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1.
Comput Methods Biomech Biomed Engin ; 25(8): 852-860, 2022 Jun.
Article in English | MEDLINE | ID: mdl-34592878

ABSTRACT

Left ventricular assist devices (LVADs) have been increasingly used as a therapy for patients with end-stage heart failure. However, a growing number of clinical observations have shown that LVADs are associated with thromboembolic events, which are potentially related to the changes in intraventricular flow. Particularly, the flow fields around the inflow cannula (IC) of the LVAD. In this study, a fluid structure interaction (FSI) simulation was conducted to evaluate the hemodynamics of a patient specific left ventricle (LV) with varying LVAD IC orientations. The LV model was obtained from computed tomography scans and modeled to have contraction and relaxation during cardiac cycles following available experimental data of LV volume changes. The LV of the patient was assumed to have an end systolic volume of 223.7 mL and a stroke volume of 46.4 mL. Four different IC positions were considered: towards the (1) septum; (2) aortic valve (AV); (3) mitral valve (MV) and (4) inferior wall (IW). The potential thrombus growth around the IC was assumed to be caused by blood stagnation regions with low velocity (<5 mm/s) and low shear rate (<60/s) flow. Mean velocity magnitudes and low blood velocity regions around the IC were numerically obtained. To quantitatively compare the thrombosis risks of the four simulation cases, the time-averaged volumes of the low-velocity regions and the low shear rate regions were calculated. The intraventricular volumes of low velocity zones based on IC orientation are 1.42 mL toward the septum, 1.14 mL toward the AV, 0.93 mL toward the MV, and 1.24 mL toward the IW. The intraventricular volumes of low shear regions based on IC orientation are 11.54 mL toward the septum, 11.15 mL toward the AV, 9.24 mL toward the MV, and 10.7 mL toward the IW. IC orientation toward the MV results in lower volumetric regions of low flow and low shear within the ventricle, which consequently may lead to a reduced risk of thrombus formation.


Subject(s)
Heart-Assist Devices , Thrombosis , Cannula/adverse effects , Heart Ventricles , Heart-Assist Devices/adverse effects , Hemodynamics , Humans , Models, Cardiovascular , Thrombosis/etiology
2.
Methods Mol Biol ; 2375: 247-260, 2022.
Article in English | MEDLINE | ID: mdl-34591313

ABSTRACT

Propper assessment of hemodynamic swirling flow patterns, vortices, may help understand the influence of disturbed flow on arterial wall pathophysiology and remodeling. Studies have shown that vortices trigger pathologic cellular changes within the vasculature such as increased inflammation and cellular apoptosis, leading to weakening of the vessel wall indicative of aneurysm development and rupture. Yet many studies qualitatively assess the presence of vortices within the vasculature or assess only their centermost region (critical point analysis) which overlooks the broader characteristics of flow, leading to a narrow view of vortices. This chapter provides a protocol for utilizing commercially available computational fluid dynamic software (ANSYS-FLUENT) to simulate realistic hemodynamic flow patterns, fluid velocity, and wall shear stress in the complex geometry of the cerebral vasculature, as well as an innovative method for assessing flow vortices. This innovative analytic methodology can identify areas of flow vortices and quantify how the broader bulk-flow (opposed to critical point) characteristics change in space and time over the cardiac cycle. Analysis of such flow structures can be used to identify specific characteristics such as vortex stability and the portion of an aneurysmal sac that is dominated by swirling flow, which may be indicative of vascular pathologies.


Subject(s)
Hemodynamics , Entropy , Humans , Hydrodynamics , Intracranial Aneurysm , Stress, Mechanical
3.
J Cardiovasc Magn Reson ; 25(1): 5, 2023 Jan 30.
Article in English | MEDLINE | ID: mdl-36717885

ABSTRACT

BACKGROUND: Decisions in the management of aortic stenosis are based on the peak pressure drop, captured by Doppler echocardiography, whereas gold standard catheterization measurements assess the net pressure drop but are limited by associated risks. The relationship between these two measurements, peak and net pressure drop, is dictated by the pressure recovery along the ascending aorta which is mainly caused by turbulence energy dissipation. Currently, pressure recovery is considered to occur within the first 40-50 mm distally from the aortic valve, albeit there is inconsistency across interventionist centers on where/how to position the catheter to capture the net pressure drop. METHODS: We developed a non-invasive method to assess the pressure recovery distance based on blood flow momentum via 4D Flow cardiovascular magnetic resonance (CMR). Multi-center acquisitions included physical flow phantoms with different stenotic valve configurations to validate this method, first against reference measurements and then against turbulent energy dissipation (respectively n = 8 and n = 28 acquisitions) and to investigate the relationship between peak and net pressure drops. Finally, we explored the potential errors of cardiac catheterisation pressure recordings as a result of neglecting the pressure recovery distance in a clinical bicuspid aortic valve (BAV) cohort of n = 32 patients. RESULTS: In-vitro assessment of pressure recovery distance based on flow momentum achieved an average error of 1.8 ± 8.4 mm when compared to reference pressure sensors in the first phantom workbench. The momentum pressure recovery distance and the turbulent energy dissipation distance showed no statistical difference (mean difference of 2.8 ± 5.4 mm, R2 = 0.93) in the second phantom workbench. A linear correlation was observed between peak and net pressure drops, however, with strong dependences on the valvular morphology. Finally, in the BAV cohort the pressure recovery distance was 78.8 ± 34.3 mm from vena contracta, which is significantly longer than currently accepted in clinical practise (40-50 mm), and 37.5% of patients displayed a pressure recovery distance beyond the end of the ascending aorta. CONCLUSION: The non-invasive assessment of the distance to pressure recovery is possible by tracking momentum via 4D Flow CMR. Recovery is not always complete at the ascending aorta, and catheterised recordings will overestimate the net pressure drop in those situations. There is a need to re-evaluate the methods that characterise the haemodynamic burden caused by aortic stenosis as currently clinically accepted pressure recovery distance is an underestimation.


Subject(s)
Aortic Valve Stenosis , Bicuspid Aortic Valve Disease , Humans , Predictive Value of Tests , Aortic Valve Stenosis/diagnostic imaging , Magnetic Resonance Imaging/methods , Aortic Valve/diagnostic imaging , Hemodynamics , Magnetic Resonance Spectroscopy , Blood Flow Velocity/physiology
4.
Curr Opin Cardiol ; 38(2): 108-115, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36718620

ABSTRACT

PURPOSE OF REVIEW: The following review is intended to provide a summary of contemporary cardiogenic shock (CS) profiling and diagnostic strategies, including biomarker and hemodynamic-based (invasive and noninvasive) monitoring, discuss clinical differences in presentation and trajectory between acute myocardial infarction (AMI)-CS and heart failure (HF)-CS, describe transitions to native heart recovery and heart replacement therapies with a focus on tailored management and emerging real-world data, and emphasize trends in team-based initiatives and interventions for cardiogenic shock including the integration of protocol-driven care. RECENT FINDINGS: This document provides a broad overview of contemporary scientific consensus statements as well as data derived from randomized controlled clinical trials and observational registry working groups focused on cardiogenic shock management. SUMMARY: This review highlights the increasingly important role of pulmonary artery catheterization in AMI-CS and HF-CS cardiogenic shock and advocates for routine application of algorithmic approaches with interdisciplinary care pathways. Cardiogenic shock algorithms facilitate the integration of clinical, hemodynamic, and imaging data to determine the most appropriate patient hemodynamic support platform to achieve adequate organ perfusion and decongestion.


Subject(s)
Heart Failure , Myocardial Infarction , Humans , Shock, Cardiogenic/diagnosis , Shock, Cardiogenic/therapy , Myocardial Infarction/therapy , Cardiotonic Agents , Hemodynamics
5.
J Vis Exp ; (191)2023 Jan 13.
Article in English | MEDLINE | ID: mdl-36715405

ABSTRACT

Neonatal piglets have been extensively used as translational models for perinatal asphyxia. In 2007, we adapted a well-established piglet asphyxia model by introducing cardiac arrest. This enabled us to study the impact of severe asphyxia on key outcomes, including the time taken for the return of spontaneous circulation (ROSC), as well as the effect of chest compressions according to alternative protocols for cardiopulmonary resuscitation. Due to the anatomical and physiological similarities between piglets and human neonates, piglets serve as good models in studies of cardiopulmonary resuscitation and hemodynamic monitoring. In fact, this cardiac arrest model has provided evidence for guideline development through research on resuscitation protocols, pathophysiology, biomarkers, and novel methods for hemodynamic monitoring. Notably, the incidental finding that a substantial fraction of piglets have pulseless electrical activity (PEA) during cardiac arrest may increase the applicability of the model (i.e., it may be used to study pathophysiology extending beyond the perinatal period). However, the model generation is technically challenging and requires various skill sets, dedicated personnel, and a fine balance of the measures, including the surgical protocols and the use of sedatives/analgesics, to ensure a reasonable rate of survival. In this paper, the protocol is described in detail, as well as experiences with adaptations to the protocol over the years.


Subject(s)
Asphyxia Neonatorum , Cardiopulmonary Resuscitation , Heart Arrest , Animals , Swine , Humans , Infant, Newborn , Asphyxia , Return of Spontaneous Circulation , Heart Arrest/therapy , Hemodynamics , Cardiopulmonary Resuscitation/methods , Asphyxia Neonatorum/therapy , Disease Models, Animal
6.
Methods Mol Biol ; 2616: 83-96, 2023.
Article in English | MEDLINE | ID: mdl-36715930

ABSTRACT

Laser speckle contrast imaging (LSCI) offers the ability to measure relative cerebral blood flow (CBF) through the intact skull in mice. LSCI can be used to measure changes in cortical CBF in the middle cerebral artery occlusion/reperfusion (MCAo/R) stroke model. However, because conventional LSCI approaches are designed to image from above, uninterrupted measurement of CBF during the MCAo/R procedure is not possible due to the need to repeatedly reposition the mouse between prone and supine positions. We present a modified method to perform LSCI measurement from beneath the surgical preparation, thus allowing uninterrupted measurement of relative CBF from baseline through re-introduction of blood flow. We provide a 3D printable imaging platform and corresponding head frame, as well as methods to improve skull clarity in young and aged mice.


Subject(s)
Infarction, Middle Cerebral Artery , Stroke , Mice , Animals , Infarction, Middle Cerebral Artery/diagnostic imaging , Laser Speckle Contrast Imaging , Hemodynamics , Cerebrovascular Circulation/physiology , Laser-Doppler Flowmetry/methods
7.
Methods Mol Biol ; 2616: 97-111, 2023.
Article in English | MEDLINE | ID: mdl-36715931

ABSTRACT

Laser speckle contrast imaging (LSCI) is a label-free optical imaging technique that can quantify flow dynamics across an entire image. Multi-exposure speckle imaging (MESI) is an extension of LSCI that allows for reproducible and quantifiable measurements of flow. MESI has the potential to provide quantitative cerebral blood flow information in both preclinical and clinical applications; in fact, MESI can be extended to resolve the flow dynamics in any exposed tissue. A MESI system can be divided into three primary components: (i) the illumination optics, consisting of the optical source and a method of modulating and gating the illumination intensity; (ii) the collection optics, consisting of a high-speed camera that can be triggered and gated to match the pulsed illumination; and finally (iii) post-processing hardware and software to extract the flow information from the recorded raw intensity images. In the following protocol, we offer a guide to design, operate, and test a MESI system.


Subject(s)
Cerebrovascular Circulation , Hemodynamics , Optical Imaging/methods , Lasers
8.
Sci Rep ; 13(1): 1660, 2023 Jan 30.
Article in English | MEDLINE | ID: mdl-36717578

ABSTRACT

Increased intra-individual variability of a variety of biomarkers is generally associated with poor health and reflects physiological dysregulation. Correlations among these biomarker variabilities should then represent interactions among heterogeneous biomarker regulatory systems. Herein, in an attempt to elucidate the network structure of physiological systems, we probed the inter-variability correlations of 22 biomarkers. Time series data on 19 blood-based and 3 hemodynamic biomarkers were collected over a one-year period for 334 hemodialysis patients, and their variabilities were evaluated by coefficients of variation. The network diagram exhibited six clusters in the physiological systems, corresponding to the regulatory domains for metabolism, inflammation, circulation, liver, salt, and protein. These domains were captured as latent factors in exploratory and confirmatory factor analyses (CFA). The 6-factor CFA model indicates that dysregulation in each of the domains manifests itself as increased variability in a specific set of biomarkers. Comparison of a diabetic and non-diabetic group within the cohort by multi-group CFA revealed that the diabetic cohort showed reduced capacities in the metabolism and salt domains and higher variabilities of the biomarkers belonging to these domains. The variability-based network analysis visualizes the concept of homeostasis and could be a valuable tool for exploring both healthy and pathological conditions.


Subject(s)
Hemodynamics , Renal Dialysis , Humans , Biomarkers , Homeostasis/physiology
9.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 37(1): 46-51, 2023 Jan 15.
Article in Chinese | MEDLINE | ID: mdl-36708115

ABSTRACT

Objective: To study the hemodynamic characteristics of concealed perforator flap in mini-pigs by ultrasonic Doppler technique. Methods: Seven 7-month-old mini-pigs, weighing 20-25 kg, were included in the study. The saphenous artery perforator flap (group A, n=4), saphenous artery concealed perforator flap (group B, n=5), and saphenous artery concealed perforator flap combined with sarcolemma (group C, n=5) models were established randomly on both hind limbs of pigs. The pigs and flap survival conditions were observed after operation. The percentage of flap survival area was calculated by Photoshop CS5 software at 5 days after operation. Ultrasonic Doppler technique was performed on the flaps before operation and at immediate, 3 days, and 5 days after operation to record the hemodynamic changes of the flaps. The hemodynamic indicators of saphenous artery (inner diameter, peak systoli velocity, resistance index, and blood flow) and saphenous vein (inner diameter, maximum velocity, and blood flow) were recorded. Results: At 1 day after operation, 1 pig died of infection, and the rest survived until the experiment was completed. Finally, the 3 flaps of group A, 4 of group B, and 5 of group C were included in the study. The flaps of the 3 groups all showed swelling after operation, which was most significant at 3 days. At 3 days after operation, the flaps in group B showed partial bruising and necrosis. At 5 days after operation, the flaps in groups A and C were basically alive, and the necrosis area of flap in group B increased further. The percentage of flap survival area in groups A, B, and C were 99.7%±0.5%, 74.8%±26.4%, and 100%, respectively. The percentage of flap was significantly lower in group B than in groups A and C (P<0.05). There was no significant difference between groups A and C (P>0.05). There were significant differences in the hemodynamic indicators of saphenous artery and vein between different time points in 3 groups (P<0.05). There was no significant difference in each indicator between groups at each time point (P>0.05). Conclusion: Both the saphenous artery concealed perforator flap and the flap combined with sarcolemma have stable blood flow, but the survival area of the latter was better than the former.


Subject(s)
Perforator Flap , Animals , Swine , Swine, Miniature , Ultrasonics , Skin Transplantation , Hemodynamics , Necrosis , Models, Animal
10.
Sci Rep ; 13(1): 1615, 2023 Jan 28.
Article in English | MEDLINE | ID: mdl-36709361

ABSTRACT

We previously reported the neuroprotective potential of combined hydrogen (H2) gas ventilation therapy and therapeutic hypothermia (TH) by assessing the short-term neurological outcomes and histological findings of 5-day neonatal hypoxic-ischemic (HI) encephalopathy piglets. However, the effects of H2 gas on cerebral circulation and oxygen metabolism and on prognosis were unknown. Here, we used near-infrared time-resolved spectroscopy to compare combined H2 gas ventilation and TH with TH alone. Piglets were divided into three groups: HI insult with normothermia (NT, n = 10), HI insult with hypothermia (TH, 33.5 ± 0.5 °C, n = 8), and HI insult with hypothermia plus H2 ventilation (TH + H2, 2.1-2.7%, n = 8). H2 ventilation and TH were administered and the cerebral blood volume (CBV) and cerebral hemoglobin oxygen saturation (ScO2) were recorded for 24 h after the insult. CBV was significantly higher at 24 h after the insult in the TH + H2 group than in the other groups. ScO2 was significantly lower throughout the 24 h after the insult in the TH + H2 group than in the NT group. In conclusion, combined H2 gas ventilation and TH increased CBV and decreased ScO2, which may reflect elevated cerebral blood flow to meet greater oxygen demand for the surviving neurons, compared with TH alone.


Subject(s)
Hypothermia, Induced , Hypothermia , Hypoxia-Ischemia, Brain , Animals , Swine , Hypothermia/therapy , Hydrogen/therapeutic use , Hypothermia, Induced/methods , Hemodynamics , Hypoxia-Ischemia, Brain/pathology , Oxygen/metabolism , Animals, Newborn
11.
Medicine (Baltimore) ; 102(4): e32743, 2023 Jan 27.
Article in English | MEDLINE | ID: mdl-36705345

ABSTRACT

RATIONALE: Methylene blue (MB) has been used to increase blood pressure in septic shock, acting on the activity of guanylate cyclase and nitric oxide synthase. PATIENCE CONCERNS: The aim of this study is to demonstrate the benefit of MB in early phase of septic shock.Diagnoses: We report 6 cases of patients with septic shock with up to 72 hours of evolution. INTERVENTIONS: We used MB after fluid replacement, use of norepinephrine and vasopressin. Patients received a loading dose of MB and maintenance for 48 hours. OUTCOMES: All patients presented a reduction in the dose of vasopressors and lactate levels soon after the administration of the loading dose of MB, an effect that was maintained with the maintenance dose for 48 hours. Interleukin 6 and interleukin 8 were elevated at the beginning of the septic condition, with a progressive and marked reduction after the beginning of MB infusion, demonstrating a role of MB in reducing the inflammatory activity. LESSONS: This case series suggests that MB used early in the treatment of septic shock may be useful in reducing vasopressor dose and lactate levels. Further studies are still required to further validate these findings.


Subject(s)
Methylene Blue , Shock, Septic , Humans , Methylene Blue/pharmacology , Methylene Blue/therapeutic use , Hemodynamics , Blood Pressure/physiology , Vasoconstrictor Agents/therapeutic use , Norepinephrine/therapeutic use , Lactates
12.
Blood ; 141(4): 327-328, 2023 Jan 26.
Article in English | MEDLINE | ID: mdl-36701169
13.
J Trauma Acute Care Surg ; 94(2): 220-225, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36694333

ABSTRACT

BACKGROUND: The feasibility of nonoperative management for high-grade blunt splenic injuries (BSIs) has been suggested in recent studies. The purpose of this study was to assess nationwide trends in the management of isolated high-grade BSIs. We hypothesized that isolated high-grade BSIs are more frequently being managed nonoperatively. METHODS: The American College of Surgeons Trauma Quality Improvement Program database was queried to identify patients (16 years or older) with isolated high-grade BSIs (Abbreviated Injury Scale, ≥3) between 2013 and 2019. Patients were divided into two groups based on their hemodynamic status (hemodynamically stable [HS] and hemodynamically unstable [HU]). The primary outcome was the rate of total splenectomy each year, and the secondary outcome was the use of splenic angioembolization (SAE). Multiple regression models were created to estimate annual trends in splenectomy and SAE. RESULTS: A total of 6,747 patients with isolated high-grade BSIs were included: 5,714 (84.7%) and 1,033 (15.3%) in HS and HU groups, respectively. In the HS group, the rate of overall splenectomy was significantly decreased (from 22.9% in 2013 to 12.6% in 2019; odds ratio [OR] for 1-year increment, 0.850; 95% confidence interval [CI], 0.815-0.886; p < 0.001), and the use of SAE was significantly increased (from 12.5% in 2013 to 20.9% in 2019; OR, 1.107; 95% CI, 1.065-1.150; p < 0.001). In the HU group, the overall splenectomy rate was unchanged (from 69.8% in 2013 to 50.8% in 2019; OR, 0.931; 95% CI, 0.865-1.002; p = 0.071), whereas SAE was significantly increased (from 12.7% in 2013 to 28.8% in 2019; OR, 1.176; 95% CI, 1.079-1.284; p < 0.001). CONCLUSION: We observed significant trends toward more frequent use of nonoperative management in high-grade BSIs with hemodynamic stability. Further studies are warranted to define the role of SAE, especially in patients with hemodynamic instability. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.


Subject(s)
Abdominal Injuries , Embolization, Therapeutic , Wounds, Nonpenetrating , Humans , Spleen/injuries , Splenectomy , Abdominal Injuries/therapy , Hemodynamics , Wounds, Nonpenetrating/therapy , Wounds, Nonpenetrating/surgery , Injury Severity Score , Retrospective Studies , Treatment Outcome
15.
J Cardiovasc Magn Reson ; 25(1): 3, 2023 Jan 26.
Article in English | MEDLINE | ID: mdl-36698129

ABSTRACT

BACKGROUND: Bicuspid aortic valve (BAV) disease is associated with increased risk of aortopathy. In addition to current intervention guidelines, BAV mediated changes in aortic 3D hemodynamics have been considered as risk stratification measures. We aimed to evaluate the association of 4D flow cardiovascular magnetic resonance (CMR) derived voxel-wise aortic reverse flow with aortic dilation and to investigate the role of aortic valve regurgitation (AR) and stenosis (AS) on reverse flow in systole and diastole. METHODS: 510 patients with BAV (52 ± 14 years) and 120 patients with trileaflet aortic valve (TAV) (61 ± 11 years) and mid-ascending aorta diameter (MAAD) > 35 mm who underwent CMR including 4D flow CMR were retrospectively included. An age and sex-matched healthy control cohort (n = 25, 49 ± 12 years) was selected. Voxel-wise reverse flow was calculated in the aorta and quantified by the mean reverse flow in the ascending aorta (AAo) during systole and diastole. RESULTS: BAV patients without AS and AR demonstrated significantly increased systolic and diastolic reverse flow (222% and 13% increases respectively, p < 0.01) compared to healthy controls and also had significantly increased systolic reverse flow compared to TAV patients with aortic dilation (79% increase, p < 0.01). In patients with isolated AR, systolic and diastolic AAo reverse flow increased significantly with AR severity (c = - 83.2 and c = - 205.6, p < 0.001). In patients with isolated AS, AS severity was associated with an increase in both systolic (c = - 253.1, p < 0.001) and diastolic (c = - 87.0, p = 0.02) AAo reverse flow. Right and left/right and non-coronary fusion phenotype showed elevated systolic reverse flow (> 17% increase, p < 0.01). Right and non-coronary fusion phenotype showed decreased diastolic reverse flow (> 27% decrease, p < 0.01). MAAD was an independent predictor of systolic (p < 0.001), but not diastolic, reverse flow (p > 0.1). CONCLUSION: 4D flow CMR derived reverse flow associated with BAV was successfully captured even in the absence of AR or AS and in comparison to TAV patients with aortic dilation. Diastolic AAo reverse flow increased with AR severity while AS severity strongly correlated with increased systolic reverse flow in the AAo. Additionally, increasing MAAD was independently associated with increasing systolic AAo reverse flow. Thus, systolic AAo reverse flow may be a valuable metric for evaluating disease severity in future longitudinal outcome studies.


Subject(s)
Aortic Diseases , Aortic Valve Insufficiency , Aortic Valve Stenosis , Bicuspid Aortic Valve Disease , Heart Valve Diseases , Humans , Cross-Sectional Studies , Retrospective Studies , Heart Valve Diseases/complications , Heart Valve Diseases/diagnostic imaging , Dilatation , Predictive Value of Tests , Aortic Valve/diagnostic imaging , Aortic Valve/pathology , Aortic Valve Stenosis/pathology , Aortic Diseases/complications , Hemodynamics , Magnetic Resonance Spectroscopy
16.
Proc Natl Acad Sci U S A ; 120(5): e2202435120, 2023 Jan 31.
Article in English | MEDLINE | ID: mdl-36693103

ABSTRACT

The neural circuit of the brain is organized as a hierarchy of functional units with wide-ranging connections that support information flow and functional connectivity. Studies using MRI indicate a moderate coupling between structural and functional connectivity at the system level. However, how do connections of different directions (feedforward and feedback) and regions with different excitatory and inhibitory (E/I) neurons shape the hemodynamic activity and functional connectivity over the hierarchy are unknown. Here, we used functional MRI to detect optogenetic-evoked and resting-state activities over a somatosensory pathway in the mouse brain in relation to axonal projection and E/I distribution. Using a highly sensitive ultrafast imaging, we identified extensive activation in regions up to the third order of axonal projections following optogenetic excitation of the ventral posteriomedial nucleus of the thalamus. The evoked response and functional connectivity correlated with feedforward projections more than feedback projections and weakened with the hierarchy. The hemodynamic response exhibited regional and hierarchical differences, with slower and more variable responses in high-order areas and bipolar response predominantly in the contralateral cortex. Electrophysiological recordings suggest that these reflect differences in neural activity rather than neurovascular coupling. Importantly, the positive and negative parts of the hemodynamic response correlated with E/I neuronal densities, respectively. Furthermore, resting-state functional connectivity was more associated with E/I distribution, whereas stimulus-evoked effective connectivity followed structural wiring. These findings indicate that the structure-function relationship is projection-, cell-type- and hierarchy-dependent. Hemodynamic transients could reflect E/I activity and the increased complexity of hierarchical processing.


Subject(s)
Connectome , Neurovascular Coupling , Mice , Animals , Brain/physiology , Brain Mapping/methods , Hemodynamics , Neurovascular Coupling/physiology , Magnetic Resonance Imaging , Neural Pathways/physiology , Nerve Net/physiology , Connectome/methods
18.
Biomolecules ; 13(1)2023 Jan 03.
Article in English | MEDLINE | ID: mdl-36671480

ABSTRACT

Severe aortic stenosis (AS) is a common pathological condition in an ageing population imposing significant morbidity and mortality. Based on distinct hemodynamic features, i.e., ejection fraction (EF), transvalvular gradient and stroke volume, four different AS subtypes can be distinguished: (i) normal EF and high gradient, (ii) reduced EF and high gradient, (iii) reduced EF and low gradient, and (iv) normal EF and low gradient. These subtypes differ with respect to pathophysiological mechanisms, cardiac remodeling, and prognosis. However, little is known about metabolic changes in these different hemodynamic conditions of AS. Thus, we carried out metabolomic analyses in serum samples of 40 AS patients (n = 10 per subtype) and 10 healthy blood donors (controls) using ultrahigh-performance liquid chromatography-tandem mass spectroscopy. A total of 1293 biochemicals could be identified. Principal component analysis revealed different metabolic profiles in all of the subgroups of AS (All-AS) vs. controls. Out of the determined biochemicals, 48% (n = 620) were altered in All-AS vs. controls (p < 0.05). In this regard, levels of various acylcarnitines (e.g., myristoylcarnitine, fold-change 1.85, p < 0.05), ketone bodies (e.g., 3-hydroxybutyrate, fold-change 11.14, p < 0.05) as well as sugar metabolites (e.g., glucose, fold-change 1.22, p < 0.05) were predominantly increased, whereas amino acids (e.g., leucine, fold-change 0.8, p < 0.05) were mainly reduced in All-AS. Interestingly, these changes appeared to be consistent amongst all AS subtypes. Distinct differences between AS subtypes were found for metabolites belonging to hemoglobin metabolism, diacylglycerols, and dihydrosphingomyelins. These findings indicate that relevant changes in substrate utilization appear to be consistent for different hemodynamic subtypes of AS and may therefore reflect common mechanisms during AS-induced heart failure. Additionally, distinct metabolites could be identified to significantly differ between certain AS subtypes. Future studies need to define their pathophysiological implications.


Subject(s)
Aortic Valve Stenosis , Ventricular Dysfunction, Left , Humans , Stroke Volume , Hemodynamics
19.
Int J Environ Res Public Health ; 20(2)2023 Jan 12.
Article in English | MEDLINE | ID: mdl-36674158

ABSTRACT

BACKGROUND: Blood flow restriction is characterized as a method used during exercise at low loads of around 20-40% of a repetition maximum, or at a low-moderate intensity of aerobic exercise, in which cuffs that occlude the proximal part of the extremities can partially reduce arterial flow and fully restrict the venous flow of the musculature in order to achieve the same benefits as high-load exercise. OBJECTIVE: The main objective of this systematic literature review was to analyze the effects of BFR intervention on pain, functionality, and quality of life in subjects with neuromusculoskeletal pathologies. METHODS: The search to carry out was performed in PubMed, Cochrane, EMBASE, PEDro, CINHAL, SPORTDiscus, Trip Medical Database, and Scopus: "kaatsu" OR "ischemic training" OR "blood flow restriction" OR "occlusion resistance training" OR "vascular occlusion" OR "vascular restriction". RESULTS: After identifying 486 papers and eliminating 175 of them due to duplication and 261 after reading the title and abstract, 50 papers were selected. Of all the selected articles, 28 were excluded for not presenting a score equal to or higher than 6 points on the PEDro scale and 8 for not analyzing the target outcome variables. Finally, 14 papers were selected for this systematic review. CONCLUSIONS: The data collected indicate that the blood flow restriction tool is a therapeutic alternative due to its effectiveness under different exercise modalities. The benefits found include decreases in pain thresholds and improvement in the functionality and quality of life of the neuro-musculoskeletal patient during the first six weeks. However, the results provided by this tool are still not clear for medium- and long-term interventions.


Subject(s)
Quality of Life , Resistance Training , Humans , Regional Blood Flow/physiology , Hemodynamics , Exercise/physiology , Resistance Training/methods , Pain
20.
Sci Rep ; 13(1): 1102, 2023 Jan 20.
Article in English | MEDLINE | ID: mdl-36670185

ABSTRACT

In the recent era, the nanofluid's transportation due to the Jeffrey-Hemal flow phenomenon (i.e., carrying fluid through a converging/diverging channel) has significant applications in numerous engineering and science technologies. Therefore, multi-disciplinary evolution and research motivated us to present current attempt. The aim of this attempt is to present Jeffrey-Hamel mechanism of the nanofluid through non-parallel channel under thermally balance non-Darcy permeable medium impacts. The nanomaterial is represented using the Buongiorno nanofluid model. The investigation also includes zero mass flux impacts as well as variable rheological fluid properties. The influences of temperature jump are also encountered in the current analysis. The governing flow expressions under the Jeffrey-Hemal analysis are made dimensionless utilizing the similarity variables. The dimensionless equations are then solved using the analytical scheme (homotopy method) and the obtained series solutions are convergent. The influences of the involved parameters on concerned profiles are investigated through graphs. Force of drag, Nusselt and Sherwood numbers are elaborated graphically. In this analysis, intensification in Prandtl number enhances the heat transfer rate whereas decrement is seen in heat transfer rate for larger thermal slip parameter. Further, mass diffusivity parameter adversely affects the mass transfer rate. The current analysis incorporates numerous industrial and technological processes including transportation, material synthesis, microfluidics, high-power Xrays, biomedical, solid-state lighting, microelectronics, scientific measurement, medicine, molten polymers extrusion via converging dies, cold drawing operation related to polymer industry etc.


Subject(s)
Nanostructures , Hot Temperature , Rheology , Hemodynamics , Microfluidics
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