Comparison of very-high-frequency ultrasound assessment of radial arterial wall layers after first and repeated transradial coronary procedures

Background Transradial coronary procedure （TRP） traumatizes the radial artery （RA）, especially resulting in changes to arterial wall morphology. This study explored the significance of the early onset of traumatic effects to wall layers of the RA following the first TRP （FTRP） and repeat TRP （RTRP） using very-high-frequency ultrabiomicroscopy （VHFUBM）. Methods A total of 1431 patients that re- ceived TRP were divided into the FTRP group that comprised 781 patients and the RTRP group that comprised 650 patients depending on the number of procedures. Two-dimensional RA images were acquired by 30-55 MHz ultrasound one day before and one day after the pro- cedure. Results After TRP, the incidence of intimal tears, medial dissections and external elastic lamina fracture were greater in the RTRP （P 〈 0.001）. The RTRP group showed significantly thicker intimal thickness （IT）, media thickness （MT）, adventitia thickness and all complex layer thicknesses as compared with the FTRP group （P 〈 0.001）. Conclusions Multivariate linear regression analysis discovered that repeated TRP and other observations were independent predictors of increased IT in post-operative RA. VHFUBM provides an approach to study structural and histopathological injury in the wall layers of RA which showed increased trauma to the RA following RTRP.

Long-term effects of biodegradable versus durable polymercoated sirolimus-eluting stents on arterial wall morphology as assessed by virtual histology intravascular ultrasound

Objectives To assess long-term coronary arterial response to biodegradable polymer-coated sirolimus-eluting stent(BSES) in vivo by using virtual histology intravascular ultrasound(VH-IVUS).Methods 41 patients were enrolled in this study and VH-IVUS was performed to assess the native artery vascular responses to BSES compared with durable polymer-coated SES(DSES) during long-term follow-up(median =8 months).The presence of necrotic core abutting to the lumen was evaluated at follow-up.Results With similar in-stent late luminal loss(0.15[0.06,0.30]vs 0.19[0.03, 0.30]mm,P=0.772),the overall incidence of necrotic core abutting to the lumen was significantly less in BSES than DSES group(44%vs.63%,P=0.019)(proximal 18%,stented site 14%and distal 12%in BSES group,proximal 19%, stented site 28%and distal 16%in DSES group).Compared with stented segments each other,the DSES -treated segments had a significant higher incidence of necrotic core abutting to the lumen through the stent struts(73%vs.36%, P=0.005).In addition,more multiple necrotic core abutting to the lumen was observed in DSES group(overall:63%vs. 36%,P=0.015).Furthermore,among the total number of stented segments with necrotic core abutting to the lumen, DSES -treated lesions had more multiple necrotic core abutting to the lumen through the stent struts than BSES -treated lesions in evidence(74%vs.33%,P=0.027).Conclusions By VH-IVUS analysis at follow-up,a greater frequency of stable lesion morphometry was shown in lesions treated with BSESs compared with lesions treated with DSESs.The major reason was BSES produced less toxicity to the arterial wall and facilitated neointimal healing as a result of polymer coating on drug-eluting stent(DES) surface biodegraded as time went by.

Viscoelastic Models for Passive Arterial Wall Dynamics

This paper compares two models predicting elastic and viscoelastic properties of large arteries.Models compared include a Kelvin(standard linear)model and an extended 2-term exponential linear viscoelastic model.Models were validated against in-vitro data from the ovine thoracic descending aorta and the carotid artery.Measurements of blood pressure data were used as an input to predict vessel cross-sectional area.Material properties were predicted by estimating a set of model parameters that minimize the difference between computed and measured values of the cross-sectional area.The model comparison was carried out using generalized analysis of variance type statistical tests.For the thoracic descending aorta,results suggest that the extended 2-term exponential model does not improve the ability to predict the observed cross-sectional area data,while for the carotid artery the extended model does statistically provide an improved fit to the data.This is in agreement with the fact that the aorta displays more complex nonlinear viscoelastic dynamics,while the stiffer carotid artery mainly displays simpler linear viscoelastic dynamics.

Effects of fluid recirculation on mass transfer from the arterial surface to flowing blood

The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.

Effect of arteriosclerotic intracranial arterial vessel wall enhancement on downstream collateral flow

Background:The effect of arteriosclerotic intracranial arterial vessel wall enhancement(IAVWE)on downstream collateral flow found in vessel wall imaging(VWI)is not clear.Regardless of the mechanism underlying IAVWE on VWI,damage to the patient’s nervous system caused by IAVWE is likely achieved by affecting downstream cerebral blood flow.The present study aimed to investigate the effect of arteriosclerotic IAVWE on downstream collateral flow.Methods:The present study recruited 63 consecutive patients at the Second Hospital of Hebei Medical University from January 2021 to November 2021 with underlying atherosclerotic diseases and unilateral middle cerebral artery(MCA)M1-segment stenosis who underwent an magnetic resonance scan within 3 days of symptom onset.The patients were divided into 4 groups according to IAVWE and the stenosis ratio(Group 1,n=17;Group 2,n=19;Group 3,n=13;Group 4,n=14),and downstream collateral flow was analyzed using three-dimensional pseudocontinuous arterial spin labeling(3D-pCASL)and RAPID software.The National Institutes of Health Stroke Scale(NIHSS)scores of the patients were also recorded.Two-factor multivariate analysis of variance using Pillai’s trace was used as the main statistical method.Results:No statistically significant difference was found in baseline demographic characteristics among the groups.IAVWE,but not the stenosis ratio,had a statistically significant significance on the late-arriving retrograde flow proportion(LARFP),hypoperfusion intensity ratio(HIR),and NIHSS scores(F=20.941,P<0.001,Pillai’s trace statistic=0.567).The between-subject effects test showed that IAVWE had a significant effect on the three dependent variables:LARFP(R^(2)=0.088,F=10.899,P=0.002),HIR(R^(2)=0.234,F=29.354,P<0.001),and NIHSS(R^(2)=114.339,F=33.338,P<0.001).Conclusions:Arteriosclerotic IAVWE significantly reduced downstream collateral flow and affected relevant neurological deficits.It was an independent factor affecting downstream collateral flow and NIHSS scores,which should be a focus of future studies.Trial Registration:ChiCTR.org.cn,ChiCTR2100053661.

Mechanics of formation and rupture of human aneurysm

The mechanical response of the human arterial wall under the combined loading of inflation, axial extension, and torsion is examined within the framework of the large deformation hyper-elastic theory. The probability of the aneurysm formation is explained with the instability theory of structure, and the probability of its rupture is explained with the strength theory of material. Taking account of the residual stress and the smooth muscle activities, a two layer thick-walled circular cylindrical tube model with fiber-reinforced composite-based incompressible anisotropic hyper-elastic materials is employed to model the mechanical behavior of the arterial wall. The deformation curves and the stress distributions of the arterial wall are given under normal and abnormal conditions. The results of the deformation and the structure instability analysis show that the model can describe the uniform inflation deformation of the arterial wall under normal conditions, as well as formation and growth of an aneurysm under abnormal conditions such as the decreased stiffness of the elastic and collagen fibers. From the analysis of the stresses and the material strength, the rupture of an aneurysm may also be described by this model if the wall stress is larger than its strength.

Educational Status and Risks of Cardiovascular Disease in Awka, Southeast Nigeria

Background and Objectives: All over the world, cardiovascular risks constitute a heavy healthcare burden, affecting people with different levels of education, across economies in both the developed and the developing ones. Differences in educational levels in cardiovascular risks have not been completely defined. This study was set out to evaluate the influence of levels of education on the risks of cardiovascular disease in an urban community in Awka, southeast Nigeria. Methodology: In this cross sectional study of 294 subjects conducted in Awka in 2017, biodata, anthropometric and demographic data were obtained. A questionnaire was used to extract information on smoking, alcohol use, tobacco snuff use, diabetes mellitus status, time spent at work > 10 hours daily and night sleep duration < 4 hours. Blood pressure and body mass index were measured. Data were analyzed and the association between levels of education and the potential cardiovascular risks determined. Results: The prevalence of smoking was 5.4%, tobacco snuff use 5.4%, alcohol 42.2%, thickened arterial wall 27.2%, meat protein 91.8%, diabetes mellitus 9.5%, time spent at work > 10 hours daily 29.3%, obesity 33.3%, hypertension 58.5%, night sleep < 4 hours 5.4%. Levels of education has association with tobacco use (p = 0.009), alcohol use (p = 0.013), thickened arterial wall (p < 0.001), diabetes mellitus (p < 0.001), time spent at work > 10 hours daily (p < 0.001), obesity (p = 0.020), hypertension (p < 0.001), meat consumption (p = 0.047). However, smoking and night sleep < 4 hours have no significant association with levels of education, p = 0.415, and p = 0.132. Conclusion: There was variability in the prevalence of cardiovascular risks at different levels of education. The prevalence of smoking and night sleep duration < 4 hours did not vary with levels of education. The prevalence of tobacco snuff and thickened arterial wall was high in primary education holders and meat consumption in secondary education. Alcohol prevalence increased with increasing levels of education. Diabetes mellitus, time spent oat work > 10 hours daily, hypertension and obesity increased in prevalence with increasing levels of education but declined with tertiary education.

An ultrasound simulation method for carotid arteries with a wall structure of three membranes

Ultrasound simulation for carotid arteries is helpful to the performance assessments of vessel wall detection and signal processing methods by using ultrasound techniques. An ul- trasound simulation method of carotid artery wall with a three-membrane structure is proposed in present study. According to the ultrasound speckle distributions varying with the shapes and densities of scatterer distributions, as well as the statistic results of the clinical images, the parameters of distributions, densities and intensities of scatterers for different kinds of tissues in the carotid artery phantoms are determined. Each region is acoustically characterized using FIELD II software to produce the radio frequency echo signals, from which ultrasound images are derived. The results based on 30 simulations show that the echo distributions of the intimae, mediae, adventitias and blood are consistent with the clinical ones. Moreover, compared with the results from the central frequency of 8 MHz, the mean measurements for thicknesses of the intima, media and adventitia membranes, as well as the lumen diameter from the simulation images based on 12 MHz are the same as the preset ones, and the maximum relative errors are the 4.01%, 1.25%, 0.04% and 0.15%, respectively. The simulation under this condition is more realistic.

THEORETICAL AND COMPUTATIONAL INVESTIGATIONS OF NONLINEAR WAVE PROPAGATIONS IN ARTERIES(Ⅰ)——A THEORETICAL MODEL OF NONLINEAR PULSE WAVE PROPAGATIONS

In this paper, a new theoretical model of nonlinear wave propagations in arteries with surrounding tissues was put forward. The equations of motion for the blood vessels and their peripheral tissues as a system have been derived. These equations were expressed in terms of the stresses of the vessel wall and fluid, and the geometry of the blood vessel. They can be used to solve numerically the problems for the propagations of nonlinear pulse waves in arteries together with the momentum and continuity equations of incompressible-viscous flow, as well as the constitutive equations of fluid and vessel wall. The numerical solutions can involve pressure, velocities and flowrate of the blood flow, as well as displacements, velocities and stresses of the vessel wall. These physical variables of propagations of pulse waves in arteries are all of significance physiologically and clinically.