Steady Flow Left Ventricle Unloading Is Superior to Pulsatile Pressure Augmentation Venting During Venoarterial Extracorporeal Membrane Oxygenation Support

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) shunts venous blood to the systemic arterial circulation to provide end-organ perfusion while increasing afterload that may impede left ventricle (LV) ejection and impair cardiac recovery. To maintain flow across the aortic valve and reduce risk of lethal clot formation, secondary mechanical circulatory support (MCS) devices are increasingly used despite limited understanding of their effects on cardiac function. This study sought to quantify the effects of VA-ECMO and combined with either intraaortic balloon pump (IABP) or percutaneous ventricular assist device (pVAD) on LV physiologic state and perfusion metrics in a porcine model of acute cardiogenic shock. Shock was induced through serial left anterior descending artery microbead embolization followed by initiation of VA-ECMO support and then placement of either IABP or pVAD. Hemodynamic measurements, LV pressure-volume loops, and carotid artery blood flow were evaluated before and after institution of combined MCS. The IABP decreased LV end-diastolic pressure by a peak of 15% while slightly increasing LV stroke work compared with decreases of more than 60% and 50% with the pVAD, respectively. The pVAD also demonstrated increased coronary perfusion and systemic pressure gradients in comparison to the IABP. Combined support with VA-ECMO and pVAD improves cardiovascular state in comparison to IABP.

A transformer-based pyramid network for coronary calcified plaque segmentation in intravascular optical coherence tomography images

Characterizing coronary calcified plaque (CCP) provides essential insight into diagnosis and treatment of atherosclerosis. Intravascular optical coherence tomography (OCT) offers significant advantages for detecting CCP and even automated segmentation with recent advances in deep learning techniques. Most of current methods have achieved promising results by adopting existing convolution neural networks (CNNs) in computer vision domain. However, their performance can be detrimentally affected by unseen plaque patterns and artifacts due to inherent limitation of CNNs in contextual reasoning. To overcome this obstacle, we proposed a Transformer-based pyramid network called AFS-TPNet for robust, end-to-end segmentation of CCP from OCT images. Its encoder is built upon CSWin Transformer architecture, allowing for better perceptual understanding of calcified arteries at a higher semantic level. Specifically, an augmented feature split (AFS) module and residual convolutional position encoding (RCPE) mechanism are designed to effectively enhance the capability of Transformer in capturing both fine-grained features and global contexts. Extensive experiments showed that AFS-TPNet trained using Lovasz Loss achieved superior performance in segmentation CCP under various contexts, surpassing prior state-of-the-art CNN and Transformer architectures by more than 6.58% intersection over union (IoU) score. The application of this promising method to extract CCP features is expected to enhance clinical intervention and translational research using OCT.

Dynamic load modulation predicts right heart tolerance of left ventricular cardiovascular assist in a porcine model of cardiogenic shock

Ventricular assist devices (VADs) offer mechanical support for patients with cardiogenic shock by unloading the impaired ventricle and increasing cardiac outflow and subsequent tissue perfusion. Their ability to adjust ventricular assistance allows for rapid and safe dynamic changes in cardiac load, which can be used with direct measures of chamber pressures to quantify cardiac pathophysiologic state, predict response to interventions, and unmask vulnerabilities such as limitations of left-sided support efficacy due to intolerance of the right heart. We defined hemodynamic metrics in five pigs with dynamic peripheral transvalvular VAD (pVAD) support to the left ventricle. Metrics were obtained across a spectrum of disease states, including left ventricular ischemia induced by titrated microembolization of a coronary artery and right ventricular strain induced by titrated microembolization of the pulmonary arteries. A sweep of different pVAD speeds confirmed mechanisms of right heart decompensation after left-sided support and revealed intolerance. In contrast to the systemic circulation, pulmonary vascular compliance dominated in the right heart and defined the ability of the right heart to adapt to left-sided pVAD unloading. We developed a clinically accessible metric to measure pulmonary vascular compliance at different pVAD speeds that could predict right heart efficiency and tolerance to left-sided pVAD support. Findings in swine were validated with retrospective hemodynamic data from eight patients on pVAD support. This methodology and metric could be used to track right heart tolerance, predict decompensation before right heart failure, and guide titration of device speed and the need for biventricular support.

Single-Cell RNA Sequencing Reveals That Adaptation of Human Aortic Endothelial Cells to Antiproliferative Therapies Is Modulated by Flow-Induced Shear Stress

BACKGROUND

Endothelial cells (ECs) are capable of quickly responding in a coordinated manner to a wide array of stresses to maintain vascular homeostasis. Loss of EC cellular adaptation may be a potential marker for cardiovascular disease and a predictor of poor response to endovascular pharmacological interventions such as drug-eluting stents. Here, we report single-cell transcriptional profiling of ECs exposed to multiple stimulus classes to evaluate EC adaptation.

METHODS

Human aortic ECs were costimulated with both pathophysiological flows mimicking shear stress levels found in the human aorta (laminar and turbulent, ranging from 2.5 to 30 dynes/cm2) and clinically relevant antiproliferative drugs, namely paclitaxel and rapamycin. EC state in response to these stimuli was defined using single-cell RNA sequencing.

RESULTS

We identified differentially expressed genes and inferred the TF (transcription factor) landscape modulated by flow shear stress using single-cell RNA sequencing. These flow-sensitive markers differentiated previously identified spatially distinct subpopulations of ECs in the murine aorta. Moreover, distinct transcriptional modules defined flow- and drug-responsive EC adaptation singly and in combination. Flow shear stress was the dominant driver of EC state, altering their response to pharmacological therapies.

CONCLUSIONS

We showed that flow shear stress modulates the cellular capacity of ECs to respond to paclitaxel and rapamycin administration, suggesting that while responding to different flow patterns, ECs experience an impairment in their transcriptional adaptation to other stimuli.

Fully automated construction of three-dimensional finite element simulations from Optical Coherence Tomography

Despite recent advances in diagnosis and treatment, atherosclerotic coronary artery diseases remain a leading cause of death worldwide. Various imaging modalities and metrics can detect lesions and predict patients at risk; however, identifying unstable lesions is still difficult. Current techniques cannot fully capture the complex morphology-modulated mechanical responses that affect plaque stability, leading to catastrophic failure and mute the benefit of device and drug interventions. Finite Element (FE) simulations utilizing intravascular imaging OCT (Optical Coherence Tomography) are effective in defining physiological stress distributions. However, creating 3D FE simulations of coronary arteries from OCT images is challenging to fully automate given OCT frame sparsity, limited material contrast, and restricted penetration depth. To address such limitations, we developed an algorithmic approach to automatically produce 3D FE-ready digital twins from labeled OCT images. The 3D models are anatomically faithful and recapitulate mechanically relevant tissue lesion components, automatically producing morphologies structurally similar to manually constructed models whilst including more minute details. A mesh convergence study highlighted the ability to reach stress and strain convergence with average errors of just 5.9% and 1.6% respectively in comparison to FE models with approximately twice the number of elements in areas of refinement. Such an automated procedure will enable analysis of large clinical cohorts at a previously unattainable scale and opens the possibility for in-silico methods for patient specific diagnoses and treatment planning for coronary artery disease.

Interventional therapies for pulmonary embolism

Pulmonary embolism (PE) is the leading cause of in-hospital death and the third most frequent cause of cardiovascular death. The clinical presentation of PE is variable, and choosing the appropriate treatment for individual patients can be challenging. Traditionally, treatment of PE has involved a choice of anticoagulation, thrombolysis or surgery; however, a range of percutaneous interventional technologies have been developed that are under investigation in patients with intermediate-high-risk or high-risk PE. These interventional technologies include catheter-directed thrombolysis (with or without ultrasound assistance), aspiration thrombectomy and combinations of the aforementioned principles. These interventional treatment options might lead to a more rapid improvement in right ventricular function and pulmonary and/or systemic haemodynamics in particular patients. However, evidence from randomized controlled trials on the safety and efficacy of these interventions compared with conservative therapies is lacking. In this Review, we discuss the underlying pathophysiology of PE, provide assistance with decision-making on patient selection and critically appraise the available clinical evidence on interventional, catheter-based approaches for PE treatment. Finally, we discuss future perspectives and unmet needs.

CardioVision: A fully automated deep learning package for medical image segmentation and reconstruction generating digital twins for patients with aortic stenosis

Aortic stenosis (AS) is the most prevalent heart valve disease in western countries that poses a significant public health challenge due to the lack of a medical treatment to prevent valve calcification. Given the aging population demographic, the prevalence of AS is projected to rise, resulting in a progressively significant healthcare and economic burden. While surgical aortic valve replacement (SAVR) has been the gold standard approach, the less invasive transcatheter aortic valve replacement (TAVR) is poised to become the dominant method for high- and medium-risk interventions. Computational simulations using patient-specific models, have opened new research avenues for optimizing emerging devices and predicting clinical outcomes. The traditional techniques of generating digital replicas of patients' aortic root, native valve, and calcification are time-consuming and labor-intensive processes requiring specialized tools and expertise in anatomy. Alternatively, deep learning models, such as the U-Net architecture, have emerged as reliable and fully automated methods for medical image segmentation. Two-dimensional U-Nets have been shown to produce comparable or more accurate results than trained clinicians' manual segmentation while significantly reducing computational costs. In this study, we have developed a fully automatic AI tool capable of reconstructing the digital twin geometry and analyzing the calcification distribution on the aortic valve. The developed automatic segmentation package enables the modeling of patient-specific anatomies, which can then be used to simulate virtual interventional procedures, optimize emerging prosthetic devices, and predict clinical outcomes.

Histological examination of renal nerve distribution, density, and function in humans

BACKGROUND

Renal denervation is optimised when guided by knowledge of nerve distribution.

AIMS

We aimed to assess sympathetic nerve distribution along the renal arteries, especially in post-bifurcation vessel segments.

METHODS

Renal arteries and surrounding tissue from 10 body donors were collected and examined histologically. Immunohistochemical staining was used to analyse nerve distribution and to identify afferent and efferent sympathetic nerves.

RESULTS

A total of 6,781 nerves surrounding 18 renal arteries were evaluated. The mean lumen-nerve distance of the left renal artery (2.32±1.95 mm) was slightly greater than the right (2.29±2.03 mm; p=0.161); this varied across the arteries' courses: 3.7±2.3 mm in proximal segments, 2.5±2.0 mm in middle segments, 1.9±1.6 mm in distal prebifurcation segments and 1.3±1.0 mm in post-bifurcation segments (p<0.001). The number of nerves per quadrant was highest in the proximal segments (13.7±18.6), followed by the middle (9.7±7.9), distal prebifurcation (8.0±7.6), and distal post-bifurcation (4.3±4.0) segments (p<0.001). Circumferentially, the number of nerves was highest in the superior (7.8±9.4) and the ventral (7.6±13.1) quadrants (p=0.638). The mean tyrosine hydroxylase (TH) to calcitonin gene-related peptide (CGRP) ratio increased from proximal (37.5±33.5) to distal (72.0±7.2 in the post-bifurcation segments; p<0.001). Thirty-eight neuroganglia were identified along 14 (78%) renal arteries.

CONCLUSIONS

Nerves converge to the renal arteries' lumen in the distal segments and along branches, resulting in the lowest number of nerves per quadrant and the shortest lumen-nerve distance in the distal post-bifurcation segments. Efferent nerves occur predominantly, and the ratio of efferent to afferent nerves continues to increase in the vessels' course.

RNF41 orchestrates macrophage-driven fibrosis resolution and hepatic regeneration

Hepatic inflammation is a common trigger of chronic liver disease. Macrophage activation is a predictive parameter for survival in patients with cirrhosis. Ring finger protein 41 (RNF41) negatively regulates proinflammatory cytokines and receptors; however, the precise involvement of macrophage RNF41 in liver cirrhosis remains unknown. Here, we sought to understand how RNF41 dictates macrophage fate in hepatic fibrosis and repair within the inflammatory milieu. We found that RNF41 expression is down-regulated in CD11b+ macrophages recruited to mouse fibrotic liver and to patient cirrhotic liver regardless of cirrhosis etiology. Prolonged inflammation with TNF-α progressively reduced macrophage RNF41 expression. We designed a macrophage-selective gene therapy with dendrimer-graphite nanoparticles (DGNPs) to explore the influence of macrophage RNF41 restoration and depletion in liver fibrosis and regeneration. RNF41 expression induced in CD11b+ macrophages by DGNP-conjugated plasmids ameliorated liver fibrosis, reduced liver injury, and stimulated hepatic regeneration in fibrotic mice with or without hepatectomy. This therapeutic effect was mainly mediated by the induction of insulin-like growth factor 1. Conversely, depletion of macrophage RNF41 worsened inflammation, fibrosis, hepatic damage, and survival. Our data reveal implications of macrophage RNF41 in the control of hepatic inflammation, fibrosis, and regeneration and provide a rationale for therapeutic strategies in chronic liver disease and potentially other diseases characterized by inflammation and fibrosis.

Monocyte-endothelial cell interactions in vascular and tissue remodeling

Monocytes are circulating leukocytes of innate immunity derived from the bone marrow that interact with endothelial cells under physiological or pathophysiological conditions to orchestrate inflammation, angiogenesis, or tissue remodeling. Monocytes are attracted by chemokines and specific receptors to precise areas in vessels or tissues and transdifferentiate into macrophages with tissue damage or infection. Adherent monocytes and infiltrated monocyte-derived macrophages locally release a myriad of cytokines, vasoactive agents, matrix metalloproteinases, and growth factors to induce vascular and tissue remodeling or for propagation of inflammatory responses. Infiltrated macrophages cooperate with tissue-resident macrophages during all the phases of tissue injury, repair, and regeneration. Substances released by infiltrated and resident macrophages serve not only to coordinate vessel and tissue growth but cellular interactions as well by attracting more circulating monocytes (e.g. MCP-1) and stimulating nearby endothelial cells (e.g. TNF-α) to expose monocyte adhesion molecules. Prolonged tissue accumulation and activation of infiltrated monocytes may result in alterations in extracellular matrix turnover, tissue functions, and vascular leakage. In this review, we highlight the link between interactions of infiltrating monocytes and endothelial cells to regulate vascular and tissue remodeling with a special focus on how these interactions contribute to pathophysiological conditions such as cardiovascular and chronic liver diseases.

Cerebrovascular super-resolution 4D Flow MRI - Sequential combination of resolution enhancement by deep learning and physics-informed image processing to non-invasively quantify intracranial velocity, flow, and relative pressure

The development of cerebrovascular disease is tightly coupled to regional changes in intracranial flow and relative pressure. Image-based assessment using phase contrast magnetic resonance imaging has particular promise for non-invasive full-field mapping of cerebrovascular hemodynamics. However, estimations are complicated by the narrow and tortuous intracranial vasculature, with accurate image-based quantification directly dependent on sufficient spatial resolution. Further, extended scan times are required for high-resolution acquisitions, and most clinical acquisitions are performed at comparably low resolution (>1 mm) where biases have been observed with regard to the quantification of both flow and relative pressure. The aim of our study was to develop an approach for quantitative intracranial super-resolution 4D Flow MRI, with effective resolution enhancement achieved by a dedicated deep residual network, and with accurate quantification of functional relative pressures achieved by subsequent physics-informed image processing. To achieve this, our two-step approach was trained and validated in a patient-specific in-silico cohort, showing good accuracy in estimating velocity (relative error: 15.0 ± 0.1%, mean absolute error (MAE): 0.07 ± 0.06 m/s, and cosine similarity: 0.99 ± 0.06 at peak velocity) and flow (relative error: 6.6 ± 4.7%, root mean square error (RMSE): 0.56 mL/s at peak flow), and with the coupled physics-informed image analysis allowing for maintained recovery of functional relative pressure throughout the circle of Willis (relative error: 11.0 ± 7.3%, RMSE: 0.3 ± 0.2 mmHg). Furthermore, the quantitative super-resolution approach is applied to an in-vivo volunteer cohort, effectively generating intracranial flow images at <0.5 mm resolution and showing reduced low-resolution bias in relative pressure estimation. Our work thus presents a promising two-step approach to non-invasively quantify cerebrovascular hemodynamics, being applicable to dedicated clinical cohorts in the future.

Moderate intensity exercise in pregnant patients with cardiovascular disease: A pilot study

BACKGROUND

Exercise in pregnancy has proven health benefits, yet the safety of exercise in patients with pre-existing cardiovascular disease (CVD) has not been established. Our aim was to determine the feasibility and safety profile of moderate intensity exercise during pregnancy in patients with CVD, compared with those without CVD.

METHODS

This is a prospective single center pilot study of a moderate intensity exercise regimen, with data collection through wearable fitness trackers and personal exercise logs in pregnant patients with and without pre-existing CVD. The primary outcome was Doppler umbilical artery systolic to diastolic (S/D) ratio measured between 32 and 34 weeks' gestation. The secondary outcomes were adverse maternal and fetal events, trends in wearable fitness tracker data, C-reactive protein levels, and weight changes.

RESULTS

At baseline, the CVD group (62% congenital heart disease) took part in more prepregnancy walking, less weightlifting, and had a higher body mass index compared to the control group, and on average walked 539 fewer steps per day during pregnancy than the control group. Resting heart rate (HR) was found to increase in both groups up to 30 weeks' gestation. The cardiovascular disease group displayed an overall lower exercise intensity, as measured by the ability to increase HR with exercise over resting heart rate 1 hour prior to exercise at study baseline (45% vs 59% P < .001). Umbilical artery S/D ratio was normal in both groups. No differences were seen in adverse events between groups.

CONCLUSIONS

This pilot study of moderate intensity exercise in pregnant individuals with pre-existing CVD demonstrated that patients with CVD were not able to increase their HR during exercise throughout pregnancy compared to those in the control group. Although a small study group, this data supports the hypothesis that exercise interventions during pregnancy for patients with CVD are feasible without evidence abnormal fetal Doppler profiles. Further studies using wearable fitness trackers may provide the opportunity to understand how to safely tailor exercise programs to pregnant individuals with CVD.

Optimization of 3D autologous chondrocyte-seeded polyglycolic acid scaffolds to mimic human ear cartilage

Auricular reconstruction in children with microtia is one of the more complex procedures in plastic surgery. Obtaining sufficient native material to build an ear requires harvesting large fragments of rib cartilage in children. Herein, we investigated how to optimize autologous chondrocyte isolation, expansion and re-implantation using polyglycolic acid (PGA) scaffolds for generating enough cartilage to recapitulate a whole ear starting from a small ear biopsy. Ear chondrocytes isolated from human microtia subjects grew slower than microtia rib or healthy ear chondrocytes and displayed a phenotypic shift due to the passage number. Rabbit ear chondrocytes co-cultured with mesenchymal stem cells (MSC) at a 50 : 50 ratio recapitulated the cartilage biological properties in vitro. However, PGA scaffolds with different proportions of rabbit chondrocytes and MSC did not grow substantially in two months when subcutaneously implanted in immunosuppressed mice. In contrast, rabbit chondrocyte-seeded PGA scaffolds implanted in immunocompetent rabbits formed a cartilage 10 times larger than the original PGA scaffold. This cartilage mimicked the biofunctional and mechanical properties of an ear cartilage. These results indicate that autologous chondrocyte-seeded PGA scaffolds fabricated following our optimized procedure have immense potential as a solution for obtaining enough cartilage for auricular reconstruction and opens new avenues to redefine autologous cartilage replacement.

A new integrative approach to assess aortic stenosis burden and predict objective functional improvement after TAVR

Background

A non-negligible rate of patients undergoing transcatheter aortic valve replacement (TAVR) do not report symptomatic improvement or even die in the short-midterm. We sought to assess the degree of objective functional recovery after TAVR and its prognostic implications and to develop a predictive model.

Methods

In a cohort of patients undergoing TAVR, a prospective evaluation of clinical, anatomical, and physiological parameters was conducted before and after the procedure. These parameters were derived from echocardiography, non-invasive analysis of arterial pulse waves, and cardiac tomography. Objective functional improvement 6 months after TAVR was assessed using a 6-min walk test and nitro-terminal pro-brain natriuretic peptide (NT-proBNP) levels. The derived predictive model was prospectively validated in a different cohort. A clinical follow-up was conducted at 2 years.

Results

Among the 212 patients included, objective functional improvement was observed in 169 patients (80%) and subjective improvement in 187 (88%). Patients with objective functional improvement showed a much lower death rate at 2 years (9% vs. 31% p = 0.0002). Independent predictors of improvement were as follows: mean aortic gradient of ≥40 mmHg, augmentation index₇₅ of ≥45%, the posterior wall thickness of ≤12 mm, and absence of atrial fibrillation. A simple integer-based point score was developed (GAPA score), which showed an area under the curve of 0.81 for the overall cohort and 0.78 for the low-gradient subgroup. In a validation cohort of 216 patients, these values were 0.75 and 0.76, respectively.

Conclusion

A total of 80% of patients experienced objective functional improvement after TAVR, showing a significantly lower 2-year mortality rate. A predictive score was built that showed a good discriminative performance in overall and low-gradient populations.

Aortic Dissection is Determined by Specific Shape and Hemodynamic Interactions

The aim of this study was to determine whether specific three-dimensional aortic shape features, extracted via statistical shape analysis (SSA), correlate with the development of thoracic ascending aortic dissection (TAAD) risk and associated aortic hemodynamics. Thirty-one patients followed prospectively with ascending thoracic aortic aneurysm (ATAA), who either did (12 patients) or did not (19 patients) develop TAAD, were included in the study, with aortic arch geometries extracted from computed tomographic angiography (CTA) imaging. Arch geometries were analyzed with SSA, and unsupervised and supervised (linked to dissection outcome) shape features were extracted with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), respectively. We determined PLS-DA to be effective at separating dissection and no-dissection patients ([Formula: see text]), with decreased tortuosity and more equal ascending and descending aortic diameters associated with higher dissection risk. In contrast, neither PCA nor traditional morphometric parameters (maximum diameter, tortuosity, or arch volume) were effective at separating dissection and no-dissection patients. The arch shapes associated with higher dissection probability were supported with hemodynamic insight. Computational fluid dynamics (CFD) simulations revealed a correlation between the PLS-DA shape features and wall shear stress (WSS), with higher maximum WSS in the ascending aorta associated with increased risk of dissection occurrence. Our work highlights the potential importance of incorporating higher dimensional geometric assessment of aortic arch anatomy in TAAD risk assessment, and in considering the interdependent influences of arch shape and hemodynamics as mechanistic contributors to TAAD occurrence.

Sprayable Hydrogel for Instant Sealing of Vascular Anastomosis

Bleeding-related complications following vascular surgeries occur in up to half of the patients-500 000 cases annually in the United States alone. This results in additional procedures, increased mortality rate, and prolonged hospitalization, posing a burden on the healthcare system. Commercially available materials rely, in large, on forming covalent bonds between the tissue and the biomaterial to achieve adhesion. Here, it is shown that a biomaterial based on oxidized alginate and oxidized dextran together with polyamidoamine (PAMAM) dendrimer amine provides simultaneous electrostatic and covalent interactions between the biomaterial and the tissue, maximizing adhesion. This study finds that the material withstands supraphysiological pressures (≈300 mmHg) and prevents bleeding in a rabbit aortic puncture model and in a pig carotid bilateral poly(tetrafluoroethylene) graft model-achieving superior performance to commercially available materials such as Tisseel and BioGlue. Material biocompatibility is validated in comprehensive in vitro and in vivo studies in accordance with the US Food and Drug Administration (FDA) guidelines, including in vitro neutral red uptake test, subcutaneous implantation in rabbits, ames genotoxicity, and guinea pig maximization test. This material has the potential to provide with adequate seal and reduced complications following complex vascular surgeries, including hard-to-seal tissue-graft interfaces.

A soft robotic sleeve mimicking the haemodynamics and biomechanics of left ventricular pressure overload and aortic stenosis

Preclinical models of aortic stenosis can induce left ventricular pressure overload and coarsely control the severity of aortic constriction. However, they do not recapitulate the haemodynamics and flow patterns associated with the disease. Here we report the development of a customizable soft robotic aortic sleeve that can mimic the haemodynamics and biomechanics of aortic stenosis. By allowing for the adjustment of actuation patterns and blood-flow dynamics, the robotic sleeve recapitulates clinically relevant haemodynamics in a porcine model of aortic stenosis, as we show via in vivo echocardiography and catheterization studies, and a combination of in vitro and computational analyses. Using in vivo and in vitro magnetic resonance imaging, we also quantified the four-dimensional blood-flow velocity profiles associated with the disease and with bicommissural and unicommissural defects re-created by the robotic sleeve. The design of the sleeve, which can be adjusted on the basis of computed tomography data, allows for the design of patient-specific devices that may guide clinical decisions and improve the management and treatment of patients with aortic stenosis.

Tissue-Engineered Endothelial Cells Induce Sustained Vascular Healing Through Early Induction of Vascular Repair

Background

Perivascular implantation of tissue-engineered endothelial cells (TEEC) after vascular injury profoundly inhibits neointimal hyperplasia. However, the time course and mechanism by which this effect occurs remain unknown. By developing genetically modified TEEC that express a “suicide gene,” we can control the time during which the TEEC could exert their effect and determine the length of time TEEC need to be present following vascular injury to exert their inhibitory effect on long-term neointimal hyperplasia.

Methods

Bovine aortic endothelial cells (BAE) were transfected with the human herpes simplex virus thymidine kinase (tk) gene to render them sensitive to ganciclovir (GCV). These BAE+tk were grown to confluence on Gelfoam and shown to have the same growth kinetics and biologic potency as control cells but were sensitive to GCV at low concentrations. The BAE+tk were grown on Gelfoam and placed in the perivascular space around balloon-injured rat carotid arteries. Rats randomly received BAE-tk, BAE+tk, or nothing (control) after balloon injury. GCV was administered early (days 1–7), late (days 5–11), or not at all.

Results

Two weeks after injury, extensive neointimal hyperplasia was observed in control animals with an intima:media (I:M) area ratio of 0.80 ± 0.19. Early administration of GCV killed the BAE in constructs with TK sensitivity and eliminated the impact of TEEC regulation of intimal hyperplasia (0.45 ± 0.06). Intimal hyperplasia was still effectively reduced in animals with implants containing BAE-tk or BAE+tk which received GCV late (0.11 ± 0.04 and 0.19 ± 0.05). Immunohistochemistry demonstrated the lethal effect of GCV on TK-sensitive cells.

Conclusions

The application of perivascular TEEC for only the first few days after injury had a significant inhibitory effect on intimal hyperplasia. This is in contrast to the results obtained in this same animal model with the infusion of isolated anti-smooth muscle cell proliferative agents. This suggests that the mechanism of action of TEEC may be upstream from smooth muscle cell proliferation. Moreover, the use of this technique to further elucidate biologic mechanisms will prove invaluable in the tissue engineering field.

Lay Summary

We report a novel, genetically altered tissue-engineered endothelial cell (TEEC) implant that inhibits neointimal hyperplasia after experimental vascular injury. The viability of these implants can be carefully controlled and suggest a putative mechanism by which TEEC recapitulate control over the vascular response to injury.

Substratum interactions determine immune response to allogeneic transplants of endothelial cells

Endothelial cells (ECs) are central to vascular health but also interact with and regulate the immune system. Changes in endothelial state enable immune cells to migrate into the tissue to facilitate repair and fight infection. ECs modulate the function of immune cells through the expression of adhesion molecules, chemokines, major histocompatibility complex (MHC), and an array of co-stimulatory and inhibitor molecules. These interactions allow ECs to act as antigen presenting cells (APCs) and influence the outcome of immune recognition. This study elucidates how EC microenvironment, vascular cell biology, and immune response are not only connected but interdependent. More specifically, we explored how cell-substratum interactions influence EC antigen presentation and co-stimulation, and how these differences affect allorecognition in animal models of cell transplantation. Investigation of EC state was carried out using RNA sequencing while assessment of the allogeneic response includes measurements of immune cell cytotoxic ability, T cell proliferation, cytokine release, serum antibodies, and histological staining. Differences in substratum led to divergent EC phenotypes which in turn influenced immune response to transplanted cells, both due to the physical barrier of matrix-adhesion and differences in expression of surface markers. ECs grown in 2D on tissue culture plastic or in 3D on collagen scaffolds had significantly different basal levels of MHC expression, co-stimulatory and adhesion molecules. When treated with cytokines to mimic an inflammatory state, ECs did not converge to a single phenotype but rather responded differently based on their substratum. Generally, 3D ECs were more responsive to inflammatory stimuli than 2D ECs. These unique expression patterns measured in vitro also influence immune recognition in vivo. ECs grown in 2D were more likely to provoke a cytotoxic response while 3D ECs induced T cell proliferation. ECs are uniquely configured to sense not only local flow and mechanical forces but a range of markers related to systemic state, including immune function. ECs interact with immune cells with differing results depending on the environment in which the EC-lymphocyte interaction occurs. Therefore, understanding this relationship is essential to predicting and modifying the outcome of EC-immune interacts. We specifically examined the relationship between EC substratum and allorecognition.

Framework for lumen-based nonrigid tomographic coregistration of intravascular images

Purpose: Modern medical imaging enables clinicians to effectively diagnose, monitor, and treat diseases. However, clinical decision-making often relies on combined evaluation of either longitudinal or disparate image sets, necessitating coregistration of multiple acquisitions. Promising coregistration techniques have been proposed; however, available methods predominantly rely on time-consuming manual alignments or nontrivial feature extraction with limited clinical applicability. Addressing these issues, we present a fully automated, robust, nonrigid registration method, allowing for coregistering of multimodal tomographic vascular image datasets using luminal annotation as the sole alignment feature. Approach: Registration is carried out by the use of the registration metrics defined exclusively for lumens shapes. The framework is primarily broken down into two sequential parts: longitudinal and rotational registration. Both techniques are inherently nonrigid in nature to compensate for motion and acquisition artifacts in tomographic images. Results: Performance was evaluated across multimodal intravascular datasets, as well as in longitudinal cases assessing pre-/postinterventional coronary images. Low registration error in both datasets highlights method utility, with longitudinal registration errors-evaluated throughout the paired tomographic sequences-of 0.29 ± 0.14    mm ( < 2 longitudinal image frames) and 0.18 ± 0.16    mm ( < 1 frame) for multimodal and interventional datasets, respectively. Angular registration for the interventional dataset rendered errors of 7.7 ° ± 6.7 ° , and 29.1 ° ± 23.2 ° for the multimodal set. Conclusions: Satisfactory results across datasets, along with additional attributes such as the ability to avoid longitudinal over-fitting and correct nonlinear catheter rotation during nonrigid rotational registration, highlight the potential wide-ranging applicability of our presented coregistration method.

Accelerated neutral atom beam (ANAB) modified polyethylene for decreased wear and reduced bacteria colonization: An in vitro study

Ultra-high molecular weight polyethylene (UHMWPE) model implants were modified using accelerated neutral atom beam (ANAB) technology and tested for in vitro wear properties and bacteria colonization. Material characterization studies using atomic force microscopy (AFM), surface energy, and in vitro protein adsorption events were also conducted to better understand the mechanism behind such wear properties and bacteria colonization. ANAB modified UHMWPE showed significantly reduced wear properties compared to controls due to nanostructured features, greater surface energy, and improved adsorption of lubricin, a synovial fluid lubricating protein. There was significantly greater adsorption of proteins known to reduce bacteria colonization (specifically, mucin, casein, and lubricin) after 4 h on UHMWPE after ANAB treatment. Such changes in initial protein events led to significantly decreased bacteria (including methicillin resistant Staph. aureus (or MRSA), Staph. aureus, E. coli, multi-drug resistant E. coli, Pseudomonas aeruginosa and Staph. epidermidis) colonization after 24 h without resorting to antibiotic use.

Simulation of Fluid-Structure Interaction in Extracorporeal Membrane Oxygenation Circulatory Support Systems

Extracorporeal membrane oxygenation (ECMO) is a vital mechanical circulatory support modality capable of restoring perfusion for the patient in circulatory failure. Despite increasing adoption of ECMO, there is incomplete understanding of its effects on systemic hemodynamics and how the vasculature responds to varying levels of continuous retrograde perfusion. To gain further insight into the complex ECMO:failing heart circulation, computational fluid dynamics simulations focused on perfusion distribution and hemodynamic flow patterns were conducted using a patient-derived aorta geometry. Three case scenarios were simulated: (1) healthy control; (2) 90% ECMO-derived perfusion to model profound heart failure; and, (3) 50% ECMO-derived perfusion to model the recovering heart. Fluid-structure interface simulations were performed to quantify systemic pressure and vascular deformation throughout the aorta over the cardiac cycle. ECMO support alters pressure distribution while decreasing shear stress. Insights derived from computational modeling may lead to better understanding of ECMO support and improved patient outcomes.

Accelerated Neutral Atom Beam (ANAB) Modified Poly-Ether-Ether-Ketone for Increasing In Vitro Bone Cell Functions and Reducing Bacteria Colonization Without Drugs or Antibiotics

Poly-ether-ether-ketone (PEEK) has become the spinal implant material of choice due to its radiolucency, low elastic modulus, manufacturability, and mechanical durability. However, studies have highlighted less that optimal cytocompatibility properties of conventional PEEK leading to decreased bone growth and/or extensive bacteria infection. In order to improve the surface properties of PEEK for orthopedic applications, here, Accelerated Neutral Atom Beam (ANAB) technology was used to modify PEEK and such samples were tested In Vitro for osteoblast (bone-forming cell) functions and bacterial colonization. Results showed significantly improved osteoblast responses (such as deposition of calcium containing mineral as well as alkaline phosphatase, osteocalcin, osteopontin, and osteonectin synthesis) on ANAB modified PEEK compared to controls due to optimized surface energy from nanostructured features and greater exposure of PEEK chemistry. ANAB treatment enhanced protein absorption (specifically, mucin, casein, and lubricin) to the PEEK surface and consequently significantly reduced bacterial (including methicillin resistant Staph. aureus (or MRSA), E. coli, and Staph. epidermidis) colonization. Collectively, this study introduces ANAB treated PEEK as a novel material that should be further studied for a wide range of improved orthopedic applications.

Effect of anatomical variation on extracorporeal membrane oxygenation circulatory support: A computational study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) via femoral cannulation is a vital intervention capable of rapidly restoring perfusion for patients in shock. Despite increasing use to provide circulatory support, its hemodynamic effects are poorly understood and the impact of patient-specific anatomical variation on perfusion is unknown. This study investigates the complex failing heart-mechanical circulatory support circulation and analyzes the effect of patient-specific vascular anatomical variations on hemodynamics and end-organ perfusion.

METHODS

Patient-specific vascular geometries were constructed from segmenting clinical computerized tomography angiography images and quantitatively compared using tortuosity, curvature, torsion, and lumen diameter. Computational fluid dynamic simulations were performed on a subset of geometries selected to represent a range of anatomical variation. Heart failure severity was modeled by varying the relative fraction of total flow provided by the heart and the extracorporeal circuit. A 3-element lumped parameter model was applied to accurately and dynamically model distal perfusion boundary conditions. Hemodynamic parameters and end-organ perfusion were analyzed and compared to assess the effect of anatomical variation.

RESULTS

Pulsatile antegrade cardiac perfusion and ECMO retrograde perfusion collide in the aorta to form a dynamic watershed region. The size, position, and variation of this region over the cardiac cycle is substantially altered by patient anatomical region. Increased vascular tortuosity reduces the proximal extent of flow from circulatory support and decreases the size of the watershed region.

CONCLUSIONS

Patient vascular anatomy is a key determinant of the ECMO-failing heart circulation that alters the location and extent of the watershed region and affects the tissues at risk for differential hypoxia and circuit-derived thromboemboli for a given level of support.

Morphometric analysis of the human common hepatic artery reveals a rich and accessible target for sympathetic liver denervation

This study quantified the distribution of nerves and adjacent anatomies surrounding human common hepatic artery (CHA) as guidance for catheter based denervation. CHA collected from cadaveric human donors (n = 20) were histologically evaluated and periarterial dimensions and distributions of nerves, lymph nodes, pancreas and blood vessels quantified by digital morphometry. Nerve abundance decreased significantly with distance from the aortic ostium (P < 0.0001) and was higher in the Superior/Inferior compared to the Anterior/Posterior quadrants (P = 0.014). In each locational group, nerves were absent from the artery wall, and starting 0.5–1.0 mm from the lumen exhibited a first order dependence on radial distance, fully defined by the median distance. Median subject-averaged nerve distance to the lumen was 2.75 mm, ranging from 2.1–3.1 mm in different arterial segments and quadrants and 2.0–3.5 mm in individuals. Inter-individual variance was high, with certain individuals exhibiting 50th and 75th nerve distances of, respectively, 3.5 and 6.5 mm The pancreas rarely approached within 4 mm of the lumen proximally and 2.5 mm more distally. The data indicate that the CHA is a rich and accessible target for sympathetic denervation regardless of sex and diabetes, with efficacy and safety most optimally balanced proximally.

Remote Speech Analysis in the Evaluation of Hospitalized Patients With Acute Decompensated Heart Failure

OBJECTIVES

This study assessed the performance of an automated speech analysis technology in detecting pulmonary fluid overload in patients with acute decompensated heart failure (ADHF).

BACKGROUND

Pulmonary edema is the main cause of heart failure (HF)-related hospitalizations and a key predictor of poor postdischarge prognosis. Frequent monitoring is often recommended, but signs of decompensation are often missed. Voice and sound analysis technologies have been shown to successfully identify clinical conditions that affect vocal cord vibration mechanics.

METHODS

Adult patients with ADHF (n = 40) recorded 5 sentences, in 1 of 3 languages, using HearO, a proprietary speech processing and analysis application, upon admission (wet) to and discharge (dry) from the hospital. Recordings were analyzed for 5 distinct speech measures (SMs), each a distinct time, frequency resolution, and linear versus perceptual (ear) model; mean change from baseline SMs was calculated.

RESULTS

In total, 1,484 recordings were analyzed. Discharge recordings were successfully tagged as distinctly different from baseline (wet) in 94% of cases, with distinct differences shown for all 5 SMs in 87.5% of cases. The largest change from baseline was documented for SM2 (218%). Unsupervised, blinded clustering of untagged admission and discharge recordings of 9 patients was further demonstrated for all 5 SMs.

CONCLUSIONS

Automated speech analysis technology can identify voice alterations reflective of HF status. This platform is expected to provide a valuable contribution to in-person and remote follow-up of patients with HF, by alerting to imminent deterioration, thereby reducing hospitalization rates. (Clinical Evaluation of Cordio App in Adult Patients With CHF; NCT03266029).

Hysteretic device characteristics indicate cardiac contractile state for guiding mechanical circulatory support device use

Background

Acute heart failure and cardiogenic shock remain highly morbid conditions despite prompt medical therapy in critical care settings. Mechanical circulatory support (MCS) is a promising therapy for these patients, yet remains managed with open-loop control. Continuous measure of cardiac function would support and optimize MCS deployment and weaning. The nature of indwelling MCS provides a platform for attaining this information. This study investigates how hysteresis modeling derived from MCS device signals can be used to assess contractility changes to provide continuous indication of changing cardiac state. Load-dependent MCS devices vary their operation with cardiac state to yield a device–heart hysteretic interaction. Predicting and examining this hysteric relation provides insight into cardiac state and can be separated by cardiac cycle phases. Here, we demonstrate this by predicting hysteresis and using the systolic portion of the hysteresis loop to estimate changes in native contractility. This study quantified this measurement as the enclosed area of the systolic portion of the hysteresis loop and correlated it with other widely accepted contractility metrics in animal studies (n = 4) using acute interventions that alter inotropy, including a heart failure model. Clinical validation was performed in patients (n = 8) undergoing Impella support.

Results

Hysteresis is well estimated from device signals alone (r = 0.92, limits of agreement: − 0.18 to 0.18). Quantified systolic area was well correlated in animal studies with end-systolic pressure–volume relationship (r = 0.84), preload recruitable stroke work index (r = 0.77), and maximum slope of left ventricular pressure (dP/dt_max) (r = 0.95) across a range of inotropic conditions. Comparable results were seen in patients with dP/dt_max (r = 0.88). Diagnostic capability from ROC analysis yielded AUC measurements of 0.92 and 0.90 in animal and patients, respectively.

Conclusions

Mechanical circulatory support hysteretic behavior can be well modeled using device signals and used to estimate contractility changes. Contractility estimate is correlated with other accepted metrics, captures temporal trends that elucidate changing cardiac state, and is able to accurately indicate changes in inotropy. Inherently available during MCS deployment, this measure will guide titration and inform need for further intervention.

Noninvasive quantification of cerebrovascular pressure changes using 4D Flow MRI

PURPOSE

Hemodynamic alterations are indicative of cerebrovascular disease. However, the narrow and tortuous cerebrovasculature complicates image-based assessment, especially when quantifying relative pressure. Here, we present a systematic evaluation of image-based cerebrovascular relative pressure mapping, investigating the accuracy of the routinely used reduced Bernoulli (RB), the extended unsteady Bernoulli (UB), and the full-field virtual work-energy relative pressure ( ν WERP) method.

METHODS

Patient-specific in silico models were used to generate synthetic cerebrovascular 4D Flow MRI, with RB, UB, and ν WERP performance quantified as a function of spatiotemporal sampling and image noise. Cerebrovascular relative pressures were also derived in 4D Flow MRI from healthy volunteers ( n = 8 ), acquired at two spatial resolutions (dx = 1.1 and 0.8 mm).

RESULTS

The in silico analysis indicate that accurate relative pressure estimations are inherently coupled to spatial sampling: at dx = 1.0 mm high errors are reported for all methods; at dx = 0.5 mm ν WERP recovers relative pressures at a mean error of 0.02 ± 0.25 mm Hg, while errors remain higher for RB and UB (mean error of -2.18 ± 1.91 and -2.18 ± 1.87 mm Hg, respectively). The dependence on spatial sampling is also indicated in vivo, albeit with higher correlative dependence between resolutions using ν WERP (k = 0.64, R2 = 0.81 for dx = 1.1 vs. 0.8 mm) than with RB or UB (k = 0.04, R2 = 0.03, and k = 0.07, R2 = 0.07, respectively).

CONCLUSION

Image-based full-field methods such as ν WERP enable cerebrovascular relative pressure mapping; however, accuracy is directly dependent on utilized spatial resolution.

Acute Stent-Induced Endothelial Denudation: Biomechanical Predictors of Vascular Injury

Recent concern for local drug delivery and withdrawal of the first Food and Drug Administration-approved bioresorbable scaffold emphasizes the need to optimize the relationships between stent design and drug release with imposed arterial injury and observed pharmacodynamics. In this study, we examine the hypothesis that vascular injury is predictable from stent design and that the expanding force of stent deployment results in increased circumferential stress in the arterial tissue, which may explain acute injury poststent deployment. Using both numerical simulations and ex vivo experiments on three different stent designs (slotted tube, corrugated ring, and delta wing), arterial injury due to device deployment was examined. Furthermore, using numerical simulations, the consequence of changing stent strut radial thickness on arterial wall shear stress and arterial circumferential stress distributions was examined. Regions with predicted arterial circumferential stress exceeding a threshold of 49.5 kPa compared favorably with observed ex vivo endothelial denudation for the three considered stent designs. In addition, increasing strut thickness was predicted to result in more areas of denudation and larger areas exposed to low wall shear stress. We conclude that the acute arterial injury, observed immediately following stent expansion, is caused by high circumferential hoop stresses in the interstrut region, and denuded area profiles are dependent on unit cell geometric features. Such findings when coupled with where drugs move might explain the drug–device interactions.

A platform for high-fidelity patient-specific structural modelling of atherosclerotic arteries: from intravascular imaging to three-dimensional stress distributions

The pathophysiology of atherosclerotic lesions, including plaque rupture triggered by mechanical failure of the vessel wall, depends directly on the plaque morphology-modulated mechanical response. The complex interplay between lesion morphology and structural behaviour can be studied with high-fidelity computational modelling. However, construction of three-dimensional (3D) and heterogeneous models is challenging, with most previous work focusing on two-dimensional geometries or on single-material lesion compositions. Addressing these limitations, we here present a semi-automatic computational platform, leveraging clinical optical coherence tomography images to effectively reconstruct a 3D patient-specific multi-material model of atherosclerotic plaques, for which the mechanical response is obtained by structural finite-element simulations. To demonstrate the importance of including multi-material plaque components when recovering the mechanical response, a computational case study was conducted in which systematic variation of the intraplaque lipid and calcium was performed. The study demonstrated that the inclusion of various tissue components greatly affected the lesion mechanical response, illustrating the importance of multi-material formulations. This platform accordingly provides a viable foundation for studying how plaque micro-morphology affects plaque mechanical response, allowing for patient-specific assessments and extension into clinically relevant patient cohorts.

Artificial intelligence to generate medical images: augmenting the cardiologist's visual clinical workflow

Artificial intelligence (AI) offers great promise in cardiology, and medicine broadly, for its ability to tirelessly integrate vast amounts of data. Applications in medical imaging are particularly attractive, as images are a powerful means to convey rich information and are extensively utilized in cardiology practice. Departing from other AI approaches in cardiology focused on task automation and pattern recognition, we describe a digital health platform to synthesize enhanced, yet familiar, clinical images to augment the cardiologist's visual clinical workflow. In this article, we present the framework, technical fundamentals, and functional applications of the methodology, especially as it pertains to intravascular imaging. A conditional generative adversarial network was trained with annotated images of atherosclerotic diseased arteries to generate synthetic optical coherence tomography and intravascular ultrasound images on the basis of specified plaque morphology. Systems leveraging this unique and flexible construct, whereby a pair of neural networks is competitively trained in tandem, can rapidly generate useful images. These synthetic images replicate the style, and in several ways exceed the content and function, of normally acquired images. By using this technique and employing AI in such applications, one can ameliorate challenges in image quality, interpretability, coherence, completeness, and granularity, thereby enhancing medical education and clinical decision-making.

A geometrically adaptable heart valve replacement

Congenital heart valve disease has life-threatening consequences that warrant early valve replacement; however, the development of a growth-accommodating prosthetic valve has remained elusive. Thousands of children continue to face multiple high-risk open-heart operations to replace valves that they have outgrown. Here, we demonstrate a biomimetic prosthetic valve that is geometrically adaptable to accommodate somatic growth and structural asymmetries within the heart. Inspired by the human venous valve, whose geometry is optimized to preserve functionality across a wide range of constantly varying volume loads and diameters, our balloon-expandable synthetic bileaflet valve analog exhibits similar adaptability to dimensional and shape changes. Benchtop and acute in vivo experiments validated design functionality, and in vivo survival studies in growing sheep demonstrated that mechanical valve expansion accommodated growth. As illustrated in this work, dynamic size adaptability with preservation of unidirectional flow in prosthetic valves thus offers a paradigm shift in the treatment of heart valve disease.

Three dimensional reconstruction of coronary artery stents from optical coherence tomography: experimental validation and clinical feasibility

The structural morphology of coronary stents (e.g. stent expansion, lumen scaffolding, strut apposition, tissue protrusion, side branch jailing, strut fracture), and the local hemodynamic environment after stent deployment are key determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to enable the geometrically accurate three-dimensional (3D) reconstruction of coronary stents. The aim of this work was to present a novel algorithm for 3D stent reconstruction of coronary artery stents based on optical coherence tomography (OCT) and angiography, and test experimentally its accuracy, reproducibility, clinical feasibility, and ability to perform computational fluid dynamics (CFD) studies. Our method has the following steps: 3D lumen reconstruction based on OCT and angiography, stent strut segmentation in OCT images, packaging, rotation and straightening of the segmented struts, planar unrolling of the segmented struts, planar stent wireframe reconstruction, rolling back of the planar stent wireframe to the 3D reconstructed lumen, and final stent volume reconstruction. We tested the accuracy and reproducibility of our method in stented patient-specific silicone models using micro-computed tomography (μCT) and stereoscopy as references. The clinical feasibility and CFD studies were performed in clinically stented coronary bifurcations. The experimental and clinical studies showed that our algorithm (1) can reproduce the complex spatial stent configuration with high precision and reproducibility, (2) is feasible in 3D reconstructing stents deployed in bifurcations, and (3) enables CFD studies to assess the local hemodynamic environment within the stent. Notably, the high accuracy of our algorithm was consistent across different stent designs and diameters. Our method coupled with patient-specific CFD studies can lay the ground for optimization of stenting procedures, patient-specific computational stenting simulations, and research and development of new stent scaffolds and stenting techniques.

Orphan nuclear receptor COUP-TFII enhances myofibroblast glycolysis leading to kidney fibrosis

Recent studies demonstrate that metabolic disturbance, such as augmented glycolysis, contributes to fibrosis. The molecular regulation of this metabolic perturbation in fibrosis, however, has been elusive. COUP-TFII (also known as NR2F2) is an important regulator of glucose and lipid metabolism. Its contribution to organ fibrosis is undefined. Here, we found increased COUP-TFII expression in myofibroblasts in human fibrotic kidneys, lungs, kidney organoids, and mouse kidneys after injury. Genetic ablation of COUP-TFII in mice resulted in attenuation of injury-induced kidney fibrosis. A non-biased proteomic study revealed the suppression of fatty acid oxidation and the enhancement of glycolysis pathways in COUP-TFII overexpressing fibroblasts. Overexpression of COUP-TFII in fibroblasts also induced production of alpha-smooth muscle actin (αSMA) and collagen 1. Knockout of COUP-TFII decreased glycolysis and collagen 1 levels in fibroblasts. Chip-qPCR revealed the binding of COUP-TFII on the promoter of PGC1α. Overexpression of COUP-TFII reduced the cellular level of PGC1α. Targeting COUP-TFII serves as a novel treatment approach for mitigating fibrosis in chronic kidney disease and potentially fibrosis in other organs.

Understanding TAVR device expansion as it relates to morphology of the bicuspid aortic valve: A simulation study

The bicuspid aortic valve (BAV) is a common and heterogeneous congenital heart abnormality that is often complicated by aortic stenosis. Although initially developed for tricuspid aortic valves (TAV), transcatheter aortic valve replacement (TAVR) devices are increasingly applied to the treatment of BAV stenosis. It is known that patient-device relationship between TAVR and BAV are not equivalent to those observed in TAV but the nature of these differences are not well understood. We sought to better understand the patient-device relationships between TAVR devices and the two most common morphologies of BAV. We performed finite element simulation of TAVR deployment into three cases of idealized aortic anatomies (TAV, Sievers 0 BAV, Sievers 1 BAV), derived from patient-specific measurements. Valve leaflet von Mises stress at the aortic commissures differed by valve configuration over a ten-fold range (TAV: 0.55 MPa, Sievers 0: 6.64 MPa, and Sievers 1: 4.19 MPa). First principle stress on the aortic wall was greater in Sievers 1 (0.316 MPa) and Sievers 0 BAV (0.137 MPa) compared to TAV (0.056 MPa). TAVR placement in Sievers 1 BAV demonstrated significant device asymmetric alignment, with 1.09 mm of displacement between the center of the device measured at the annulus and at the leaflet free edge. This orifice displacement was marginal in TAV (0.33 mm) and even lower in Sievers 0 BAV (0.23 mm). BAV TAVR, depending on the subtype involved, may encounter disparate combinations of device under expansion and asymmetry compared to TAV deployment. Understanding the impacts of BAV morphology on patient-device relationships can help improve device selection, patient eligibility, and the overall safety of TAVR in BAV.

Randomized trials of invasive cardiovascular interventions that include a placebo control: a systematic review and meta-analysis

AIMS

The difference in the benefit of invasive cardiovascular interventions compared with placebo controls has not been analysed systematically.

METHODS AND RESULTS

MEDLINE and Web of Science were searched through 29 March 2020. Randomized, placebo-controlled trials of invasive cardiovascular interventions (including catheter-based interventions and pacemaker-like devices) investigating predefined primary outcomes were included. Standardized mean differences (SMD) and odds ratios were calculated for continuous and dichotomous outcomes, respectively. Meta-regression analyses were performed to assess whether estimates of treatment effects were associated with methodological characteristics of trials. Thirty trials, including 4102 patients, were analysed. The overall risk of bias was judged to be low in only 43% of the trials. Ten trials (33%) demonstrated statistically significant superiority of invasive interventions over placebo controls for the respective predefined primary outcomes. In almost half of the 16 trials investigating continuous predefined primary outcomes, the SMD between the active and placebo procedure indicated a small (n = 4) to moderate (n = 3) treatment effect of active treatment over placebo. In contrast, one trial indicated a small treatment effect in favour of the placebo procedure. In the remaining trials, there was no relevant treatment effect of active treatment over placebo. In trials with a protocol-mandated stable and symmetrical use of co-interventions, the superiority of active procedures vs. invasive placebo procedures was significantly larger as compared with trials with frequent or unbalanced changes in co-interventions (P for interaction 0.027).

CONCLUSIONS

The additional treatment effect of invasive cardiovascular interventions compared with placebo controls was small in most trials.

False lumen pressure estimation in type B aortic dissection using 4D flow cardiovascular magnetic resonance: comparisons with aortic growth

BACKGROUND

Chronic type B aortic dissection (TBAD) is associated with poor long-term outcome, and accurate risk stratification tools remain lacking. Pressurization of the false lumen (FL) has been recognized as central in promoting aortic growth. Several surrogate imaging-based metrics have been proposed to assess FL hemodynamics; however, their relationship to enlarging aortic dimensions remains unclear. We investigated the association between aortic growth and three cardiovascular magnetic resonance (CMR)-derived metrics of FL pressurization: false lumen ejection fraction (FLEF), maximum systolic deceleration rate (MSDR), and FL relative pressure (FL ΔPmax).

METHODS

CMR/CMR angiography was performed in 12 patients with chronic dissection of the descending thoracoabdominal aorta, including contrast-enhanced CMR angiography and time-resolved three-dimensional phase-contrast CMR (4D Flow CMR). Aortic growth rate was calculated as the change in maximal aortic diameter between baseline and follow-up imaging studies over the time interval, with patients categorized as having either 'stable' (< 3 mm/year) or 'enlarging' (≥ 3 mm/year) growth. Three metrics relating to FL pressurization were defined as: (1) FLEF: the ratio between retrograde and antegrade flow at the TBAD entry tear, (2) MSDR: the absolute difference between maximum and minimum systolic acceleration in the proximal FL, and (3) FL ΔPmax: the difference in absolute pressure between aortic root and distal FL.

RESULTS

FLEF was higher in enlarging TBAD (49.0 ± 17.9% vs. 10.0 ± 11.9%, p = 0.002), whereas FL ΔPmax was lower (32.2 ± 10.8 vs. 57.2 ± 12.5 mmHg/m, p = 0.017). MSDR and conventional anatomic variables did not differ significantly between groups. FLEF showed positive (r = 0.78, p = 0.003) correlation with aortic growth rate whereas FL ΔPmax showed negative correlation (r = - 0.64, p = 0.026). FLEF and FL ΔPmax remained as independent predictors of aortic growth rate after adjusting for baseline aortic diameter.

CONCLUSION

Comparative analysis of three 4D flow CMR metrics of TBAD FL pressurization demonstrated that those that focusing on retrograde flow (FLEF) and relative pressure (FL ΔPmax) independently correlated with growth and differentiated patients with enlarging and stable descending aortic dissections. These results emphasize the highly variable nature of aortic hemodynamics in TBAD patients, and suggest that 4D Flow CMR derived metrics of FL pressurization may be useful to separate patients at highest and lowest risk for progressive aortic growth and complications.

Feasibility of remote speech analysis in evaluation of dynamic fluid overload in heart failure patients undergoing haemodialysis treatment

Aims

This study aimed to assess the ability of a voice analysis application to discriminate between wet and dry states in chronic heart failure (CHF) patients undergoing regular scheduled haemodialysis treatment due to volume overload as a result of their chronic renal failure.

Methods and results

In this single‐centre, observational study, five patients with CHF, peripheral oedema of ≥2, and pulmonary congestion‐related dyspnoea, undergoing haemodialysis three times per week, recorded five sentences into a standard smartphone/tablet before and after haemodialysis. Recordings were provided that same noon/early evening and the next morning and evening. Patient weight was measured at the hospital before and after each haemodialysis session. Recordings were analysed by a smartphone application (app) algorithm, to compare speech measures (SMs) of utterances collected over time. On average, patients provided recordings throughout 25.8 ± 3.9 dialysis treatment cycles, resulting in a total of 472 recordings. Weight changes of 1.95 ± 0.64 kg were documented during cycles. Median baseline SM prior to dialysis was 0.87 ± 0.17, and rose to 1.07 ± 0.15 following the end of the dialysis session, at noon (P = 0.0355), and remained at a similar level until the following morning (P = 0.007). By the evening of the day following dialysis, SMs returned to baseline levels (0.88 ± 0.19). Changes in patient weight immediately after dialysis positively correlated with SM changes, with the strongest correlation measured the evening of the dialysis day [slope: −0.40 ± 0.15 (95% confidence interval: −0.71 to −0.10), P = 0.0096].

Conclusions

The fluid‐controlled haemodialysis model demonstrated the ability of the app algorithm to identify cyclic changes in SMs, which reflected bodily fluid levels. The voice analysis platform bears considerable potential as a harbinger of impending fluid overload in a range of clinical scenarios, which will enhance monitoring and triage efforts, ultimately optimizing remote CHF management.

Validation study to determine the accuracy of central blood pressure measurement using the SphygmoCor XCEL cuff device in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement

Central aortic blood pressure could be helpful in the evaluation of patients with aortic stenosis (AS). The SphygmoCor XCEL device estimates central blood pressure (BP) measurement with its easy‐to‐use, operator‐independent procedure. However, this device has not been properly validated against invasive measurement in patients with severe AS. We evaluated the relationship between cuff‐brachial BP, transfer function‐estimated and invasively measured central aortic pressure in patients with severe AS before and after transcatheter aortic valve replacement (TAVR). Agreement between techniques was analyzed and, according to the ARTERY Society recommendations, the minimum acceptable error was a mean difference ± SD ≤5 ± ≤8 mm Hg. A total of 94 patients with AS undergoing TAVR had simultaneous non‐invasive and invasive measurements of central BP before and after the procedure. Before TAVR central systolic BP was in average slightly underestimated, though with wide variability, when using the default calibration of brachial‐cuff SBP (mean difference ± SD, −3 ± 15 mm Hg), and after TAVR the degree of underestimation increased (mean difference ± SD, −9 ± 13 mm Hg). The agreement tended to improve for those patients with low aortic gradient stenosis compared to those with high gradient at baseline (mean difference ± SD, −2 ± 11 mm Hg vs. −4 ± 17, respectively, p = .3). The cuff‐brachial systolic BP yielded numerically lower degree of agreement and weaker correlation with invasive measurements than SphygmoCor XCEL. In patients with severe AS the SphygmoCor XCEL cuff device, despite showing strong correlation, does not meet the ARTERY Society accuracy criteria for non‐invasive measurement of central SBP.

1α,25-Dihydroxyvitamin D3 Encapsulated in Nanoparticles Prevents Venous Neointimal Hyperplasia and Stenosis in Porcine Arteriovenous Fistulas

BACKGROUND

Few therapies prevent venous neointimal hyperplasia (VNH) and venous stenosis (VS) formation in arteriovenous fistulas (AVF). Expression of the immediate early response gene X-1 (Iex-1), also known as Ier3, is associated with VNH and stenosis in murine AVFs. The study aimed to determine if local release of Ier3 long-acting inhibitor 1α,25(OH)₂D₃ from poly(lactic-co-glycolic acid) (PLGA) nanoparticles embedded in a thermosensitive Pluronic F127 hydrogel (1,25 NP) could affect VNH/VS formation in a large animal model.

METHODS

Immediately after AVF creation in a porcine model of renal failure, 1,25 NP or vehicle control was injected into the adventitia space of AVF outflow veins. Scanning electron microscopy and dynamic light scattering characterized drug and control nanoparticles. Animals were sacrificed 3 and 28 days later for gene expression, immunohistologic, magnetic resonance imaging and angiography, and ultrasound analyses. Whole transcriptome RNA sequencing with differential gene expression analysis was performed on outflow veins of AVF.

RESULTS

Encapsulation of 1α,25(OH)₂D₃ in PLGA nanoparticles formed nanoparticles of uniform size that were similar to nanoparticles without 1α,25(OH)₂D₃. The 1,25 NP-treated AVFs exhibited lower VNH/VS, Ier3 gene expression, and IER-3, MCP-1, CD68, HIF-1α, and VEGF-A immunostaining, fibrosis, and proliferation. Blood flow and lumen area increased significantly, whereas peak systolic velocity and wall shear stress decreased. Treatment increased Young's modulus and correlated with histologic assessment of fibrosis and with no evidence of vascular calcification. RNA sequencing analysis showed changes in the expression of genes associated with inflammatory, TGFβ1, and apoptotic pathways.

CONCLUSIONS

Local release of 1,25 NP improves AVF flow and hemodynamics, and reduces stenosis in association with reduction in inflammation, apoptosis, and fibrosis in a porcine model of arteriovenous fistula.

Novel Lesional Transcriptional Signature Separates Atherosclerosis With and Without Diabetes in Yorkshire Swine and Humans

[Figure: see text].

A Computational Fluid Dynamics Study of the Extracorporeal Membrane Oxygenation-Failing Heart Circulation

Extracorporeal membrane oxygenation (ECMO) is increasingly deployed to provide percutaneous mechanical circulatory support despite incomplete understanding of its complex interactions with the failing heart and its effects on hemodynamics and perfusion. Using an idealized geometry of the aorta and its major branches and a peripherally inserted return cannula terminating in the iliac artery, computational fluid dynamic simulations were performed to (1) quantify perfusion as function of relative ECMO flow and (2) describe the watershed region produced by the collision of antegrade flow from the heart and retrograde ECMO flow. To simulate varying degrees of cardiac failure, ECMO flow as a fraction of systemic perfusion was evaluated at 100%, 90%, 75%, and 50% of total flow with the remainder supplied by the heart calculated from a patient-derived flow waveform. Dynamic boundary conditions were generated with a three-element lumped parameter model to accurately simulate distal perfusion. In profound failure (ECMO providing 90% or more of flow), the watershed region was positioned in the aortic arch with minimal pulsatility observed in the flow to the visceral organs. Modest increases in cardiac flow advanced the watershed region into the thoracic aorta with arch perfusion entirely supplied by the heart.