Blood Flow Patterns Research Articles

CFD Simulation of upstream blood pressure dynamics in common carotid artery stenosis with a focus on the effects of beta-blocker intervention

ABSTRACT The study aims to correlate the variation of blood pressure (BP) proximal to the stenosed portion in a stenosed Common Carotid Artery (CCA) with the degree of stenosis. A 3D model of a bifurcated Carotid artery section including the CCA, Internal carotid artery (ICA) and External Carotid Artery (ECA) has been employed for a time-dependent analysis of the blood flow patterns. A physiological pulsatile velocity profile for blood has been assumed, with blood being modelled as a non-Newtonian fluid displaying the Carreau–Yasuda rheological behaviour. The effect of antihypertensive medications of the beta-blocker class, on the upstream BP, has been analysed through the simulation model, in an attempt to assess the efficacy of these medications in atherosclerotic patients. The findings indicate a reduced efficacy of beta-blockers in case of severe stenosis (≥ 75%); with the efficacy decreasing with the enhancement of stenosis extent above 75%.

Respiratory sinus arrhythmia in humans: Correlation analysis with breathing-specific heart rate

In adult humans at rest, pulmonary ventilation and cardiac output share similar values, both approximately 5 L/min. Airflow is intermittent, with tidal volumes exceeding dead space, low breathing frequency (fresp), and zero air velocity at both end-inspiration and end-expiration. In contrast, the cardiac pump is in series with the vasculature, such that the small stroke volume and high heart rate (HR) (fh) allow for quasi-continuous blood flow. Based on experimental findings in dogs, it has been suggested that an elevated fh during inspiration (known as respiratory sinus arrhythmia [RSA]) decreases the disparity between air and blood flow patterns. Thus, one might hypothesize a positive correlation between the peak-trough difference of instantaneous fh (ΔHR’ = HR’peak – HR’trough) and the breathing-specific fh (fh/fresp). To test this hypothesis, we combined breath-by-breath data for ΔHR’ from several previous studies, resulting in a database of over 600 subjects. This extensive dataset allowed us to construct statistically meaningful correlations between ΔHR’ and variables associated with RSA (fh, fresp, HR’peak, and HR’trough). A strong statistically significant (r > 0.9) correlation between fh/fresp and ΔHR’ was observed. These findings support the hypothesis that RSA may be a mechanism for improving the match between the quasi-continuous blood flow and the intermittent airflow.

CFD Investigation of Mechanical Heart Valve Orientations in Modulating Left Ventricular Hemodynamics

This study provides a comprehensive computational analysis of how mechanical heart valve orientations impact left ventricular (LV) hemodynamics, with potential implications for surgical valve placement. Focusing on monoleaflet valves (MLV) and bileaflet valves (BLV), the research explores how different valve angles influence blood flow patterns within the LV chamber. The analysis includes velocity contours, streamline patterns, vorticity contours, and temporal velocity fluctuations to elucidate the effects of valve orientation on LV performance. Findings indicate that valve orientation significantly influences flow coherence and blood velocity. For instance, a 20-degree orientation in the MLV alters jet flow in ways that could affect wall shear stress distribution. At a 45-degree angle, the MLV produces a more centralized jet flow, enhancing flow uniformity and aligning more closely with physiological conditions. In contrast, a 55-degree angle skews the jet flow, potentially leading to adverse hemodynamic effects. Similarly, BLV orientations at 45, 55, 60, and 70 degrees showed that lower angles improved flow efficiency, reducing energy losses and minimizing the risk of regurgitation, while higher angles led to turbulent and potentially damaging flow patterns. Comparative results at a 45-degree orientation demonstrated the superior performance of BLV in regulating normal velocity, with BLV reducing average blood velocity by 38.77% compared to a 29.53% reduction with MLV. These results underscore the importance of optimizing mechanical heart valve orientations to enhance left ventricular hemodynamics. The findings carry significant clinical implications, supporting evidence-based valve placement decisions that can substantially improve patient outcomes, survival rates and long-term cardiovascular health.

A predictive model of shear thrombus growth for the coronary arteries using integrated numerical simulation and artificial intelligence

Cardiovascular disorders are among the most common causes of death worldwide. The formation of a thrombus alters blood flow patterns and impairs blood flow. Therefore, blood flow prediction can aid in an improved understanding of various medical disorders, and developing innovative diagnostic procedures and therapies. Numerical simulations are time-consuming and computationally expensive, and this approach for complex computational domains is prohibitively costly. Therefore, the neural network method is an effective approach for the solution of the corresponding problems. This study aimed to forecast wall shear stress in arteries with varying degrees of stenosis. The prediction approach involved a multi-layer perceptron, with the hyperparameters tuned by the Slime Mould algorithm throughout the training phase. The Hemocell model was used by combining the lattice Boltzmann and immersed boundary methods to generate input datasets for the prediction model. R-squared and root-mean-squared error statistical indices were used to evaluate the outcomes of the predictions. The results indicate that the R-squared values for the testing data were 0.965, 0.959, 0.955, 0.929, and 0.903, respectively, for stenosis levels of 90%, 80%, 60%, 40%, and 20%. The article demonstrates thrombus growth relative to stenosis location across varying levels of blockage. Notably, thrombus growth predominantly occurs before the stenosis peak in lower blockage cases, while higher blockages exhibit growth primarily after the peak.

Evaluation of coiling endovascular technique on treatment of middle cerebral artery cerebral aneurysms in different blood hematocrits: A numerical study

Intracranial aneurysms are localized dilatations of the cerebral arteries that carry a risk of rupture and subsequent subarachnoid hemorrhage, a life-threatening condition. Middle cerebral artery (MCA) aneurysms are a common type of intracranial aneurysm, and endovascular treatment using coils or flow diverters is a common intervention approach. Understanding the hemodynamics, or blood flow patterns, within MCA aneurysms and how they are affected by endovascular treatment is crucial for improving patient outcomes. This numerical study investigates the hemodynamics of blood flow within MCA aneurysms before and after endovascular treatment. Patient-specific geometric models of MCA aneurysms were reconstructed from medical imaging data. Simulations using computational fluid dynamics were conducted to examine flow characteristics, wall shear stress, and additional hemodynamic factors within the aneurysms. The study assessed and contrasted the impact of coil embolization and flow diverter placement on the hemodynamics inside the aneurysms. The findings offer a deeper understanding of the intricate flow dynamics within MCA aneurysms and illustrate the ways in which endovascular treatments can modify these dynamics.

Abstract 4131796: Non-Contact Biometric System for Early Detection of Hypertension and Diabetes Using AI and RGB Imaging

Introduction: In recent years, the development of wearable devices and bioinformation analysis applications utilizing smartphone sensors has seen significant advancements. Despite these technological strides, their adoption and sustained use remain limited to health-conscious individuals. The general populace, particularly those indifferent to health management, stands to miss out on the potential benefits of wearable technologies due to a lack of engagement. This disconnect underscores the necessity for more accessible health monitoring solutions. Research Questions and Goals: This study aims to bridge the gap in health monitoring accessibility by introducing a system capable of non-invasive, non-contact acquisition of biometric information. Such a system seeks to democratize the early detection and prevention of diseases across various demographics. Methods and Results: A prospective cohort clinical study was conducted in a hospital setting with approximately 200 consenting patients and healthy controls. Images of the subjects' faces and hands were captured with a high-speed camera, and blood pressure measurements were taken simultaneously for correlation. A machine learning algorithm was developed to analyze skin blood flow and spectral features from these images to identify potential diseases. The study specifically focused on early detection of hypertension and diabetes. Hypertension was categorized for individuals with systolic blood pressure ≥115 mmHg or diastolic blood pressure ≥75 mmHg. Diabetes was identified in subjects with HbA1c levels ≥6.5 or those previously diagnosed. The algorithm's performance in detecting hypertension showed a 94.2% in alignment with the AHA guidelines for stage1 hypertension, based on pulse wave features. For a subset including 40% early hypertension cases, accuracy rates were 86.2% for 30-second data segments and 80.9% for 5-second segments. For diabetes detection, the application of the algorithm to video data achieved a 75.3%, utilizing blood flow patterns as markers. Hypertension and diabetes were analyzed using different features. Conclusions: The integration of AI algorithms with video data analysis of skin and blood vessels demonstrates a promising avenue for the non-contact, early detection of hypertension and diabetes. This approach not only offers a viable non-contact monitoring technology, but also represents a significant leap towards inclusive, accessible health care prevention and management strategies.

Investigating the impact of vessel geometry on cerebral aneurysm formation using multi-phase blood flow models

Cerebral aneurysms represent a life-threatening condition associated with considerable morbidity and mortality rates. The formation of cerebral aneurysms is influenced by various factors, including vessel geometry, blood flow characteristics, and hemodynamic forces. In this study, we investigate the impact of vessel geometry on the formation of cerebral aneurysms utilizing computational fluid dynamics (CFD) simulations for multi-phase blood flow models.More precisely, we employ the Finite Volume Method to numerically solve the Navier-Stokes equations for simulating blood flow. To accurately capture the intricate nature of blood behavior, we utilize a multiphase blood flow model, as blood consists of red blood cells, white blood cells, and platelets suspended in the blood plasma.Our results demonstrate that the local curvature of the vessel has a pronounced effect on the blood flow patterns and hemodynamic forces within the vessel. Specifically, our simulations indicate that an increase in vessel curvature can lead to the formation of regions of high stress and flow stagnation, both of which are known to be associated with an increased risk of aneurysm formation.The current study provides significant insights into the impact of vessel geometry on the formation of cerebral aneurysms. The obtained results may aid in designing treatment and preventive strategies for cerebral aneurysms, while also contributing to the existing body of knowledge on the subject. Additionally, the approach developed in this study can be applied to investigate various other vascular pathologies, including arterial stenosis and atherosclerosis.

A Mathematical Modeling of Newtonian Blood Flow Through Arterial Mild Stenosis

Mathematical models in health science are usually used to study the blood flow behaviors into the artery. The blood flow through the artery is modeled as an incompressible and homogenous Newtonian fluid, and the flow is assumed to be steady and laminar. Stenosis is an abnormal narrowing in arteries for excess fat deposition that restricts the normal pattern of blood flow through arteries and may cause a heart attack. It is evident that the stenosis in artery may develop due to the accumulation of fat, cholesterol, and abnormal intravascular growth of tissue. The stenosis is to be symmetric about the axis of artery and the flow of blood is axisymmetric. The shear stress has direct proportional relation with both length and height of stenosis. This study uses Navier-Stokes equations in a cylindrical coordinate system and assumes axial symmetry under laminar flow to discuss the blood flow through the mild stenosis artery.

Calculation of intraprocedural hemodynamics with computational functional dynamic in mitral valve edge-to-edge repair

Abstract Background Hemodynamic outcomes in patients undergoing transcatheter edge-to-edge-repair of the mitral valve (M-TEER) are difficult to predict. Computational functional dynamic (CFD) is frequently used in biomedical engineering to simulate blood flow patterns under various conditions. The authors developed a standardized workflow for individualized analyses and investigated the hemodynamic of mitral regurgitation volumes and gradients by using CFD. Methods 20 patients from two high volume centers who suffered from severe mitral regurgitation (MR) and underwent full cycle cardiac computed tomography (CT) prior procedure were enrolled. Baseline computed tomography and intraprocedural data were analyzed. Based on the specific valve morphology, individualized CFD-simulations were performed to calculate MR volumes prior to intervention and estimate hemodynamics after M-TEER. Results CFD-analyses of 20 patients (mean age 80±4 years, 60% male) showed excellent correlation between baseline PISA method-based MR volumes (45±23ml) measured in transesophageal echocardiography (TEE) and CFD-based calculation (45±26ml; R=0.917; P<0.001) as well as between TEE-measured mean baseline effective regurgitant orifice area (EROA; 27±16mm²) and CFD-measured EROA (24±18mm²; R=0.869; P<0.001)). After device implantation, correlation between intraprocedural TEE-measured and CFD-estimated correlation for residual MR volumes (R=0.949; P<0.001) and EROA (R=0.841; P<0.001) remained robust. Post-interventional mean diastolic pressure gradient (TEE) was 3.6±2.8mmHg which was in close correlation with the CFD estimated gradient (3.0±1.8mmHg, R=0.905; P<0.001). Conclusions This is the first study to use a CFD-standardized workflow for predicting hemodynamic changes in patients undergoing M-TEER using data from two different centers. In the future, CFD-based analyses might serve as a key-diagnostic tool for predicting residual MR volumes and gradients for M-TEER-procedures.Comparison of TEE and CFD flow patternBland-Altman-Blots

Ultrasonographic and functional evaluation of forearm circulation with occluded radial artery

Abstract Introduction The transradial approach (TRA) has gained popularity in cardiology procedures. This study aims to evaluate forearm and hand arterial circulation in radial artery (RA) occlusion (RAO) patients after coronary angiography (CAG) and percutaneous coronary interventions (PCI). The ulnar (UA) and anterior interosseous artery (AIA) can compensate for RAO. Methods A prospective, observational study was conducted on 40 RAO patients after CAG/PCI. Ultrasonographic and functional evaluation (Barbeau test) of collateral circulation through AIA or UA were performed. Statistical analyses were applied to evaluate various Doppler ultrasound parameters and the anatomical characteristics of the RAO. Results The RAO group mean age was 71.22 ± 9.99 years, and 45% were male. RA, UA, and AIA showed significant differences in peak systolic velocity, end-diastolic velocity, arterial diameter, total flow volume, and stroke volume (p < 0.01). Pulse quality over RA and UA also differed significantly (p < 0.0001). Blood flow direction in the distal RA segment divided patients into an antegrade flow group (50%) from AIA and a retrograde flow group (50%) from UA. The Barbeau test results varied among RAO patients, with type D being the most common. Anatomical locations of RAO included the anatomical snuffbox (10%), wrist (60%), and forearm (30%). The logistic regression model revealed that the Barbeau test results on Finger 2 (p=0.0006, OR=0.1398) and Finger 4 (p=0.004, OR 0.2843) were significant predictors for the occurrence of antegrade or retrograde blood flow in the distal RA when RAO occurred. Furthermore, when the RA was occluded, the study revealed that a palpable pulse over the RA was still possible in 15% of cases. Conclusion Ultrasonographic evaluation and the Barbeau test can assess collateral circulation and predict blood flow patterns in RAO patients. Further research is needed to validate these findings, explore additional factors influencing collateral circulation and access route selection, and investigate the clinical implications of different RAO anatomical locations in cardiology procedures.Radial Artery OcclusionThe pulse quality over RA/UA with RAO

Computational evaluating on the role of sac centerline length on hemorrhage risk of anterior cerebral artery with saccular aneurysm

The present article investigates geometrical features of an aneurysm, particularly the sac centerline length (SCL), in determining the hemodynamic environment within the aneurysm for evaluation of the hemorrhage risk. Indeed, understanding how these geometric characteristics influence blood flow patterns is essential for assessing rupture risk and optimizing treatment strategies. Computational fluid dynamic is used to perform computational modeling of the blood hemodynamic in Anterior Communicating Artery (ACA) cases. Wall shear stress (WSS), Oscillatory Shear Index (OSI) and pressure over sac surface are investigated and compared for selected saccular aneurysm to evaluate risk of aneurysm rupture when sac centerline length is varied. Comparison of the results show that the inverse relationship between sac centerline length and these key hemodynamic parameters (OSI, velocity, WSS) underscores the importance of geometrical factors in assessing aneurysm rupture risk. Longer sac centerline lengths appear to be associated with more stable flow dynamics and reduced mechanical stress, while shorter sac lengths correlate with more disturbed and high-stress conditions.

Optimizing Lower Extremity Local Flap Reconstruction in Peripheral Vascular Disease.

Local flaps remain a valuable reconstructive tool as a means for limb salvage for patients with advanced arterial disease. Our single-center, retrospective cohort study aims to compare the outcomes of different patterns of blood flow affected by vascular disease to pedicles in local flap reconstruction of the foot and ankle. A retrospective review of 92 patients and 103 flaps was performed. On angiograms, pattern of blood flow to the flap pedicle was determined to be direct inline flow (DF) or indirect flow (IF). Patterns of IF were either by arterial-arterial connections (AC) or unnamed randomized collaterals (RC). Primary outcomes were immediate flap success and limb salvage. Comparative analyses were performed using the χ2 and Fisher tests for categorical variables. Among all flaps, 73.8% (n = 76/103) had DF and 26.2% (n = 27/103) had IF. Both groups experienced similar rates of immediate flap success (DF = 97.3% vs IF = 92.6%, P = 0.281) and limb salvage (DF = 75.% vs IF = 66.7%, P = 0.403). However, the rate of contralateral amputation was significantly higher in the IF group (26.9% vs 5.3%, P = 0.006). When comparing the 3 distinct patterns of blood flow (DF vs AC vs RC), pedicled flaps were more commonly supplied by DF and AC, while random pattern flaps were more commonly supplied by RC (P = 0.042). Alternative routes of revascularization can maintain local flap viability and achieve similar rates of limb salvage but risks contralateral amputation. We found that pedicled and local muscle flaps require inline blood flow or blood supply by ACs. Meanwhile, random pattern flap can be supported by random collaterals.

Numerical Study of the Effect of the Port Angle of the Superior Vena Cava Supplying Cannula on Hemodynamics in the Right Atrium in VV-ECMO.

Objective: To elucidate the pattern of the influence of the port angle of the superior vena cava supplying cannula (SVCS) on hemodynamics within the right atrium in VV-ECMO. Methods: A three-dimensional model of the right atrium was established based on CT images of a real patient. The 3D models of the SVCS and inferior vena cava draining cannula (IVCD) were established based on the Edwards 18Fr and Medos 22Fr real intubation models, respectively. Based on these models, three-dimensional models of the SVCS ports with bending angles of -90°, -60°, -30°, 0°, 30°, 60°, and 90° in the plane formed by the centerline of the SVCS and the center point of the tricuspid valve (TV) were established. Transient-state computational fluid dynamics (CFD) was performed to clarify the right atrium blood flow pattern and hemodynamic states at different SVCS port orientation angles. The velocity clouds, wall pressure, wall shear stress (WSS), relative residence time (RRT), and recirculation fraction (RF) were calculated to assess hemodynamic changes in the right atrium at different angles of the port of the SVCS. Results: As the angle of the port of the superior chamber cannula changed, the location of the high-velocity blood impingement from the SVCS changed, and the pattern of blood flow within the right atrium was dramatically altered. The results for the maximum right atrial wall pressure were 13,472 pa, 13,424 pa, 10,915 pa, 7680.2 pa, 5890.3 pa, 5597.6 pa, and 7883.5 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the mean right atrial wall pressure were 6788.9 pa, 8615.1 pa, 8684.9 pa, 6717.2 pa, 5429.2 pa, 5455.6 pa, and 7117.8 pa ( -90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). The results of the maximum right atrial wall WSS in the seven cases were 63.572 pa, 55.839 pa, 31.705 pa, 39.531 pa, 40.11 pa, 28.474 pa, and 35.424 (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively, and the results of the mean right atrial wall WSS results were 3.8589 pa, 3.6706 pa, 3.3013 pa, 3.2487 pa, 2.3995 pa, 1.3304 pa, and 2.0747 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively. The results for the area percentage of high RRT in the seven cases were 3.44%, 2.23%, 4.24%, 1.83%, 3.69%, 7.73%, and 3.68% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the RF were 21.57%, 23.24%, 19.78%, 12.57%, 10.24%, 5.07%, and 8.05% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). Conclusions: The more the port of the SVCS is oriented toward the TV, the more favorable it is for reducing RF and the impingement of blood flow in the right atrial wall, but there may be an increased risk of RRT. The opposite orientation of the SVCS port to the TV is not conducive to reducing flow impingement on the right atrial wall and RF.

Effects of Different Eccentric Cycling Intensities on Brachial Artery Endothelial Shear Stress and Blood Flow Patterns

ABSTRACT Eccentric exercise has gained attention as a novel exercise modality that increases muscle performance at a lower metabolic demand. However, vascular responses to eccentric cycling (ECC) are unknown, thus gaining knowledge regarding endothelial shear stress (ESS) during ECC may be crucial for its application in patients. The purpose of this study was to explore ECC-induced blood flow patterns and ESS across three different intensities in ECC. Eighteen young, apparently healthy subjects were recruited for two laboratory visits. Maximum oxygen consumption, power output, and blood lactate (BLa) threshold were measured to determine workload intensities. Blood flow patterns in the brachial artery were measured via ultrasound imaging and Doppler on an eccentric ergometer during a 5 min workload steady exercise test at low (BLa of 0–2 mmol/L), moderate (BLa 2–4 mmol/L), and high intensity (BLa levels > 4 mmol/L). There was a significant increase in the antegrade ESS in an intensity-dependent manner (baseline: 44.2 ± 8.97; low: 55.6 ± 15.2; moderate: 56.0 ± 10.5; high: 70.7 ± 14.9, all dynes/cm2, all p values < 0.0002) with the exception between low and moderate and Re (AU) showed turbulent flow at all intensities. Regarding retrograde flow, ESS also increased in an intensity-dependent manner (baseline 9.72 ± 4.38; low: 12.5 ± 3.93; moderate: 15.8 ± 5.45; high: 15.7 ± 6.55, all dynes/cm2, all p values < 0.015) with the exception between high and moderate and Re (AU) showed laminar flow in all intensities. ECC produced exercise-induced blood flow patterns that are intensity-dependent. This suggests that ECC could be beneficial as a modulator of endothelial homeostasis.

Low or oscillatory shear stress and endothelial permeability in atherosclerosis.

Endothelial shear stress is a tangential stress derived from the friction of the flowing blood on the endothelial surface of the arterial wall and is expressed in units of force/unit area (dyne/cm2). Branches and bends of arteries are exposed to complex blood flow patterns that generate low or oscillatory endothelial shear stress, which impairs glycocalyx integrity, cytoskeleton arrangement and endothelial junctions (adherens junctions, tight junctions, gap junctions), thus increasing endothelial permeability. The lipoproteins and inflammatory cells penetrating intima due to the increased endothelial permeability characterizes the pathological changes in early stage of atherosclerosis. Endothelial cells are critical sensors of shear stress, however, the mechanisms by which the complex shear stress regulate endothelial permeability in atherosclerosis remain unclear. In this review, we focus on the molecular mechanisms of the endothelial permeability induced by low or oscillatory shear stress, which will shed a novel sight in early stage of atherosclerosis.

Two-phase magnetohydrodynamic blood flow through curved porous artery

Blood arteries are important part of our cardiovascular system. A comprehensive study of shape and anatomy of blood arteries allows to elucidate the dynamics of blood flow in these arteries. Typically, the arteries are a curved-tube like structure, with arterial walls exhibiting a composition of various porous layers. The current study embarks on a theoretical exploration of a two-fluid model of blood flow and heat transfer through the curved artery under an influence of a magnetic field. The artery walls are composed of Brinkman and Darcy layers. The blood flows through a curved artery exerts centrifugal forces on the arterial walls that leads to change the blood flow patterns. The significant effects of curvature along with the intensity of an applied magnetic field on the blood flow patterns, heat transfer, and resistance impedance in curved artery have been investigated in the present work. The mathematical model of the proposed work is tackled by the homotopy analysis method using physically relevant boundary and interface conditions. The significant outcome of the present work is that the heat transfer rate increases with the increase in the curvature parameter, and it reduces on raising the couple stress parameter and Hartmann number. The novelty of this work lies in the consideration blood flow and heat transfer in inner endothelial layers of curved porous artery. The result presented in this work is vital to assess the condition of atherosclerosis, aneurysms, vasculties, blood clot, etc.; beyond this, the present model can be extended for medical diagnostics, treatment planning, medical device design, drug delivery optimization, and biomedical engineering research. This study can ultimately contribute for improved patient care and outcomes in cardiovascular medicine.

Laser ablation for preventing coronary obstruction and maintaining coronary access in redo-TAVR: A proof of concept.

Redo-transcatheter aortic valve replacement (TAVR) is a promising treatment for transcatheter aortic valve degeneration, becoming increasingly relevant with an aging population. In redo-TAVR, the leaflets of the initial (index) transcatheter aortic valve (TAV) are displaced vertically when the second TAV is implanted, creating a cylindrical cage that can impair coronary cannulation and flow. Preventing coronary obstruction and maintaining coronary access is essential, especially in young and low-risk patients undergoing TAVR. This study aimed to develop a new leaflet modification strategy using laser ablation to prevent coronary obstruction and facilitate coronary access after repeat TAVR. To evaluate the feasibility of the leaflet modification technique using laser ablation, the initial phase of this study involved applying a medical-grade ultraviolet laser for ablation through pericardial tissue. Following this intervention, computational fluid dynamics simulations were utilized to assess the efficacy of the resulting perforations in promoting coronary flow. These simulations played a crucial role in understanding the impact of the modifications on blood flow patterns, ensuring these changes would facilitate the restoration of coronary circulation. Laser ablation of pericardium leaflets was successful, demonstrating the feasibility of creating openings in the TAV leaflets. Flow simulation results show that ablation of index valve leaflets can effectively mitigate the flow obstruction caused by sinus sequestration in redo-TAVR, with the extent of restoration dependent on the number and location of the ablated openings. Laser ablation could be a viable method for leaflet modification in redo-TAVR, serving as a new tool in interventional procedures.

Associations of Cerebral Blood Flow Patterns With Gray and White Matter Structure in Patients With Temporal Lobe Epilepsy.

Neuroimaging studies in patients with temporal lobe epilepsy (TLE) show widespread brain network alterations beyond the mesiotemporal lobe. Despite the critical role of the cerebrovascular system in maintaining whole-brain structure and function, changes in cerebral blood flow (CBF) remain incompletely understood in the disease. Here, we studied whole-brain perfusion and vascular network alterations in TLE and assessed its associations with gray and white matter compromises and various clinical variables. We included individuals with and without pharmaco-resistant TLE who underwent multimodal 3T MRI, including arterial spin labelling, structural, and diffusion-weighted imaging. Using surface-based MRI mapping, we generated individualized cortico-subcortical profiles of perfusion, morphology, and microstructure. Linear models compared regional CBF in patients with controls and related alterations to morphological and microstructural metrics. We further probed interregional vascular networks in TLE, using graph theoretical CBF covariance analysis. The effects of disease duration were explored to better understand the progressive changes in perfusion. We assessed the utility of perfusion in separating patients with TLE from controls using supervised machine learning. Compared with control participants (n = 38; mean ± SD age 34.8 ± 9.3 years; 20 females), patients with TLE (n = 24; mean ± SD age 35.8 ± 10.6 years; 12 females) showed widespread CBF reductions predominantly in fronto-temporal regions (Cohen d -0.69, 95% CI -1.21 to -0.16), consistent in a subgroup of patients who remained seizure-free after surgical resection of the seizure focus. Parallel structural profiling and network-based models showed that cerebral hypoperfusion may be partially constrained by gray and white matter changes (8.11% reduction in Cohen d) and topologically segregated from whole-brain perfusion networks (area under the curve -0.17, p < 0.05). Negative effects of progressive disease duration further targeted regional CBF profiles in patients (r = -0.54, 95% CI -0.77 to -0.16). Perfusion-derived classifiers discriminated patients from controls with high accuracy (71% [70%-82%]). Findings were robust when controlling for several methodological confounds. Our multimodal findings provide insights into vascular contributions to TLE pathophysiology affecting and extending beyond mesiotemporal structures and highlight their clinical potential in epilepsy diagnosis. As our work was cross-sectional and based on a single site, it motivates future longitudinal studies to confirm progressive effects, ideally in a multicentric setting.

Differentiating optic neuropathies using laser speckle flowgraphy: Evaluating blood flow patterns in the optic nerve head and peripapillary choroid.

To compare blood flow (BF) impairment patterns in different optic neuropathies using laser speckle flowgraphy (LSFG). This retrospective study enrolled 24 eyes of 24 patients with non-arteritic anterior ischemic optic neuropathy (NAAION), 59 eyes of 59 patients with optic neuritis (ON), 677 eyes of 677 patients with open-angle glaucoma (OAG), and 110 eyes of 110 controls. The patient backgrounds of all groups were compared. Ophthalmologic findings were evaluated, adjusting for age, sex, blood pressure, pulse rate, and underlying systemic diseases with 1:1 optimal propensity score matching. We used LSFG to obtain optic nerve head (ONH) vessel-area mean blur rate (MBR; ONH-MV), ONH tissue-area MBR (ONH-MT), and choroidal MBR. The NAAION and ON groups were compared with the control and OAG groups. Best-corrected visual acuity was worse in the NAAION, ON, and OAG groups than in controls (p < 0.001). Circumpapillary retinal nerve fibre layer thickness was higher in the NAAION and ON groups and lower in the OAG group than in controls (p < 0.001). Compared to controls, the NAAION and OAG groups had significantly lower ONH-MV, ONH-MT, and choroidal MBR (p < 0.05). Additionally, the NAAION group had lower ONH-MV and choroidal MBR than the OAG group (p = 0.003 and p < 0.001, respectively) but no difference in ONH-MT (p = 0.857). The ON group had significantly lower ONH-MV and choroidal MBR compared to the controls (p < 0.001 and p = 0.022, respectively) but no difference in ONH-MT (p = 0.773). Optic neuropathies showed different patterns of ocular BF impairment. Therefore, LSFG can be a useful tool for differentiating optic neuropathies.

The New Frontiers of Fetal Imaging: MRI Insights into Cardiovascular and Thoracic Structures.

Fetal magnetic resonance imaging (fMRI) represents a second-line imaging modality that provides multiparametric and multiplanar views that are crucial for confirming diagnoses, detecting associated pathologies, and resolving inconclusive ultrasound findings. The introduction of high-field magnets and new imaging sequences has expanded MRI's role in pregnancy management. Recent innovations in ECG-gating techniques have revolutionized the prenatal evaluation of congenital heart disease by synchronizing imaging with the fetal heartbeat, thus addressing traditional challenges in cardiac imaging. Fetal cardiac MRI (fCMR) is particularly valuable for assessing congenital heart diseases, especially when ultrasound is limited by poor imaging conditions. fCMR allows for detailed anatomical and functional evaluation of the heart and great vessels and is also useful for diagnosing additional anomalies and analyzing blood flow patterns, which can aid in understanding abnormal fetal brain growth and placental perfusion. This review emphasizes fMRI's potential in evaluating cardiac and thoracic structures, including various gating techniques like metric optimized gating, self-gating, and Doppler ultrasound gating. The review also covers the use of static and cine images for structural and functional assessments and discusses advanced techniques like 4D-flow MRI and T1 or T2 mapping for comprehensive flow quantification and tissue characterization.