Corpora cavernosa fibroblasts mediate penile erection.

Penile erection is mediated by the corpora cavernosa, a trabecular-like vascular bed that enlarges upon vasodilation, but its regulation is not completely understood. Here, we show that perivascular fibroblasts in the corpora cavernosa support vasodilation by reducing norepinephrine availability. The effect on penile blood flow depends on the number of fibroblasts, which is regulated by erectile activity. Erection dynamically alters the positional arrangement of fibroblasts, temporarily down-regulating Notch signaling. Inhibition of Notch increases fibroblast numbers and consequently raises penile blood flow. Continuous Notch activation lowers fibroblast numbers and reduces penile blood perfusion. Recurrent erections stimulate fibroblast proliferation and limit vasoconstriction, whereas aging reduces the number of fibroblasts and lowers penile blood flow. Our findings reveal adaptive, erectile activity-dependent modulation of penile blood flow by fibroblasts.

Imágenes Doppler de arterias intrapulmonares dentro de la atelectasia y su impacto en la poscarga del ventrículo derecho con ecocardiografía transesofágica / Doppler images of intrapulmonary arteries within atelectasis and its impact on right ventricular afterload with transesophageal echocardiography

La cirugía cardíaca por toracoscopia videoasistida (VATS) requiere ventilación unipulmonar (VUP) y monitorización con ecografía transesofágica (ETE). Utilizando Doppler color y espectral es posible estudiar el patrón de flujo sanguíneo en los vasos pulmonares dentro del pulmón atelectasiado. El objetivo de este reporte de casos es evidenciar la habilidad de la ETE para detectar el flujo sanguíneo dentro del pulmón atelectásico, así como también valorar la resistencia vascular pulmonar (RVP) y poscarga del ventrículo derecho, utilizando esta misma herramienta. Hallazgos: Tres adultos anestesiados y ventilados mecánicamente programados para cirugía cardíaca por VATS fueron escaneados con ETE cardiopulmonar. Una vez que se realizó la VUP quedando el pulmón derecho sin ventilar, la sonda se giró desde el corazón para lograr un escaneo pulmonar 2D y con Doppler color para detectar el flujo de sangre dentro del parénquima pulmonar consolidado. Se pudo identificar el patrón de flujo correspondiente a las ramas de la arteria intrapulmonar. La RVP fue registrada aplicando Doppler pulsado cardíaco, basal luego de la inducción de anestesia general, a los 20min de la VUP y al finalizar la VUP, luego de realizar una maniobra de reclutamiento alveolar (MRA) que condujo a la resolución completa de la consolidación mencionada. Conclusiones: La ETE cardiopulmonar es una herramienta de imagen semiinvasiva que permite no solo el diagnóstico y estudio de atelectasias inducidas por VUP, sino también el análisis del shunt dentro de esta consolidación y sus posibles consecuencias en la RVP.(AU)

Video-assisted thoracoscopy (VATS) cardiac surgery requires one-lung ventilation (OLV) and transoesophageal ultrasound (TOE) monitoring. Colour and spectral Doppler make it possible to study the pattern of blood flow in the pulmonary vessels within the atelectatic lung. In this case report we describe how TOE can be used to detect blood flow within the atelectatic lung and to assess pulmonary vascular resistance (PVR) and right ventricular afterload. Findings: Three anaesthetised, mechanically ventilated adults scheduled for VATS cardiac surgery were monitored using TOE. After left OLV, the transducer was rotated away from the heart to obtain 2D colour Doppler images of blood flow within the consolidated lung parenchyma. We were able to identify the flow pattern of the intrapulmonary branches of the pulmonary artery. PVR was recorded using pulsed cardiac Doppler at baseline, after induction of general anaesthesia, 20min after OLV and at the end of OLV, and after performing an alveolar recruitment manoeuvre (ARM) that led to complete resolution of the aforementioned consolidation. Conclusions: TOE is a semi-invasive imaging tool that can be used to diagnose and study PVR-induced atelectasis and to analyse the resulting pulmonary shunt and its possible effect on PVR.(AU)

Incorporating Unresolved Stresses in Blood Damage Modeling: Energy Dissipation More Accurate Than Reynolds Stress Formulation.

OBJECTIVE: Reynolds Averaged Navier Stokes (RANS) models are often used as the basis for modeling blood damage in turbulent flows. To predict blood damage by turbulence stresses that are not resolved in RANS, a stress formulation that represents the corresponding scales is required. Here, we compare two commonly employed stress formulations: a scalar stress representation that uses Reynolds stresses as a surrogate for unresolved fluid stresses, and an effective stress formulation based on energy dissipation. METHODS: We conducted unsteady RANS simulations of the CentriMag blood pump with three different closure models and a Large Eddy Simulation (LES) for reference. We implemented both stress representations in all models and compared the resulting total stress distributions in Eulerian and Lagrangian frameworks. RESULTS: The Reynolds-stress-based approach overestimated the contribution of unresolved stresses in RANS, with differences between closure models of up to several orders of magnitude. With the dissipation-based approach, the total stresses predicted with RANS deviated by about 50% from the LES reference, which was more accurate than only considering resolved stresses. CONCLUSION: The Reynolds-stress-based formulation proved unreliable for estimating scalar stresses in our RANS simulations, while the dissipation-based approach provided an accuracy improvement over simply neglecting unresolved stresses. SIGNIFICANCE: Our results suggest that dissipation-based inclusion of unresolved stresses should be the preferred choice for blood damage modeling in RANS.

On the driver of blood circulation beyond the heart.

The heart is widely acknowledged as the unique driver of blood circulation. Recently, we discovered a flow-driving mechanism that can operate without imposed pressure, using infrared (IR) energy to propel flow. We considered the possibility that, by exploiting this mechanism, blood vessels, themselves, could propel flow. We verified the existence of this driving mechanism by using a three-day-old chick-embryo model. When the heart was stopped, blood continued to flow for approximately 50 minutes, albeit at a lower velocity. When IR was introduced, the postmortem flow increased from ~41.1 ± 25.6 µm/s to ~153.0 ± 59.5 µm/s (n = 6). When IR energy was diminished under otherwise physiological conditions, blood failed to flow. Hence, this IR-dependent, vessel-based flow-driving mechanism may indeed operate in the circulatory system, complementing the action of the heart.

[Integrated strategy for biomarkers of stable coronary heart disease with phlegm and blood stasis syndrome based on RNA-seq and network pharmacology].

This study aimed to analyze the biological foundation and biomarkers of stable coronary heart disease(CHD) with phlegm and blood stasis(PBS) syndrome based on RNA-seq and network pharmacology. Peripheral blood nucleated cells from five CHD patients with PBS syndrome, five CHD patients with non-PBS syndrome, and five healthy adults were collected for RNA-seq. The specific targets of CHD with PBS syndrome were determined by differential gene expression analysis and Venn diagram analysis. The active ingredients of Danlou Tablets were screened out from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform, and the "component-target" prediction was completed through PubChem and SwissTargetPrediction. The "drug-ingredient-target-signaling pathway" network of Danlou Tablets against CHD with PBS syndrome was optimized by Cytoscape software. After the target biomarkers were identified, 90 participants were enrolled for diagnostic tests, and 30 CHD patients with PBS syndrome were included in before-and-after experiment to determine the therapeutic effect of Danlou Tablets on those targets. As revealed by RNA-seq and Venn diagram analysis, 200 specific genes were identified for CHD with PBS syndrome. A total of 1 118 potential therapeutic targets of Danlou Tablets were predicted through network pharmacology. Through integrated analysis of the two gene sets, 13 key targets of Danlou Tablets in the treatment of CHD with PBS syndrome were screened out, including CSF1, AKR1C2, PDGFRB, ARG1, CNR2, ALOX15B, ALDH1A1, CTSL, PLA2G7, LAP3, AKR1C3, IGFBP3, and CA1. They were presumably the biomarkers of CHD with PBS syndrome. The ELISA test further showed that CSF1 was significantly up-regulated in the peripheral blood of CHD patients with PBS syndrome, and was significantly down-regulated after Danlou Tablets intervention. CSF1 may be a biomarker for CHD with PBS syndrome, and it is positively correlated with the severity of the disease. The diagnostic cut-off of CSF1 for CHD with PBS syndrome was 286 pg·mL~(-1).

Reduced Left Atrial Rotational Flow Is Independently Associated With Embolic Brain Infarcts.

BACKGROUND: Up to 25% of embolic strokes occur in individuals without atrial fibrillation (AF) or other identifiable mechanisms. OBJECTIVES: This study aims to assess whether left atrial (LA) blood flow characteristics are associated with embolic brain infarcts, independently of AF. METHODS: The authors recruited 134 patients: 44 with a history of ischemic stroke and 90 with no history of stroke but CHA2DS2VASc score ≥1. Cardiac magnetic resonance (CMR) evaluated cardiac function and LA 4-dimensional flow parameters, including velocity and vorticity (a measure of rotational flow), and brain magnetic resonance imaging (MRI) was performed to detect large noncortical or cortical infarcts (LNCCIs) (likely embolic), or nonembolic lacunar infarcts. RESULTS: Patients (41% female; age 70 ± 9 years) had moderate stroke risk (median CHA2DS2VASc = 3, Q1-Q3: 2-4). Sixty-eight (51%) had diagnosed AF, of whom 58 (43%) were in AF during CMR. Thirty-nine (29%) had ≥1 LNCCI, 20 (15%) had ≥1 lacunar infarct without LNCCI, and 75 (56%) had no infarct. Lower LA vorticity was significantly associated with prevalent LNCCIs after adjustment for AF during CMR, history of AF, CHA2DS2VASc score, LA emptying fraction, LA indexed maximum volume, left ventricular ejection fraction, and indexed left ventricular mass (OR: 2.06 [95% CI: 1.08-3.92 per SD]; P = 0.027). By contrast, LA flow peak velocity was not significantly associated with LNCCIs (P = 0.21). No LA parameter was associated with lacunar infarcts (all P > 0.05). CONCLUSIONS: Reduced LA flow vorticity is significantly and independently associated with embolic brain infarcts. Imaging LA flow characteristics may aid identification of individuals who would benefit from anticoagulation for embolic stroke prevention, regardless of heart rhythm.

The Use of the Implantable Doppler Probe as a Blood Flow Monitoring Device in Clinical Settings: A Narrative Review of the Evidence.

OBJECTIVES: In the past decade, the implantable Doppler probe has been studied widely as a blood flow-monitoring device in reconstructive and transplant surgical specialities. Its utility as an effective postoperative monitoring technique is still debatable, with no clear guidelines in clinical practice. Here, we mapped the current evidence on the usefulness of the implantable Doppler probe as a blood flow-monitoring device. The objective was to present an up-to-date assessment of the benefits and limitations of using implantable Doppler probes in clinical and experimental clinical settings. MATERIALS AND METHODS: We conducted a literature search using the Cochrane Library and Healthcare Databases Advanced Search and using implantable Doppler probe, transplant, graft, and flap as key words. The search yielded 184 studies, with 73 studies included after exclusions. We evaluated, synthesized, and summarized the evidence from the studies in tabular form. RESULTS: There is clinical equipoise regarding the effectiveness of implantable Doppler probe as a flow sensing technique. The main reason is the lack of information and gaps in the evidence regarding the benefits and limitations of using implantable Doppler probes in clinical practice. CONCLUSIONS: The implantable Doppler probe has the potentialto be used as an adjunctpostoperativeblood flow-monitoring device. However, keeping in view of technical limitations, its signals should be interpreted alongside traditional clinical assessment techniques to determine the patency of microvascular anastomosis. Although evidence in this review will inform clinical practice in transplant and reconstructive surgical specialties, a prospective randomized controlled study with a larger patient cohort is required to evaluate the effectiveness of this probe in clinical settings.

Tissue-growth-based synthetic tree generation and perfusion simulation.

Biological tissues receive oxygen and nutrients from blood vessels by developing an indispensable supply and demand relationship with the blood vessels. We implemented a synthetic tree generation algorithm by considering the interactions between the tissues and blood vessels. We first segment major arteries using medical image data and synthetic trees are generated originating from these segmented arteries. They grow into extensive networks of small vessels to fill the supplied tissues and satisfy the metabolic demand of them. Further, the algorithm is optimized to be executed in parallel without affecting the generated tree volumes. The generated vascular trees are used to simulate blood perfusion in the tissues by performing multiscale blood flow simulations. One-dimensional blood flow equations were used to solve for blood flow and pressure in the generated vascular trees and Darcy flow equations were solved for blood perfusion in the tissues using a porous model assumption. Both equations are coupled at terminal segments explicitly. The proposed methods were applied to idealized models with different tree resolutions and metabolic demands for validation. The methods demonstrated that realistic synthetic trees were generated with significantly less computational expense compared to that of a constrained constructive optimization method. The methods were then applied to cerebrovascular arteries supplying a human brain and coronary arteries supplying the left and right ventricles to demonstrate the capabilities of the proposed methods. The proposed methods can be utilized to quantify tissue perfusion and predict areas prone to ischemia in patient-specific geometries.

Perioperative Fluid Management and Volume Assessment.

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

Sensor pré-calibrado para monitorização de pressão intravascular e minimamente invasiva do débito cardíaco, Flotrac®, para cirurgias, maiores e de alto risco / Pre-calibrated sensor for intravascular and minimally invasive monitoring of cardiac output, Flotrac®, for major and high-risk surgeries

INTRODUÇÃO: O padrão ouro atual para monitorização hemodinâmica durante cirurgias é o cateter de artéria pulmonar, que exige punção venosa profunda. O FloTrac® é um sistema para monitorização hemodinâmica minimamente invasivo pois conecta-se à uma punção arterial distal, com potencial menor risco de complicações. TECNOLOGIA: Sensor pré-calibrado para monitorização hemodinâmica contínua do débito cardíaco e da pressão intravascular, sistema FloTrac. PERGUNTA: O uso do sistema FloTrac® em pacientes submetidos a procedimentos cirúrgicos de grande porte ou de alto risco é eficaz e seguro quando comparado ao uso do cateter de artéria pulmonar? EVIDÊNCIAS CIENTÍFICAS: As buscas identificaram apenas um ensaio clínico randomizado, cujo objetivo foi comparar o efeito da terapia guiada por metas realizada utilizando o cateter de artéria pulmonar versus o sistema FloTrac® após cirurgia de revascularização miocárdica. Os pacientes do grupo FloTrac® receberam mais volume e ficaram em média cinco horas a menos em suporte ventilatório, ambos desfechos estatisticamente significativos. Estudo com alto risco de viés e certeza da evidência avaliada como muito baixa. AVALIAÇÃO ECONÔMICA (AE): O demandante optou por descartar as diferenças observadas no ensaio clínico e considerar as tecnologias com igual eficácia, adotando um modelo econômico de custo-minimização. O preço do FloTrac® foi ofertado de forma a ser equivalente ao preço do cateter de artéria pulmonar em compras públicas recentes. A busca no Banco de Preços em Saúde foi atualizada pelo parecerista e observou-se que o preço proposto (R$ 1.200,00) está acima do valor SIGTAP (R$ 518,70) e da mediana de preços das compras públicas realizadas nos últimos 18 meses (R$ 358,50 a R$ 380,00 dependendo do tamanho do cateter). ANÁLISE DE IMPACTO ORÇAMENTÁRIO (AIO): A avaliação do impacto orçamentário foi realizada por demanda aferida e considerou apenas o custo de aquisição dos cateteres. O demandante considerou o mesmo preço para as tecnologias e consequentemente impacto orçamentário zero. O impacto foi recalculado com base na mediana e média ponderada dos preços atualizados no BPS em relação ao preço ofertado sendo constatado um impacto incremental em torno de 22,5 a 33,7 milhões de reais em cinco anos. RECOMENDAÇÕES DE AGÊNCIAS DE ATS: CONSIDERAÇÕES FINAIS: A monitorização minimamente invasiva é uma opção à monitorização invasiva com potencial, porém não comprovado, de redução de risco de complicações como infecção associada ao cateter e pneumotórax. Um único ensaio clínico, com muita baixa confiabilidade demonstrou superioridade do FloTrac® em relação ao cateter de artéria pulmonar com redução de cinco horas no tempo médio de ventilação assistida. O demandante optou por considerar eficácia semelhante e ofertar o FloTrac® com preço igual à mediana de preço de compras no BPS do cateter de artéria pulmonar, ou seja, sem custos incrementais ao SUS. Porém, os valores atualizados no BPS são inferiores aos valores apresentados. RECOMENDAÇÃO PRELIMINAR DA CONITEC: Pelo exposto, o Plenário da Conitec, em sua 114ª Reunião Ordinária, no dia 09 de novembro de 2022, deliberou por unanimidade que a matéria fosse disponibilizada em Consulta Pública com recomendação preliminar desfavorável à incorporação do FloTrac®, sistema para monitorização do débito cardíaco minimamente invasivo em cirurgias de grande porte e de alto risco. Os membros da Conitec consideraram que o preço da tecnologia é superior ao preço do cateter de artéria pulmonar hoje disponibilizado no SUS, o que é divergente da proposta apresentada pelo demandante de igualdade de preços e impacto orçamental nulo. Após revisão das compras realizadas nos últimos 18 meses, o preço proposto do FloTrac® (R$ 1.200,00), em relação ao preço do cateter de artéria pulmonar, encontra-se significativamente superior ao valor SIGTAP (R$ 518,70), média ponderada (R$ 380 a R$ 651,34 cateteres 7,0/7,5 french) ou mediana de preços (R$ 358,50 a R$ 380,00 cateteres 7,0/7,5 french) e que por isso causaria um impacto orçamentário incremental sem comprovação de benefícios clínicos ou de segurança que justificassem o investimento. CONSULTA PÚBLICA: Foram recebidas 7 contribuições, sendo todas de experiência e opinião. Diante das argumentações apresentadas, o plenário da Conitec entendeu que não houve argumentação suficiente para mudança de entendimento acerca de sua recomendação preliminar, com base em evidência científica frágil. Desse modo, a Comissão, diante das incertezas quanto ao real benefício do dispositivo, manteve a posição desfavorável à incorporação do sensor pré-calibrado para monitorização hemodinâmica contínua do débito cardíaco e da pressão intravascular, sistema FloTrac. RECOMENDAÇÃO FINAL DA CONITEC: Diante do exposto, os membros presentes do Comitê de Produtos e Procedimentos da Conitec, em sua 116ª Reunião Ordinária, realizada no dia 15 de março de 2023, deliberaram, por unanimidade, recomendar a não incorporação, no SUS, sensor pré-calibrado para monitorização de pressão intravascular e minimamente invasiva do débito cardíaco, FloTrac®, para cirurgias de grande porte e de alto risco. Para essa recomendação, a Conitec considerou que a consulta pública não trouxe elementos novos que alterassem a recomendação preliminar. Foi assinado o registro de deliberação nº 801/2023. DECISÃO: Não incorporar, no âmbito do Sistema Único de Saúde - SUS, o sensor pré-calibrado para monitorização de pressão intravascular e minimamente invasiva do débito cardíaco, FloTrac®, para cirurgias de grande porte e de alto risco, publicada no Diário Oficial da União nº 74, seção 1, página 195, em 18 de abril de 2023.

Dialysis prescription: Determinants and relationship with intradialytic complications and the dialysis dose. A prospective study

Introduction: Dialysis still remains the most common modality for the treatment of end stage kidney disease and it could be maneuvered to augment its dose, minimize complications and improve outcome. Dialysis prescription is a brief of how dialysis is to be given and involves adjustments in patients' characteristics, disease or dialytic procedure. This study aimed to assess the determinants of the prescribed dialysis and its relationship with intradialytic complications and the dialysis dose. Methods: A prospective study in which 1248 sessions for 232 consented participants with end stage kidney disease on maintenance hemodialysis were studied from 2017-2020. Biodata was taken, participants were examined and blood samples were taken to determine electrolytes, urea/creatinine and hematocrit. Pearson's correlation was used to determine the strength of association between dialysis dose and some variables. Results: Determinants of the prescribed dose were dialysis frequency (P<0.001), and predialysis systolic blood pressure (P<0.001) and packed cell volume (P<0.001). Dialysis sessions without significant intradialytic blood pressure changes were most likely to be completed, as sessions with intra-dialysis hypotension were most likely to be terminated. Participants dialyzed with high flux dialyzers, via an arterovenous fistula, higher blood flow and ultrafiltration rates had higher dialysis doses (P<0.001 in all instances). Conclusion: Higher dialysis doses were achieved with higher blood flow and ultrafiltration rates. Intradialytic hypotension was common with dialysis termination, higher blood flow and ultrafiltration rates. Intradialytic hypertension was common with low flux dialyzers. An optimized dialysis prescription is needed to deliver an adequate dialysis dose and minimize complications

Acute effects of exercise with blood flow restriction on endothelial function in healthy young and older populations: a systematic review / Efeitos agudos do exercício com restrição do fluxo sanguíneo na função endotelial de jovens e idosos saudáveis: uma revisão sistemática

The objective of this review is to identify the acute effects of blood flow restriction (BFR) with vs without exercise on endothelial function in healthy individuals and the changes in endothelial function in young and older adults following different levels of exclusive BFR vs free flow. Systematic searches were performed in the following databases: PubMed, Web of Science, Scopus, and Cochrane Library, from inception to July 17, 2021. The studies included healthy individuals who underwent assessments of endothelial function before and after experimental protocols through endothelium-dependent flow-mediated dilatation. In total, 4890 studies were screened, and 6 studies of moderate-to-high methodological quality (Physiotherapy Evidence Database scores 6 ­ 10) including 82 subjects (aged 24 ­ 68 years) were eligible. Overall, flow-mediated dilatation increased in the non-cuffed arm immediately and 15 minutes after exercise, with no change in the cuffed arm (BFR of 60 ­ 80 mmHg). In protocols without exercise, cuff pressures of 25 ­ 30 mmHg applied for 30 minutes did not promote changes in the endothelial function, while those > 50 mmHg induced a dose-dependent attenuation of flow-mediated dilatation only in young individuals. A moderate level of BFR appears to have no effect on endothelial function after acute exercise. In non-exercise conditions, reductions in flow-mediated dilatation seem to result from increased retrograde shear provoked by cuff pressures ≥ 50 mmHg in young but not in older adults. An exercise-related increase in antegrade shear rate leads to a greater nitric oxide-mediated vasodilator response. However, BFR appears to attenuate this effect in young but not in older individuals. (AU)

O objetivo desta revisão foi identificar os efeitos agudos da restrição do fluxo sanguíneo (RFS) com vs. sem exercício na função endotelial de indivíduos saudáveis, bem como as alterações na função endotelial em jovens e idosos após diferentes níveis de RFS vs. fluxo livre. Pesquisas sistemáticas foram realizadas nas bases United States National Library of Medicine (PubMed), Web of Science, Scopus e Cochrane Library até 17 de julho de 2021. Os estudos incluíram indivíduos saudáveis que avaliaram a função endotelial antes e após protocolos experimentais, por meio da dilatação mediada por fluxo. Foi selecionado o total de 4.890 estudos, e foram elegíveis seis de moderada a alta qualidade metodológica (Physioterapy Evidence Database 6 ­ 10 pontos), incluindo 82 indivíduos (24 ­ 68 anos). No geral, a dilatação mediada por fluxo aumentou no braço sem manguito, imediatamente e 15 minutos após o exercício, sem alteração no braço com manguito (RFS de 60 ­ 80 mmHg). Em protocolos sem exercício, pressões do manguito de 25 ­ 30 mmHg aplicadas por 30 minutos não promoveram alterações na função endotelial, enquanto aquelas > 50 mmHg induziram uma atenuação dose-dependente da dilatação mediada por fluxo em indivíduos jovens. Um nível moderado de RFS parece não ter efeito na função endotelial após uma sessão de exercício. Em condições sem exercício, as reduções na dilatação mediada por fluxo parecem resultar do aumento do cisalhamento retrógrado provocado por pressões do manguito ≥ 50 mmHg em jovens, mas não em idosos. O aumento da taxa de cisalhamento anterógrado relacionada ao exercício leva a maior resposta vasodilatadora mediada pelo óxido nítrico. No entanto, a RFS parece atenuar esse efeito em jovens, mas não em . (AU)

Modeling a 3-D multiscale blood-flow and heat-transfer framework for realistic vascular systems.

Modeling of biological domains and simulation of biophysical processes occurring in them can help inform medical procedures. However, when considering complex domains such as large regions of the human body, the complexities of blood vessel branching and variation of blood vessel dimensions present a major modeling challenge. Here, we present a Voxelized Multi-Physics Simulation (VoM-PhyS) framework to simulate coupled heat transfer and fluid flow using a multi-scale voxel mesh on a biological domain obtained. In this framework, flow in larger blood vessels is modeled using the Hagen-Poiseuille equation for a one-dimensional flow coupled with a three-dimensional two-compartment porous media model for capillary circulation in tissue. The Dirac distribution function is used as Sphere of Influence (SoI) parameter to couple the one-dimensional and three-dimensional flow. This blood flow system is coupled with a heat transfer solver to provide a complete thermo-physiological simulation. The framework is demonstrated on a frog tongue and further analysis is conducted to study the effect of convective heat exchange between blood vessels and tissue, and the effect of SoI on simulation results.

Multimodal Assessment of Systemic Blood Flow in Infants.

The assessment of systemic blood flow is a complex and comprehensive process with clinical, laboratory, and technological components. Despite recent advancements in technology, there is no perfect bedside tool to quantify systemic blood flow in infants that can be used for clinical decision making. Each option has its own merits and limitations, and evidence on the reliability of these physiology-based assessment processes is evolving. This article provides an extensive review of the interpretation and limitations of methods to assess systemic blood flow in infants, highlighting the importance of a comprehensive and multimodal approach in this population.

Alterations in cardiac output in fetuses with congenital heart disease.

OBJECTIVE: Fetuses with severe congenital heart disease (CHD) have altered blood flow patterns. Prior work to assess fetal combined cardiac output (CCO) is limited by sample size and lack of longitudinal gestational data. Our aim was to evaluate CCO in CHD fetuses to determine whether the presence of single ventricle (SV) physiology or aortic obstruction impacts fetal blood flow and cardiovascular hemodynamics. METHOD: Prospective study including singleton fetuses with CHD (n = 141) and controls (n = 118) who underwent a mid- and late-gestation fetal echocardiogram. Ventricular cardiac output was calculated using the standard computation. Combined cardiac output was derived as the sum of the right and left cardiac outputs and indexed to estimated fetal weight. RESULTS: Fetuses with two ventricle (2V) CHD had significantly higher CCO compared to controls and SV CHD fetuses. Fetuses with SV-CHD had similar CCO compared to controls. Fetuses with 2V-CHD and aortic obstruction had significantly higher CCO than fetuses with SV-CHD and aortic obstruction. CONCLUSION: Our findings suggest that the SV can compensate and increase CCO despite the lack of a second functioning ventricle, however, the degree of compensation may be insufficient to support the increased blood flow needed to overcome the hemodynamic and physiologic alternations seen with severe CHD.

CD97 promotes spleen dendritic cell homeostasis through the mechanosensing of red blood cells.

Dendritic cells (DCs) are crucial for initiating adaptive immune responses. However, the factors that control DC positioning and homeostasis are incompletely understood. We found that type-2 conventional DCs (cDC2s) in the spleen depend on Gα13 and adhesion G protein-coupled receptor family member-E5 (Adgre5, or CD97) for positioning in blood-exposed locations. CD97 function required its autoproteolytic cleavage. CD55 is a CD97 ligand, and cDC2 interaction with CD55-expressing red blood cells (RBCs) under shear stress conditions caused extraction of the regulatory CD97 N-terminal fragment. Deficiency in CD55-CD97 signaling led to loss of splenic cDC2s into the circulation and defective lymphocyte responses to blood-borne antigens. Thus, CD97 mechanosensing of RBCs establishes a migration and gene expression program that optimizes the antigen capture and presentation functions of splenic cDC2s.