Hemodynamic Studies Research Articles

Guidelines for the diagnosis and treatment of idiopathic portal hypertension, extrahepatic portal obstruction, and Budd-Chiari syndrome in Japan.

This is the English version of the guidelines for the diagnosis and treatment of idiopathic portal hypertension, extrahepatic portal obstruction, and Budd-Chiari syndrome, which were established and revised in 2018 by the Aberrant Portal Hemodynamics Study Group under the jurisdiction of the Ministry of Health, Labor, and Welfare in Japan. These guidelines are excerpts, and the full version consists of 86 clinical questions and explanations, totaling 183 pages in Japanese.

Additive manufacturing of personalized scaffolds for vascular cell studies in large arteries: A case study on carotid arteries in sickle cell disease patients

Patient-specific models have increasingly gained significance in medical and research domains. In the context of hemodynamic studies, computational fluid dynamics emerges as a highly innovative and promising approach. We propose to augment these computational studies with cell-based experiments in individualized artery geometries using personalized scaffolds and vascular cell experiments. Previous research has demonstrated that the development of Sickle Cell Disease (SCD)-Related Vasculopathy is dependent on personal geometries and flow characteristics of the carotid artery. This fact leaves conventional animal experiments unsuitable for gaining patient-specific insights into cellular signaling, as they cannot replicate the personalized geometry. These personalized dynamics of cellular signaling may further impact disease progression, yet remains unclear. This paper presents a six-step methodology for creating personalized large artery scaffolds, focusing on high-precision models that yield biologically interpretable patient-specific results. The methodology outlines the creation of personalized large artery models via Additive Manufacturing suitably for supporting cell culture and other cellular experiments. Additionally, it discusses how different Computer-Aided-Design (CAD) construction modes can be used to obtain high-precision personalized models, while simplifying model reconfigurations and facilitating adjustments to general designs such as system connections to bioreactors, fluidic systems and visualization tools. A proposal for quality control measures to ensure geometric congruence for biological relevance of the results is added. This innovative, interdisciplinary approach appears promising for gaining patient-specific insights into pathophysiology, highlighting the importance of personalized medicine for understanding complex diseases.

Hemodynamics study of anterior cerebral artery with different sac centerline lengths for rupture risk assessment.

The present research extensively investigates the significance of the sac centerline length of the anterior cerebral artery (ACA) on aneurysm rupture risk. Hemodynamic factors influencing aneurysm rupture are assessed to identify critical regions prone to rupture. Wall shear stress is analyzed by modeling blood flow in three real saccular ACA cases with varying sac centerline lengths. A one-way fluid-solid interaction (FSI) model is employed to examine the interaction between blood flow and vessel deformation. The computational study reveals that wall shear stress on the ACA saccular aneurysm wall is significantly higher when the sac centerline length is shorter. Conversely, the mean oscillatory index changes with different sac centerline lengths, showing that an increase in sac centerline length leads to higher blood oscillation within the sac area in ACA cases.

Pearls and Pitfalls of Epicardial Echocardiography for Implantation of Impella CP Devices in Ovine Models.

The Impella CP is a percutaneously inserted temporary left ventricular assist device used in clinical practice and in translational research into cardiogenic shock, perioperative cardiac surgery, acute cardiac failure and mechanical circulatory support. Fluoroscopic guidance is usually used for insertion of an Impella, thus limiting insertion to within catheterization laboratories. Transthoracic, transoesophageal and intracardiac echocardiography have been reported to guide Impella CP implantation with identified specific limitations stemming from the surgical, anatomical and equipment factors. We conducted translational prospective descriptive feasibility investigation as a part of two other hemodynamic Impella studies. It showed the successful application of epicardial echocardiographic scanning for implantation of Impella CP devices in ovine models, from which details of the technique and identified pitfalls are described with practical solutions for future investigators and clinicians. Many described findings are relevant to any other echocardiographic techniques when adequate imaging of the Impella and relevant anatomical structures is achievable.

P168 CHARACTERIZATION OF THE HEMODYNAMIC PATTERN OF CONTROLLED HYPERTENSIVE PATIENTS

Background: Hemodynamic alterations have been described in hypertensive disease. However, we still do not know if the identification of an altered hemodynamic pattern in patients with controlled hypertension could predict cardiovascular risk or evolution of hypertension. Objective: to identify the hemodynamic pattern of hypertensive patients with BP values in goals. Methods: Controlled hypertensive subjects were recruited (n = 107) and included a control group of normotensive subjects (n: 35.9). A non-invasive hemodynamic study (Z Logic, lying down / standing) was performed, and the cardiac index (CI) and vascular resistance index (VRI) data were recorded for the determination of the hemodynamic pattern. Hypodynamic pattern was considered: CI <2.5 L / min / m2 and VRI> 2500 dynas.seg.cm-5.m2; Hyperdynamic pattern IC> 4,4 L / min / m2 and VRI <2500 dynas.seg.cm-5.m2 Results: The SBP / DBP of the HTA group was 133.09 +/- 6.01 / 82.4 +/-7.2 mm Hg; and of the NT group was SBP/ DBP 123.6 +/- 9.7 / 75.5 +/- 8.9. The CI and VRI of the HTA group obtained was 2.81 l / m2 / min and 2842.31 dynas that, without corresponding to a hypodynamic pattern, showed a predominance of the VRI increase. In the control group of NT subjects, the values were 3.23 and 2289.23, respectively, corresponding to a normal pattern. The values obtained were different between both groups (p <.05). Conclusions: Controlled hypertensive patients with hypertension goals have a hemodynamics pattern with an increase in the VRI different from that of normotensive subjects. These results coincide with those reported by Ferrario and col. The relevance of the imbalance found could only be analyzed in the context of long-term follow-up to identify whether it is a predictor of CV events and / or complications.

Research on Experimental Hypertension in Prague (1966-2009).

The study of ontogenetic aspects of water and electrolyte metabolism performed in the Institute of Physiology (Czechoslovak Academy of Sciences) led to the research on the increased susceptibility of immature rats to salt-dependent forms of hypertension since 1966. Hemodynamic studies in developing rats paved the way to the evaluation of hemodynamic mechanisms during the development of genetic hypertension in SHR. A particular attention was focused on altered renal function and kidney damage in both salt and genetic hypertension with a special respect to renin-angiotensin system. Renal damage associated with hypertension progression was in the center of interest of several research groups in Prague. The alterations in ion transport, cell calcium handling and membrane structure as well as their relationship to abnormal lipid metabolism were studied in a close cooperation with laboratories in Munich, Glasgow, Montreal and Paris. The role of NO and oxidative stress in various forms of hypertension was a subject of a joint research with our Slovak colleagues focused mainly on NO-deficient hypertension elicited by chronic L-NAME administration. Finally, we adopted a method enabling us to evaluate the balance of vasoconstrictor and vasodilator mechanisms in BP maintenance. Using this method we demonstrated sympathetic hyperactivity and relative NO deficiency in rats with either salt-dependent or genetic hypertension. At the end of the first decennium of this century we were ready to modify our traditional approach towards modern trends in the research of experimental hypertension. Keywords: Salt-dependent hypertension o Genetic hypertension o Body fluids o Hemodynamics o Ion transport o Cell membrane structure and function o Renal function o Renin-angiotensin systems.

Intravenous infusions of mesenchymal stromal cells have cumulative beneficial effects in a porcine model of chronic ischemic cardiomyopathy.

The development of cell therapy as a widely-available clinical option for ischemic cardiomyopathy is hindered by the invasive nature of current cell delivery methods. Furthermore, the rapid disappearance of cells after transplantation provides a cogent rationale for using repeated cell doses, which, however, has not been done thus far in clinical trials because it is not feasible with invasive approaches. The goal of this translational study was to test the therapeutic utility of the intravenous route for cell delivery. Pigs with chronic ischemic cardiomyopathy induced by myocardial infarction received one or three intravenous doses of allogeneic bone marrow mesenchymal stromal cells (MSCs) or placebo 35 days apart. Rigor guidelines, including blinding and randomization, were strictly followed. A comprehensive assessment of LV function was conducted with three independent methods (echocardiography, magnetic resonance imaging, and hemodynamic studies). The results demonstrate that three doses of MSCs improved both load-dependent and independent indices of left ventricular (LV) function and reduced myocardial hypertrophy and fibrosis; in contrast, one dose failed to produce most of these benefits. To our knowledge, this is the first study to show that intravenous infusion of a cell product improves LV function and structure in a large animal model of chronic ischemic cardiomyopathy and that repeated infusions are necessary to produce robust effects. This study, conducted in a clinically-relevant model, supports a new therapeutic strategy based on repeated intravenous infusions of allogeneic MSCs and provides a foundation for a first-in-human trial testing this strategy in patients with chronic ischemic cardiomyopathy.

Haemodynamic study of left nonthrombotic iliac vein lesions: a preliminary report

Nonthrombotic iliac vein lesions (NIVLs) are significant causes of chronic venous insufficiency (CVI) in the left lower limb and symptom recurrence following left lower limb varicose vein treatment. The goal of this study was to explore the haemodynamic and morphological characteristics of iliac veins in patients with NIVLs. Pressure at the caudal end of the stenotic left common iliac vein (LCIV) segment, local blood flow velocity, and time-averaged wall shear stress in the stenotic segment exhibited positive correlations with the clinical CVI classification (R = 0.92, p < 0.001; R = 0.94, p < 0.001; R = 0.87, p < 0.001), while the relative retention time showed a negative correlation (R = -0.94, p < 0.001). The pressure difference (∆P) between the two ends of the stenotic segment and the velocity difference (∆V) between the stenotic segment and the caudal end were positively correlated with the clinical classification (R = 0.92, p < 0.001; R = 0.9, p < 0.001). The cross-sectional area stenosis rate and length of the stenotic LCIV segment were positively correlated with the clinical classification (R = 0.93, p < 0.001; R = 0.63, p < 0.001). The results suggest that haemodynamic assessment of the iliac vein could effectively portray blood flow disturbances in stenotic segments of the LCIV, potentially reflecting the degree of iliac vein stenosis. Haemodynamic indicators are correlated with the severity of clinical CVI symptoms.

Development of idealized human aortic models for in vitro and in silico hemodynamic studies.

The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies. This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings. Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models. The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.

Distal Ventricular Pacing for Drug-Refractory Mid-Cavity Obstructive Hypertrophic Cardiomyopathy: A Randomized, Placebo-Controlled Trial of Personalized Pacing.

Patients with refractory, symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy have few therapeutic options. Right ventricular pacing is associated with modest hemodynamic and symptomatic improvement, and LV pacing pilot data suggest therapeutic potential. We hypothesized that site-specific pacing would reduce LVMCO gradients and improve symptoms. Patients with symptomatic-drug-refractory LVMCO were recruited for a randomized, blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical right ventricular pacing sites were assessed during an invasive hemodynamic study of multisite pacing. Patient-specific pacing-site and atrioventricular delays, defining PPoP, were selected on the basis of LVMCO gradient reduction and acceptable pacing parameters. Patients were randomized to 6 months of active PPoP or backup pacing in a crossover design. The primary outcome examined invasive gradient change with best-site pacing. Secondary outcomes assessed quality of life and exercise following randomization to PPoP. A total of 17 patients were recruited; 16 of whom met primary end points. Baseline New York Heart Association was 3±0.6, despite optimal medical therapy. Hemodynamic effects were assessed during pacing at the right ventricular apex and at a mean of 8 LV sites. The gradients in all 16 patients fell with pacing, with maximum gradient reduction achieved via LV pacing in 14 (88%) patients and right ventricular apex in 2. The mean baseline gradient of 80±29 mm Hg fell to 31±21 mm Hg with best-site pacing, a 60% reduction (P<0.0001). One cardiac vein perforation occurred in 1 case, and 15 subjects entered crossover; 2 withdrawals occurred during crossover. Of the 13 completing crossover, 9 (69%) chose active pacing in PPoP configuration as preferred setting. PPoP was associated with improved 6-minute walking test performance (328.5±99.9 versus 285.8±105.5 m; P=0.018); other outcome measures also indicated benefit with PPoP. In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic patients with LVMCO. URL: https://clinicaltrials.gov/study; Unique Identifier: NCT03450252.

Patient-specific bicuspid aortic valve hemodynamics study based on computer simulation and in vitro experiment

Patient-specific bicuspid aortic valve hemodynamics study based on computer simulation and in vitro experiment

A hemodynamic study of the relationship between the left and right liver volumes and the blood flow distribution in portal vein branches.

Cirrhosis patients often exhibit clinical symptoms such as right liver atrophy, portal hypertension, spleen enlargement and increased blood supply, which exhibit considerable variation between the left and right liver sections. These differences are hypothesized to stem from disparities in blood flow within the left and right portal vein (PV) branches. However, rigorous quantitative evidence remains scarce. We mainly aim at quantitatively revealing the relationship between the blood flow rates of two PV branches and liver volumes, and providing quantitative evidence and theoretical support for the diagnosis and treatment of cirrhosis from the perspective of hemodynamics. Five cirrhotic patients and two healthy volunteers from Beijing Friendship Hospital are investigated. Their PV blood flow models are established based on computed tomography (CT) images and finite volume simulations. The volume of the left and right liver lobes are measured in 3-matic. The distributions of blood source in the PV branches are tracked by streamline analysis. The blood flow rates are quantitatively counted by integrating the blood source velocities. Linear analysis is performed to build the relationship between liver volumes and PV blood flow distributions. Streamline analysis reveals significant differences in blood distribution between the left and right PV branches. The majority of blood from the superior mesenteric vein (SMV) flowed into the right portal vein (RPV), while most blood from the splenic vein (SV) entered the left portal vein (LPV). The main PV pressure drop linearly increases with the SV blood velocity for all PV structures of patients and healthy volunteers. The flow rate ratio QRPV/QLPV demonstrates an increase in tandem with the volume ratio VR/VL, exhibiting a linear correlation with the Pearson correlation coefficient being 0.93. The differences in the blood distributions are consistent with the clinicians' knowledge and validate our simulations. We demonstrated a linear increase in PV pressure with elevated SV blood velocity. Additionally, the volumes of the left and right hepatic lobes exhibited a positive correlation with blood flow rates in the corresponding PV branches.

Vicious Circle With Venous Hypertension, Irregular Flow, Pathological Venous Wall Remodeling, and Valve Destruction in Chronic Venous Disease: A Review.

Substantial advances occurred in phlebological practice in the last two decades. With the use of modern diagnostic equipment, the patients' venous hemodynamics can be examined in detail in everyday practice. Application of venous segments for arterial bypasses motivated studies on the effect of hemodynamic load on the venous wall. New animal models have been developed to study hemodynamic effects on the venous system. In vivo and in vitro studies revealed cellular phase transitions of venous endothelial, smooth muscle, and fibroblastic cells and changes in connective tissue composition, under hemodynamic load and at different locations of the chronically diseased venous system. This review is an attempt to integrate our knowledge from epidemiology, paleoanthropology and anthropology, clinical and experimental hemodynamic studies, histology, cell physiology, cell pathology, and molecular biology on the complex pathomechanism of this frequent disease. Our conclusion is that the disease is initiated by limited genetic adaptation of mankind not to bipedalism but to bipedalism in the unmoving standing or sitting position. In the course of the disease several pathologic vicious circles emerge, sustained venous hypertension inducing cellular phase transitions, chronic wall inflammation, apoptosis of cells, pathologic dilation, and valvular damage which, in turn, further aggravate the venous hypertension.

Multicenter hemodynamic assessment of the LOT-CRT strategy: when is one lead enough for resynchronization?

Abstract Background Left bundle branch area pacing (LBBAP) has been postulated as an alternative to traditional cardiac resynchronization therapy via biventricular pacing (BiV) in heart failure patients with wide QRS. Limited data is available regarding the acute hemodynamic response of LBBAP and the combination of LBBAP and coronary venous (LVcv) pacing (LOT-CRT). Purpose We sought to compare the acute hemodynamic and ECG effects of traditional CRT (BiV or LV-only) versus LBBAP and LOT-CRT in CRT candidates with advanced conduction disease. Methods In this multi-centre study (5 EU and 7 US centres), 48 subjects (mean age 65.8 years, 67% males, LV ejection fraction 29.4%) with either nonspecific interventricular conduction delay (NIVCD, n = 29) or left bundle branch block (LBBB; n =19; based upon strict criteria AHA/ACC/HRS plus Strauss) underwent an acute hemodynamic study to determine the % change in +LV dP/dtmax from baseline atrial pacing versus BiV, LBBAP, or LOT-CRT. Each therapy pacing configuration was applied 4 times at 5 different atrioventricular (AV) delays. QRS shortening was assessed using standard 12-lead ECG. Results Successful LBBAP lead implantation was achieved in 27 patients (56%) using current EHRA criteria. Twenty-one patients (44%) were categorized as deep septal pacing (DSP), due to suboptimal lead penetration or advanced left conduction system disease with broad paced QRS complexes and absent V1-r-wave. The increase in AV-optimized dP/dtmax for the different pacing configurations is displayed in the Figure, left panel. LOT-CRT dP/dtmax % improvement was 25.8%, significantly higher than LBBAP configurations (p&amp;lt;0.01), either unipolar-LBBAP (19.3%), or bipolar-LBBAP (16.4%), but not different from BiV (26.4%). QRS shortening was greater in LOT-CRT (29.5ms) vs. unipolar-LBBAP (11.9ms), bipolar-LBBAP (11.7ms), or BiV (18.5ms), all p&amp;lt;0.01. Sub-group analysis indicated the hemodynamic benefit of adding LVcv pacing when LBBAP strategy was pursued (Figure, right panel) depended on obtaining LBBAP rather than DSP (p &amp;lt; 0.01) and baseline QRS duration (p = 0.03). The largest benefit was observed among subjects with a baseline QRS wider than the observed cohort mean (171ms) and DSP only, where LOT-CRT provided 14.5% (5.0-24.1%) greater dP/dtmax improvement and 20.8ms (12.8-28.8ms) greater QRS duration shortening than unipolar DSP. Conclusions In a CRT cohort with advanced conduction disease, LOT-CRT provided greater acute hemodynamic benefit than LBBAP strategy (i.e. including also DSP cases). Patients with wider QRS or suboptimal outcome of LBBAP strategy (DSP) are more likely to benefit from addition of a LVcv lead to implement LOT-CRT.Figure 1

#3050 Hemodynamic study of hypertensive disorders in pregnancy using cardiothoracic bioimpedance

Abstract Background and Aims Hypertensive disorders in pregnancy (HDP) are a major cause of maternal and perinatal morbidity and mortality. There is still a need for the development of biomarkers for early diagnosis of the severity of the condition. Thoracic electrical bioimpedance (TEB) is a non-invasive hemodynamic technique based on the resistance to the flow of electrical current. We investigated hemodynamic changes in pregnant/postpartum women with HDP using TEB. Method A retrospective observational study was conducted in pregnant and postpartum women with hypertension monitored by TEB. Indirect changes were analyzed in: cardiac work, left cardiac work index (LCWI kg⋅m/m2) and calculated cardiac output (CO ml/min=systolic volume -SV ml- × heart rate -HR bpm-); fluid status, thoracic fluid content index (TFCI l/kOhm/m2); and resistances, systemic vascular resistance index (SVRI dyn.s.cm-5.m2). Normality of variables was assessed by Shapiro-Wilk test and correlation analysis was performed by Pearson/Spearman tests. Statistical inference between the hypertension-preeclampsia and pregnancy-postpartum groups was performed using Student's/Mann-Whitney U tests. Analysis was performed using STATA 12. Results Fifty-five patients were included with a mean age of 36.5 years (SD 4.54), 69% were older than 35 years. Pregnant women accounted for 86% of the TEB evaluations, the majority (93.6%) in the third trimester. There was chronic hypertension in 7.27% and pre-eclampsia in 18.18% of previous pregnancies. The diagnoses were: pre-eclampsia (56.36%), gestational hypertension (40%) and HELLP syndrome (3.64%). The mean blood pressure was 144/89 (SD 16/11) mmHg. Mean proteinuria was 363.2 (range: 10.3-23220) mg/g. The median values were as follow: LCWI: 5.05 (IQR: 1.4) kg⋅m/m2; CO: 6352 (IQR: 2345) ml/min; TFCI: 17.9 (IQR: 6.3) l/kOhm/m2; SVRI: 2167.63 (SD: 462.87) dyn.s.cm-5.m2. LCWI showed a weak positive correlation with systolic blood pressure (SBP) and a strong correlation with diastolic blood pressure (DBP) (Rho 0.2899 and 0.5176, respectively). There was also a positive and moderate correlation between SVRI and SBP and DBP (r 0.4265 and 0.4019, respectively). There was no correlation between CO or TFCI and SBP or DBP. No statistically significant differences in hemodynamic parameters were found between gestational hypertension and pre-eclampsia, nor between pregnant and postpartum women. Conclusion Increased blood pressure in the setting of HDP correlates with increased LCWI and systemic resistance independent of fluid retention. An increase in systemic vascular resistance measured by TEB (which decreases in normal pregnancy) may be an early diagnostic marker of HDP. These findings require further validation in a larger cohort, including a control group of pregnant women without hypertension.

Association Between Plasma Aldosterone Concentration and Intraglomerular Hemodynamics in Primary Aldosteronism.

In primary aldosteronism (PA), aldosterone could affect glomerular hemodynamics by elevating renal vascular resistance and glomerular capillary pressure. However, the relationship between plasma aldosterone concentrations (PAC) and glomerular hemodynamics including efferent arteriolar resistance (Re), and afferent arteriolar resistance (Ra) in humans is still unclear. The aim of this study was to investigate the relationships of PAC with intraglomerular hemodynamic parameters in patients with PA. An observational study of glomerular hemodynamics was performed using simultaneous measurements of plasma clearance of para-aminohippurate and inulin (Cin; glomerular filtration rate (GFR)) in 17 patients with PA. Kidney function was evaluated by Cin, estimated GFR based on serum creatine (eGFRcre) and serum cystatin C (eGFRcys) and creatine clearance (Ccr). Intraglomerular hemodynamic parameters, including Re, Ra, and intraglomerular hydrostatic pressure (Pglo) were calculated using Gomez's formulae. In the 17 PA cases, PAC was significantly correlated with Cin (rho = 0.752, P = 0.001) and eGFRcys (rho = 0.567, P = 0.018), but was not correlated with eGFRcre and Ccr. PAC was also significantly correlated with Pglo, Re, and urinary protein/day (rho = 0.775, P = 0.0004, rho = 0.625, P = 0.009, and rho = 0.625, P = 0.007, respectively). Multivariable regression analysis showed that PAC was significantly associated with Cin and Re. In comparing aldosterone-producing adenoma (APA) and non-APA cases, Cin was significantly elevated in APA (P = 0.037), whereas eGFRcre, eGFRcys, and Ccr were not. Re tended to be higher in APA (P = 0.064). These results suggest high aldosterone causes glomerular hyperfiltration by constricting Re. Cin, but not eGFRcre and Ccr, may be useful for evaluating kidney function in PA.

Vascular function and skeletal fragility: a study of tonometry, brachial hemodynamics, and bone microarchitecture.

Osteoporosis and cardiovascular disease frequently occur together in older adults; however, a causal relationship between these 2 common conditions has not been established. By the time clinical cardiovascular disease develops, it is often too late to test whether vascular dysfunction developed before or after the onset of osteoporosis. Therefore, we assessed the association of vascular function, measured by tonometry and brachial hemodynamic testing, with bone density, microarchitecture, and strength, measured by HR-pQCT, in 1391 individuals in the Framingham Heart Study. We hypothesized that decreased vascular function (pulse wave velocity, primary pressure wave, brachial pulse pressure, baseline flow amplitude, and brachial flow velocity) contributes to deficits in bone density, microarchitecture and strength, particularly in cortical bone, which is less protected from excessive blood flow pulsatility than the trabecular compartment. We found that individuals with increased carotid-femoral pulse wave velocity had lower cortical volumetric bone mineral density (tibia: -0.21 [-0.26, -0.15] standardized beta [95% CI], radius: -0.20 [-0.26, -0.15]), lower cortical thickness (tibia: -0.09 [-0.15, -0.04], radius: -0.07 [-0.12, -0.01]) and increased cortical porosity (tibia: 0.20 [0.15, 0.25], radius: 0.21 [0.15, 0.27]). However, these associations did not persist after adjustment for age, sex, height, and weight. These results suggest that vascular dysfunction with aging may not be an etiologic mechanism that contributes to the co-occurrence of osteoporosis and cardiovascular disease in older adults. Further study employing longitudinal measures of HR-pQCT parameters is needed to fully elucidate the link between vascular function and bone health.

Integrating Computational and Biological Hemodynamic Approaches to Improve Modeling of Atherosclerotic Arteries.

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.

Hemodynamics of the VenusP Valve System™-an in vitro study.

This study aims to evaluate the fluid dynamic characteristics of the VenusP Valve System™ under varying cardiac outputs in vitro. A thorough hemodynamic study of the valve under physiological cardiac conditions was conducted and served as an independent assessment of the performance of the valve. Flow fields downstream of the valve near the pulmonary bifurcation were quantitatively studied by two-dimensional Particle Image Velocimetry (PIV). The obtained flow field was analyzed for potential regions of flow stasis and recirculation, and elevated shear stress and turbulence. High-speed en face imaging capturing the leaflet motion provided data for leaflet kinematic modeling. The experimental conditions for PIV studies were in accordance with ISO 5840-1:2021 standard, and two valves with different lengths and different orientations were studied. Results show good hemodynamics performance for the tested valves according to ISO 5840 standard without significant regions of flow stasis. Observed shear stress values are all well below established hemolysis limits.

Abstract 1089: Noninvasive Assessment Of Aortic Biomechanics Using 4-D Flow And Cardiovascular Magnetic Resonance In A Porcine Model Of Aortic Coarctation

Objectives: Aortic coarctation (COA) is a congenital heart disease that results from narrowing of the aorta, contributing to increased cardiovascular morbidity. Current animal models are limited by stenotic mechanism and study longevity. We introduce a porcine model of COA, treated with a novel growth stent and imaged with advanced MRI techniques, to obtain hemodynamic metrics. Methods: A total of 14 piglets, 4 sham, 4 coarcted controls (CC) and 6 coarcted stents (CS), underwent surgical creation of a COA. The timeline is detailed in Figure 1. Serial imaging was obtained on a 3.0T MRI scanner. Hemodynamic metrics were acquired in predefined vascular planes (Ensight, CEI) to assess net flow, velocities and helical or vortical flow. CMR image analysis using cvi42 (Circle, Canada) included T1 maps and cardiac function. Results: Analyses are shown at 20 weeks. For CMR, there were no differences in cardiac function metrics, left ventricular mass or T1 mapping. In the 4D Flow analysis, shown in Figure 2, ascending aortic flow averages 62.5 mL/cycle in the CS group, higher than the sham and CC groups (p= &lt;0.05). Both CS and CC animals have increased post-stenotic velocities (&gt;1.5m/s), compared to the sham aorta (p= 0.01). All coarcted aortas, both CS and CC, exhibited helical flow and post-stenotic dilatation. Conclusions: No hemodynamic differences were seen with CMR, reflecting minimal adverse myocardial remodeling. 4D MRI data revealed locational differences in flow, velocity and collateralization. In conclusion, this work illustrates a successful longitudinal large animal model of COA and validates advanced imaging methods in the study of vascular hemodynamics.