, we evaluated if RIs for males and females were necessary using correlation and covariate analysis. Second, mean (M) and standard deviation (SD) age-related equations were obtained for cSBP and cAIx, using parametric regression methods based on fractional polynomials. Third, age specific percentiles curves were generated. Fourth, body height specific percentiles curves were generated using a similar procedure. The obtained equations (considering age as independent variable) for all subjects (cSBP
0.26 and (cAIx + 12.001)0.5 ) were as follows: cSBP Mean = 3.0581 + 0.2189 log(Age) - 0.001044Age; cSBP SD = -0.03919 + 0.1535 log(Age) - 0.004564Age; cAIx mean = 9.5226 - 6.1599 log(Age) + 0.1450Age; cAIx SD = 1.3880 - 0.8468 log(Age) + 0.03212Age. This study, performed in Argentinean healthy children, adolescents, and young adults with ages of 5 to 22 years, provides the first RIs and percentile curves of cSBP and cAIx. Additionally, specific body height-related cAIx percentiles are reported for the analyzed population. The RIs and percentiles contribute to the knowledge of arterial dynamic evolution along the normal aging process and the interpretation of data obtained in clinical research and daily clinical practice.- Published
- 2018
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13. Carotid Intima Media Thickness Reference Intervals for a Healthy Argentinean Population Aged 11-81 Years.
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Diaz A, Bia D, Zócalo Y, Manterola H, Larrabide I, Lo Vercio L, Del Fresno M, and Cabrera Fischer E
- Abstract
Reference intervals (RIs) of carotid intima media thickness (CIMT) from large healthy population are still lacking in Latin America. The aim of this study was to determine CIMT RIs in a cohort of 1012 healthy subjects from Argentina. We evaluated if RIs for males and females and for left and right carotids were necessary. Second, mean and standard deviation (SD) age-related equations were obtained for left, right, and average (left + right)/2) CIMT using parametric regression methods based on fractional polynomials, in order to obtain age-specific percentiles curves. Age-specific percentile curves were obtained. Males showed higher A-CIMT (0.577 ± 0.003 mm versus 0.566 ± 0.004 mm, P = 0.039) in comparison with females. For males, the equations were as follows: A-CIMT mean = 0.42 + 8.14 × 10
-5 ⁎Age2 ; A-CIMT SD = 5.9 × 10-2 + 1.09 × 10-5 ⁎Age2 . For females, they were as follows: A-CIMT mean = 0.40 + 8.20 × 10-5 ⁎Age2 ; A-CIMT SD = 4.67 × 10-2 + 1.63 × 10-5 ⁎Age2 . Our study provides the largest database concerning RIs of CIMT in healthy people in Argentina. Specific RIs and percentiles of CIMT for children, adolescents, and adults are now available according to age and gender, for right and left common carotid arteries.- Published
- 2018
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14. Arterial Stiffness in Haemodialyzed Patients: Findings and Controversies.
- Author
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Cabrera-Fischer E, Zocalo Y, Wray S, and Bia D
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- Animals, Arteries physiopathology, Cardiovascular Diseases diagnosis, Cardiovascular Diseases mortality, Cardiovascular Diseases therapy, Humans, Kidney Failure, Chronic diagnosis, Kidney Failure, Chronic mortality, Kidney Failure, Chronic physiopathology, Risk Assessment, Risk Factors, Treatment Outcome, Water-Electrolyte Balance, Arteries surgery, Arteriovenous Shunt, Surgical adverse effects, Arteriovenous Shunt, Surgical mortality, Cardiovascular Diseases physiopathology, Kidney Failure, Chronic therapy, Models, Cardiovascular, Renal Dialysis adverse effects, Renal Dialysis mortality, Upper Extremity blood supply, Vascular Stiffness
- Abstract
Vascular research in end-stage renal diseases is an interesting field in which the characterization of arterial stiffness proved to be valuable to predict morbidity and mortality. Particularly, patients on renal replacement therapy have been reported to have significant increases in arterial stiffness and cardiovascular mortality. The clinical relevance of the measurement of arterial stiffness is linked to therapeutical and preventive interventions. The purpose of this work is to analyze the results of the scientific research in the field of arterial stiffness, in which hemodialyzed patients were involved, emphasizing on clinical and in-vitro research carried out by our group compared to contributions previously reported in the specialized literature. These investigations are necessary to improve diagnostic strategies and monitor the arterial response to therapeutical interventions in chronic kidney disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)
- Published
- 2018
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15. Aortic-Radial Pulse Wave Velocity Ratio in End-stage Renal Disease Patients: Association with Age, Body Tissue Hydration Status, Renal Failure Etiology and Five Years of Hemodialysis.
- Author
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Bia D, Valtuille R, Galli C, Wray S, Armentano R, Zócalo Y, and Cabrera-Fischer E
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- Age Factors, Aged, Blood Pressure, Body Composition, Case-Control Studies, Cross-Sectional Studies, Diabetic Nephropathies diagnosis, Diabetic Nephropathies etiology, Diabetic Nephropathies physiopathology, Electric Impedance, Female, Humans, Kidney Failure, Chronic diagnosis, Kidney Failure, Chronic etiology, Kidney Failure, Chronic physiopathology, Male, Middle Aged, Predictive Value of Tests, Risk Factors, Time Factors, Treatment Outcome, Water-Electrolyte Balance, Aorta physiopathology, Diabetic Nephropathies therapy, Kidney Failure, Chronic therapy, Pulse Wave Analysis, Radial Artery physiopathology, Renal Dialysis adverse effects, Vascular Stiffness
- Abstract
Introduction: The etiology of the end-stage renal disease (ESRD) and the hydration status may be involved in the arterial stiffening process observed in hemodialyzed patients. The ratio between carotid-femoral and carotid-radial pulse wave velocity (PWV ratio) was recently proposed to characterize the patient-specific stiffening process., Aims: to analyze: (1) the PWV-ratio in healthy and hemodialyzed subjects, analyzing potential changes associated to etiologies of the ESRD, (2) the PWV-ratio and hydration status using multiple-frequency bioimpedance and, (3) the effects of hemodialysis on PWV-ratio in a 5-year follow-up., Methods: PWV-ratio was evaluated in 151 patients differentiated by the pathology determining their ESRD. Total body fluid (TBF), intra and extra cellular fluid (ICF, ECF) were measured in 65 of these patients using bioelectrical-impedance. The association between arterial, hemodynamic or fluid parameters was analyzed. PWV-ratio was evaluated in a group of patients (n = 25) 5 years later (follow-up study)., Results: PWV-ratio increased in the ESRD cohort with respect to the control group (1.03 ± 0.23 vs. 1.31 ± 0.37; p < 0.001). PWV-ratio in the diabetic nephropathy group was higher than in all other etiological groups (1.61 ± 0.33; p < 0.05). PWV-ratio was associated with TBF (r = -0.238; p < 0.05), ICF (r = -0.323; p < 0.01), ECF/ICF (r = 0.400; p < 0.001) and ECF/TBF (r = 0.403; p < 0.001). PWV-ratio calculated in ESRD patients in 2007 increased 5 years later (1.14 ± 0.32 vs. 1.43 ± 0.44; p < 0.005)., Conclusions: PWV-ratio increased the most in patients with diabetic nephropathy. PWV ratio was significantly associated with age and body hydration status, but not with the blood pressure. PWV-ratio could be considered a blood pressure-independent parameter, associated with the age and hydration status of the patient.
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- 2017
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16. Hemodialysis Decreases the Etiologically-Related Early Vascular Aging Observed in End-Stage Renal Disease: A 5-Year Follow-Up Study.
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Bia D, Galli C, Zócalo Y, Valtuille R, Wray S, Armentano R, and Cabrera-Fischer E
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- Aging, Carotid Arteries physiopathology, Case-Control Studies, Femoral Artery physiopathology, Follow-Up Studies, Humans, Kidney Failure, Chronic complications, Pulse Wave Analysis methods, Kidney Failure, Chronic therapy, Renal Dialysis
- Abstract
Aims: To analyze the early vascular aging (EVA) in end-stage renal disease (ESRD) patients, attempting to determine a potential association between EVA and the etiology of ESRD, and to investigate the association of hemodialysis and EVA in ESRD patients during a 5-year follow-up period., Methods: Carotid-femoral pulse wave velocity (cfPWV) was obtained in 151 chronically hemodialyzed patients (CHP) and 283 control subjects, and in 25 CHP, who were followed-up after a 5-year lapse., Results: cfPWV increased in ESRD patients compared to control subjects. The cfPWV-age relationship was found to have a steeper increase in ESRD patients. The highest cfPWV and EVA values were observed in patients with diabetic nephropathy. Regression analysis demonstrated a significant reduction of the EVA in HD patients on a 5-year follow-up., Conclusion: Patients in ESRD showed higher levels of EVA. cfPWV and EVA differed in ESRD patients depending on their renal failure etiology. CHP showed an EVA reduction after a 5-year follow-up period., (© 2016 S. Karger AG, Basel.)
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- 2017
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17. Vascular cryografts offer better biomechanical properties in chronically hemodialyzed patients: role of cryograft type, arterial pathway, and diabetic nephropathy as matching determinants.
- Author
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Zócalo Y, Bia D, Armentano RL, Galli C, Pérez H, Saldías M, Alvarez I, Valtuille R, and Cabrera-Fischer E
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- Aged, Arteries transplantation, Biomechanical Phenomena, Cryopreservation, Diabetic Nephropathies therapy, Humans, Kidney Failure, Chronic therapy, Middle Aged, Polytetrafluoroethylene, Pulse, Renal Dialysis, Arteries physiology, Blood Vessel Prosthesis, Diabetic Nephropathies physiopathology, Elasticity, Kidney Failure, Chronic physiopathology, Transplants
- Abstract
This study aimed to characterize the following: (i) in chronically hemodialyzed subjects (CHDSs), with and without diabetic nephropathy (DN), and in healthy subjects (non-CHDSs) different arterial pathways stiffness to determine potential pathology-dependent, etiology- and/or pathway-dependent differences; and (ii) the biomechanical mismatch (BM) between arteries from non-CHDSs or CHDSs (with and without DN) and arterial cryografts, venous cryografts, and synthetic prosthesis to determine arterial pathway, pathology, and/or etiology-related differences in the substitute of election in terms of BM. Carotid-femoral and carotid-brachial pulse wave velocity (PWV) were measured in 30 non-CHDSs and 71 CHDSs (11 with DN). In addition, PWV was measured in arterial (elastic and muscular) and venous cryografts and in expanded polytetrafluorethylene prosthesis. The arterial pathways regional differences and the subjects' arterial pathways-substitutes BM were calculated. Arterial stiffness levels and regional differences were higher in CHDS than in non-CHDS. Among CHDS, those with DN showed higher stiffness in the aorto-femoral pathway and larger regional differences. Cryografts showed always the least BM. Non-CHDS and CHDS differed in the cryograft of election. In CHDS, the BM was related with the cryograft type, arterial pathway, and renal disease etiology. The BM could be minimized, selecting the most adequate cryograft type, taking into account the recipient specific characteristic (i.e., arterial pathway and renal disease etiology).
- Published
- 2010
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18. Reversal blood flow component as determinant of the arterial functional capability: theoretical implications in physiological and therapeutic conditions.
- Author
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Bia D, Zócalo Y, Armentano RL, de Forteza E, and Cabrera-Fischer E
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- Animals, Biomechanical Phenomena, Blood Pressure, Elasticity, Hemodynamics, Models, Cardiovascular, Sheep, Stress, Mechanical, Aorta physiology, Aorta physiopathology, Blood Flow Velocity
- Abstract
In several physiological, pathological, and therapeutic circumstances, the arterial blood flow is acutely modified, increasing, in some vascular segments the reversal (SSR) and oscillatory (SSO) components of the shear stress. Recently, in an in vivo model we found a relationship between acute changes in SSR and SSO, and variations in the arterial viscoelasticity. As the arterial viscoelasticity and diameter are the main determinants of the arterial buffering (BF) and conduit (CF) functions, changes in those functions could be expected associated with variations in SSR and SSO. The aim was to analyze the association between acute increases in SSR and SSO, and changes in the aortic CF and BF. Aortic flow, pressure, and diameter were measured in 16 sheep under basal and high reversal and oscillatory flow conditions (high SSR and SSO). Aortic BF and CF were quantified, and their potential association with the SSR and SSO components were analyzed. During high reversal flow rate conditions, a smooth muscle contraction-pattern was evidenced, with an increase in BF and a decrease in CF. Changes in BF and CF were associated with the changes in SSR and SSO. The acute effects on the arterial wall biomechanics of variations in SSR and SSO could contribute to comprehend their chronic effects, and the meaning of the acute vascular effects of changes in SSR and SSO would depend on the situation. Increases in SSR and SSO could be associated with smooth muscle tone increase-dependent changes in arterial BF and CF.
- Published
- 2009
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19. Cryografts implantation in human circulation would ensure a physiological transition in the arterial wall energetics, damping and wave reflection.
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Bia D, Barra JG, Armentano RL, Zócalo Y, Pérez H, Saldías M, Alvarez I, and Cabrera Fischer EI
- Subjects
- Adult, Blood Pressure, Carotid Artery, Common diagnostic imaging, Carotid Artery, Common transplantation, Elasticity, Heart Rate, Humans, Male, Materials Testing, Middle Aged, Models, Cardiovascular, Prosthesis Design, Stress, Mechanical, Ultrasonography, Bioprosthesis, Blood Vessel Prosthesis, Blood Vessel Prosthesis Implantation instrumentation, Carotid Artery, Common physiology, Cryopreservation, Pulsatile Flow
- Abstract
Each artery conduces blood (conduit function, CF) and smoothes out the pulsatility (buffering function, BF), while keeping its wall protected against the high oscillations of the pulse waves (damping function, xi). These functions depend on each segment viscoelasticity and capability to store and dissipate energy. When a graft/prosthesis is implanted, the physiological gradual transition in the viscoelasticity and functionality of adjacent arterial segments is disrupted. It remains to be elucidated if the cryografts would allow keeping the physiological biomechanical transition. The aim of this study was to evaluate the cryografts capability to reproduce the functional, energetic and reflection properties of patients' arteries and fresh homografts. Common carotid's pressure, diameter and wall-thickness were recorded in vivo (15 patients) and in vitro (15 cryografts and 15 fresh homografts from donors). Calculus: elastic (Epd) and viscous (Vpd) indexes, CF, BF, dissipated (WD) and stored (WPS) energy and xi. The graft-patient's artery matching was evaluated using the reflection coefficient (Gamma) and reflected power (WGamma). Cryografts did not show differences in Epd, Vpd, BF, CF, WD, WPS, and xi, in respect to fresh homografts and patients' arteries, ensuring a reduced Gamma and WGamma. Cryografts could be considered as alternatives in arterial reconstructions since they ensure the gradual transition of patients' arteries biomechanical and functional behavior.
- Published
- 2008
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20. [The adventitia reduces left ventricular dynamic afterload via smooth muscle activation-dependent mechanisms].
- Author
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Bia D, Zócalo Y, Armentano RL, Camús J, de Forteza E, and Cabrera-Fischer E
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- Animals, Brachiocephalic Trunk physiology, Female, In Vitro Techniques, Sheep, Connective Tissue physiology, Muscle, Smooth, Vascular physiology, Ventricular Function, Left physiology
- Abstract
Introduction and Objectives: Ventricular dynamic afterload depends on arterial viscoelastic and geometric properties. Vasoactive factors produced in the adventitia modulate arterial tone. However, it is still not known whether the adventitia is involved in determining the magnitude of the dynamic afterload. The aim of this study was to investigate the role played by the adventitia, via smooth muscle-dependent mechanisms, in determining dynamic afterload., Methods: The diameter, pressure and flow in brachiocephalic trunks from sheep were measured before and after removal of the adventitia, both in vivo with muscular reactivity preserved (n=8) and in vitro with muscular reactivity abolished (n=8). All studies were performed under similar hemodynamic conditions. Dynamic afterload was determined from elastic and viscous arterial responses, elastic and viscous work, arterial characteristic impedance, and pulse wave velocity. Comparison of in vivo and in vitro findings enabled smooth muscle-dependent changes to be evaluated., Results: Only in vivo, did removal of the adventitia lead to a reduction in vessel diameter (17.32 [2.02] vs 15.46 [1.28] mm) and to increases in elastic (7.21 [1.39] vs 15.59 [3.00] x 10(6) dyn.cm(-2)) and viscous (5.16 [2.04] vs 9.87 [2.00] x 10(5) dyn.s.cm(-2)) arterial responses, elastic (6.15 [1.08] vs 9.20 [0.76] x 10(-2) J/m2) and viscous work (11.61 [2.25] vs 15.20 [2.37] x 10(-3) J/m2), impedance (223.97 [136.11] vs 396.33 [182.27] dyn x s x cm(-3)), and pulse wave velocity (397.70 [31.21] vs 598.78 [28.04] cm.s(-1)) (P<.05). The reduction in diameter and the increases in elastic and viscous responses are evidence of muscular activation., Conclusions: The adventitia may contribute to the control of ventricular dynamic afterload by means of mechanisms dependent on muscular tone.
- Published
- 2007
21. Acute increase in reversal blood flow during counterpulsation is associated with vasoconstriction and changes in the aortic mechanics.
- Author
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Bia D, Zócalo Y, Armentano R, de Forteza E, and Cabrera-Fischer E
- Subjects
- Animals, Elasticity, Endothelium, Vascular, Humans, Muscle, Smooth, Vascular, Sheep, Aorta, Blood Flow Velocity, Blood Pressure, Heart-Assist Devices, Models, Cardiovascular, Vasoconstriction
- Abstract
While the effects of increases in forward blood flow on the arterial diameter and elasticity are known, the effects of reversal flow on the arterial properties remain to be characterized. The intra-aortic balloon pumping (IABP), the device most frequently used in circulatory support, acts generating changes in aortic flow (i.e. increasing reversal flow). Recently, in vitro studies showed that flow reversion reduces the endothelial release of relaxing factors. Hence, vascular smooth muscle (VSM) dependent changes in the aortic properties would be expected during IABP. The aim was to analyze the changes in flow during IABP and to characterize the potential effects of reversal blood flow on the aortic biomechanics. Pressure, flow and diameter were measured in sheep, before and during IABP circulatory support. Potential effects of IABP-dependent high reversal flow conditions on viscous and elastic aortic modulus were analyzed, using isobaric analysis. Flow and pressure waveforms were analyzed in the time domain, and the contribution of oscillatory forward and backward waves to the IABP-dependent changes in flow patterns were evaluated. We found that IABP changed mainly diastolic blood flow, with an increase in the reversal flow, secondary to an increase in the oscillatory backward wave amplitude. The acute increase in reversal flow during IABP was associated with vasoconstriction and changes in the aortic mechanics, possibly due to VSM activation.
- Published
- 2007
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22. [Regional differences in viscosity, elasticity and wall buffering function in systemic arteries: pulse wave analysis of the arterial pressure-diameter relationship].
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Bia D, Aguirre I, Zócalo Y, Devera L, Cabrera Fischer E, and Armentano R
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- Animals, Biomechanical Phenomena, Cardiovascular Physiological Phenomena, Pulse, Sheep, Arteries physiology, Elasticity, Viscosity
- Abstract
Introduction and Objectives: Regional variations in the incidence of vascular diseases have been related to regional differences in arterial viscoelasticity. The aim of this study was to characterize the differences in the elastic and viscous modulus and in wall buffering function between central and peripheral systemic arteries, through a time-series analysis of the pressure-diameter relationship., Material and Method: Pressure and diameter were measured in seven arterial segments (carotid, brachiocephalic trunk, ascending aorta, proximal, middle and distal descending thoracic aorta, and femoral artery) from six sheep. Each segment was mounted on an in vitro mock circulatory system and perfused with Tyrode solution, with a pulse frequency of 1.8 Hz and systemic pressure levels. We used the Kelvin-Voigt model to calculate the pressure-diameter elastic (Epd, mmHg/mm) and viscous (Vpd, mmHg.s/mm) modulus, and to quantify the local wall buffering function (Vpd/Epd). We also calculated the incremental Young's and pressure-strain elastic modulus and pulse wave velocity for each segment., Results: The elastic and viscous modulus increased from proximal to distal segments. The wall buffering function did not differ significantly between arteries. The lower rigidity of the central arteries compared to the distal ones may indicate that the systolic arterial compliance function is concentrated in the central arterial segments. On the other hand, the greater viscosity in the distal segments may indicate that viscous energy loss is concentrated in these segments., Conclusions: Arterial elasticity and viscosity can be interpreted as properties that are dependent on the region of the vessel, whereas wall buffering function can be considered region-independent.
- Published
- 2005
23. Chronic aortic counterpulsation with latissimus dorsi in heart failure: clinical follow-up.
- Author
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Trainini J, Barisani JC, Cabrera Fischer EI, Chada S, Christen AI, and Elencwajg B
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- Adult, Aged, Aorta, Thoracic diagnostic imaging, Cardiac Catheterization, Cineangiography, Electric Stimulation, Female, Follow-Up Studies, Heart Failure diagnostic imaging, Heart Failure physiopathology, Humans, Male, Middle Aged, Myocardial Contraction, Postoperative Period, Pulmonary Wedge Pressure, Stroke Volume, Treatment Outcome, Aorta, Thoracic surgery, Counterpulsation methods, Heart Failure therapy, Muscle, Skeletal transplantation, Surgical Flaps, Vascular Surgical Procedures methods
- Abstract
Background: Dynamic aortomyoplasty is an alternative technique to heart transplantation. The goal of our study was to evaluate the benefits of aortic counterpulsation obtained by dynamic thoracic aortomyoplasty in patients with heart failure refractory to pharmacologic treatment and contraindications to heart transplant or cardiomyoplasty., Methods: In this study we compared preoperative and postoperative data from five out of six carefully selected patients who were treated with dynamic thoracic aortomyoplasty. This surgical technique wraps the right latissimus dorsi muscle flap around the ascending aorta. This muscle flap was electrically stimulated during diastole, following a muscle-conditioning protocol, to obtain diastolic augmentation. At the 6-month follow-up period we evaluated, invasively and noninvasively, the hemodynamic and clinical effects of aortomyoplasty., Results: We observed a significant decrease in the number of hospitalizations (P = 0.01), NYHA functional class (P = 0.01), cardiothoracic ratio (P = 0.02), right ventricular diameter (P = 0.03), left atrial diameter (P = 0.04), and pulmonary artery systolic pressure (P = 0.04); and a significant increase in the 6-minute walking test (P = 0.01), cardiac index (P = 0.04), noninvasive evaluation of diastolic augmentation (P = 0.01), left ventricular shortening fraction (P = 0.01), and radioisotopic left ventricular ejection fraction (P = 0.02). We also found a nonsignificant decrease in the left ventricular diameter (P = 0.08) and wedge pressure (P = 0.19); and a nonsignificant increase in peak oxygen consumption (P = 0.13)., Conclusions: Dynamic thoracic aortomyoplasty in heart failure resulted in an important improvement of hemodynamic parameters, heart functional data, and clinical functional class, when comparing preoperative data with the 6-month follow-up data.
- Published
- 1999
- Full Text
- View/download PDF
24. Dynamic abdominal and thoracic aortomyoplasty in heart failure: assessment of counterpulsation.
- Author
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Cabrera Fischer EI, Christen AI, de Forteza E, and Risk MR
- Subjects
- Animals, Hemodynamics, Muscle, Skeletal transplantation, Sheep, Surgical Flaps, Aorta, Abdominal surgery, Aorta, Thoracic surgery, Counterpulsation methods, Heart Failure therapy
- Abstract
Background: Aortic counterpulsation, either biologic or mechanical, is a useful technique to support circulation during left ventricular dysfunction., Methods: In this study we used an induced cardiac failure model in acute open chest sheep to compare hemodynamic improvements between thoracic and abdominal aortic counterpulsation. This was achieved with left latissimus dorsi and left hemidiaphragm muscle flaps., Results: Thoracic and abdominal aortic counterpulsation in heart failure resulted in a significant improvement of hemodynamic parameters. Subendocardial viability index, defined as diastolic pressure-time index to systolic tension-time index, in thoracic and abdominal aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance was performed by electrical stimulation of each muscle flap. A new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve was tested, obtaining a correlation coefficient with the subendocardial viability index of 0.758 (p<0.001). Values of subendocardial viability index and counterpulsation index showed minimal variability., Conclusions: Treatment of experimentally induced cardiac failure with dynamic abdominal aortic counterpulsation allows an effective hemodynamic improvement in open chest sheep. Furthermore, this diastolic arterial pressure augmentation could be evaluated through a new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve.
- Published
- 1999
- Full Text
- View/download PDF
25. Dynamic aortomyoplasty: clinical experience.
- Author
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Trainini J, Barisani J, Elencwajg B, Cabrera Fischer E, Ahuad A, and Roncoroni A
- Subjects
- Aorta physiopathology, Cardiomyopathy, Dilated physiopathology, Cardiomyopathy, Dilated surgery, Chagas Cardiomyopathy physiopathology, Chagas Cardiomyopathy surgery, Contraindications, Heart Failure physiopathology, Heart Transplantation, Hemodynamics physiology, Humans, Male, Middle Aged, Postoperative Complications physiopathology, Aorta surgery, Cardiomyoplasty methods, Counterpulsation methods, Heart Failure surgery
- Abstract
Dynamic aortomyoplasty has been the subject of experimentation for the treatment of congestive heart failure during the last few years. This method consists of diastolic counterpulsation of the ascending aorta through the stimulation of the latissimus dorsi wrapped around it. This report describes the results of aortomyoplasty in a patient with dilated cardiomyopathy resulting from Chagas' disease and contraindications for heart transplantation or cardiomyoplasty.
- Published
- 1997
26. Non-invasive assessment of systemic elastic behaviour in hypertensive patients: analysis of possible determinants.
- Author
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Christen AI, Sánchez RA, Baglivo HP, Armentano RL, Risk MR, and Cabrera Fischer EI
- Subjects
- Adolescent, Adult, Age Factors, Aged, Algorithms, Arteries diagnostic imaging, Arteries pathology, Blood Flow Velocity physiology, Blood Pressure physiology, Blood Viscosity physiology, Carotid Artery, Common diagnostic imaging, Carotid Artery, Common pathology, Carotid Artery, Common physiopathology, Diastole, Elasticity, Female, Heart Rate physiology, Humans, Humerus blood supply, Humerus diagnostic imaging, Linear Models, Male, Middle Aged, Pulsatile Flow physiology, Radial Artery diagnostic imaging, Radial Artery pathology, Radial Artery physiopathology, Ultrasonography, Vascular Capacitance physiology, Viscosity, Arteries physiopathology, Hypertension physiopathology
- Abstract
Knowledge about the viscoelastic behaviour of the arterial wall has been proved to have physiological importance and clinical usage. Our purpose was to study the changes of the systemic arterial wall's elastic properties non-invasively, in patients with established essential and with borderline hypertension, and to evaluate its possible determinants. Three groups of normotensive, borderline and established essential hypertensive patients were evaluated. Arterial pulse wave velocity (PWV) was measured and arterial compliance (Cm) was derived in all patients. Pulse wave velocity was obtained from the pressure values of digitized carotid and radial arteries. Arterial compliance (Cm = dD/dP with P pressure and D diameter) was calculated using a formula derived from the Bramwell and Hill equation: Cm = (1,334 x D)/(2 rho x PWV2), where for D humeral diameter was used as measured by high resolution echograph, and rho is the blood density (rho = 1.06). Pulse wave velocity was significantly higher in established essential hypertensive patients with respect to normotensive patients (p < 0.05). Arterial compliance was significantly diminished in established and in borderline hypertensive patients with respect to normotensive patients (p < 0.05), which implies early alterations in hypertensive cardiovascular disease. Multiple regression analysis of the cofactors showed that age and diastolic pressure are independent determinants of Cm. Impairment of the arterial wall's intrinsic elastic properties was demonstrated in established essential hypertension, independent of age and diastolic pressure.
- Published
- 1997
27. Hemodynamic effects of cardiomyoplasty in an experimental model of acute heart failure and atrial fibrillation.
- Author
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Cabrera Fischer EI, Chachques JC, Christen AI, Risk MR, and Carpentier A
- Subjects
- Acetylcholine toxicity, Animals, Atrial Fibrillation chemically induced, Cardiomyoplasty, Disease Models, Animal, Dogs, Electric Stimulation, Female, Heart Failure chemically induced, Male, Propranolol toxicity, Treatment Outcome, Ventricular Function, Left physiology, Atrial Fibrillation surgery, Blood Pressure physiology, Cardiac Output physiology, Heart Failure surgery, Vascular Resistance physiology
- Abstract
The aim of our work was to study the hemodynamic effects of dynamic cardiomyoplasty on an acute animal model of atrial fibrillated heart failure. Eight anesthetized open chest dogs suffering from atrial fibrillation and heart failure, obtained by topic acetylcholine and propranolol, were treated by a cardiomyoplasty procedure performed with an electrostimulated latissimus dorsi muscle flap (LDMF). Values considered for analysis during LDMF stimulation were selected from cardiac cycles with R-R intervals similar to those when the LDMF was not stimulated (+/- 20 ms). Atrial fibrillated heart failure showed a significant increase of systemic vascular resistance, end diastolic left ventricular pressure (EDLVP) and right atrial pressure (p < 0.05), and a significant decrease in cardiac output, systolic left ventricular pressure (SLVP), and mean aortic pressure (p < 0.05) compared with control values. LDMF stimulation in atrial fibrillated heart failure resulted in a significant increase of SLVP, cardiac output, and mean aortic pressure (p < 0.05) and a significant decrease of systemic vascular resistance, EDLVP, and right atrial pressure (p < 0.05) compared with nonstimulated values. The highest LVP values were obtained with R-R intervals long enough to allow an adequate LV filling. We conclude that dynamic cardiomyoplasty provides an appropriate recovery in this animal model of atrial fibrillated heart failure. Cardiomyoplasty is an appropriate procedure for cardiac assist when R-R intervals allow an adequate LV filling.
- Published
- 1996
- Full Text
- View/download PDF
28. [Cardiomyoplasty as treatment of chronic severe cardiac failure].
- Author
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Chachques JC, Acar C, Cabrera Fischer E, and Carpentier A
- Subjects
- Activities of Daily Living, Evaluation Studies as Topic, Follow-Up Studies, Heart Failure mortality, Humans, Middle Aged, Time Factors, Cardiomyoplasty, Heart Failure surgery
- Abstract
Introduction and Objectives: Cardiac assistance from skeletal muscle is now emerging as an alternative to transplant surgery. The principle of cardiomyoplasty is chronic electrostimulation of the latissimus muscle flap wrapped around the heart to obtain a phasic activity which can be integrated to ventricular kinetics. Cardiomyoplasty is appropriate for patients with cardiac insufficiency refractory to optimal medical treatment. This includes cardiac failure of ischemic and non-obstructive cardiomyopathies. Worldwide clinical experience with this technique involves more than 500 cases., Material and Methods: The Broussais Hospital clinical experience involves 80 patients, operated between 1985 and 1995. All of them were closely followed in the postoperative period., Results: Recent basic and clinical data have shown that cardiomyoplasty effects on ventricular performance are due to: 1) augmentation of pump function: 2) limitation of cardiac dilatation; 3) reduction of ventricular wall stress, and 4) reverse remodeling of the left ventricular geometry. Remarkably, continuous fatigue free contraction of the latissimus dorsi muscle at the frequency of the heart has been obtained for periods exceeding 10 years in humans. Five patients underwent cardiac transplantation due to refractory heart failure., Conclusions: Clinical experience has demonstrated that cardiomyoplasty is an efficient technique to assist patients with severe refractory cardiac failure. In the great majority of cases it reverses the heart failure and increases life expectancy. Moreover, the functional class and the quality-of-life are significantly improved. Cardiomyoplasty does not preclude the use of future orthotopic heart transplantation.
- Published
- 1996
29. [Assisted circulation to the right ventricle through pulmonary counterpulsation using a biological method].
- Author
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Lacoste MO, Fernandes J, Christen AI, Chachques JC, and Cabrera Fischer EI
- Subjects
- Animals, Blood Pressure, Dogs, Electrocardiography, Surgical Flaps, Ventricular Dysfunction, Right physiopathology, Aorta surgery, Counterpulsation methods, Pulmonary Artery surgery, Ventricular Dysfunction, Right therapy
- Abstract
Purpose: To study the hemodynamic effects of latissimus dorsi dynamic pulmonaroplasty in open chest animals., Methods: Six anesthetized mongrel dogs were subjected to diastolic counterpulsation using electrically stimulated latissimus dorsi muscle flap wrapped around the aortic and pulmonary arteries roots and gated to the surface electrocardiogram. Aortic and Pulmonanary pressures as well as cardiac output and cardiac index were measured., Results: Diastolic counterpulsation resulted in a significant increase in cardiac output (from 2.35 +/- 0.26 to 2.45 +/- 0.28 l/min) (p < 0.005) and cardiac index (from 0.108 +/- 0.020 to 0.113 +/- 0.020 l/min/kg) (p < 0.05). The diastolic pulmonary arterial efficiency index showed a significant increase when latissimus dorsi stimulation was on (from 8.37 +/- 0.60 to 11.65 +/- 0.83 mmHg); (p < 0.005)., Conclusion: Latissimus dorsi dynamic pulmonaroplasty provides an effective means of arterial counter pulsation in open chest dogs.
- Published
- 1995
30. Single beat evaluation of circumferential aortic elastin elastic modulus in conscious dogs. Potential application in non-invasive measurements.
- Author
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Armentano RL, Cabrera Fischer EI, Barra JG, Levenson JA, Simon AC, and Pichel RH
- Subjects
- Algorithms, Animals, Blood Pressure, Collagen physiology, Diastole physiology, Dogs, Elastin physiology, Male, Models, Cardiovascular, Regression Analysis, Signal Processing, Computer-Assisted, Stress, Mechanical, Systole physiology, Aorta physiology, Elasticity
- Abstract
A description of the arterial wall elastic properties comprehends both collagen and elastin, clearly shown in a biphasic stress-strain relationship. From chronically instrumented conscious dogs, aortic pressure-diameter curves can be obtained in a single beat, which is impossible to perform in human beings. In control conditions, the collagen fibers are almost not distended and the resistance to stretch is mainly supported by the elastin fibers. Therefore, the mechanical properties of the aorta are almost purely elastic in the basal beat to beat conditions. In this study we propose and test five indexes, which include as variables: systolic, diastolic and mean arterial pressure and diameter; besides, arterial compliance and pressure-strain elastic modulus as suggested to evaluate the elastic behaviour of the elastic fibers. This data can be easily obtained by non-invasive methods, such as Doppler-ultrasound techniques and auscultative esphygmomanometrical measurements, while the indexes evaluated can be retrieved from a single beat evaluation. Of three measurements performed in chronically instrumented conscious dogs on different days, one of these indexes, the ME5 = [formula: see text] x Rdias proved to be an accurate and reliable parameter to evaluate the mechanical behaviour of arteries. This kind of parameter may be useful for research and evaluation of several diseases that markedly alter the arterial wall compliance.
- Published
- 1994
31. Active and passive effects of antihypertensive drugs on large artery diameter and elasticity in human essential hypertension.
- Author
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Chau NP, Simon A, Vilar J, Cabrera-Fischer E, Pithois-Merli I, and Levenson J
- Subjects
- Adult, Aged, Aging physiology, Arteries anatomy & histology, Arteries physiology, Blood Pressure drug effects, Blood Pressure physiology, Brachial Artery anatomy & histology, Brachial Artery diagnostic imaging, Brachial Artery drug effects, Compliance, Elasticity, Female, Humans, Male, Middle Aged, Models, Biological, Muscle, Smooth, Vascular drug effects, Ultrasonography, Vasodilation drug effects, Antihypertensive Agents pharmacology, Arteries drug effects, Hypertension physiopathology
- Abstract
The effects of antihypertensive drugs on the large arteries consist of two parts: the passive effect due to the change in pressure and the active effect, the drug action per se. This study proposes a method of dissociating the passive effect from the active effect. The diameter of the arterial artery was determined by the pulsed Doppler method and the pulse wave velocity of the brachioradial artery by mecanography. Arterial compliance was calculated by the Bramwell-Hill formula. Active and passive effects were determined by a logarithmic pressure-diameter model. This model was supported by in situ direct measurements of blood pressure and diameter in a segment of the femoral artery in dogs. Six drugs, cadralazine, ketanserin, medroxalol, nitrendipine, captopril, and isosorbide dinitrate, administered orally, were tested in 70 essential hypertensive patients. For all drugs, the pressure reduction induced a passive decrease in arterial diameter (p less than 0.02 to p less than 0.01). Cadralazine actively decreased arterial diameter (p less than 0.01), ketanserin had no active effect on diameter, and medroxalol, nitrendipine, captopril, and isosorbide dinitrate actively increased arterial diameter (p less than 0.05, p less than 0.01, p less than 0.01, and p less than 0.01, respectively). For all drugs, the pressure reduction also induced a passive increase in arterial compliance (p less than 0.05 to p less than 0.01). However, only nitrendipine, captopril, and isosorbide dinitrate actively increased arterial compliance (p less than 0.01, p less than 0.05, and p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1992
- Full Text
- View/download PDF
32. Temporary mechanical circulatory support for severe cardiac failure: experimental study.
- Author
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Cabrera Fischer EI, Chachques JC, Garcia A, Pichel RH, Morales MC, and Carpentier A
- Subjects
- Animals, Dogs, Equipment Design, Halothane, Heart Failure chemically induced, Counterpulsation instrumentation, Heart Failure therapy, Heart-Assist Devices, Hemodynamics physiology
- Abstract
We describe a technique for mechanical cardiac assistance in an acute model of severe cardiac failure. Cardiac dysfunction was induced by a high dose of halothane in 13 dogs. Seven served as controls. Following median sternotomy, a pneumatically driven device was implanted in the other six dogs in a para-aortic position, using a simple surgical technique without cardiopulmonary bypass. The aorta was cross-clamped during cardiac assistance. During hemodynamic studies, the seven control animals with induced cardiac failure showed high end-diastolic left ventricular and right atrial pressures with low cardiac index and systolic left ventricular and aortic pressures. All dogs in this group died within 30 minutes. Use of a monovalvular cardiac assist device in the experimental group of six dogs to pump blood from the aortic root to the descending aorta in a counterpulsation manner, confirmed good preservation of systemic hemodynamic parameters after induction of heart failure. All animals in this treated group survived more than 45 minutes. Hemodynamically, the device acts as a new ventricle and the impaired left ventricle functionally becomes a left atrium. This condition is clinically appropriate for recovery of left ventricular function in severe acute myocardial failure.
- Published
- 1991
33. Dynamic aortomyoplasty to assist left ventricular failure.
- Author
-
Chachques JC, Grandjean PA, Cabrera Fischer EI, Latremouille C, Jebara VA, Bourgeois I, and Carpentier A
- Subjects
- Animals, Blood Pressure, Cardiac Output, Low surgery, Goats, Hemodynamics, Myocardial Contraction, Pericardium transplantation, Surgical Flaps, Aorta surgery, Assisted Circulation methods, Counterpulsation methods, Muscles transplantation
- Abstract
The efficacy of skeletal muscle contractile force to augment left ventricular function has been demonstrated experimentally and clinically by the cardiomyoplasty procedure. Another approach in biomechanical cardiac assistance is the use of electrostimulated skeletal muscle in an extracardiac position. We describe an autologous counterpulsating device using the native ascending aorta as a ventricular chamber wrapped by an electrostimulated latissimus dorsi muscle flap (LDMF). This model avoids thrombotic complications observed in skeletal muscle neo-ventricles associated with prosthetic chambers. In 8 goats, a right LDMF was transferred to the thoracic cavity by removal of the second rib. In 4 goats, the diameter of the aorta was enlarged by surgical implantation (using lateral clamping) of an autologous pericardial patch. The LDMF was wrapped around the ascending aorta and electrostimulated using an external diastolic pulse generator connected to a sensing myocardial lead and to LDMF pacing electrodes. Hemodynamic studies were performed (left ventricular, aortic, and pulmonary artery pressures and rate of rise of left ventricular pressure). The LDMF diastolic counterpulsation was performed using a burst of 30 Hz, with a delay from the R wave adjusted to provide optimal diastolic augmentation. Percent increase in the subendocardial viability index was calculated during unassisted and assisted cardiac cycles (1:2) at baseline and after acute heart failure induced by the administration of high doses of propranolol hydrochloride (3 mg/kg intravenously). Diastolic aortic counterpulsation by the stimulated LDMF resulted in a significant improvement in the subendocardial viability index both at baseline and after induced cardiac failure in both groups, though the increase was greater in the group with aortic enlargement.
- Published
- 1990
- Full Text
- View/download PDF
34. Telemetry of aortic pressure in unrestrained animals: validation of the method over a wide range of blood pressure (from 40 to 200 mmHg).
- Author
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Armentano R, Cabrera-Fischer E, Breitbart G, Pichel R, Levenson J, and Chau NP
- Subjects
- Animals, Antihypertensive Agents pharmacology, Blood Pressure drug effects, Blood Pressure physiology, Cardiovascular Agents pharmacology, Dogs, Telemetry methods, Aorta, Thoracic physiology, Blood Pressure Determination methods, Blood Pressure Monitors
- Abstract
A telemetric method has been designed for continuous measurement of intra-arterial aortic blood pressure in the unrestrained dog. The system used a Konigsberg P7 transducer, a temperature-compensated voltage-controlled oscillator, an FM transmitter, and an FM tuner to convert the signal received into a voltage proportional to aortic blood pressure. The method was validated by comparison with a standard direct method (using cables for transmission). Over a wide range of blood pressure obtained by hypotensive and hypertensive drugs (in total about 2500 data points, ranging from 40 to 200 mmHg), the telemetric method gave almost the same result as the direct method. Absolute error (telemetric measure minus standard measure) was normally distributed, with a mean value of -0.44 mmHg, and a standard deviation of 3.37 mmHg. The telemetric method was designed for future studies on the chronobiology of blood pressure in normal condition, in stress conditions and under drugs.
- Published
- 1990
35. Animal model of acute pulmonary thromboembolism treated by local recirculation of streptokinase through the lung.
- Author
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Cabrera Fischer EI, Willshaw P, de Forteza E, Biagetti M, Altman R, Morales MC, Pichel RH, and Favaloro RG
- Subjects
- Acute Disease, Animals, Disease Models, Animal, Dogs, Hemodynamics, Lung pathology, Male, Perfusion methods, Pulmonary Embolism pathology, Pulmonary Embolism physiopathology, Time Factors, Pulmonary Circulation, Pulmonary Embolism drug therapy, Streptokinase administration & dosage
- Abstract
Massive acute pulmonary thromboembolism has a high mortality within the first few hours. Surgical intervention can remove only larger thrombi. Systemic fibrinolytic administration requires many hours for adequate treatment. We describe an anesthetized dog model of acute, massive, disseminated pulmonary thromboembolism achieved by injection of 1.7 ml/kg of 1-hour-old thrombi directly into the pulmonary artery. The emboli were lysed with 50,000 IU streptokinase recirculated for 20 minutes through the isolated pulmonary vascular bed by use of a roller pump while the systemic bed was supported by conventional cardiopulmonary bypass. On reestablishing natural circulation all hemodynamic parameters returned to preembolism values. Success of lysis was histologically confirmed. Perfusion of the pulmonary vascular bed without inclusion of streptokinase in the perfusate worsened the hemodynamic state of the animals compared with an untreated nonperfused control group.
- Published
- 1987
36. Experimental acute right ventricular failure and right ventricular assist in the dog.
- Author
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Cabrera Fischer EI, Willshaw P, Armentano RL, Besansón Delbo MI, Pichel RH, and Favaloro RG
- Subjects
- Animals, Coronary Artery Bypass adverse effects, Disease Models, Animal, Dogs, Heart Ventricles surgery, Myocardial Infarction etiology, Myocardial Infarction surgery, Postoperative Complications, Assisted Circulation, Heart Ventricles physiopathology, Heart-Assist Devices
- Abstract
We describe a technique for the production of acute progressive right ventricular failure in experimental animals that mimics the hemodynamic characteristics of right ventricular failure found in some patients being weaned from extracorporeal circulation after surgical repair of left ventricular abnormalities. The technique combines three alterations of right ventricular state: excision of the tricuspid valve, ventriculotomy, and ligation of the right coronary artery. Seven control dogs died within 3 hours after this intervention. Death was due to low cardiac output as a result of low left atrial and pulmonary arterial pressures. Right atrial pressure was high. Use of a right ventricular assist device in an additional seven dogs to pump blood from the right atrium to the pulmonary artery confirmed good preservation of left ventricular function by reestablishing adequate left ventricular filling pressure. All seven dogs survived for more than 3 hours. The validity of the technique in restricting failure principally to the right ventricle was thus demonstrated.
- Published
- 1985
37. Detection of left ventricular regional myocardial ischaemia in dogs by intraventricular conductance catheter.
- Author
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Cabrera Fischer EI, Spinelli JC, Willshaw P, Crottogini AJ, De Forteza E, Clavin O, Valentinuzzi ME, and Pichel RH
- Subjects
- Animals, Blood Pressure, Coronary Disease pathology, Coronary Disease physiopathology, Dogs, Electrodes, Heart Ventricles physiopathology, Myocardium pathology, Cardiac Catheterization methods, Coronary Disease diagnosis, Electric Conductivity
- Abstract
Nine adult mongrel dogs were instrumented with ultrasonic microcrystals to measure left ventricular basal anteroposterior diameter and midwall myocardial segment length near the cardiac apex. Pneumatic cuff occluders were positioned around the left circumflex coronary artery near its origin and around the left anterior descending coronary artery two thirds of the way along its length. A pressure microtransducer was implanted into the left ventricle. Ten days after instrumentation the animals were anaesthetised with morphine chlorhydrate and pentobarbital sodium. An eight electrode catheter was advanced into the left ventricle to measure ventricular apical and basal regional and total electrical conductance. Minor ischaemia caused by occlusion of the left anterior descending artery was detected only by the electrode pair located near the apex, as decreased local ejection fraction. Major ischaemia caused by left circumflex artery occlusion was detected by both apical and basal electrode pairs and by total conductance, the three conductance signals indicating reduced ejection fractions compared with control values. The basal diameter signal indicated that basal regional motility changed only during major ischaemia, thus confirming the specificity of the changes in the basal conductance signals. The apical segment length signal confirmed the altered motility indicated by the apical conductance signal. These results suggest that regional wall motion abnormalities may be detected by the use of a multielectrode conductance catheter.
- Published
- 1988
- Full Text
- View/download PDF
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