Hemodynamic Properties Research Articles

Spatial Transcriptomic Profiling of Human Saphenous Vein Exposed to Ex Vivo Arterial Haemodynamics-Implications for Coronary Artery Bypass Graft Patency and Vein Graft Disease.

Vein graft disease is the process by which saphenous vein grafts, utilised for revascularisation during coronary artery bypass graft surgery, undergo an inflammation-driven intimal hyperplasia and accelerated atherosclerosis process in subsequent years after implantation. The role of the arterial circulation, particularly the haemodynamic properties' impact on graft patency, have been investigated but have not to date been explored in depth at the transcriptomic level. We have undertaken the first-in-man spatial transcriptomic analysis of the long saphenous vein in response to ex vivo acute arterial haemodynamic stimulation, utilising a combination of a custom 3D-printed perfusion bioreactor and the 10X Genomics Visium Spatial Gene Expression technology. We identify a total of 413 significant genes (372 upregulated and 41 downregulated) differentially expressed in response to arterial haemodynamic conditions. These genes were associated with pathways including NFkB, TNF, MAPK, and PI3K/Akt, among others. These are established pathways involved in the initiation of an early pro-inflammatory response, leukocyte activation and adhesion signalling, tissue remodelling, and cellular differentiation. Utilising unsupervised clustering analysis, we have been able to classify subsets of the expression based on cell type and with spatial resolution. These findings allow for further characterisation of the early saphenous vein graft transcriptional landscape during the earliest stage of implantation that contributes to vein graft disease, in particular validation of pathways and druggable targets that could contribute towards the therapeutic inhibition of processes underpinning vein graft disease.

Diastolic dysfunction: assessment and implications on the single ventricle circulation.

Patients with a functionally single ventricle (SV) are palliated with a series of procedures leading to a Fontan circulation. Over the life span, a substantial proportion of SV patients develop heart failure that can arise from circulatory or ventricular failure. Diastolic dysfunction (DD) is an important determinant of adverse outcomes in SV patients. However, assessment and categorization of DD in the SV remains elusive. We review recent literature and developments in assessment of DD in the SV and its relation to clinical outcomes. DD is prevalent in the SV and associated with worse outcomes. Occult DD can be exposed with provocative testing by exercise or preload challenge during catheterization. Likewise, sensitivity to detect DD may be increased via assessment of atrial function and strain imaging. Recent studies revisiting previous concepts such as incoordinate diastolic wall motion show that these are associated with SV end-diastolic pressures and post-Fontan recovery, yielding accessible DD assessment. Emerging technologies such as ultrafast ultrasound (UFUS) can provide noninvasive assessment of myocardial stiffness, inefficient diastolic flow patterns and intraventricular pressure gradients, thereby yielding new tools and insights into diastolic myocardial and hemodynamic properties. Characterizing DD in the SV continues to have substantial limitations, necessitating synthesis of multiple parameters into an overall assessment, accounting for their change over time, and in the context of the patient's clinical status. New and emerging techniques may help advance DD assessment and the ability to track response to treatment of new targets.

Inotropic Agents: Are We Still in the Middle of Nowhere?

Inotropes are prescribed to enhance myocardial contractility while vasopressors serve to improve vascular tone. Although these medications remain a life-saving therapy in cardiovascular clinical scenarios with hemodynamic impairment, the paucity of evidence on these drugs makes the choice of the most appropriate vasoactive agent challenging. As such, deep knowledge of their pharmacological and hemodynamic effects becomes crucial to optimizing hemodynamic profile while reducing the potential adverse effects. Given this perspective, it is imperative for cardiologists to possess a comprehensive understanding of the underlying mechanisms governing these agents and to discern optimal strategies for their application across diverse clinical contexts. Thus, we briefly review these agents' pharmacological and hemodynamic properties and their reasonable clinical applications in cardiovascular settings. Critical interpretation of available data and the opportunities for future investigations are also highlighted.

Outcomes of transfemoral TAVR using two new‐generation devices in patients with horizontal aorta

AbstractBackgroundChallenging anatomies and comorbidities have impact on success in transcatheter aortic valve replacement (TAVR). There is controversy whether the extent of the aortic angle (AA) has an impact on procedural outcomes. Matched comparative outcome data of new generation transcatheter heart valves (THVs) in horizontal aorta (HA) are scarce.MethodsA total of 1582 patients with severe native aortic stenosis (AS) treated with the SAPIEN3 Ultra (Ultra; n = 526) or ACURATE Neo2 (Neo2; n = 1056) THVs from January 2017 to January 2023 were analyzed. Patients with non‐horizontal aortas (AA < 51.7°, n = 841) were excluded. The population was matched by 1‐to‐1 nearest‐neighbor matching (Ultra, n = 246; Neo2, n = 246). Clinical and procedural outcome were evaluated according to VARC‐3 recommendations.ResultsTechnical success (93.1% vs. 94.7%, p = 0.572) was high after Ultra and Neo2. Device success (80.5% vs. 89.8%, p = 0.05) was inferior with Ultra. Neo2 reveals superior hemodynamic properties with lower rate of severe prosthesis patient mismatch (12.0% vs. 3.7%, p = 0.001) and elevated gradients (20 mmHg: 11.9% vs. 1.7%, p < 0.001). Ultra showed a lower rate of relevant paravalvular regurgitation (mild paravalvular regurgitation or Valve‐in‐Valve due to paravalvular regurgitation: 0.0% vs. 3.7%, p = 0.004). The rate of procedural bailout maneuvers (0.8% vs. 0.4%, p = 1.000) and thirty‐day all‐cause mortality (1.3% vs. 2.2%, p = 0.496) was similar.ConclusionTransfemoral TAVR in patients with severe aortic stenosis and HA, using the balloon expandable Sapien3 Ultra and self‐expanding ACURATE Neo2 prosthesis, is feasible and safe. Therefore, valve selection between these platforms should be made irrespective of the aortic angle by a team experienced with both valves based on their specific advantages. Large, randomized trials in this sub‐group of patients would be necessary to compare long term outcomes.

Conventional and Doppler ultrasonographic diagnosis of subclinical pregnancy toxemia with altered serum cortisol and biochemical parameters in pregnant does

The pathogenesis and diagnosis of subclinical pregnancy toxemia (SCPT) remain elusive and need further investigation in pregnant does. Therefore, the aim of our study was to describe the typical properties of hepatic venous hemodynamics by Doppler ultrasonography. A total of 70 pregnant does were classified based on the blood serum concentrations of β-hydroxybutyric acid (βHBA), pregnant does were categorized into control group (βHBA concentrations <0.8 mmol/L; n = 40) and SCPT group (βHBA concentrations >0.8 mmol/L; n = 30). DRAMISKI 4vet slim diagnostic ultrasound scanner with B, M, and Doppler (color, power, pulsing wave) modes was used for diagnosis of SCPT. Total serum cortisol level was quantitative using chemiluminescent immunoassay. Serum glucose, triglycerides, cholesterol, HDL and LDL- cholesterol and LDH- cholesterol were measured by colorimetric and kinetic methods. Liver ultrasonography of does with SCPT had been shown mild fatty infiltration with rounded margin, which was characterized by hyperechoic area. There was a significant decrease in the values of portal vein diameter (PVD), portal vein area (PVA), portal mean velocity (PMV) and portal blood flow (PBF) in SCPT does compared to control pregnant does. PVD, PVA and PBF were negatively correlated with βHBA concentrations in does with SCPT (P < 0.05). PVD was inversely associated with serum cholesterol and triglycerides concentrations (P < 0.05). In conclusions, Doppler ultrasonography examinations of pregnant does with SCPT indicate abnormal hepatic variation. Reduced PVD, PVA, PMV and PBF together with increased βHBA concentrations could predict SCPT in does with fair sensitivity and specificity.

Analysis of ischemic stroke-mediated effects on blood–brain barrier properties along the arteriovenous axis assessed by intravital two-photon imaging

Early breach of the blood–brain barrier (BBB) and consequently extravasation of blood-borne substances into the brain parenchyma is a common hallmark of ischemic stroke. Although BBB breakdown is associated with an increased risk of cerebral hemorrhage and poor clinical prognosis, the cause and mechanism of this process are largely unknown. The aim of this study was to establish an imaging and analysis protocol which enables investigation of the dynamics of BBB breach in relation to hemodynamic properties along the arteriovenous axis. Using longitudinal intravital two-photon imaging following photothrombotic induction of ischemic stroke through a cranial window, we were able to study the response of the cerebral vasculature to ischemia, from the early critical hours to the days/weeks after the infarct. We demonstrate that disruption of the BBB and hemodynamic parameters, including perturbed blood flow, can be studied at single-vessel resolution in the three-dimensional space as early as 30 min after vessel occlusion. Further, we show that this protocol permits longitudinal studies on the response of individual blood vessels to ischemia over time, thus enabling detection of (maladaptive) vascular remodeling such as intussusception, angiogenic sprouting and entanglement of vessel networks. Taken together, this in vivo two-photon imaging and analysis protocol will be useful in future studies investigating the molecular and cellular mechanisms, and the spatial contribution, of BBB breach to disease progression which might ultimately aid the development of new and more precise treatment strategies for ischemic stroke.

A constrained constructive optimization model of branching arteriolar networks in rat skeletal muscle.

Blood flow regulation within the microvasculature reflects a complex interaction of regulatory mechanisms and varies spatially and temporally according to conditions such as metabolism, growth, injury, and disease. Understanding the role of microvascular flow distributions across conditions is of interest to investigators spanning multiple disciplines; however, data collection within networks can be labor-intensive and challenging due to limited resolution. To overcome these experimental challenges, computational network models that can accurately simulate vascular behavior are highly beneficial. Constrained constructive optimization (CCO) is a commonly used algorithm for vascular simulation, particularly well known for its adaptability toward vascular modeling across tissues. The present work demonstrates an implementation of CCO aimed to simulate a branching arteriolar microvasculature in healthy skeletal muscle, validated against literature including comprehensive rat gluteus maximus vasculature datasets, and reviews a list of user-specified adjustable model parameters to understand how their variability affects the simulated networks. Network geometric properties, including mean element diameters, lengths, and numbers of bifurcations per order, Horton's law ratios, and fractal dimension, demonstrate good validation once model parameters are adjusted to experimental data. This model successfully demonstrates hemodynamic properties such as Murray's law and the network Fahraeus effect. Application of centrifugal and Strahler ordering schemes results in divergent descriptions of identical simulated networks. This work introduces a novel CCO-based model focused on generating branching skeletal muscle microvascular arteriolar networks based on adjustable model parameters, thus making it a valuable tool for investigations into skeletal muscle microvascular structure and tissue perfusion.NEW & NOTEWORTHY The present work introduces a CCO-based algorithm for generating branching arteriolar networks, with adjustable model parameters to enable modeling in varying skeletal muscle tissues. The geometric and hemodynamic parameters of the generated networks have been comprehensively validated using experimental data collected previously in-house and from literature. This is one of few validated CCO-based models to specialize in skeletal muscle microvasculature and acts as a beneficial tool for investigating the microvasculature for hypothesis testing and validation.

Inhaled NO at a crossroads in cardiac surgery: current need to improve mechanistic understanding, clinical trial design and scientific evidence.

Inhaled nitric oxide (NO) has been used in pediatric and adult perioperative cardiac intensive care for over three decades. NO is a cellular signaling molecule that induces smooth muscle relaxation in the mammalian vasculature. Inhaled NO has the unique ability to exert its vasodilatory effects in the pulmonary vasculature without any hypotensive side-effects in the systemic circulation. In patients undergoing cardiac surgery, NO has been reported in numerous studies to exert beneficial effects on acutely lowering pulmonary artery pressure and reversing right ventricular dysfunction and/or failure. Yet, various investigations failed to demonstrate significant differences in long-term clinical outcomes. The authors, serving as an advisory board of international experts in the field of inhaled NO within pediatric and adult cardiac surgery, will discuss how the existing scientific evidence can be further improved. We will summarize the basic mechanisms underlying the clinical applications of inhaled NO and how this translates into the mandate for inhaled NO in cardiac surgery. We will move on to the popular use of inhaled NO and will talk about the evidence base of the use of this selective pulmonary vasodilator. This review will elucidate what kind of clinical and biological barriers and gaps in knowledge need to be solved and how this has impacted in the development of clinical trials. The authors will elaborate on how the optimization of inhaled NO therapy, the development of biomarkers to identify the target population and the definition of response can improve the design of future large clinical trials. We will explain why it is mandatory to gain an international consensus for the state of the art of NO therapy far beyond this expert advisory board by including the different major players in the field, such as the different medical societies and the pharma industry to improve our understanding of the real-life effects of inhaled NO in large scale observational studies. The design for future innovative randomized controlled trials on inhaled NO therapy in cardiac surgery, adequately powered and based on enhanced biological phenotyping, will be crucial to eventually provide scientific evidence of its clinical efficacy beyond its beneficial hemodynamic properties.

Hemodynamic property incorporated brain tumor segmentation by deep learning and density-based analysis of dynamic susceptibility contrast-enhanced magnetic resonance imaging (MRI).

Magnetic resonance imaging (MRI) is a primary non-invasive imaging modality for tumor segmentation, leveraging its exceptional soft tissue contrast and high resolution. Current segmentation methods typically focus on structural MRI, such as T1-weighted post-contrast-enhanced or fluid-attenuated inversion recovery (FLAIR) sequences. However, these methods overlook the blood perfusion and hemodynamic properties of tumors, readily derived from dynamic susceptibility contrast (DSC) enhanced MRI. This study introduces a novel hybrid method combining density-based analysis of hemodynamic properties in time-dependent perfusion imaging with deep learning spatial segmentation techniques to enhance tumor segmentation. First, a U-Net convolutional neural network (CNN) is employed on structural images to delineate a region of interest (ROI). Subsequently, Hierarchical Density-Based Scans (HDBScan) are employed within the ROI to augment segmentation by exploring intratumoral hemodynamic heterogeneity through the investigation of tumor time course profiles unveiled in DSC MRI. The approach was tested and evaluated using a cohort of 513 patients from the open-source University of Pennsylvania glioblastoma database (UPENN-GBM) dataset, achieving a 74.83% Intersection over Union (IoU) score when compared to structural-only segmentation. The algorithm also exhibited increased precision and localized predictions of heightened segmentation boundary complexity, resulting in a 146.92% increase in contour complexity (ICC) compared to the reference standard provided by the UPENN-GBM dataset. Importantly, segmenting tumors with the developed new approach uncovered a negative correlation of the tumor volume with the scores in the Karnofsky Performance Scale (KPS) clinically used for assessing the functional status of patients (-0.309), which is not observed with the prevailing segmentation standard. This work demonstrated that including hemodynamic properties of tissues from DSC MRI can improve existing structural or morphological feature-based tumor segmentation techniques with additional information on tumor biology and physiology. This approach can also be applied to other clinical indications that use perfusion MRI for diagnosis or treatment monitoring.

Clinical and morphological features of Osler-Weber-Randu disease with signs of visceral injury

Randu-Osler-Weber disease or hereditary hemorrhagic telangiectasia is an autosomal dominant disorder characterized by dilated capillaries and veins, which are usually localized on the skin and mucous membranes of the oral cavity, as well as in the respiratory, urinary and digestive tracts. The anatomical basis of the disease is damage to blood vessels with degeneration and hypoplasia of the muscle and elastic layers, resulting in focal thinning of the vessel walls with further expansion of their lumen. Violation of angiogenesis persists throughout the patient's life, and is manifested by the formation of aneurysms, telangiectasias, and arteriovenous shunts. The average life expectancy of patients with burdened heredity is 63.2 years. The peak of mortality occurs at the age of 50, which is mainly associated with acute complications of the disease. However, among people suffering from Randu-Osler-Weber disease there are also long-lived people who die at the age of 70-79 years, and the cause of death is the complication of the main disease and the addition of chronic diseases. The purpose of this article is to consider in more detail possible manifestations and complications, methods of treatment of Randu-Osler-Weber disease for timely recognition of the disease and provision of timely medical assistance. This article describes a case of an abdominal form of hereditary hemorrhagic telangiectasia in an 82-year-old patient. The results of the postmortem pathomorphological examination of damaged tissues due to Randu-Osler-Weber disease are presented. During the study of micropreparations of the mucous lip, small intestine, mesentery of the small intestine and liver, groups of vessels were found, the wall of which is thinned in places and thickened in places, in the wall of these vessels there is a decrease or complete absence of muscle and elastic fibers, only endothelium is present, surrounded by loose connective tissue, postcapillary venules expand and anastomose with arterioles. In the lumen of these falsely developed vessels, mixed thrombi are determined. An elderly patient suffered from a combined pathology: hereditary hemorrhagic telangiectasia with arterio-venous malformations in the liver, heart, mesentery, small intestine, and coronary heart disease. These processes were complicated by the development of congestive heart failure, which disturbed the hemodynamic and rheological properties of blood and contributed to the occurrence of thrombosis of arterio-venous malformations in the mesentery and the wall of the small intestine. In the following, necrosis of the loops of the small intestine occurred with the development of diffuse purulent-fibrinous peritonitis and endogenous intoxication. Patients with hereditary hemorrhagic telangiectasia have a higher risk of bleeding and neurological complications, including anemia, cerebral abscess, stroke, venous thrombosis, and heart failure, because of late diagnosis of this hereditary disease. Early diagnosis is based on clinical data and careful collection of family history. In 90% of patients under the age of 40, the diagnosis of hereditary hemorrhagic telangiectasia can be established using the Curaçao criteria. This disease brings a significant amount of suffering in everyday life for both patients and their families, and requires significant attention of a multidisciplinary team of doctors at every stage of medical care.

Evaluation of Hemodynamic Properties After Chimney and Fenestrated Endovascular Aneurysm Repair

ObjectivesFenestrated (FEVAR) and chimney (ChEVAR) endovascular aortic repair have been applied in anatomically suitable complex aortic aneurysms. However, local hemodynamic changes may occur after repair. This study aimed to compare FEVAR’s and ChEVAR’s hemodynamic properties, focusing on visceral arteries. MethodsPre- and post-operative computed tomography angiographies (CTAs) have been used to reconstruct patient-based models. Data of three patients, for each modality, were analyzed. Following geometric reconstruction, computational fluid dynamics (CFD) simulations were used to extract near-wall and intravascular hemodynamic indicators, as pressure drops, velocity, wall shear stress (WSS), time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT) and local normalized helicity (LNH). ResultsAn overall improvement in hemodynamics was detected after repair, with either technique. Preoperatively, a disturbed pro-thrombotic WSS profile was recorded in several zones of the sac. The LNH results showed a better organization of the helical structures at post-operative setting, decreasing thrombus formation, with both modalities. Similarly, TAWSS increased and OSI decreased post-operatively, signaling non-disturbed blood flow. The RRT was locally reduced. The flow in visceral arteries tended to be more streamlined in ChEVAR, compared to evident recirculation regions at renal and superior mesenteric artery fenestrations (p=0.06). ConclusionChEVAR and FEVAR seem to improve hemodynamics towards normal values with a reduction of recirculation zones in the main graft and aortic branches. Visceral artery flow comparison revealed that ChEVAR tended to present lower recirculation regions at parallel grafts’ entries while FEVAR showed less intense flow regurgitation in visceral stents.

Flow and irreversible mechanism of pure and hybridized non-Newtonian nanofluids through elastic surfaces with melting effects

Abstract The significance of nanofluid research in nanotechnology, pharmaceutical, drug delivery, food preparation, and chemotherapy employing single- and two-phase nanofluid models has drawn the attention of researchers. The Tiwari–Das model does not capture the diffusion and random movement of nanoparticles (NPs) when they are injected into complex functional fluids. In order to fix the peculiar behavior of NPs, more complex models like the Buongiorno model are coupled with the single-phase model. To examine the heat-mass transfer attributes of nanofluids, a single- and two-phase mixture model is coupled for the first time. The effect of hybrid NPs on the hemodynamic properties of the blood flow through a stretched surface with interface slip in the neighborhood of the stagnation point is examined. Due to their significance in medicinal uses and nominal toxicity, blood is loaded with zinc–iron ( ZnO − F e 2 O 3 ) {\rm{ZnO}}\left-{\rm{F}}{{\rm{e}}}_{2}{{\rm{O}}}_{3}) NPs. However, blood is speculated to have the hematocrit viscosity of the Powell–Eyring fluid. The single-phase model predicts an improvement in heat transport due to an increased volumetric friction of NPs, while the two-phase models provide closer estimates of heat-mass transfer due to Brownian and thermophoretic phenomena. Entropy evaluation predicts the details of irreversibility. The mathematical structures are effectively solved with a Runge–Kutta fourth-order algorithm along with a shooting mechanism. The Eyring–Powell parameters decrease the drag coefficient and mass/thermal transport rate. A higher estimation of the slip, material, and magnetic parameters decreases the flow behavior. The Bejan number increases with the diffusion parameter and decreases as the magnetic and Brinkman numbers increase. The effect of iron oxide ( F e 2 O 3 ) \left({\rm{F}}{{\rm{e}}}_{2}{{\rm{O}}}_{3}) is observed to be dominant.

Left main coronary artery morphological phenotypes and its hemodynamic properties.

Atherosclerosis may be linked to morphological defects that lead to variances in coronary artery hemodynamics. Few objective strategies exit at present for generalizing morphological phenotypes of coronary arteries in terms of hemodynamics. We used unsupervised clustering (UC) to classify the morphology of the left main coronary artery (LM) and looked at how hemodynamic distribution differed between phenotypes. In this study, 76 LMs were obtained from 76 patients. After LMs were reconstructed with coronary computed tomography angiography, centerlines were used to extract the geometric characteristics. Unsupervised clustering was carried out using these characteristics to identify distinct morphological phenotypes of LMs. The time-averaged wall shear stress (TAWSS) for each phenotype was investigated by means of computational fluid dynamics (CFD) analysis of the left coronary artery. We identified four clusters (i.e., four phenotypes): Cluster 1 had a shorter stem and thinner branches (n = 26); Cluster 2 had a larger bifurcation angle (n = 10); Cluster 3 had an ostium at an angulation to the coronary sinus and a more curved stem, and thick branches (n = 10); and Cluster 4 had an ostium at an angulation to the coronary sinus and a flatter stem (n = 14). TAWSS features varied widely across phenotypes. Nodes with low TAWSS (L-TAWSS) were typically found around the branching points of the left anterior descending artery (LAD), particularly in Cluster 2. Our findings demonstrated that UC is a powerful technique for morphologically classifying LMs. Different LM phenotypes exhibited distinct hemodynamic characteristics in certain regions. This morphological clustering method could aid in identifying people at high risk for developing coronary atherosclerosis, hence facilitating early intervention.

Hemodynamic-based virtual surgery design of double-patch repair for pulmonary arterioplasty in tetralogy of Fallot

Background and objectiveSurgical correction of pulmonary artery stenosis (PAS) is essential to the prognosis of patients with tetralogy of Fallot (TOF). The double-patch method of pulmonary arterioplasty is usually applied in case of multiple stenosis in TOF patients’ pulmonary artery (PA) and when PAS cannot be relieved by the single-patch method. The surgical planning for the double-patch design remains challenging. The purpose of this study is to investigate the double-patch design with different angulations between the left pulmonary artery (LPA) and the right pulmonary artery (RPA), and to understand postoperative hemodynamic alterations by the application of computer-aided design (CAD) and computational fluid dynamics (CFD) techniques. MethodsThe three-dimensional model of the PA was reconstructed based on preoperative computed tomography imaging data obtained from the patient with TOF. Three postoperative models with different designs of double-patch were created by “virtual surgery” using the CAD technique. Double-Patch 120 Model was created with double patches implanted in the main pulmonary artery (MPA) and the PA bifurcation and without changing the spatial position of PA. The angulation between the LPA and the RPA was defined as θ, which equaled to 120° in Pre-Operative Model and Double-Patch 120 Model. Based on Double-Patch 120 Model, Double-Patch 110 Model and Double-Patch 130 Model were generated with θ equaled to 110° and 130°, respectively. Combined with CFD, the differences of velocity streamlines, wall shear stress (WSS), flow distribution ratio (FDR), and energy loss (EL) were compared to analyze postoperative pulmonary flow characteristics. ResultsThe values of velocity and WSS decreased significantly after virtual surgery. Obvious vortices and swirling flows were observed downstream of the stenosis of RPA and LPA in Pre-Operative Model, while fewer vortices developed along the anterior wall of the expanded lumens of RPA, especially in Double-Patch 110 Model. With the relief of PAS, two relatively higher WSS regions were observed at the posterior walls of RPA and LPA. The maximum WSS values in these regions of Double-Patch 110 Model were lower than those in Double-Patch 120 Model and Double-Patch 130 Model. Furthermore, the FDRs were elevated and the ELs were greatly reduced. It was found that Double-Patch 110 Model with the angulation between the LPA and the RPA equaled to 110° showed relatively better properties of hemodynamics than other models. ConclusionsThe angulation between the LPA and the RPA is an important factor that should be integrated in the double-patch design for TOF repair. Virtual surgery based on patient-specific vascular model and computational hemodynamics can be used to provide assistance for individualized surgical planning of double-patch arterioplasty.

Benefits of Posterior Leaflet Preservation in Patients undergoing Mitral Valve Replacement Surgery: A Prospective Interventional Study

Introduction: Mitral Valve Replacement (MVR), an important treatment for rheumatic mitral valve disease, is being widely promoted worldwide. MVR using the total leaflet preservation technique can produce good results; however, patient-specific factors and anatomical considerations must be taken into account when selecting the appropriate surgical approach. Aim: To investigate the benefits of Posterior Leaflet Preservation (PLP) in MVR in individuals with severe mitral stenosis. Materials and Methods: The current prospective interventional study included patients with Rheumatic Heart Disease (RHD) who had severe mitral valve stenosis and/or regurgitation and underwent MVR between December 2019 and December 2021 in the Department of Cardiothoracic and Vascular Surgery at Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India. The study included 50 patients with MVR (PLP) to preserve the posterior leaflets and 50 patients with classic MVR (no PLP). Left Ventricular Ejection Fraction (LVEF), Left Ventricular End-Systolic Diameter (LVESD), and Left Ventricular End-Diastolic Diameter (LVEDD) were measured before surgery, one, three, and six months after surgery. Results: The majority of patients in the present study were between 23 and 46 years old. The PLP group consisted of 17 men and 33 women, while the non-PLP group had 16 men and 34 women. The difference in cross-clamp time between Group-A and B was significant (p=0.0001). Cardiopulmonary Bypass (CPB) time was significantly different between Group-A and B (p=0.001). Only 4 (8%) patients in Group-A had low cardiac output syndrome, compared with 8 (16%) of patients in Group-B. Comparison of LVEF between groups over time revealed no significant difference (p=0.05). The mean change in LVEF from pre-operative to six months in Group-A was significant (p=0.004), but there was no significant change in Group-B (p=0.25). Conclusion: PLP had no improved beneficial outcome on left ventricular performance in cases with rheumatic stenosis during the six-month follow-up. Even after long-term follow-up, haemodynamic valve properties do not alter with adequate PLP

Biomechanical factors and atherosclerosis localization: insights and clinical applications.

Although the entire vascular bed is constantly exposed to the same risk factors, atherosclerosis manifests a distinct intra-individual pattern in localization and progression within the arterial vascular bed. Despite shared risk factors, the development of atherosclerotic plaques is influenced by physical principles, anatomic variations, metabolic functions, and genetic pathways. Biomechanical factors, particularly wall shear stress (WSS), play a crucial role in atherosclerosis and both low and high WSS are associated with plaque progression and heightened vulnerability. Low and oscillatory WSS contribute to plaque growth and arterial remodeling, while high WSS promotes vulnerable changes in obstructive coronary plaques. Axial plaque stress and plaque structural stress are proposed as biomechanical indicators of plaque vulnerability, representing hemodynamic stress on stenotic lesions and localized stress within growing plaques, respectively. Advancements in imaging and computational fluid dynamics techniques enable a comprehensive analysis of morphological and hemodynamic properties of atherosclerotic lesions and their role in plaque localization, evolution, and vulnerability. Understanding the impact of mechanical forces on blood vessels holds the potential for developing shear-regulated drugs, improving diagnostics, and informing clinical decision-making in coronary atherosclerosis management. Additionally, Computation Fluid Dynamic (CFD) finds clinical applications in comprehending stent-vessel dynamics, complexities of coronary bifurcations, and guiding assessments of coronary lesion severity. This review underscores the clinical significance of an integrated approach, concentrating on systemic, hemodynamic, and biomechanical factors in atherosclerosis and plaque vulnerability among patients with coronary artery disease.

In vitro hemodynamics of fabric composite membrane for cardiac valve prosthesis replacement

This study aimed to investigate the hemodynamics of a novel fabric composite that can be used as a substitute for bovine pericardium. The structure is composed of ultrahigh molecular weight polyethylene (UHMWPE) fabric coated with thermoplastic polyurethane (TPU) membranes on both sides. In vitro experiments were carried out on two composite valve samples with different specifications and a bovine pericardial one with the same dimension and structure. Hemodynamic properties including the effective orifice area (EOA) and regurgitant fraction (RF) were obtained and compared through pulsatile-flow testing in a pulse duplicator. Using the particle image velocimetry (PIV) technique, frames of the downstream velocity field in the aortic valve chamber were captured during cardiac cycles. Then, the field of Reynolds shear stress (RSS), viscous shear stress (VSS), and turbulent kinetic energy (TKE) at peak systole were calculated. A fluid–structure interaction (FSI) model has also been used to verify the pulsatile-flow testing. Compared with the bovine pericardial valve, composite valves have nosuperiority regarding EOA and RF due to their slightly higher rigidity. However, shear stresses of composite valves were lower than those of the bovine pericardial valve indicating more stable blood flows, which means that composite leaflets have the potential to reduce the risks of thrombosis and hemolysis induced by the mechanical contact between the blood flow and leaflets of valve prostheses.

Significance of End-Diastolic Forward Flow in Patients With Repaired Tetralogy of Fallot - Its Interaction With the Left Ventricular Property and End Organ Damage.

Although right ventricular (RV) enlargement may affect RV diastolic dysfunction assessed by end-diastolic forward flow (EDFF) in patients with repaired tetralogy of Fallot (TOF), EDFF may also be modified by left ventricular (LV) hemodynamics. We hypothesized that EDFF is affected by LV hemodynamics, not limited to RV diastolic stiffening.Methods and Results: Among 145 consecutive patients with repaired TOF who underwent catheterization, hemodynamic properties in 47 with consistent EDFF and 75 without EDFF were analyzed. Compared with patients without EDFF, those with EDFF had a large RV volume with a high regurgitant fraction. Although cardiac index and central venous pressure (CVP) were similar, contrast injection augmented CVP and LV end-diastolic pressure (EDP) in patients with vs. those without EDFF, suggesting compromised diastolic reserve. In patients with EDFF, the velocity-time integral (VTI) of EDFF was positively correlated with LVEDP and systemic vascular resistance, in addition to RV EDP. EDFF-VTI was correlated with hepatic venous wedge pressure and markers of hepatic dysfunction. Subanalysis of the older (≥6 years) half of the study cohort revealed that EDFF was associated with bi-atrial enlargement independent of RV volume, highlighting the pronounced role of EDFF on the diastolic property in the aged cohort. EDFF-VTI in patients with repaired TOF reflects RV diastolic dysfunction, affected by the left heart system. EDFF-VTI indicates blood stagnation, which may be attributed to end-organ damage.

In vivo characterization of the optical and hemodynamic properties of the human sternocleidomastoid muscle through ultrasound-guided hybrid near-infrared spectroscopies

Objective. In this paper, we present a detailed in vivo characterization of the optical and hemodynamic properties of the human sternocleidomastoid muscle (SCM), obtained through ultrasound-guided near-infrared time-domain and diffuse correlation spectroscopies. Approach. A total of sixty-five subjects (forty-nine females, sixteen males) among healthy volunteers and thyroid nodule patients have been recruited for the study. Their SCM hemodynamic (oxy-, deoxy- and total hemoglobin concentrations, blood flow, blood oxygen saturation and metabolic rate of oxygen extraction) and optical properties (wavelength dependent absorption and reduced scattering coefficients) have been measured by the use of a novel hybrid device combining in a single unit time-domain near-infrared spectroscopy, diffuse correlation spectroscopy and simultaneous ultrasound imaging. Main results. We provide detailed tables of the results related to SCM baseline (i.e. muscle at rest) properties, and reveal significant differences on the measured parameters due to variables such as side of the neck, sex, age, body mass index, depth and thickness of the muscle, allowing future clinical studies to take into account such dependencies. Significance. The non-invasive monitoring of the hemodynamics and metabolism of the sternocleidomastoid muscle during respiration became a topic of increased interest partially due to the increased use of mechanical ventilation during the COVID-19 pandemic. Near-infrared diffuse optical spectroscopies were proposed as potential practical monitors of increased recruitment of SCM during respiratory distress. They can provide clinically relevant information on the degree of the patient's respiratory effort that is needed to maintain an optimal minute ventilation, with potential clinical application ranging from evaluating chronic pulmonary diseases to more acute settings, such as acute respiratory failure, or to determine the readiness to wean from invasive mechanical ventilation.

Hydrogel-polyurethane fiber composites with enhanced microarchitectural control for heart valve replacement.

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single-phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde-fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D-printed hydrogel coating setup was developed to make valve composites for device-level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2 ) met ISO 5840-2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post-spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel-polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model-directed fabrication toward optimizing durability as a function of fiber microarchitecture.