Change In Lumen Area Research Articles

Risk factors for thrombotic events in systemic lupus erythematosus patients with antiphospholipid antibodies: insights from morphometric measurements of carotid arteries.

To identify the correlation between thrombosis and atherosclerosis in systemic lupus erythematosus (SLE) patients with antiphospholipid antibodies (aPLs) (SLE/aPLs) through high-resolution magnetic resonance imaging (HR-MRI) of the carotid artery. A single-center, cross-sectional study was conducted. We collected consecutive patients with SLE/aPLs and healthy controls who underwent carotid HR-MRI examinations. The morphometric characteristics of the common carotid artery (CCA), internal carotid artery (ICA), external carotid artery (ECA), and carotid bulb (Sinus) were measured, and the differences in morphometric parameters between different groups were analyzed. A total of 144 carotid arteries were analyzed. Compared with the control group, the wall area, wall thickness (WT and WTmax), and normalized wall index of CCA, ICA, ECA, and Sinus were increased in patients with SLE/aPLs, and the total vascular area (TVA) of CCA, ICA, and Sinus, and the bifurcation angle (BIFA) of ICA-ECA were also increased. A negative lupus anticoagulant (LAC) (with or without positive anticardiolipin antibody (aCL) or anti-β2glycoprotein antibody (aβ2GPI)) contributed to illustrating lower increased TVA and thickened vessel walls of CCA and ICA in SLE/aPLs patients without thrombotic events. Logistic regression analysis showed that WTmaxSinus and WTmaxGlobal were independent risk factors for thrombotic events in SLE/aPLs patients. The receiver operator characteristic curve showed that the cut-off value of WTmaxSinus was 2.855 mm, and WTmaxGlobal was 3.370 mm. HR-MRI ensures the complete and accurate measurement of carotid morphometric parameters. Compared with the control group, the carotid artery in patients with SLE/aPLs is mainly characterized by diffusely thickened vessel walls, and the patients with thrombotic events showed additional higher vascular area of CCA and ICA, and BIFA of ICA-ECA without significant change in lumen area. The carotid arteries of SLE/aPLs patients with thrombotic events exhibited significant vessel wall thickening in all segments except ECA compared to those without thrombotic events. LAC-negative and non-thrombotic events distinguish relatively early atherosclerosis in the carotid arteries in patients with SLE/aPLs. Patients with SLE/aPLs that possess circumscribed thickened carotid vessel walls (>3.370 mm), particularly thickened at the Sinus (>2.855 mm), may require management strategies for the risk of thrombotic events.

First randomised controlled trial comparing the sirolimus-eluting bioadaptor with the zotarolimus-eluting drug-eluting stent in patients with de novo coronary artery lesions: 12-month clinical and imaging data from the multi-centre, international, BIODAPTOR-RCT

The DynamX™ bioadaptor is the first coronary implant technology with a unique mechanism of unlocking the bioadaptor frame after polymer resorption over 6 months, uncaging the vessel while maintaining a dynamic support to the vessel. It aims to achieve the acute performance of drug-eluting stents (DES) with the advantages of restoration of vessel function. This international, single blinded, randomised controlled (1:1) trial compared a sirolimus-eluting bioadaptor with a contemporary zotarolimus-eluting stent (DES) in 34 hospitals in Europe, Japan and New Zealand. Patients with de novo coronary lesions and absence of acute myocardial infarction were enrolled from January 2021 to Feburary 2022. The implantation of the bioadaptor followed the standards of DES. An imaging subset of 100 patients had angiographic and intravascular ultrasound assessments, and 20 patients additionally optical coherence tomography. Data collection will continue through 5 years, we herein report 12-month data based on an intention-to-treat population. This trial is registered at ClinicalTrials.gov (NCT04192747). 445 patients were randomised between January 2021 and February 2022. Device, lesion and procedural success rates, and acute gain were similar amongst the groups. The primary endpoint, 12-month target lesion failure, was 1.8% [95% CI: 0.5; 4.6] (n=4) versus 2.8% [95% CI: 1.0; 6.0] (n=6), pnon-inferiority < 0.001 for the bioadaptor and the DES, respectively (Δ-1.0% [95% CI:-3.3; 1.4]). One definite or probable device thrombosis occurred in each group. The 12-month imaging endpoints showed superior effectiveness of the bioadaptor such as in-device late lumen loss (0.09mm [SD 0.34] versus 0.25mm [SD 0.39], p=0.04), and restored compliance and cyclic pulsatility (%mid in-device lumen area change of 7.5% versus 2.7%, p<0.001). This is the first randomised controlled trial comparing the novel bioadaptor technology against a contemporary DES. The bioadaptor demonstrated similar acute performance and 12-month clinical outcomes, and superior imaging endpoints including restoration of vessel function. The study was funded by Elixir Medical.

Comparison of Parameters for Assessment of Carotid Stiffness and Their Association with Carotid Atherosclerosis in Rural Australian Adults: A Pilot Study.

Carotid stiffness has been associated with the development and progression of carotid artery disease and is an independent factor for stroke and dementia. There has also been a lack of comparison of different ultrasound-derived carotid stiffness parameters and their association with carotid atherosclerosis. This pilot study aimed to investigate the associations between carotid stiffness parameters (derived via ultrasound echo tracking) and the presence of carotid plaques in Australian rural adults. In cross-sectional analyses, we assessed forty-six subjects (68 ± 9 years; mean ± SD) who underwent carotid ultrasound examinations. Carotid stiffness was assessed by a noninvasive echo-tracking method, measuring and comparing multiple carotid stiffness parameters, including stroke change in diameter (ΔD), stroke change in lumen area (ΔA), β- stiffness index, pulse wave velocity beta (PWV-β), compliance coefficient (CC), distensibility coefficient (DC), Young's elastic modulus (YEM), Peterson elastic modulus (Ep), and strain. Carotid atherosclerosis was assessed bilaterally by the presence of plaques in the common and internal carotid arteries, while carotid stiffness was assessed at the right common carotid artery. β-stiffness index, PWV-β, and Ep were significantly higher (p = 0.006, p = 0.004, p = 0.02, respectively), whilst ΔD, CC, DC, and strain were lower among subjects with carotid plaques (p = 0.036, p = 0.032, p = 0.01, p = 0.02, respectively) comparing to subjects without carotid plaques. YEM and ΔA did not significantly differ among the groups. Carotid plaques were associated with age, history of stroke, coronary artery disease, and previous coronary interventions. These results suggest that unilateral carotid stiffness is associated with the presence of carotid plaques.

Association of Shear Stress with Subsequent Lumen Remodeling in Hemodialysis Arteriovenous Fistulas.

Blood flow-induced wall shear stress is a strong local regulator of vascular remodeling, but its effects on arteriovenous fistula (AVF) remodeling are unclear. In this prospective cohort study, we used computational fluid dynamics simulations and statistical mixed-effects modeling to investigate the associations between wall shear stress and AVF remodeling in 120 participants undergoing AVF creation surgery. Postoperative magnetic resonance imaging data at 1 day, 6 weeks, and 6 months were used to derive current wall shear stress by computational fluid dynamic simulations and to quantify subsequent changes in AVF lumen cross-sectional area at 1-mm intervals along the proximal artery and AVF vein. Combining artery and vein data, prior mean wall shear stress was significantly associated with lumen area expansion. Mean wall shear stress at day 1 was significantly associated with change in lumen area from day 1 to week 6 (11% larger area per interquartile range [IQR] higher mean wall shear stress, 95% confidence interval [95% CI], 5% to 18%; n =101), and mean wall shear stress at 6 weeks was significantly associated with change in lumen area from 6 weeks to month 6 (14% larger area per IQR higher, 95% CI, 3% to 28%; n =52). The association of mean wall shear stress at day 1 with lumen area expansion from day 1 to week 6 differed significantly by diabetes ( P =0.009): 27% (95% CI, 17% to 37%) larger area per IQR higher mean wall shear stress without diabetes and 9% (95% CI, -1% to 19%) with diabetes. Oscillatory shear index at day 1 was significantly associated with change in lumen area from day 1 to week 6 (5% smaller area per IQR higher oscillatory shear index, 95% CI, 3% to 7%), and oscillatory shear index at 6 weeks was significantly associated with change in lumen from 6 weeks to month 6 (7% smaller area per IQR higher oscillatory shear index, 95% CI, 2% to 11%). Wall shear stress spatial gradient was not significantly associated with subsequent remodeling. In a joint model, wall shear stress and oscillatory shear index statistically significantly interacted in their associations with lumen area expansion in a complex nonlinear fashion. Higher wall shear stress and lower oscillatory shear index were associated with greater lumen expansion after AVF creation surgery.

24-Month Clinical Follow-Up and Mechanistic Insights From Intravascular Imaging Following Coronary Implantation of the Novel DynamX Bioadaptor Platform

Background/purposeConventional stents “cage” the coronary arteries, impairing vascular function and physiology. The DynamX Bioadaptor is a cobalt‑chromium platform with uncaging elements, designed to improve arterial pulsatility, vasomotion, compliance, and positive adaptive remodelling which may attenuate late clinical events associated with the caging of arteries through conventional stents. We present the first 24-month outcomes of this device. Methods/materialsThis European multicenter study enrolled 50 patients with 50 de novo lesions treated with the DynamX Bioadaptor. Clinical follow-up is scheduled until 36 months and imaging follow-up was performed at 9–12 months. Results24-month endpoints were target lesion failure (2 cardiac deaths), myocardial infarction (1 non-target vessel myocardial infarction), target vessel revascularisation (n = 0), and definite or probable device thrombosis (n = 0). No endpoint events occurred beyond 9 months. Paired intravascular ultrasound analysis of 18 patients from a single center revealed a 0.22 mm2 increase in device cross-sectional area at 9–12 months. Pulsatility analysis showed an increase of in-device lumen area change by 46 % compared to the caged post-procedural configuration, reducing the compliance mismatch between the treated and not-treated vessel segments (segmental compliance). Likewise, vasomotion in response to nitroglycerin improved from 0.03mm2 post-procedure to 0.17mm2 at follow-up. Conclusions24-month clinical data demonstrate promising safety and efficacy of the DynamX Bioadaptor. Imaging data confirmed its unique capacity to improve arterial pulsatility, vasomotion, compliance and positive adaptive remodelling after “uncaging” which might have led to the promising clinical outcomes that need to be confirmed in larger studies.

Validation of the Reduced Unified Continuum Formulation Against In Vitro 4D-Flow MRI.

We previously introduced and verified the reduced unified continuum formulation for vascular fluid-structure interaction (FSI) against Womersley's deformable wall theory. Our present work seeks to investigate its performance in a patient-specific aortic setting in which assumptions of idealized geometries and velocity profiles are invalid. Specifically, we leveraged 2D magnetic resonance imaging (MRI) and 4D-flow MRI to extract high-resolution anatomical and hemodynamic information from an in vitro flow circuit embedding a compliant 3D-printed aortic phantom. To accurately reflect experimental conditions, we numerically implemented viscoelastic external tissue support, vascular tissue prestressing, and skew boundary conditions enabling in-plane vascular motion at each inlet and outlet. Validation of our formulation is achieved through close quantitative agreement in pressures, lumen area changes, pulse wave velocity, and early systolic velocities, as well as qualitative agreement in late systolic flow structures. Our validated suite of FSI techniques offers a computationally efficient approach for numerical simulation of vascular hemodynamics. This study is among the first to validate a cardiovascular FSI formulation against an in vitro flow circuit involving a compliant vascular phantom of complex patient-specific anatomy.

Predicting Coronary Stenosis Progression Using Plaque Fatigue From IVUS-Based Thin-Slice Models: A Machine Learning Random Forest Approach.

Introduction: Coronary stenosis due to atherosclerosis restricts blood flow. Stenosis progression would lead to increased clinical risk such as heart attack. Although many risk factors were found to contribute to atherosclerosis progression, factors associated with fatigue is underemphasized. Our goal is to investigate the relationship between fatigue and stenosis progression based on in vivo intravascular ultrasound (IVUS) images and finite element models. Methods: Baseline and follow-up in vivo IVUS and angiography data were acquired from seven patients using Institutional Review Board approved protocols with informed consent obtained. Three hundred and five paired slices at baseline and follow-up were matched and used for plaque modeling and analysis. IVUS-based thin-slice models were constructed to obtain the coronary biomechanics and stress/strain amplitudes (stress/strain variations in one cardiac cycle) were used as the measurement of fatigue. The change of lumen area (DLA) from baseline to follow-up were calculated to measure stenosis progression. Nineteen morphological and biomechanical factors were extracted from 305 slices at baseline. Correlation analyses of these factors with DLA were performed. Random forest (RF) method was used to fit morphological and biomechanical factors at baseline to predict stenosis progression during follow-up. Results: Significant correlations were found between stenosis progression and maximum stress amplitude, average stress amplitude and average strain amplitude (p < 0.05). After factors selection implemented by random forest (RF) method, eight morphological and biomechanical factors were selected for classification prediction of stenosis progression. Using eight factors including fatigue, the overall classification accuracy, sensitivity and specificity of stenosis progression prediction with RF method were 83.61%, 86.25% and 80.69%, respectively. Conclusion: Fatigue correlated positively with stenosis progression. Factors associated with fatigue could contribute to better prediction for atherosclerosis progression.

High-intensity statin treatment is associated with reduced plaque structural stress and remodelling of artery geometry and plaque architecture.

AimsPlaque structural stress (PSS) is a major cause of atherosclerotic plaque rupture and major adverse cardiovascular events (MACE). We examined the predictors of changes in peak and mean PSS (ΔPSSpeak, ΔPSSmean) in three studies of patients receiving either standard medical or high-intensity statin (HIS) treatment.Methods and resultsWe examined changes in PSS, plaque size, and composition between 7348 co-registered baseline and follow-up virtual-histology intravascular ultrasound images in patients receiving standard medical treatment (controls, n = 18) or HIS (atorvastatin 80 mg, n = 20, or rosuvastatin 40 mg, n = 22). The relationship between changes in PSSpeak and plaque burden (PB) differed significantly between HIS and control groups (P < 0.001). Notably, PSSpeak increased significantly in control lesions with PB >60% (P = 0.04), but not with HIS treatment. However, ΔPSSpeak correlated poorly with changes in lumen and plaque area or PB, plaque composition, or lipid lowering. In contrast, ΔPSSpeak correlated significantly with changes in lumen curvature, irregularity, and roughness (P < 0.05), all of which were reduced in HIS patients. ΔPSSmean correlated with changes in lumen area, PA, PB, and circumferential calcification, and was unchanged with either treatment.ConclusionOur observational study shows that PSSpeak changes over time were associated with baseline disease severity and treatment. The PSSpeak increase seen in advanced lesions with standard treatment was associated with remodelling artery geometry and plaque architecture, but this was not seen after HIS treatment. Smoothing plaques by reducing plaque/lumen roughness, irregularity, and curvature represents a novel mechanism whereby HIS may reduce PSS and, thus may protect against plaque rupture and MACE.

Volumetric coronary endothelial function assessment: a feasibility study exploiting stack-of-stars 3D cine MRI and image-based respiratory self-gating.

Abnormal coronary endothelial function (CEF), manifesting as depressed vasoreactive responses to endothelial-specific stressors, occurs early in atherosclerosis, independently predicts cardiovascular events, and responds to cardioprotective interventions. CEF is spatially heterogeneous along a coronary artery in patients with atherosclerosis, and thus recently developed and tested non-invasive 2D MRI techniques to measure CEF may not capture the extent of changes in CEF in a given coronary artery. The purpose of this study was to develop and test the first volumetric coronary 3D MRI cine method for assessing CEF along the proximal and mid-coronary arteries with isotropic spatial resolution and in free-breathing. This approach, called 3D-Stars, combines a 6 min continuous, untriggered golden-angle stack-of-stars acquisition with a novel image-based respiratory self-gating method and cardiac and respiratory motion-resolved reconstruction. The proposed respiratory self-gating method agreed well with respiratory bellows and center-of-k-space methods. In healthy subjects, 3D-Stars vessel sharpness was non-significantly different from that by conventional 2D radial in proximal segments, albeit lower in mid-portions. Importantly, 3D-Stars detected normal vasodilatation of the right coronary artery in response to endothelial-dependent isometric handgrip stress in healthy subjects. Coronary artery cross-sectional areas measured using 3D-Stars were similar to those from 2D radial MRI when similar thresholding was used. In conclusion, 3D-Stars offers good image quality and shows feasibility for non-invasively studying vasoreactivity-related lumen area changes along the proximal coronary artery in 3D during free-breathing.

Blood Flow Velocity Pulsatility and Arterial Diameter Pulsatility Measurements of the Intracranial Arteries Using 4D PC-MRI

4D phase contrast magnetic resonance imaging (PC-MRI) allows for the visualization and quantification of the cerebral blood flow. A drawback of software that is used to quantify the cerebral blood flow is that it oftentimes assumes a static arterial luminal area over the cardiac cycle. Quantifying the lumen area pulsatility index (aPI), i.e. the change in lumen area due to an increase in distending pressure over the cardiac cycle, can provide insight in the stiffness of the arteries. Arterial stiffness has received increased attention as a predictor in the development of cerebrovascular disease. In this study, we introduce software that allows for measurement of the aPI as well as the blood flow velocity pulsatility index (vPI) from 4D PC-MRI. The internal carotid arteries of seven volunteers were imaged using 7 T MRI. The aPI and vPI measurements from 4D PC-MRI were validated against measurements from 2D PC-MRI at two levels of the internal carotid arteries (C3 and C7). The aPI and vPI computed from 4D PC-MRI were comparable to those measured from 2D PC-MRI (aPI: mean difference: 0.03 (limits of agreement: −0.14 – 0.23); vPI: 0.03 (−0.17–0.23)). The measured blood flow rate for the C3 and C7 segments was similar, indicating that our proposed software correctly captures the variation in arterial lumen area and blood flow velocity that exists along the distal end of the carotid artery. Our software may potentially aid in identifying changes in arterial stiffness of the intracranial arteries caused by pathological changes to the vessel wall.

Efficacy and Safety of Intravascular Lithotripsy in Calcified Coronary Lesions: A Systematic Review and Meta-Analysis

BackgroundIntravascular lithotripsy (IVL) is a recently introduced therapeutic modality in the management of calcified coronary lesions (CCAD). IVL delivers sonic pressure waves to modulate calcium, hence promote vessel compliance and optimize stent deployment. MethodsWe performed a comprehensive literature search for studies that evaluated the utility of adjunctive IVL. The primary outcomes of our study were the clinical success, defined as the ability of IVL to produce residual diameter stenosis <50% (RDS < 50%) after stenting with no evidence of in-hospital major adverse cardiac events, and the angiographic success, defined as success in facilitating stent delivery with RDS < 50% and without serious angiographic complications. The secondary outcomes included post-IVL and post-stenting changes in lumen area, calcium angle, and the maximum calcium thickness. Proportional analysis was used for binary data and mean difference was used for continuous data. All meta-analyses were conducted using a random-effect model and 95% confidence intervals (CIs) were included. ResultsA total of eight single-arm observational studies, including 980 patients (1011 lesions), were included. 48.8% of the patients presented with acute coronary syndrome. Severe calcifications were present in 97% of lesions. Clinical success was achieved in 95.4% of patients (95%CI:92.9%–97.9%). Angiographic success was achieved in 97% of patients (95%CI:95%–99%). There was an overall increase in postprocedural lumen area as well as significant reduction of calcium angle and maximum calcium thickness. ConclusionsIVL seems to have excellent efficacy and safety in the management of CCAD. However, adequately powered RCTs are needed to evaluate IVL compared to other calcium/plaque modifying techniques.

In-Stent Restenosis Progression in Human Superficial Femoral Arteries: Dynamics of Lumen Remodeling and Impact of Local Hemodynamics

In-stent restenosis (ISR) represents a major drawback of stented superficial femoral arteries (SFAs). Motivated by the high incidence and limited knowledge of ISR onset and development in human SFAs, this study aims to (i) analyze the lumen remodeling trajectory over 1-year follow-up period in human stented SFAs and (ii) investigate the impact of altered hemodynamics on ISR initiation and progression. Ten SFA lesions were reconstructed at four follow-ups from computed tomography to quantify the lumen area change occurring within 1-year post-intervention. Patient-specific computational fluid dynamics simulations were performed at each follow-up to relate wall shear stress (WSS) based descriptors with lumen remodeling. The largest lumen remodeling was found in the first post-operative month, with slight regional-specific differences (larger inward remodeling in the fringe segments, p < 0.05). Focal re-narrowing frequently occurred after 6 months. Slight differences in the lumen area change emerged between long and short stents, and between segments upstream and downstream from stent overlapping portions, at specific time intervals. Abnormal patterns of multidirectional WSS were associated with lumen remodeling within 1-year post-intervention. This longitudinal study gave important insights into the dynamics of ISR and the impact of hemodynamics on ISR progression in human SFAs.

Baseline local hemodynamics as predictor of lumen remodeling at 1-year follow-up in stented superficial femoral arteries

In-stent restenosis (ISR) is the major drawback of superficial femoral artery (SFA) stenting. Abnormal hemodynamics after stent implantation seems to promote the development of ISR. Accordingly, this study aims to investigate the impact of local hemodynamics on lumen remodeling in human stented SFA lesions. Ten SFA models were reconstructed at 1-week and 1-year follow-up from computed tomography images. Patient-specific computational fluid dynamics simulations were performed to relate the local hemodynamics at 1-week, expressed in terms of time-averaged wall shear stress (TAWSS), oscillatory shear index and relative residence time, with the lumen remodeling at 1-year, quantified as the change of lumen area between 1-week and 1-year. The TAWSS was negatively associated with the lumen area change (ρ = − 0.75, p = 0.013). The surface area exposed to low TAWSS was positively correlated with the lumen area change (ρ = 0.69, p = 0.026). No significant correlations were present between the other hemodynamic descriptors and lumen area change. The low TAWSS was the best predictive marker of lumen remodeling (positive predictive value of 44.8%). Moreover, stent length and overlapping were predictor of ISR at follow-up. Despite the limited number of analyzed lesions, the overall findings suggest an association between abnormal patterns of WSS after stenting and lumen remodeling.

Central airway collapse is related to obesity independent of asthma phenotype.

Late-onset non-allergic asthma in obesity is characterized by an abnormally compliant, collapsible lung periphery; it is not known whether this abnormality exists in proximal airways. We sought to compare collapsibility of central airways between lean and obese individuals with and without asthma. A cross-sectional study comparing luminal area and shape (circularity) of the trachea, left mainstem bronchus, right bronchus intermedius and right inferior lobar bronchus at RV and TLC by CT was conducted. In 11 lean controls (BMI: 22.4 (21.5, 23.8) kg/m2 ), 10 lean individuals with asthma (23.6 (22.0, 24.8) kg/m2 ), 10 obese controls (45.5 (40.3, 48.5) kg/m2 ) and 21 obese individuals with asthma (39.2 (35.8, 42.9) kg/m2 ), lumen area and circularity increased significantly with an increase in lung volume from RV to TLC for all four airways (P < 0.05 for all). Changes in area and circularity with lung volume were similar in obese individuals with and without asthma, and both obese groups had severe airway collapse at RV. In multivariate analysis, change in lumen area was related to BMI and change in circularity to waist circumference, but neither was related to asthma diagnosis. Excessive collapse of the central airways is related to obesity, and occurs in both obese controls and obese asthma. Increased airway collapse could contribute to ventilation abnormalities in obese individuals particularly at lower lung volumes, and complicate asthma in obese individuals.

Relationship between non-culprit lesion plaque characteristics changes and in-stent neoatherosclerosis formation: 1-year follow-up optical coherence tomography study.

The relationship between the in-stent neoatherosclerosis (ISNA) formation and the plaque's characteristic changes in the non-culprit lesion is unclear. We aim to investigate the plaque characteristics changes at non-culprit lesions between patients with ISNA and without ISNA formation at 1-year follow-up. We retrospectively enrolled patients who had DES implantation in de novo lesion and underwent immediately after stenting and 1-year follow-up optical coherence tomography (OCT) examination. OCT-defined ISNA was defined as the presence of lipid-laden neointima or calcification within the culprit stent with a longitudinal extension of ≥1 mm. Non-culprit lesions were divided into two groups: ISNA group (with ISNA) and non-ISNA group (without ISNA). Plaque characteristics of non-culprit lesions were evaluated at baseline and 1-year follow-up. In total, 89 patients with 89 non-culprit lesions (ISNA: n = 37; non-ISNA: n = 52) were included in the analyses. The lesions in the ISNA group show a smaller minimum lumen area compared to the non-ISNA group at 1-year follow-up (2.57 ± 1.08 mm2 versus 3.20 ± 1.62 mm2, p = 0.044). The lesions of the ISNA group show a significant decrease in minimum lumen area changes percent (-7.25% versus 6.46%, p = 0.039). And there are more lesions with minimum lumen area (64.9% versus 38.5%, p = 0.014) and minimum lumen diameter (64.9% versus 40.4%, p = 0.023) decrease in the ISNA group. Furthermore, the lesions in ISNA group have more plaques with lipid core length increase (25.0% versus 10.0%, p = 0.040), more plaques with FCT decrease (50.0% versus 74.0%, p = 0.027) and less TCFA change to non-TCFA (33.3% versus 87.5%, p = 0.010). The plaque characteristic changes in non-culprit lesions are closely related to ISNA formation. The ISNA formation may accompany by a tardier plaque stabilization process in non-culprit lesions.

Tissue traction microscopy to quantify muscle contraction within precision-cut lung slices.

In asthma, acute bronchospasm is driven by contractile forces of airway smooth muscle (ASM). These forces can be imaged in the cultured ASM cell or assessed in the muscle strip and the tracheal/bronchial ring, but in each case, the ASM is studied in isolation from the native airway milieu. Here, we introduce a novel platform called tissue traction microscopy (TTM) to measure ASM contractile force within porcine and human precision-cut lung slices (PCLS). Compared with the conventional measurements of lumen area changes in PCLS, TTM measurements of ASM force changes are 1) more sensitive to bronchoconstrictor stimuli, 2) less variable across airways, and 3) provide spatial information. Notably, within every human airway, TTM measurements revealed local regions of high ASM contraction that we call "stress hotspots". As an acute response to cyclic stretch, these hotspots promptly decreased but eventually recovered in magnitude, spatial location, and orientation, consistent with local ASM fluidization and resolidification. By enabling direct and precise measurements of ASM force, TTM should accelerate preclinical studies of airway reactivity.

Feasibility of in-vivo estimation of the brachial artery area-pressure relation from CINE and real-time MRI during upper arm cuff inflations.

We investigate the basic feasibility of estimating the brachial artery area-pressure relationship from MRI data obtained during pressure cuff inflations in-vivo. We acquired cross-sectional real-time MR images and cardiac-gated CINE MR images from the upper arm of a single male subject at rest during supra-systolic pressure cuff inflations and deflations. We estimate from the MR images the lumen area changes of the brachial artery, and, simultaneously, from the cuff pressure the systemic blood pressure of the subject. We reconstruct the area-pressure curve from two real-time and three CINE independent measurements. The area-pressure curve can be reconstructed, and it is plausible and appears largely consistent with the literature using other methods. MR imaging during pressure cuff inflations is an easy to use, non-invasive candidate method to estimate the brachial artery pressure-area curve.

Lumen area change (Delta Lumen) between inspiratory and expiratory multidetector computed tomography as a measure of severe outcomes in asthmatic patients

Quantitative computed tomographic (QCT) biomarkers of airway morphology hold potential for understanding and monitoring regional airway remodeling in asthmatic patients. We sought to determine whether the change in airway lumen area between total lung capacity (TLC) and functional residual capacity (FRC) lung volumes measured from CT imaging data was correlated with severe outcomes in asthmatic patients. We studied 152 asthmatic patients (90 female and 62 male patients) and 33 healthy subjects (12 female and 21 male subjects) using QCT. Postprocessing of airways at generations 1 to 5 (1=trachea) was performed for wall area percentage, wall thickness percentage (WT%), lumen area at baseline total lung capacity (LATLC), lumen area at baseline functional residual capacity (LAFRC), and low attenuation area at FRC. Anew metric (reflecting remodeling, distal air trapping, or both), Delta Lumen, was determined as follows: Percentage difference in lumen area (LATLC-LAFRC)/LATLC×100. Postprocessing of 4501 airway segments was performed (3681 segments in the 152 patients with asthma and 820 segments in the 33 healthy subjects; range, 17-28 segments per subject). Delta Lumen values were negatively correlated with WT% and low attenuation area (P<.01) in asthmatic patients. Delta Lumen values were significantly lower for airway generations 3 to 5 (segmental airways) in subjects undergoing hospitalization because of exacerbation and in patients with refractory asthma requiring treatment with systemic corticosteroids. WT% and low attenuation area were positively and Delta Lumen values were negatively associated with systemic corticosteroid treatment (P<.05), suggesting that a reduced Delta Lumen value is a potential outcome biomarker in patients with severe asthma. Reduced Delta Lumen value in the central airways measured by using QCT is a promising exploratory biomarker of unstable refractory asthma that warrants further study.

Endothelial shear stress 5 years after implantation of a coronary bioresorbable scaffold.

As a sine qua non for arterial wall physiology, local hemodynamic forces such as endothelial shear stress (ESS) may influence long-term vessel changes as bioabsorbable scaffolds dissolve. The aim of this study was to perform serial computational fluid dynamic (CFD) simulations to examine immediate and long-term haemodynamic and vascular changes following bioresorbable scaffold placement. Coronary arterial models with long-term serial assessment (baseline and 5 years) were reconstructed through fusion of intravascular optical coherence tomography and angiography. Pulsatile non-Newtonian CFD simulations were performed to calculate the ESS and relative blood viscosity. Time-averaged, systolic, and diastolic results were compared between follow-ups. Seven patients (seven lesions) were included in this analysis. A marked heterogeneity in ESS and localised regions of high blood viscosity were observed post-implantation. Percent vessel area exposed to low averaged ESS (<1 Pa) significantly decreased over 5 years (15.92% vs. 4.99%, P < 0.0001) whereas moderate (1-7 Pa) and high ESS (>7 Pa) did not significantly change (moderate ESS: 76.93% vs. 80.7%, P = 0.546; high ESS: 7.15% vs. 14.31%, P = 0.281), leading to higher ESS at follow-up. A positive correlation was observed between baseline ESS and change in lumen area at 5 years (P < 0.0001). Maximum blood viscosity significantly decreased over 5 years (4.30 ± 1.54 vs. 3.21± 0.57, P = 0.028). Immediately after scaffold implantation, coronary arteries demonstrate an alternans of extremely low and high ESS values and localized areas of high blood viscosity. These initial local haemodynamic disturbances may trigger fibrin deposition and thrombosis. Also, low ESS can promote neointimal hyperplasia, but may also contribute to appropriate scaffold healing with normalisation of ESS and reduction in peak blood viscosity by 5 years.

PP.13.01] ASSOCIATION BETWEEN NECK CIRCUMFERENCE, AORTIC AND CAROTID STIFFNESS IN HEALTHY ADOLECENTS THE MACISTE STUDY

Objective: Introduction: Obesity has a negative impact on arterial distensibility. Neck circumference (NC) is a marker of upper body adiposity and is linked to unfavourable metabolic profile among young subjects. The association between NC and arterial stiffness is unknown. We evaluated the association between NC and other measures of adiposity, with carotid-femoral pulse wave velocity (cf-PWV) and carotid stiffness (CS) in healthy adolescents. Design and method: Methods: 431 individuals (mean age 16.9 ± 1.4y, SBP/DBP 124/67 ± 11/7 mmHg) attending the Liceo Donatelli High School in Terni, Italy, were evaluated. cf-PWV was measured with applanation tonometry (SphygmoCor device, subtracted distance). CS was measured with Carotid Studio (Quipu): a contour tracking algorithm was applied to B-mode longitudinal scans of common carotid artery to obtain diameter changes, stroke change in lumen area (δA) and lumen area (A). The cross-sectional distensibility coefficient (DC = δA /(A*PP)) was converted (Bramwell-Hill equation) into a carotid stiffness parameter (CS = (DC*ρ)-1/2, ρ=blood density) with same measurement units of PWV. Carotid waveform was calibrated to brachial MAP/DBP. Brachial MAP was derived from brachial tonometry calibrated to brachial SBP/DBP. Results: Average NC was 33 ± 3 cm, average cf-PWV 4.9 ± 0.8 m/s, average CS 4.3 ± 0.6 m/s. NC, as well as other measures of adiposity (BMI, BMI z-score, waist and hip circumferences, waist-hip ratio, waist-height ratio), showed some degrees of association with both cf-PWV and CS (Table). The association between NC and CS was the only association which remained significant after adjustement for age, sex and MAP (partial R = 0.13, p < 0.01), and also after further adjustment for BMI (partial R = 0.10, p = 0.03).Conclusions: In adolescents, NC and other measures of global and local adiposity showed significant associations with cf-PWV and CS. The association between NC and CS was independent from age, sex, MAP and BMI. Both local and systemic factors may be involved in explaining this relationship. NC may help in identifying adolescents with increased CS.