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2.
Nat Commun ; 11(1): 5209, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060602

RESUMO

Chronic high-thoracic and cervical spinal cord injury (SCI) results in a complex phenotype of cardiovascular consequences, including impaired left ventricular (LV) contractility. Here, we aim to determine whether such dysfunction manifests immediately post-injury, and if so, whether correcting impaired contractility can improve spinal cord oxygenation (SCO2), blood flow (SCBF) and metabolism. Using a porcine model of T2 SCI, we assess LV end-systolic elastance (contractility) via invasive pressure-volume catheterization, monitor intraparenchymal SCO2 and SCBF with fiberoptic oxygen sensors and laser-Doppler flowmetry, respectively, and quantify spinal cord metabolites with microdialysis. We demonstrate that high-thoracic SCI acutely impairs cardiac contractility and substantially reduces SCO2 and SCBF within the first hours post-injury. Utilizing the same model, we next show that augmenting LV contractility with the ß-agonist dobutamine increases SCO2 and SCBF more effectively than vasopressor therapy, whilst also mitigating increased anaerobic metabolism and hemorrhage in the injured cord. Finally, in pigs with T2 SCI survived for 12 weeks post-injury, we confirm that acute hemodynamic management with dobutamine appears to preserve cardiac function and improve hemodynamic outcomes in the chronic setting. Our data support that cardio-centric hemodynamic management represents an advantageous alternative to the current clinical standard of vasopressor therapy for acute traumatic SCI.


Assuntos
Coração/fisiopatologia , Hemodinâmica/fisiologia , Hemorragia/fisiopatologia , Fenômenos Fisiológicos Respiratórios , Traumatismos da Medula Espinal/fisiopatologia , Medula Espinal/fisiopatologia , Animais , Modelos Animais de Doenças , Dobutamina/farmacologia , Feminino , Fluxometria por Laser-Doppler , Chaperonas Moleculares/metabolismo , Norepinefrina/farmacologia , Fluxo Sanguíneo Regional/fisiologia , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/patologia , Suínos , Disfunção Ventricular Esquerda/tratamento farmacológico , Disfunção Ventricular Esquerda/fisiopatologia
3.
J Sports Med Phys Fitness ; 60(8): 1159-1166, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32955842

RESUMO

BACKGROUND: Endothelial function assessment may provide important insights into the cardiovascular function and long-term effects of exercise training. Many studies have investigated the possible negative effects on cardiovascular function due to extreme athletic performance, leading to undesirable effects. The purposes of this study were to investigate the acute effects of maximal intensity exercise on endothelium-dependent vasodilation, and to understand the patterns of flow-mediated dilation (FMD) change following maximal exercise in elite female athletes with a high-volume training history. METHODS: Twenty-six elite female soccer players (mean age, 22±4 years; BMI, 21±2 kg/m2; VO2max, 41±4 mL/kg/min) were evaluated. Brachial artery FMD was determined using high-resolution ultrasound at rest, and after 15 and 60 min of maximal cardiopulmonary exercise (CPX) testing on a treadmill. Flow velocity was measured at baseline and during reactive hyperemia at the same periods. RESULTS: Rest FMD was 12.4±5.5%. Peak diameter in response to reactive hyperemia was augmented after 15 min of CPX (3.5±0.4 vs. 3.6±0.4 mm, P<0.05), returning to resting values after 60 min. However, %FMD did not change among time periods. There were two characteristic patterns of FMD response following CPX. Compared to FMD at rest, half of the subjects responded with an increased FMD following maximum exercise (10.5±6.1 vs. 17.8±7.5%, P<0.05). The other subjects demonstrated a reduced FMD response following maximum exercise (14.2±4.3 vs. 10.9±3.2%, P<0.01). CONCLUSIONS: These results indicate that elite female soccer players presented robust brachial artery FMD at rest, with a heterogeneous FMD response to acute exercise with a 50% FMD improvement rate.


Assuntos
Endotélio Vascular/fisiologia , Exercício Físico/fisiologia , Condicionamento Físico Humano/fisiologia , Futebol/fisiologia , Vasodilatação/fisiologia , Adulto , Velocidade do Fluxo Sanguíneo , Artéria Braquial/diagnóstico por imagem , Artéria Braquial/fisiologia , Teste de Esforço , Feminino , Humanos , Fluxo Sanguíneo Regional/fisiologia , Adulto Jovem
4.
J Cardiovasc Magn Reson ; 22(1): 67, 2020 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-32912285

RESUMO

BACKGROUND: The posterior wall of the proximal internal carotid artery (ICA) is the predilection site for the development of stenosis. To optimally prevent stroke, identification of new risk factors for plaque progression is of high interest. Therefore, we studied the impact of carotid geometry and wall shear stress on cardiovascular magnetic resonance (CMR)-depicted wall thickness in the ICA of patients with high cardiovascular disease risk. METHODS: One hundred twenty-one consecutive patients ≥50 years with hypertension, ≥1 additional cardiovascular risk factor and ICA plaque ≥1.5 mm thickness and < 50% stenosis were prospectively included. High-resolution 3D-multi-contrast (time of flight, T1, T2, proton density) and 4D flow CMR were performed for the assessment of morphological (bifurcation angle, ICA/common carotid artery (CCA) diameter ratio, tortuosity, and wall thickness) and hemodynamic parameters (absolute/systolic wall shear stress (WSS), oscillatory shear index (OSI)) in 242 carotid bifurcations. RESULTS: We found lower absolute/systolic WSS, higher OSI and increased wall thickness in the posterior compared to the anterior wall of the ICA bulb (p < 0.001), whereas this correlation disappeared in ≥10% stenosis. Higher carotid tortuosity (regression coefficient = 0.764; p < 0.001) and lower ICA/CCA diameter ratio (regression coefficient = - 0.302; p < 0.001) were independent predictors of increased wall thickness even after adjustment for cardiovascular risk factors. This association was not found for bifurcation angle, WSS or OSI in multivariate regression analysis. CONCLUSIONS: High carotid tortuosity and low ICA diameter were independent predictors for wall thickness of the ICA bulb in this cross-sectional study, whereas this association was not present for WSS or OSI. Thus, consideration of geometric parameters of the carotid bifurcation could be helpful to identify patients at increased risk of carotid plaque generation. However, this association and the potential benefit of WSS measurement need to be further explored in a longitudinal study.


Assuntos
Doenças das Artérias Carótidas/diagnóstico por imagem , Artéria Carótida Interna/diagnóstico por imagem , Hemodinâmica , Angiografia por Ressonância Magnética , Idoso , Doenças das Artérias Carótidas/fisiopatologia , Artéria Carótida Interna/fisiopatologia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Placa Aterosclerótica , Valor Preditivo dos Testes , Prognóstico , Estudos Prospectivos , Fluxo Sanguíneo Regional , Fatores de Risco , Estresse Mecânico
5.
J Cardiovasc Magn Reson ; 22(1): 68, 2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32938483

RESUMO

BACKGROUND: Cardiovascular magnetic resonance (CMR) phase contrast (PC) flow measurements suffer from phase offset errors. Background subtraction based on stationary phantom measurements can most reliably be used to overcome this inaccuracy. Stationary tissue correction is an alternative and does not require additional phantom scanning. The aim of this study was 1) to compare measurements with and without stationary tissue correction to phantom corrected measurements on different GE Healthcare CMR scanners using different software packages and 2) to evaluate the clinical implications of these methods. METHODS: CMR PC imaging of both the aortic and pulmonary artery flow was performed in patients on three different 1.5 T CMR scanners (GE Healthcare) using identical scan parameters. Uncorrected, first, second and third order stationary tissue corrected flow measurement were compared to phantom corrected flow measurements, our reference method, using Medis QFlow, Circle cvi42 and MASS software. The optimal (optimized) stationary tissue order was determined per scanner and software program. Velocity offsets, net flow, clinically significant difference (deviation > 10% net flow), and regurgitation severity were assessed. RESULTS: Data from 175 patients (28 (17-38) years) were included, of which 84% had congenital heart disease. First, second and third order and optimized stationary tissue correction did not improve the velocity offsets and net flow measurements. Uncorrected measurements resulted in the least clinically significant differences in net flow compared to phantom corrected data. Optimized stationary tissue correction per scanner and software program resulted in net flow differences (> 10%) in 19% (MASS) and 30% (Circle cvi42) of all measurements compared to 18% (MASS) and 23% (Circle cvi42) with no correction. Compared to phantom correction, regurgitation reclassification was the least common using uncorrected data. One CMR scanner performed worse and significant net flow differences of > 10% were present both with and without stationary tissue correction in more than 30% of all measurements. CONCLUSION: Phase offset errors had a significant impact on net flow quantification, regurgitation assessment and varied greatly between CMR scanners. Background phase correction using stationary tissue correction worsened accuracy compared to no correction on three GE Healthcare CMR scanners. Therefore, careful assessment of phase offset errors at each individual scanner is essential to determine whether routine use of phantom correction is necessary. TRIAL REGISTRATION: Observational Study.


Assuntos
Aorta/diagnóstico por imagem , Insuficiência da Valva Aórtica/diagnóstico por imagem , Cardiopatias Congênitas/diagnóstico por imagem , Hemodinâmica , Interpretação de Imagem Assistida por Computador , Imagem Cinética por Ressonância Magnética/instrumentação , Artéria Pulmonar/diagnóstico por imagem , Insuficiência da Valva Pulmonar/diagnóstico por imagem , Adolescente , Adulto , Aorta/fisiopatologia , Insuficiência da Valva Aórtica/fisiopatologia , Velocidade do Fluxo Sanguíneo , Criança , Feminino , Cardiopatias Congênitas/fisiopatologia , Humanos , Masculino , Imagens de Fantasmas , Valor Preditivo dos Testes , Artéria Pulmonar/fisiopatologia , Insuficiência da Valva Pulmonar/fisiopatologia , Fluxo Sanguíneo Regional , Reprodutibilidade dos Testes , Estudos Retrospectivos , Índice de Gravidade de Doença , Adulto Jovem
6.
EuroIntervention ; 16(7): 532-533, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32955017
7.
Medicine (Baltimore) ; 99(37): e22002, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32925731

RESUMO

The use of tunneled cuffed catheters (TCCs) for permanent blood access is increasing as the hemodialysis population ages. However, the higher mortality and complication rates associated with their use have been significant concerns. This single-center observational cohort study aimed to investigate clinical factors affecting mortality and complications in Japanese hemodialysis patients with a TCC.We enrolled 64 consecutive patients receiving hemodialysis through a TCC between 2012 and 2019. The primary outcome was all-cause mortality and the secondary outcome was the incidence of catheter-related complications at 2 years. Cox proportional hazards models were used to examine variables associated with these outcomes.At 2 years, death from any cause and catheter-related complications occurred in 27/64 (42%) and 23/64 (36%) patients, respectively. There were 14 bacteremia events, 7 catheter obstructions, and 8 instances of restricted blood flow. Multivariate analysis showed that systolic blood pressure (SBP) < 100 mm Hg at the time of catheter insertion was associated with higher all-cause mortality (hazard ratio, 2.59; 95% confidence interval, 1.05-6.41) and catheter-related complications (hazard ratio, 2.57; 95% confidence interval, 1.52-22.2). The Kaplan-Meier analyses also showed that patients with SBP <100 mm Hg had higher mortality (P = .001) and a higher incidence of catheter-related complications (P = .0068).SBP <100 mm Hg at the time of catheter insertion is associated with mortality and catheter-related complications in hemodialysis patients using a TCC. Further multi-center studies are required to validate our results.


Assuntos
Pressão Sanguínea , Cateteres de Demora/efeitos adversos , Causas de Morte , Falência Renal Crônica/terapia , Diálise Renal/efeitos adversos , Diálise Renal/instrumentação , Idoso , Idoso de 80 Anos ou mais , Bacteriemia/etiologia , Obstrução do Cateter/etiologia , Infecções Relacionadas a Cateter/etiologia , Feminino , Humanos , Estimativa de Kaplan-Meier , Falência Renal Crônica/fisiopatologia , Masculino , Modelos de Riscos Proporcionais , Estudos Prospectivos , Fluxo Sanguíneo Regional , Fatores de Risco
8.
J Thromb Thrombolysis ; 50(4): 790-794, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32789730

RESUMO

Several autopsy studies showed microthrombi in pulmonary circulation of severe COVID-19 patients. The major limitation of these investigations is that the autopsy provided static information. Some of these alterations could be secondary to the disseminated intravascular coagulation (DIC) observed as the final standard route to the multisystem organ failure exhibited in critically ill patients. We report preliminary results of an in vivo evaluation of sublingual microcirculation in thirteen patients with severe COVID-19 requiring mechanical ventilation. We observed multiple filling defects moving within the microvessels indicative of thrombi in most of the cases 11/13 (85%). This is the first imaging documentation of microvascular thrombosis in living severe COVID-19 patients since the beginning of the hospitalization. The clinical relevance of microvascular thrombosis in this disease requires further research.


Assuntos
Coagulação Sanguínea , Infecções por Coronavirus/complicações , Microcirculação , Soalho Bucal/irrigação sanguínea , Pneumonia Viral/complicações , Trombose/fisiopatologia , Idoso , Betacoronavirus/patogenicidade , Infecções por Coronavirus/terapia , Infecções por Coronavirus/virologia , Feminino , Interações Hospedeiro-Patógeno , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/terapia , Pneumonia Viral/virologia , Fluxo Sanguíneo Regional , Respiração Artificial , Índice de Gravidade de Doença , Trombose/sangue , Trombose/diagnóstico por imagem , Trombose/virologia
9.
Am J Physiol Regul Integr Comp Physiol ; 319(3): R323-R328, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32783690

RESUMO

Black men have attenuated increases in forearm vascular conductance (FVC) and forearm blood flow (FBF) during moderate- and high-intensity rhythmic handgrip exercise compared with White men, but the underlying mechanisms are unclear. Here, we tested for the first time the hypothesis that functional sympatholysis (i.e., attenuation of sympathetic vasoconstriction in the exercising muscles) is impaired in Black men compared with White men. Thirteen White and 14 Black healthy young men were studied. FBF (duplex Doppler ultrasound) and mean arterial pressure (MAP; Finometer) were measured at rest and during rhythmic handgrip exercise at 30% maximal voluntary contraction. FVC was calculated as FBF/MAP. Sympathetic activation was induced via lower body negative pressure (LBNP) at -20 Torr for 2 min at rest and from the 3rd to the 5th min of handgrip. Sympathetic vasoconstriction was assessed as percent reductions in FVC during LBNP. The groups presented similar resting FVC, FBF, and MAP. During LBNP at rest, reductions in FVC were not different between White (-35 ± 10%) and Black men (-32 ± 14%, P = 0.616), indicating similar reflex-induced sympathetic vasoconstriction. During handgrip exercise, there were minimal reductions in FVC with LBNP in either group (White: -1 ± 7%; Black: +1 ± 8%; P = 0.523), indicating functional sympatholysis in both groups. Thus, contrary to our hypothesis, our findings indicate a preserved functional sympatholysis in healthy young Black men compared with White men, suggesting that this mechanism does not appear to contribute to reduced exercise hyperemia during moderate-intensity rhythmic handgrip in this population.


Assuntos
Exercício Físico/fisiologia , Força da Mão/fisiologia , Consumo de Oxigênio/fisiologia , Vasoconstrição/fisiologia , Adulto , Humanos , Masculino , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Sistema Nervoso Simpático/fisiopatologia
10.
J Cardiovasc Magn Reson ; 22(1): 59, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32772927

RESUMO

BACKGROUND: Anatomically pre-shaped sinus prostheses (SP) were developed to mimic the aortic sinus with the goal to preserve near physiological hemodynamic conditions after valve-sparing aortic root replacement. Although SP have shown more physiological flow patterns, a comparison to straight tube prosthesis and the analysis of derived quantitative parameters is lacking. Hence, this study sought to analyze differences in aortic wall shear stress (WSS) between anatomically pre-shaped SP, conventional straight tube prostheses (TP), and age-matched healthy subjects) using time-resolved 3-dimensional flow cardiovascular magnetic resonance (4D Flow CMR). Moreover, the WSS gradient was introduced and analyzed regarding its sensitivity to detect changes in hemodynamics and its dependency on the expression of secondary flow patterns. METHODS: Twelve patients with SP (12 male, 62 ± 9yr), eight patients with TP (6 male, 59 ± 9yr), and twelve healthy subjects (2 male, 55 ± 6yr) were examined at 3 T with a 4D Flow CMR sequence in this case control study. Six analysis planes were placed in the thoracic aorta at reproducible landmarks. The following WSS parameters were recorded: WSSavg (spatially averaged over the contour at peak systole), max. WSSseg (maximum segmental WSS), min. WSSseg (minimum segmental WSS) and the WSS Gradient, calculated as max. WSSseg - min. WSSseg. Kruskal-Wallis- and Mann-Whitney-U-Test were used for statistical comparison of groups. Occurrence and expression of secondary flow patterns were evaluated and correlated to WSS values using Spearman's correlation coefficient. RESULTS: In the planes bordering the prosthesis all WSS values were significantly lower in the SP compared to the TP, approaching the physiological optimum of the healthy subjects. The WSS gradient showed significantly different values in the four proximally localized contours when comparing both prostheses with healthy subjects. Strong correlations between an elevated WSS gradient and secondary flow patterns were found in the ascending aorta and the aortic arch. CONCLUSION: Overall, the SP has a positive impact on WSS, most pronounced at the site and adjacent to the prosthesis. The WSS gradient differed most obviously and the correlation of the WSS gradient with the occurrence of secondary flow patterns provides further evidence for linking disturbed flow, which was markedly increased in patients compared to healthy sub jects, to degenerative remodeling of the vascular wall.


Assuntos
Aorta Torácica/diagnóstico por imagem , Aorta Torácica/cirurgia , Valva Aórtica/diagnóstico por imagem , Implante de Prótese Vascular/instrumentação , Prótese Vascular , Hemodinâmica , Imagem por Ressonância Magnética , Imagem de Perfusão/métodos , Desenho de Prótese , Adulto , Idoso , Aorta Torácica/fisiopatologia , Valva Aórtica/fisiopatologia , Técnicas de Imagem de Sincronização Cardíaca , Estudos de Casos e Controles , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Fluxo Sanguíneo Regional , Estresse Mecânico , Resultado do Tratamento
11.
PLoS One ; 15(8): e0238112, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32857805

RESUMO

This longitudinal study was performed to evaluate the feasibility of detecting the interaction between wall shear stress (WSS) and plaque development. 20 ApoE-/- mice were separated in 12 mice with Western Diet and 8 mice with Chow Diet. Magnetic resonance (MR) scans at 17.6 Tesla and histological analysis were performed after one week, eight and twelve weeks. All in vivo MR measurements were acquired using a flow sensitive phase contrast method for determining vectorial flow. Histological sections were stained with Hematoxylin and Eosin, Elastica van Gieson and CD68 staining. Data analysis was performed using Ensight and a Matlab-based "Flow Tool". The body weight of ApoE-/- mice increased significantly over 12 weeks. WSS values increased in the Western Diet group over the time period; in contrast, in the Chow Diet group the values decreased from the first to the second measurement point. Western Diet mice showed small plaque formations with elastin fragmentations after 8 weeks and big plaque formations after 12 weeks; Chow Diet mice showed a few elastin fragmentations after 8 weeks and small plaque formations after 12 weeks. Favored by high-fat diet, plaque formation results in higher values of WSS. With wall shear stress being a known predictor for atherosclerotic plaque development, ultra highfield MRI can serve as a tool for studying the causes and beginnings of atherosclerosis.


Assuntos
Aorta/diagnóstico por imagem , Imagem por Ressonância Magnética , Placa Aterosclerótica/diagnóstico por imagem , Animais , Aorta/patologia , Aorta/fisiopatologia , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Aterosclerose/diagnóstico por imagem , Aterosclerose/patologia , Aterosclerose/fisiopatologia , Peso Corporal , Dieta Ocidental , Modelos Animais de Doenças , Estudos de Viabilidade , Feminino , Estudos Longitudinais , Imagem por Ressonância Magnética/instrumentação , Imagem por Ressonância Magnética/métodos , Camundongos Knockout , Placa Aterosclerótica/patologia , Placa Aterosclerótica/fisiopatologia , Distribuição Aleatória , Fluxo Sanguíneo Regional , Estresse Mecânico
12.
J Vis Exp ; (161)2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32804163

RESUMO

Coronary arterial tone along with the opening or closing of the capillaries largely determine the blood flow to cardiomyocytes at constant perfusion pressure. However, it is difficult to monitor the dynamic changes of the coronary arterioles and the capillaries in the whole heart, primarily due to its motion and non-stop beating. Here we describe a method that enables monitoring of arterial perfusion rate, pressure and the diameter changes of the arterioles and capillaries in mouse right ventricular papillary muscles. The mouse septal artery is cannulated and perfused at a constant flow or pressure with the other dynamically measured. After perfusion with a fluorescently labeled lectin (e.g., Alexa Fluor-488 or -633 labeled Wheat-Germ Agglutinin, WGA), the arterioles and capillaries (and other vessels) in right ventricle papillary muscle and septum could be readily imaged. The vessel-diameter changes could then be measured in the presence or absence of heart contractions. When genetically encoded fluorescent proteins were expressed, specific features could be monitored. For examples, pericytes were visualized in mouse hearts that expressed NG2-DsRed. This method has provided a useful platform to study the physiological functions of capillary pericytes in heart. It is also suitable for studying the effect of reagents on the blood flow in heart by measuring the vascular/capillary diameter and the arterial luminal pressure simultaneously. This preparation, combined with a state-of-the-art optic imaging system, allows one to study the blood flow and its control at cellular and molecular level in the heart under near-physiological conditions.


Assuntos
Arteríolas/diagnóstico por imagem , Capilares/diagnóstico por imagem , Imageamento Tridimensional , Pericitos/fisiologia , Animais , Arteríolas/efeitos dos fármacos , Arteríolas/fisiologia , Capilares/efeitos dos fármacos , Capilares/fisiologia , Cateterismo , Corantes Fluorescentes/metabolismo , Hemodinâmica/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Perfusão , Pericitos/efeitos dos fármacos , Pinacidil/farmacologia , Pressão , Fluxo Sanguíneo Regional/efeitos dos fármacos , Fluxo Sanguíneo Regional/fisiologia , Vasoconstrição/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologia , Aglutininas do Germe de Trigo/metabolismo
14.
Radiol Med ; 125(9): 838-850, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32671554

RESUMO

4D Flow is an emerging MR technique enabling three-dimensional and cardiac phase-resolved flowmetry with ECG-gated phase-contrast MRI that increased the speed of data acquisitions, accuracy and robustness. The method is promoting researches in areas that have not been fully addressed before in the cardiovascular system, such as flowmetry of the bloodstream across the valves, within the heart chambers, complexed flow dynamics such as vortex, helical or retrograde. Wall shear stress and other potential biomarkers derived from 4D Flow are known to be related to vascular wall diseases such as atherosclerosis. In this review, fundamental concepts of 4D Flow technique and post-processing, benefits and limitations as well as its clinical applications are discussed, and the importance of quality control and validation of the method is emphasized. New ideas inspired by 4D Flow can help clinicians and MR scientists further understand the role of flow dynamics in health sciences, diseases and various aspects of cardiovascular physiology.


Assuntos
Circulação Coronária/fisiologia , Imagem Cinética por Ressonância Magnética/métodos , Velocidade do Fluxo Sanguíneo , Eletrocardiografia/métodos , Humanos , Hidrodinâmica , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Imagem por Ressonância Magnética/métodos , Fluxo Sanguíneo Regional/fisiologia , Resistência ao Cisalhamento/fisiologia
15.
PLoS One ; 15(6): e0234861, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32603330

RESUMO

OBJECTIVE: To examine whether the cardiac, renal and uterine physiological hemodynamic changes during gestation are altered in rats with an early and prolonged exposure to a high fat diet (HFD). METHODS: Arterial pressure and cardiac, renal, uterine and radial arteries hemodynamic changes during gestation were examined in adult SD rats exposed to normal (13%) (n = 8) or high (60%) (n = 8) fat diets from weaning. Plethysmography, high-resolution high-frequency ultrasonography and clearance of an inulin analog were used to evaluate the arterial pressure and hemodynamic changes before and at days 7, 14 and 19 of gestation. RESULTS: Arterial pressure was higher (P<0.05) in rats with high than in those with normal (NFD) fat diet before pregnancy (123 ±3 and 110 ±3 mmHg, respectively) and only decreased at day 14 of gestation in rats with NFD (98±4 mmHg, P<0.05). A significant increment in stroke volume (42 ±10%) and cardiac output (51 ±12%) was found at day 19 of pregnancy in rats with NFD. The changes in stroke volume and cardiac output were similar in rats with NFD and HFD. When compared to the values obtained before pregnancy, a transitory elevation in renal blood flow was found at day 14 of pregnancy in both groups. However, glomerular filtration rate only increased (P<0.05) in rats with NFD at days 14 (20 ±7%) and 19 (27 ±8%) of gestation. The significant elevations of mean velocity, and velocity time integral throughout gestation in radial (127 ±26% and 111 ±23%, respectively) and uterine (91 ±16% and 111 ±25%, respectively) arteries of rats with NFD were not found in rats with an early and prolonged HFD. SUMMARY: This study reports novel findings showing that the early and prolonged exposure to a HFD leads to a significant impairment in the renal, uterine and radial arteries hemodynamic changes associated to gestation.


Assuntos
Artérias/fisiopatologia , Vasos Coronários/fisiopatologia , Dieta Hiperlipídica/efeitos adversos , Fenômenos Fisiológicos da Nutrição Animal , Animais , Artérias/diagnóstico por imagem , Pressão Sanguínea/fisiologia , Vasos Coronários/diagnóstico por imagem , Feminino , Taxa de Filtração Glomerular/fisiologia , Rim/irrigação sanguínea , Modelos Animais , Gravidez , Ratos , Fluxo Sanguíneo Regional/fisiologia , Volume Sistólico/fisiologia , Ultrassonografia , Útero/irrigação sanguínea , Útero/diagnóstico por imagem
16.
PLoS One ; 15(7): e0235392, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32726315

RESUMO

Platelets upregulate the generation of thrombin and reinforce the fibrin clot which increases the incidence risk of venous thromboembolism (VTE). However, the role of platelets in the pathogenesis of venous cardiovascular diseases remains hard to quantify. An experimentally validated model of thrombin generation dynamics is formulated. The model predicts that a high platelet count increases the peak value of generated thrombin as well as the endogenous thrombin potential (ETP) as reported in experimental data. To investigate the effects of platelets density, shear rate, and wound size on the initiation of blood coagulation, we calibrate a previously developed model of venous thrombus formation and implement it in 3D using a novel cell-centered finite-volume solver. We conduct numerical simulations to reproduce in vitro experiments of blood coagulation in microfluidic capillaries. Then, we derive a reduced one-equation model of thrombin distribution from the previous model under simplifying hypotheses and we use it to determine the conditions of clotting initiation on the platelet count, the shear rate, and the plasma composition. The initiation of clotting also exhibits a threshold response to the size of the wounded region in good agreement with the reported experimental findings.


Assuntos
Coagulação Sanguínea/fisiologia , Plaquetas/fisiologia , Modelos Teóricos , Contagem de Plaquetas/métodos , Testes de Coagulação Sanguínea , Plaquetas/metabolismo , Fibrina/metabolismo , Humanos , Agregação Plaquetária/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Resistência ao Cisalhamento/fisiologia , Trombina/metabolismo , Tromboplastina/metabolismo , Trombose/metabolismo , Trombose/fisiopatologia , Veias/metabolismo , Veias/fisiologia
17.
PLoS One ; 15(6): e0235377, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32603351

RESUMO

The purpose of this study was to investigate whether a six-week, twice weekly resistance training (4 sets at 30% 1-RM until failure) with practical blood flow restriction (BFR) using 7cm wide cuffs with a twist lock placed below the patella is superior to training without BFR (NoBFR) concerning muscle mass and strength gains in calf muscles. A two-group (BFR n = 12, mean age 27.33 (7.0) years, training experience 7.3 (7.0) years; NoBFR n = 9, mean age 28.9 (7.4) years, training experience 7.1 (6.6) years) randomized matched pair design based on initial 1-RM was used to assess the effects on structural and functional adaptations in healthy males (Perometer calf volume [CV], gastrocnemius muscle thickness using ultrasound [MT], 7-maximal hopping test for leg stiffness [LS], 1-RM smith machine calf raise [1-RM], and visual analogue scale as a measure of pain intensity [VAS]). The mean number of repetitions completed per training session across the intervention period was higher in the NoBFR group compared to the BFR group (70 (16) vs. 52 (9), p = 0.002). VAS measured during the first session increased similarly in both groups from first to fourth set (p<0.001). No group effects or time×group interactions were found for CV, MT, LS, and 1-RM. However, there were significant time effects for MT (BFR +0.07 cm; NoBFR +0.04; p = 0.008), and 1-RM (BFR +40 kg; NoBFR +34 kg; p<0.001). LS and CV remained unchanged through training. VAS in both groups were similar, and BFR and NoBFR were equally effective for increasing 1-RM and MT in trained males. However, BFR was more time efficient, due to lesser repetition per training session.


Assuntos
Adaptação Fisiológica , Força Muscular/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Adulto , Humanos , Masculino , Músculo Esquelético/fisiologia , Treinamento de Resistência/métodos , Adulto Jovem
18.
Artigo em Inglês | MEDLINE | ID: mdl-32708408

RESUMO

The current pool of data investigating the effects of a single resistance exercise session on endothelial function is divergent and inconclusive. Therefore, the purpose of the present study was to evaluate the effect of a single resistance exercise session on flow-mediated dilation (FMD) in trained individuals. Eleven healthy, young, recreationally resistance-trained individuals participated in the study. After determining the resistance exercise workload, the participants performed three sets of 10-12 repetition of leg press and leg extension exercises. By using ultrasound equipment, brachial artery FMD was assessed before (PRE) and 30 min after (POST) the resistance exercise protocol or resting (control) to evaluate endothelial function. A significant reduction in FMD response (PRE: 5.73% ± 1.21% vs. POST: 4.03% ± 1.94%, p < 0.01) after resistance exercise was observed, accompanied by a large effect size (d = 1.05). No significant difference was observed in FMD in the control condition (PRE: 5.82% ± 1.19% vs. POST: 5.66% ± 1.24%, p = 0.704). Additionally, no significant difference in baseline brachial artery diameter between resistance exercise (PRE: 3.30 ± 0.32 vs. POST: 3.40 ± 0.34 mm, p = 0.494) and resting (PRE: 3.64 ± 0.41 vs. POST: 3.67 ± 0.62 mm, p = 0.825) was observed. Our findings showed that a single resistance exercise session induced a reduction in FMD in resistance-trained individuals.


Assuntos
Artéria Braquial/diagnóstico por imagem , Artéria Braquial/fisiologia , Endotélio Vascular/fisiologia , Exercício Físico/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Treinamento de Resistência , Vasodilatação/fisiologia , Adulto , Dilatação , Endotélio Vascular/diagnóstico por imagem , Feminino , Voluntários Saudáveis , Humanos , Masculino , Ultrassonografia , Adulto Jovem
19.
Am J Physiol Regul Integr Comp Physiol ; 319(2): R142-R147, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32663039

RESUMO

Earlier reports suggest that limb venous distension evokes reflex increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) (i.e., venous distension reflex). Our recent report also shows that suction of arterially occluded limb evokes venous distension reflex. We postulate that the venous distension reflex contributes to autonomic responses to orthostatic stress. In this study, we hypothesized that orthostatic tolerance would be linked to the MSNA response seen with lower limb suction. Fifteen healthy subjects were tested in the supine position. Negative pressure (-100 mmHg) was applied on an arterially occluded lower limb for 2 min. MSNA from the peroneal nerve in the limb not exposed to suction, ECG, and BP (Finometer) was recorded throughout the study. Limb occlusion without suction was used as a control trial. In a separate visit, the individual's orthostatic tolerance was assessed using a graded lower body negative pressure (LBNP) tolerance test. Mean arterial BP and MSNA (18.6 ± 1.9 to 23.6 ± 2.0 bursts/min) significantly (both P < 0.05) increased during limb suction. Orthostatic tolerance index positively correlated (R = 0.636, P = 0.011) with the MSNA response seen with suction during occlusion. Since the venous distension reflex strength correlates with the level of orthostatic tolerance, we speculate that lower-limb venous distension reflex engagement increases the sympathetic responses during orthostatic challenge and serves to maintain BP with postural stress.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Extremidade Inferior/fisiologia , Reflexo/fisiologia , Sistema Nervoso Simpático/fisiologia , Adulto , Feminino , Frequência Cardíaca/fisiologia , Humanos , Pressão Negativa da Região Corporal Inferior , Masculino , Fluxo Sanguíneo Regional
20.
Arterioscler Thromb Vasc Biol ; 40(9): e240-e255, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32698687

RESUMO

OBJECTIVE: To determine if endothelial dysfunction in a mouse model of diet-induced obesity and in obese humans is mediated by the suppression of endothelial Kir (inwardly rectifying K+) channels. Approach and Results: Endothelial dysfunction, observed as reduced dilations to flow, occurred after feeding mice a high-fat, Western diet for 8 weeks. The functional downregulation of endothelial Kir2.1 using dominant-negative Kir2.1 construct resulted in substantial reductions in the response to flow in mesenteric arteries of lean mice, whereas no effect was observed in arteries of obese mice. Overexpressing wild-type-Kir2.1 in endothelium of arteries from obese mice resulted in full recovery of the flow response. Exposing freshly isolated endothelial cells to fluid shear during patch-clamp electrophysiology revealed that the flow-sensitivity of Kir was virtually abolished in cells from obese mice. Atomic force microscopy revealed that the endothelial glycocalyx was stiffer and the thickness of the glycocalyx layer reduced in arteries from obese mice. We also identified that the length of the glycocalyx is critical to the flow-activation of Kir. Overexpressing Kir2.1 in endothelium of arteries from obese mice restored flow- and heparanase-sensitivity, indicating an important role for heparan sulfates in the flow-activation of Kir. Furthermore, the Kir2.1-dependent component of flow-induced vasodilation was lost in the endothelium of resistance arteries of obese humans obtained from biopsies collected during bariatric surgery. CONCLUSIONS: We conclude that obesity-induced impairment of flow-induced vasodilation is attributed to the loss of flow-sensitivity of endothelial Kir channels and propose that the latter is mediated by the biophysical alterations of the glycocalyx.


Assuntos
Células Endoteliais/metabolismo , Endotélio Vascular/metabolismo , Glicocálix/metabolismo , Artérias Mesentéricas/metabolismo , Obesidade/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Vasodilatação , Adulto , Animais , Células Cultivadas , Dieta Hiperlipídica , Modelos Animais de Doenças , Endotélio Vascular/fisiopatologia , Feminino , Heparitina Sulfato/metabolismo , Humanos , Masculino , Mecanotransdução Celular , Potenciais da Membrana , Artérias Mesentéricas/fisiopatologia , Camundongos , Pessoa de Meia-Idade , Obesidade/genética , Obesidade/fisiopatologia , Canais de Potássio Corretores do Fluxo de Internalização/genética , Fluxo Sanguíneo Regional
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