The definition of low wall shear stress and its effect on plaque progression estimation in human coronary arteries

Wall shear stress (WSS), the frictional force of the blood on the vessel wall, plays a crucial role in atherosclerotic plaque development. Low WSS has been associated with plaque growth, however previous research used different approaches to define low WSS to investigate its effect on plaque progression. In this study, we used four methodologies to allocate low, mid and high WSS in one dataset of human coronary arteries and investigated the predictive power of low WSS for plaque progression. Coronary reconstructions were based on multimodality imaging, using intravascular ultrasound and CT-imaging. Vessel-specific flow was measured using Doppler wire and computational fluid dynamics was performed to calculate WSS. The absolute WSS range varied greatly between the coronary arteries. On the population level, the established pattern of most plaque progression at low WSS was apparent in all methodologies defining the WSS categories. However, for the individual patient, when using measured flow to determine WSS, the absolute WSS values range so widely, that the use of absolute thresholds to determine low WSS was not appropriate to identify regions at high risk for plaque progression

Regional Aortic Wall Shear Stress Increases over Time in Patients with a Bicuspid Aortic Valve

Background: Aortic wall shear stress (WSS) is a known predictor of ascending aortic growth in patients with a bicuspid aortic valve (BAV). The aim of this study was to study regional WSS and changes over time in BAV patients. Methods: BAV patients and age-matched healthy controls underwent four-dimensional (4D) flow cardiovascular magnetic resonance (CMR). Regional, peak systolic ascending aortic WSS, aortic valve function, aortic stiffness measures, and aortic dimensions were assessed. In BAV patients, 4D flow CMR was repeated after 3 years of follow-up and both at baseline and follow-up computed tomography angiography (CTA) were acquired. Aortic growth (volume increase of ≥5%) was measured on CTA. Regional WSS differences within patients’ aorta and WSS changes over time were analyzed using linear mixed-effect models and were associated with clinical parameters. Results: Thirty BAV patients (aged 34 years [interquartile range (IQR) 25–41]) were included in the follow-up analysis. Additionally, another 16 BAV patients and 32 healthy controls (aged 33 years [IQR 28–48]) were included for other regional analyses. Magnitude, axial, and circumferential WSS increased over time (all p &lt; 0.001) irrespective of aortic growth. The percentage of regions exposed to a magnitude WSS &gt;95th percentile of healthy controls increased from 21% (baseline 506/2400 regions) to 31% (follow-up 734/2400 regions) (p &lt; 0.001). WSS angle, a measure of helicity near the aortic wall, decreased during follow-up. Magnitude WSS changes over time were associated with systolic blood pressure, peak aortic valve velocity, aortic valve regurgitation fraction, aortic stiffness indexes, and normalized flow displacement (all p &lt; 0.05). Conclusion: An increase in regional WSS over time was observed in BAV patients, irrespective of aortic growth. The increasing WSSs, comprising a larger area of the aorta, warrant further research to investigate the possible predictive value for aortic dissection.</p

Aortic geometry and long-term outcome in patients with a repaired coarctation

Objective This study aims to compare aortic morphology between repaired coarctation patients and controls, and to identify aortic morphological risk factors for hypertension and cardiovascular events (CVEs) in coarctation patients. Methods Repaired coarctation patients with computed tomography angiography (CTA) or magnetic resonance angiography (MRA) were included, followed-up and compared with sex-matched and age-matched controls. Three-dimensional aortic shape was reconstructed using patients' CTA or MRA, or four-dimensional flow cardiovascular magnetic resonance in controls, and advanced geometrical characteristics were calculated and visualised using statistical shape modelling. In patients, we examined the association of geometrical characteristics with (1) baseline hypertension, using multivariable logistic regression; and (2) cardiovascular events (CVE, composite of aortic complications, coronary artery disease, ventricular arrhythmias, heart failure hospitalisation, stroke, transient ischaemic attacks and cardiovascular death), using multivariable Cox regression. The least absolute shrinkage and selection operator (LASSO) method selected the most informative multivariable model. Results Sixty-five repaired coarctation patients (23 years (IQR 19-38)) were included, of which 44 (68%) patients were hypertensive at baseline. After a median follow-up of 8.7 years (IQR 4.8-15.4), 27 CVEs occurred in 20 patients. Aortic arch dimensions were smaller in patients compared with controls (diameter p&lt;0.001, wall surface area p=0.026, volume p=0.007). Patients had more aortic arch torsion (p&lt;0.001) and a higher curvature (p&lt;0.001). No geometrical characteristics were associated with hypertension. LASSO selected left ventricular mass, male sex, tortuosity and age for the multivariable model. Left ventricular mass (p=0.014) was independently associated with CVE, and aortic tortuosity showed a trend towards significance (p=0.070). Conclusion Repaired coarctation patients have a smaller aortic arch and a more tortuous course of the aorta compared with controls. Besides left ventricular mass index, geometrical features might be of importance in long-term risk assessment in coarctation patients.</p

Aortic geometry and long-term outcome in patients with a repaired coarctation

Objective This study aims to compare aortic morphology between repaired coarctation patients and controls, and to identify aortic morphological risk factors for hypertension and cardiovascular events (CVEs) in coarctation patients. Methods Repaired coarctation patients with computed tomography angiography (CTA) or magnetic resonance angiography (MRA) were included, followed-up and compared with sex-matched and age-matched controls. Three-dimensional aortic shape was reconstructed using patients' CTA or MRA, or four-dimensional flow cardiovascular magnetic resonance in controls, and advanced geometrical characteristics were calculated and visualised using statistical shape modelling. In patients, we examined the association of geometrical characteristics with (1) baseline hypertension, using multivariable logistic regression; and (2) cardiovascular events (CVE, composite of aortic complications, coronary artery disease, ventricular arrhythmias, heart failure hospitalisation, stroke, transient ischaemic attacks and cardiovascular death), using multivariable Cox regression. The least absolute shrinkage and selection operator (LASSO) method selected the most informative multivariable model. Results Sixty-five repaired coarctation patients (23 years (IQR 19-38)) were included, of which 44 (68%) patients were hypertensive at baseline. After a median follow-up of 8.7 years (IQR 4.8-15.4), 27 CVEs occurred in 20 patients. Aortic arch dimensions were smaller in patients compared with controls (diameter p&lt;0.001, wall surface area p=0.026, volume p=0.007). Patients had more aortic arch torsion (p&lt;0.001) and a higher curvature (p&lt;0.001). No geometrical characteristics were associated with hypertension. LASSO selected left ventricular mass, male sex, tortuosity and age for the multivariable model. Left ventricular mass (p=0.014) was independently associated with CVE, and aortic tortuosity showed a trend towards significance (p=0.070). Conclusion Repaired coarctation patients have a smaller aortic arch and a more tortuous course of the aorta compared with controls. Besides left ventricular mass index, geometrical features might be of importance in long-term risk assessment in coarctation patients.</p

Shear stress is uncoupled from atheroprotective KLK10 in atherosclerotic plaques.

Background and aims Physiological shear stress promotes vascular homeostasis by inducing protective molecules in endothelial cells (EC). However, physiological shear stress has been linked to atherosclerosis progression in some individuals with heightened cardiovascular risk. To address this apparent paradox, we hypothesized that diseased arteries may exhibit reduced responsiveness to the protective effects of physiological shear stress. Consequently, we compared the transcriptome of EC exposed to physiological shear stress in healthy arteries versus atherosclerotic conditions. Methods Employing 3D light sheet imaging and computational fluid dynamics, we identified NOS3 as a marker of physiological shear stress in both healthy and atherosclerotic murine arteries. Single-cell RNA sequencing was performed on EC from healthy (C57BL/6) mice, mildly diseased (Apoe−/− normal diet) mice, and highly diseased (Apoe−/− high fat diet) mice. The transcriptomes of Nos3high cells (exposed to physiological shear stress) were compared among the groups. Results Nos3high EC were associated with several markers of physiological shear stress in healthy arteries. Clustering of Nos3high EC revealed 8 different EC subsets that varied in proportion between healthy and diseased arteries. Cluster-specific nested functional enrichment of gene ontology terms revealed that Nos3high EC in diseased arteries were enriched for inflammatory and apoptotic gene expression. These alterations were accompanied by changes in several mechanoreceptors, including the atheroprotective factor KLK10, which was enriched in Nos3high EC in healthy arteries but markedly reduced in severely diseased arteries. Conclusions Physiological shear stress is uncoupled from atheroprotective KLK10 within atherosclerotic plaques. This sheds light on the complex interplay between shear stress, endothelial function, and the progression of atherosclerosis in individuals at risk of cardiovascular complications

Identifying lipid traces of atherogenic mechanisms in human carotid plaque

Background and aims: Lipids play an important role in atherosclerotic plaque development and are interesting candidate predictive biomarkers. However, the link between circulating lipids, accumulating lipids in the vessel wall, and plaque destabilization processes in humans remains largely unknown. This study aims to provide new insights into the role of lipids in atherosclerosis using lipidomics and mass spectrometry imaging to investigate lipid signatures in advanced human carotid plaque and plasma samples. Methods: We used lipidomics and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) to investigate lipid signatures of advanced human carotid plaque and plasma obtained from patients who underwent carotid endarterectomy (n = 14 out of 17 whose plaque samples were analyzed by DESI-MSI). Multivariate data analysis and unsupervised clustering were applied to identify lipids that were the most discriminative species between different patterns in plaque and plasma. These patterns were interpreted by quantitative comparison with conventional histology. Results: Lipidomics detected more than 300 lipid species in plasma and plaque, with markedly different relative abundances. DESI-MSI visualized the spatial distribution of 611 lipid-related m/z features in plaques, of which 330 m/z features could be assigned based on exact mass, comparison to the lipidomic data, and high mass resolution MSI. Matching spatial lipid patterns to histological areas of interest revealed several molecular species that were colocalized with pertinent disease processes in plaque including specific sphingomyelin and ceramide species with calcification, phospholipids and free fatty acids with inflammation, and triacylglycerols and phosphatidylinositols with fibrin-rich areas.Conclusions: By comparing lipid species in plaque and plasma, we identified those circulating species that were also prominently present in plaque. Quantitative comparison of lipid spectral patterns with histology revealed the presence of specific lipid species in destabilized plaque areas, corroborating previous in vitro and animal studies.</p

Shear stress is uncoupled from atheroprotective KLK10 in atherosclerotic plaques

Physiological shear stress promotes vascular homeostasis by inducing protective molecules in endothelial cells (EC). However, physiological shear stress has been linked to atherosclerosis progression in some individuals with heightened cardiovascular risk. To address this apparent paradox, we hypothesized that diseased arteries may exhibit reduced responsiveness to the protective effects of physiological shear stress. Consequently, we compared the transcriptome of EC exposed to physiological shear stress in healthy arteries versus atherosclerotic conditions. Employing 3D light sheet imaging and computational fluid dynamics, we identified NOS3 as a marker of physiological shear stress in both healthy and atherosclerotic murine arteries. Single-cell RNA sequencing was performed on EC from healthy (C57BL/6) mice, mildly diseased (Apoe normal diet) mice, and highly diseased (Apoe high fat diet) mice. The transcriptomes of Nos3 cells (exposed to physiological shear stress) were compared among the groups. Nos3 EC were associated with several markers of physiological shear stress in healthy arteries. Clustering of Nos3 EC revealed 8 different EC subsets that varied in proportion between healthy and diseased arteries. Cluster-specific nested functional enrichment of gene ontology terms revealed that Nos3 EC in diseased arteries were enriched for inflammatory and apoptotic gene expression. These alterations were accompanied by changes in several mechanoreceptors, including the atheroprotective factor KLK10, which was enriched in Nos3 EC in healthy arteries but markedly reduced in severely diseased arteries. Physiological shear stress is uncoupled from atheroprotective KLK10 within atherosclerotic plaques. This sheds light on the complex interplay between shear stress, endothelial function, and the progression of atherosclerosis in individuals at risk of cardiovascular complications. [Abstract copyright: Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.

Aortic geometry and long-term outcome in patients with a repaired coarctation

Objective This study aims to compare aortic morphology between repaired coarctation patients and controls, and to identify aortic morphological risk factors for hypertension and cardiovascular events (CVEs) in coarctation patients. Methods Repaired coarctation patients with computed tomography angiography (CTA) or magnetic resonance angiography (MRA) were included, followed-up and compared with sex-matched and age-matched controls. Three-dimensional aortic shape was reconstructed using patients' CTA or MRA, or four-dimensional flow cardiovascular magnetic resonance in controls, and advanced geometrical characteristics were calculated and visualised using statistical shape modelling. In patients, we examined the association of geometrical characteristics with (1) baseline hypertension, using multivariable logistic regression; and (2) cardiovascular events (CVE, composite of aortic complications, coronary artery disease, ventricular arrhythmias, heart failure hospitalisation, stroke, transient ischaemic attacks and cardiovascular death), using multivariable Cox regression. The least absolute shrinkage and selection operator (LASSO) method selected the most informative multivariable model. Results Sixty-five repaired coarctation patients (23 years (IQR 19-38)) were included, of which 44 (68%) patients were hypertensive at baseline. After a median follow-up of 8.7 years (IQR 4.8-15.4), 27 CVEs occurred in 20 patients. Aortic arch dimensions were smaller in patients compared with controls (diameter p<0.001, wall surface area p=0.026, volume p=0.007). Patients had more aortic arch torsion (p<0.001) and a higher curvature (p<0.001). No geometrical characteristics were associated with hypertension. LASSO selected left ventricular mass, male sex, tortuosity and age for the multivariable model. Left ventricular mass (p=0.014) was independently associated with CVE, and aortic tortuosity showed a trend towards significance (p=0.070). Conclusion Repaired coarctation patients have a smaller aortic arch and a more tortuous course of the aorta compared with controls. Besides left ventricular mass index, geometrical features might be of importance in long-term risk assessment in coarctation patients

Mechanical wall stress and wall shear stress are associated with atherosclerosis development in non-calcified coronary segments

Background and aims: Atherosclerotic plaque onset and progression are known to be affected by local biomechanical factors. While the role of wall shear stress (WSS) has been studied, the impact of another biomechanical factor, namely mechanical wall stress (MWS), remains poorly understood. In this study, we investigated the association of MWS, independently and combined with WSS, towards atherosclerosis in coronary arteries. Methods: Thirty-four human coronary arteries were analyzed using near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) and optical coherence tomography (OCT) at baseline and after 12 months. Baseline WSS and MWS were calculated using computational models, and wall thickness (ΔWT) and lipid-rich necrotic core size (ΔLRNC) change were measured in non-calcified coronary segments. The arteries were further divided into 1.5 mm/45° sectors and categorized as plaque-free or plaque sectors. For each category, associations between biomechanical factors (WSS &amp; MWS) and changes in coronary wall (ΔWT &amp; ΔLRNC) were studied using linear mixed models. Results: In plaque-free sectors, higher MWS (p &lt; 0.001) was associated with greater vessel wall growth. Plaque sectors demonstrated wall thickness reduction over time, likely due to medical therapy, where higher levels of WSS and WMS, individually and combined, (p &lt; 0.05) were associated with a greater reduction. Sectors with low MWS combined with high WSS demonstrated the highest LRNC increase (p &lt; 0.01). Conclusions:In this study, we investigated the association of the (largely-overlooked) biomechanical factor MWS with coronary atherosclerosis, individually and combined with WSS. Our results demonstrated that both MWS and WSS significantly correlate with atherosclerotic plaque initiation and development.</p

Micro Spectroscopic Photoacoustic (μsPA) imaging of advanced carotid atherosclerosis

Atherosclerosis is a lipid-driven and an inflammatory disease of the artery walls. The composition of atherosclerotic plaque stratifies the risk of a specific plaque to cause a cardiovascular event. In an optical resolution photoacoustic microscopy setup, of 45 μm resolution, we extracted plaque lipid photoacoustic (PA) spectral signatures of human endarterectomy samples in the range of 1150–1240 nm, using matrix assisted laser desorption ionization mass spectrometry imaging as a reference. We found plaque PA signals to correlate best with sphingomyelins and cholesteryl esters. PA signal spectral variations within the plaque area were compared to reference molecular patterns and absorption spectra of lipid laboratory standards. Variability in the lipid spectroscopic features extracted by principal component analysis of all samples revealed three distinct components with peaks at: 1164, 1188, 1196 and 1210 nm. This result will guide the development of PA-based atherosclerosis disease staging capitalizing on lipidomics of atherosclerotic tissue