Arterial enlargement in response to high flow requires early expression of matrix metalloproteinases to degrade extracellular matrix

The effect of aspirin on aneurysm wall enhancement: A study in rabbits and humans

ObjectiveAneurysm wall enhancement (AWE) is a potential biomarker of inflammation within the aneurysm wall that has been correlated with a higher risk of rupture. Aspirin (ASA) may decrease AWE due to its anti-inflammatory properties. We aimed to assess the effect of ASA on AWE in an animal model and a cohort of patients with unruptured intracranial aneurysms (UIAs).MethodsThree rabbits with elastase-induced aneurysms were exposed to ASA for 8 weeks and three rabbits were used as controls. 3 T high-resolution magnetic resonance imaging (HR-MRI) was performed at 7 days and 8 weeks to evaluate changes in AWE through histological and immunohistological analyses. Additionally, we evaluated AWE in patients who underwent imaging with a 3 T HR-MRI protocol. ASA exposure was defined as daily intake of 81 mg for at least six months prior to HR-MRI. AWE was quantified using three-dimensional AWE maps and histograms.ResultsAmong rabbits exposed to ASA, the mean AWE was lower at 8 weeks compared to the controls (2.11 vs 2.15, p = 0.13). Immunostaining of the aneurysm wall in rabbits that received ASA revealed a reduced expression of CD68 + or cyclooxygenase-2 + cells, compared to the controls. A total of 99 patients with 120 UIAs were included in the HR-MRI analysis of UIAs. UIAs exposed to ASA (22/120) had significantly lower median AWE than those that were not exposed (0.60 vs 0.72, p = 0.032).ConclusionASA therapy is associated with an objective reduction in AWE, suggesting a potential role in lowering the risk of aneurysm rupture.

Assessment of vascular tortuosity in 22q11.2 deletion syndrome using optical coherence tomography angiography

PURPOSE

To quantify retinal vascular tortuosity and assess microvascular alterations in 22q11.2 deletion syndrome (22q11.2DS) using optical coherence tomography angiography (OCTA).

METHODS

This observational cross-sectional study analyzed 108 eyes from 27 patients with 22q11.2DS and 27 age- and sex-matched controls. OCTA parameters included vascular density in the superficial and deep capillary plexuses (SCP, DCP), radial peripapillary capillaries (RPC), and foveal avascular zone (FAZ). A skeletonized vascular model was generated from 6 mm × 6 mm OCTA images of the superficial plexus after Otsu binarization using Fiji (ImageJ). The vascular tortuosity index (VTI) was computed as the ratio of total vessel length to Euclidean distance via the AnalyzeSkeleton function. A generalized estimating equation (GEE) model accounted for intra-eye correlation, and a probit regression model identified OCTA predictors of 22q11.2DS.

RESULTS

OCTA revealed significantly lower vascular density in both SCP and DCP in 22q11.2DS patients. DCP density was reduced across all regions, including whole-image (p < 0.001), superior (p < 0.001), inferior (p < 0.001), and foveal regions (p = 0.020). No significant differences were found in FAZ area or RPC density. VTI was significantly higher in 22q11.2DS (p = 0.001). Probit regression identified DCP whole-image density (p = 0.009) and VTI (p = 0.028) as predictors of 22q11.2DS, with a pseudo-R² of 0.23.

CONCLUSIONS

VTI was identified as a predictor of 22q11.2DS, providing an objective measure of retinal vascular tortuosity. OCTA revealed previously unrecognized microvascular alterations, supporting its use as a non-invasive tool for vascular assessment in this population.

Correlation between Circle of Willis configuration and intracranial arterial dolichoectasia, and genetic contributions

OBJECTIVES

Intracranial arterial dolichoectasia (IADE) is characterized by the dilation, elongation, and tortuosity of intracranial arteries. We aimed to investigate the association between variations of the Circle of Willis (COW) and IADE in the general population, as well as estimate the genetic correlation between COW variations and IADE.

METHODS

A total of 981 individuals from a population-based cohort were included. Brain magnetic resonance angiography was performed to assess COW variants and measure the diameters of intracranial arteries. IADE was defined as a total intracranial volume-adjusted diameter ≥ 2 standard deviations. Logistic regression models were used to analyze the association between COW variations and IADE. The heritability and genetic correlation were estimated using genome-wide complex trait analysis (GCTA) based on single nucleotide polymorphism (SNP) array data.

RESULTS

The prevalence of IADE was 6.2 %. Hypoplastic/absent A1 segments were associated with an increase in contralateral ICA diameter (β ± SE, 0.279 ± 0.049; p = 0.001) and a decrease in ipsilateral ICA diameter (β ± SE, -0.300 ± 0.050; p = 0.001). Fetal-type posterior cerebral artery (FTP) was associated with a larger ICA diameter (β ± SE, 0.326 ± 0.048; p = 0.001) and a smaller BA diameter (β ± SE, -0.662 ± 0.043; p = 0.001). FTP revealed a positive genetic correlation with ICA dilation (rG = 0.259 ± 0.175; p = 0.0009) and a negative genetic correlation with BA dilation (rG = -0.192 ± 0.153, p = 0.015).

CONCLUSIONS

There was an association between COW variations and larger intracranial arterial diameters in the general population. Genetic factors may play a role in the development of intracranial arterial dilation and the formation of COW variants.

A Sole Case of the FGF23 Gene Mutation c.202A>G (p.Thr68Ala) Associated with Multiple Severe Vascular Aneurysms and a Hyperphosphatemic Variant of Tumoral Calcinosis-A Case Report

Tumoral calcinosis is an extremely rare genetic disease caused by mutations in three genes, GALNT3, FGF23, and KL, which disrupt phosphorus metabolism. The hallmark of this condition is the formation of tumors in the soft tissues around the joints. Other phenotypic features of tumoral calcinosis are dental involvement and brain and vascular calcifications. The clinical case reported herein presents for the first time to the scientific community the c.202A>G (p.Thr68Ala) mutation of the FGF23 gene, associated with a hyperphosphatemic variant of tumoral calcinosis and multiple severe vascular aneurysms. A female patient underwent multiple surgeries for tumor formations in her soft tissues that first appeared at the age of 12 months. On this occurrence, the patient was found to have hyperphosphatemia, low phosphate clearance, increased tubular reabsorption with normal levels of total and ionized calcium, vitamin D3, and parathyroid hormone, and no effect of treatment with sevelamer hydrochloride and a low-phosphate diet. At the age of 39, the patient underwent imaging studies due to edema and a pulsating formation in the neck area, which revealed multiple vascular aneurysms with thrombosis, for which she received operative and interventional treatment. In this connection, and because of the established phosphorus metabolism disturbance, a genetic disease was suspected. The sequence analysis and deletion/duplication testing of the 358 genes performed on this occasion revealed that the woman was homozygous for a variant of the c.202A>G (p.Thr68Ala) mutation of the FGF23 gene. The established mutation is not present in population databases. The presented clinical case is the first and only one in the world to demonstrate the role of this type of FGF23 gene mutation in the development of a hyperphosphatemic variant of tumoral calcinosis characterized by aggressive formation of multiple vascular aneurysms.

Autophagy Induced by Low Shear Stress Leads to Endothelial Glycocalyx Disruption

INTRODUCTION

Previous studies have confirmed that low shear stress (LSS) induces glycocalyx disruption, leading to endothelial dysfunction. However, the role of autophagy in LSS-induced glycocalyx disruption and relevant mechanism are not clear. In this study, we hypothesized that LSS may promote autophagy, disrupting the endothelium glycocalyx.

METHODS

Human umbilical vein endothelial cells were subjected to physiological shear stress and LSS treatments, followed by the application of autophagy inducers and inhibitors. Additionally, cells were treated with specific matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) inhibitor. The expression of autophagic markers, glycocalyx, MMP-2, and MMP-9 was measured.

RESULTS

LSS impacted the expression of endothelium autophagy markers, increasing the expression of LC3II.LC3I-1 and Beclin-1, and decreasing the levels of p62, accompanied by glycocalyx disturbance. Moreover, LSS upregulated the expression of MMP-2 and MMP-9 and downregulated the levels of syndecan-1 and heparan sulfate (HS). Additionally, expression of MMP-2 and MMP-9 was increased by an autophagy promoter but was decreased by autophagy inhibitor treatment under LSS. Autophagy and MMP-2 and MMP-9 further caused glycocalyx disruption.

CONCLUSION

LSS promotes autophagy, leading to glycocalyx disruption. Autophagy increases the expression of MMP-2 and MMP-9, which are correlated with the glycocalyx destruction induced by LSS.

The Role of Gut and Oral Microbiota in the Formation and Rupture of Intracranial Aneurysms: A Literature Review

In recent years, there has been a growing interest in the role of the microbiome in cardiovascular and cerebrovascular diseases. Emerging research highlights the potential role of the microbiome in intracranial aneurysm (IA) formation and rupture, particularly in relation to inflammation. In this review, we aim to explore the existing literature regarding the influence of the gut and oral microbiome on IA formation and rupture. In the first section, we provide background information, elucidating the connection between inflammation and aneurysm formation and presenting potential mechanisms of gut-brain interaction. Additionally, we explain the methods for microbiome analysis. The second section reviews existing studies that investigate the relationship between the gut and oral microbiome and IAs. We conclude with a prospective overview, highlighting the extent to which the microbiome is already therapeutically utilized in other fields. Furthermore, we address the challenges associated with the context of IAs that still need to be overcome.

Effect of Smoking Cessation on the Risk of Subarachnoid Hemorrhage: A Nested Case-Control Study in Korean Men

BACKGROUND

Smoking is a well-established risk factor for subarachnoid hemorrhage (SAH), and current smokers have an increased risk of SAH. However, there are insufficient data on whether smoking cessation in current smokers reduces the risk of SAH.

METHODS

A nested case-control study was conducted based on the National Health Insurance Service-National Health Screening Cohort, which comprises nationwide health claims data and a national health screening program in Korea (2002-2019). We constructed a cohort of current male smokers without a history of stroke at the baseline health screening (2002-2003). From this cohort, cases were defined as individuals who experienced a nontraumatic SAH during the follow-up period up to 2019. Five controls were matched to each case using incidence density sampling. Smoking status (continuation or cessation) before the occurrence of SAH was evaluated using the repeated national health screening program. We conducted a multivariable conditional logistic regression analysis, adjusting for alcohol consumption, physical activity, body mass index, systolic blood pressure, and fasting blood glucose levels, to evaluate the association between SAH risk and smoking cessation.

RESULTS

At baseline, there were 112 142 current male smokers. After excluding individuals with prior stroke or insufficient data, the cohort consisted of 105 223 eligible participants (mean age, 50.3±8.5 years). Among them, we identified 318 cases of SAH and 1590 matched controls. Those who quit smoking had a significantly lower risk of SAH compared with current smokers (adjusted odds ratio, 0.55 [95% CI, 0.41-0.73]). The risk of SAH decreased with a longer period of smoking cessation. The risk reduction with smoking cessation was consistent even among prior heavy smokers.

CONCLUSIONS

Smoking cessation in current male smokers reduced the risk of SAH, and the risk reduction was greater as the cessation period increased. These findings warrant intensive efforts to encourage smokers, even heavy smokers, to quit.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Brachiocephalic arteriovenous fistula maturity in end stage renal disease: The role of intraoperative brachial artery blood flow rate and peak systolic velocity

Introduction

Arteriovenous fistula (AVF) is the preferred vascular access option due to its lower risk of complications and better long-term outcomes. However, AVF maturation failure is still quite high. Achieving an adequate blood flow rate (BFR) through the AVF is essential for maintaining hemodialysis adequacy. This study aims to investigate brachial artery intraoperative BFR and peak systolic velocity (PSV) increase as a predictor of brachiocephalic AVF maturation.

Methods

A multicenter retrospective cohort study was conducted on patients with end stage renal disease undergoing brachiocephalic AVF creation from July 2019 to February 2022 from five hospitals. Doppler ultrasound examinations of BFR and PSV were collected. BFR and PSV increases were calculated by comparing pre-operative and intraoperative results. Maturity was determined at 6 weeks postoperatively.

Results

This study included 83 patients, with 50 patients (60.24%) achieving maturity at 6 weeks. Brachial artery BFR difference has an excellent diagnostic value to predict brachiocephalic AVF maturation with an area under the curve (AUC) of 97%. BFR increase of 184.58 ml/min predicts brachiocephalic AVF maturity with a sensitivity of 100%, specificity of 84.8%, and accuracy of 93.98%. Meanwhile, brachial artery PSV increase has a low diagnostic value to predict brachiocephalic AVF with an AUC of 71.2%. PSV increase of 8.97 cm/s predicts brachiocephalic AVF maturity with a sensitivity of 82%, specificity of 51.5%, and accuracy of 69.9%.

Conclusion

The increase in intraoperative brachial artery BFR and PSV in brachiocephalic AVF can be used as a useful parameter to predict AVF maturation.

Building a Scaffold for Arteriovenous Fistula Maturation: Unravelling the Role of the Extracellular Matrix

Vascular access is the lifeline for patients receiving haemodialysis as kidney replacement therapy. As a surgically created arteriovenous fistula (AVF) provides a high-flow conduit suitable for cannulation, it remains the vascular access of choice. In order to use an AVF successfully, the luminal diameter and the vessel wall of the venous outflow tract have to increase. This process is referred to as AVF maturation. AVF non-maturation is an important limitation of AVFs that contributes to their poor primary patency rates. To date, there is no clear overview of the overall role of the extracellular matrix (ECM) in AVF maturation. The ECM is essential for vascular functioning, as it provides structural and mechanical strength and communicates with vascular cells to regulate their differentiation and proliferation. Thus, the ECM is involved in multiple processes that regulate AVF maturation, and it is essential to study its anatomy and vascular response to AVF surgery to define therapeutic targets to improve AVF maturation. In this review, we discuss the composition of both the arterial and venous ECM and its incorporation in the three vessel layers: the tunica intima, media, and adventitia. Furthermore, we examine the effect of chronic kidney failure on the vasculature, the timing of ECM remodelling post-AVF surgery, and current ECM interventions to improve AVF maturation. Lastly, the suitability of ECM interventions as a therapeutic target for AVF maturation will be discussed.

Supraclinoid Internal Carotid Artery Dolichoectasia Causing Compression of the Prechiasmatic Optic Nerve

BACKGROUND AND IMPORTANCE

Intracranial arterial dolichoectasia (or dilatative arteriopathy) is characterized by abnormal elongation, tortuosity, or increase in diameter of at least one of the main cerebral vessels. Dolichoectasia can be found incidentally or can present with cranial neuropathies (including vision loss) or stroke. Here, we describe the presentation and open surgical treatment of a patient with dolichoectasia of the intracranial internal carotid artery (ICA) causing monocular vision loss.

CLINICAL PRESENTATION

A 73-year-old man presented with several months of progressive monocular vision loss and was found to have dolichoectasia of the supraclinoid ICA and subsequently underwent microsurgical decompression of the overlying affected optic nerve. The patient's postoperative convalescence was uncomplicated, and he had improvement in his right-sided monocular vision loss after surgery.

CONCLUSION

We present the case of a patient with dolichoectasia of the supraclinoid ICA causing compression of the optic nerve with resultant monocular vision loss. Timely microvascular decompression proves to be an effective technique for vision preservation in the setting of this rare pathologic entity.

Effects of abnormal vertebral arteries and the circle of Willis on vertebrobasilar dolichoectasia: A multi-scale simulation study

BACKGROUND

Vertebrobasilar dolichoectasia is a rare cerebrovascular disease characterized by obvious extension, dilation and tortuosity of vertebrobasilar artery, and its pathophysiological mechanism is not clear. This study focused on local hemodynamic changes in basilar arteries with typical vertebrobasilar dolichoectasia, together with unbalanced vertebral arteries and abnormal structures of the circle of Willis, through multi-scale modeling.

METHODS

Three-dimensional models of 3 types of vertebrobasilar arteries were constructed from magnetic resonance images. The first type has no vertebrobasilar dolichoectasia, the second type has vertebrobasilar dolichoectasia and balanced vertebral arteries, and the third type has vertebrobasilar dolichoectasia and unbalanced vertebral arteries. A lumped parameter model of the circle of Willis was established and coupled to these three-dimensional models.

FINDINGS

The results showed that unbalanced bilateral vertebral arteries, especially single vertebral artery deletion mutation, might associate with higher wall shear stress on anterior wall of basilar artery in patients with vertebrobasilar dolichoectasia. And unbalanced bilateral vertebral arteries would increase the blood pressure in basilar artery. Meanwhile, missing communicating arteries in the circle of Willis, especially bilateral posterior communicating arteries absences, would significantly increase blood pressure in basilar artery. The unilateral absence of posterior communicating arteries would increase differences in blood flow between the left and right posterior cerebral arteries.

INTERPRETATION

This study provided a multi-scale modeling method and some preliminary results for helping understand the role of hemodynamics in occurrence and development of vertebrobasilar dolichoectasia.

Incidence, kinetics, and risk factors for intra- and extracranial cerebral arteriopathies in a newborn sickle cell disease cohort early assessed by transcranial and cervical color Doppler ultrasound

The risk of stroke in children with sickle cell disease (SCD) is detected by abnormal intracranial arterial time-averaged mean of maximum velocities (TAMVs ≥200 cm/s). Recently, extracranial internal carotid artery (eICA) arteriopathy has been reported, and a cross-sectional study showed that eICA-TAMVs ≥160 cm/s are significantly associated with eICA kinkings and stenosis. The cumulative incidence of and predictive risk factors for intracranial arteriopathy are well described in sickle cell anemia (SCA=SS/Sβ0) but are lacking for SC/Sβ+ children, as is the cumulative incidence of eICA arteriopathy. We report a prospective longitudinal cohort study including 493 children with SCD (398 SCA, 95 SC/Sβ+), all assessed by transcranial and cervical color Doppler ultrasound. Cerebral MRI/MRA data were available in 375 children with SCD and neck MRA in 365 children. eICA kinkings were defined as eICA tortuosities on neck MRA, with an internal acute angle between the two adjacent segments <90°. The median follow-up was 10.6 years. The cumulative incidence of kinkings was significantly lower in SC/Sβ+ children than in children with SCA, and no SC/Sβ+ child developed intra- or extracranial stenotic arteriopathy. The 10-year KM estimate of cumulative incidence (95% CI) for eICA-TAMVs ≥160 cm/s revealed its development in the 2nd year of life in children with SCA, reaching a plateau of 17.4% (13.2–21.6%) by about 10 years of age, while the plateau for eICA stenosis was 12.3% (8.3–16.3%). eICA assessment identified 13.5% (9.3–17.7%) patients at risk of stroke who were not detected by transcranial color Doppler ultrasound. We also show, for the first time, that in addition to a congenital origin, eICA kinkings sin patients with SCD can develop progressively with aging as a function of eICA-TAMVs, themselves related to anemia severity. Ongoing hydroxyurea treatment was significantly associated with a lower risk of abnormal intracranial arteriopathy and eICA kinkings. After adjustment with hydroxyurea, baseline low hemoglobin, high reticulocyte, and WBC counts remained independent risk factors for intracranial arteriopathy, while low hemoglobin and SEN β-haplotype number were independent risk factors for extracranial arteriopathy. The association between extracranial arteriopathy and SEN β-haplotype number suggested a genetic link between the ethnic origin and incidence of eICA kinkings. This prospective cohort study shows the importance of systematically assessing the eICA and of recording biological parameters during the 2nd year of life before any intensive therapy to predict the risk of cerebral arteriopathy and treat patients with severe baseline anemia.

Plasma Matrix Metalloproeteinase-9 Is Associated with Seizure and Angioarchitecture Changes in Brain Arteriovenous Malformations

Both angiogenesis and inflammation contribute to activation of matrix metalloproeteinase-9 (MMP-9), which dissolves the extracellular matrix, disrupts the blood-brain barrier, and plays an important role in the pathogenesis of brain arteriovenous malformations (BAVMs). The key common cytokine in both angiogenesis and inflammation is interleukin 6 (IL-6). Previous studies have shown elevated systemic MMP-9 and decreased systemic vascular endothelial growth factor (VEGF) in BAVM patients. However, the clinical utility of plasma cytokines is unclear. The purpose of this study is to explore the relationship between plasma cytokines and the clinical presentations of BAVMs. Prospectively, we recruited naive BAVM patients without hemorrhage as the experimental group and unruptured intracranial aneurysm (UIA) patients as the control group. All patients received digital subtraction angiography, and plasma cytokines were collected from the lesional common carotid artery. Plasma cytokine levels were determined using a commercially available, monoclonal antibody-based enzyme-linked immunosorbent assay. Subgroup analysis based on hemorrhagic presentation and angiograchitecture was done for the BAVM group. Pearson correlations were calculated for the covariates. Means and differences for continuous and categorical variables were compared using Student's t and χ² tests respectively. Plasma MMP-9 levels were significantly higher in the BAVM group (42,945 ± 29,991 pg/mL) than in the UIA group (28,270 ± 17,119 pg/mL) (p < 0.001). Plasma MMP-9 levels in epileptic BAVMs (57,065 ± 35,732; n = 9) were higher than in non-epileptic BAVMs (35,032 ± 28,301; n = 19) (p = 0.049). Lower plasma MMP-9 levels were found in cases of BAVM with angiogenesis and with peudophlebitis. Plasma MMP-9 is a good biomarker reflecting ongoing vascular remodeling in BAVMs. Angiogenesis and pseudophlebitis are two angioarchitectural signs that reflect MMP-9 activities and can potentially serve as imaging biomarkers for epileptic BAVMs.

Degeneration and Regeneration of Smooth Muscle Cells in Two Different Abdominal Aortic Aneurysm Models in Rabbits

BACKGROUND

We aimed to investigate the formation and self-healing process of rabbit abdominal aortic aneurysm (AAA) by focus on the degeneration and regeneration of smooth muscle cells (SMCs) in elastase-induced AAA model and enlarging AAA model in rabbits.

METHODS

Sixty rabbits were equally divided into 2 aneurysm groups (Group A and Group B). Rabbits received a 10-min incubation of elastase in Group A (10 units/µL) and Group B (1 unit/µL). Rabbits underwent aortic stenosis above the incubated segment in Group B. Aortic diameter was measured and rabbits were sacrificed for histopathological and immunohistochemical studies.

RESULTS

The incubated aorta dilated immediately and ran up to maxima by day 21 in Group A. All aneurysms formed by day 21 and enlarged progressively in Group B. SMCs content, elastin content and intima-media thickness decreased significantly by day 0 in Group A. SMCs and elastic fibers were destroyed gradually in Group B, however, SMCs content was significantly lower than Group A by day 70. Intimal thickness increased significantly by day 70 in the Aneurysm groups. MMP2 maintained moderate expression in Group A, which decreased significantly by day 3 in Group B. MMP9 and RAM11 expressions were higher by day 1, but decreased significantly by day 3 in Group B.

CONCLUSIONS

Irreversible degeneration of SMCs is critical to a rapid formation of elastase-induced rabbit AAA model, and SMCs excessive regeneration accounts for the selfhealing process. SMCs degradation and regeneration remain relatively stable in an enlarging AAA model. SMCs should be the key target for studying the mechanism of AAA and intervention therapy.

Computational simulation-derived hemodynamic and biomechanical properties of the pulmonary arterial tree early in the course of ventricular septal defects

Untreated ventricular septal defects (VSDs) can lead to pulmonary arterial hypertension (PAH) characterized by elevated pulmonary artery (PA) pressure and vascular remodeling, known as PAH associated with congenital heart disease (PAH-CHD). Though previous studies have investigated hemodynamic effects on vascular mechanobiology in late-stage PAH, hemodynamics leading to PAH-CHD initiation have not been fully quantified. We hypothesize that abnormal hemodynamics from left-to-right shunting in early stage VSDs affects PA biomechanical properties leading to PAH initiation. To model PA hemodynamics in healthy, small, moderate, and large VSD conditions prior to the onset of vascular remodeling, computational fluid dynamics simulations were performed using a 3D finite element model of a healthy 1-year-old's proximal PAs and a body-surface-area-scaled 0D distal PA tree. VSD conditions were modeled with increased pulmonary blood flow to represent degrees of left-to-right shunting. In the proximal PAs, pressure, flow, strain, and wall shear stress (WSS) increased with increasing VSD size; oscillatory shear index decreased with increasing VSD size in the larger PA vessels. WSS was higher in smaller diameter vessels and increased with VSD size, with the large VSD condition exhibiting WSS >100 dyn/cm[Formula: see text], well above values typically used to study dysfunctional mechanotransduction pathways in PAH. This study is the first to estimate hemodynamic and biomechanical metrics in the entire pediatric PA tree with VSD severity at the stage leading to PAH initiation and has implications for future studies assessing effects of abnormal mechanical stimuli on endothelial cells and vascular wall mechanics that occur during PAH-CHD initiation and progression.

Melittin-loaded Iron Oxide Nanoparticles Prevent Intracranial Arterial Dolichoectasia Development through Inhibition of Macrophage-mediated Inflammation

Rationale: In intracranial arterial dolichoectasia (IADE) development, the feedback loop between inflammatory cytokines and macrophages involves TNF-α and NF-κB signaling pathways and leads to subsequent MMP-9 activation and extracellular matrix (ECM) degeneration. In this proof-of-concept study, melittin-loaded L-arginine-coated iron oxide nanoparticle (MeLioN) was proposed as the protective measure of IADE formation for this macrophage-mediated inflammation and ECM degeneration. Methods: IADE was created in 8-week-old C57BL/6J male mice by inducing hypertension and elastase injection into a basal cistern. Melittin was loaded on the surface of ION as a core-shell structure (hydrodynamic size, 202.4 nm; polydispersity index, 0.158). Treatment of MeLioN (2.5 mg/kg, five doses) started after the IADE induction, and the brain was harvested in the third week. In the healthy control, disease control, and MeLioN-treated group, the morphologic changes of the cerebral arterial wall were measured by diameter, thickness, and ECM composition. The expression level of MMP-9, CD68, MCP-1, TNF-α, and NF-κB was assessed from immunohistochemistry, polymerase chain reaction, and Western blot assay. Results: MeLioN prevented morphologic changes of cerebral arterial wall related to IADE formation by restoring ECM alterations and suppressing MMP-9 expression. MeLioN inhibited MCP-1 expression and reduced CD68-positive macrophage recruitments into cerebral arterial walls. MeLioN blocked TNF-α activation and NF-κB signaling pathway. In the Sylvian cistern, co-localization was found between the CD68-positive macrophage infiltrations and the MeLioN distributions detected on Prussian Blue and T2* gradient-echo MRI, suggesting the role of macrophage harboring MeLioN. Conclusions: The macrophage infiltration into the arterial wall plays a critical role in the MMP-9 secretion. MeLioN, designed for ION-mediated melittin delivery, effectively prevents IADE formation by suppressing macrophage-mediated inflammations and MMP activity. MeLioN can be a promising strategy preventing IADE development in high-risk populations.

New Technologies With Increased Precision Improve Understanding of Endothelial Cell Heterogeneity in Cardiovascular Health and Disease

Endothelial cells (ECs) are vital for blood vessel integrity and have roles in maintaining normal vascular function, healing after injury, and vascular dysfunction. Extensive phenotypic heterogeneity has been observed among ECs of different types of blood vessels in the normal and diseased vascular wall. Although ECs with different phenotypes can share common functions, each has unique features that may dictate a fine-tuned role in vascular health and disease. Recent studies performed with single-cell technology have generated powerful information that has significantly improved our understanding of EC biology. Here, we summarize a variety of EC types, states, and phenotypes recently identified by using new, increasingly precise techniques in transcriptome analysis.

Hemodynamics and remodeling of the portal confluence in patients with malignancies of the pancreatic head: a pilot study towards planned and circumferential vein resections

BACKGROUND

We designed a retrospective computational study to evaluate the effects of hemodynamics on portal confluence remodeling in real models of patients with malignancies of the pancreatic head.

METHODS

Patient-specific models were created according to computed tomography data. Fluid dynamics was simulated by using finite-element methods. Computational results were compared to morphological findings.

RESULTS

Five patients underwent total pancreatectomy, one had duodenopancreatectomy. Vein resection was performed en-bloc with the specimen. Histopathological findings showed that in patients without a vein stenosis and a normal hemodynamics, the three-layered wall of the vein was preserved. In patients with a stenosis > 70% of vein diameter and modified hemodynamics, the three-layered structure of the resected vein was replaced by a dense inflammatory infiltrate in absence of tumor infiltration.

CONCLUSIONS

The portal confluence involved by malignancies of the pancreatic head undergoes a remodeling that is not mainly due to a wall infiltration by the tumor but instead to a persistent pathological hemodynamics that disrupts the balance between eutrophic remodeling and degradative process of the vein wall that can lead to the complete upheaval of the three-layered vein wall. This finding can have useful surgical application in planning resection of the vein involved by tumor growth.

Identification of intima-to-media signals for flow-induced vascular remodeling using correlative gene expression analysis

Changes in blood flow can induce arterial remodeling. Intimal cells sense flow and send signals to the media to initiate remodeling. However, the nature of such intima-media signaling is not fully understood. To identify potential signals, New Zealand white rabbits underwent bilateral carotid ligation to increase flow in the basilar artery or sham surgery (n = 2 ligated, n = 2 sham). Flow was measured by transcranial Doppler ultrasonography, vessel geometry was determined by 3D angiography, and hemodynamics were quantified by computational fluid dynamics. 24 h post-surgery, the basilar artery and terminus were embedded for sectioning. Intima and media were separately microdissected from the sections, and whole transcriptomes were obtained by RNA-seq. Correlation analysis of expression across all possible intima-media gene pairs revealed potential remodeling signals. Carotid ligation increased flow in the basilar artery and terminus and caused differential expression of 194 intimal genes and 529 medial genes. 29,777 intima-media gene pairs exhibited correlated expression. 18 intimal genes had > 200 medial correlates and coded for extracellular products. Gene ontology of the medial correlates showed enrichment of organonitrogen metabolism, leukocyte activation/immune response, and secretion/exocytosis processes. This demonstrates correlative expression analysis of intimal and medial genes can reveal novel signals that may regulate flow-induced arterial remodeling.

Wall shear stress gradient is independently associated with middle cerebral artery aneurysm development: a case-control CFD patient-specific study based on 77 patients

Background

Previously published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results. Our study analysed the involvement of the combination of high wall shear stress (WSS) and a positive WSS gradient (WSSG) in IA formation.

Methods

We designed a case-control study with a selection of 38 patients with an unruptured middle cerebral artery (MCA) aneurysm and 39 non-aneurysmal controls to determine the involvement of WSS, oscillatory shear index (OSI), the WSSG and its absolute value (absWSSG) in aneurysm formation based on patient-specific CFD simulations using velocity profiles obtained from transcranial colour-coded sonography.

Results

Among the analysed parameters, only the WSSG had significantly higher values compared to the controls (11.05 vs − 14.76 [Pa/mm], P = 0.020). The WSS, absWSSG and OSI values were not significantly different between the analysed groups. Logistic regression analysis identified WSS and WSSG as significant co-predictors for MCA aneurysm formation, but only the WSSG turned out to be a significant independent prognosticator (OR: 1.009; 95% CI: 1.001–1.017; P = 0.025). Significantly more patients (23/38) in the case group had haemodynamic regions of high WSS combined with a positive WSSG near the bifurcation apex, while in the control group, high WSS was usually accompanied by a negative WSSG (14/39). From the analysis of the ROC curve for WSSG, the area under the curve (AUC) was 0.654, with the optimal cut-off value −0.37 Pa/mm. The largest AUC was recognised for combined WSS and WSSG (AUC = 0.671). Our data confirmed that aneurysms tend to form near the bifurcation apices in regions of high WSS values accompanied by positive WSSG.

Conclusions

The development of IAs is determined by an independent effect of haemodynamic factors. High WSS impacts MCA aneurysm formation, while a positive WSSG mainly promotes this process.

The Role of Oxidative Stress Markers in Predicting Acute Thrombotic Occlusion of Haemodialysis Vascular Access and Progressive Stenotic Dysfunction Demanding Angioplasty

Haemodialysis vascular access (VA) dysfunction is a major cause of morbidity in haemodialysis (HD) patients. Primary venous outflow occlusion and restenosis after percutaneous transluminal angioplasty (PTA) are two major obstacles for the long-term use of dialysis VA. It remains unclear whether oxidative stress markers can be used as predictors for thrombotic occlusion of VA and progressive stenosis dysfunction demanding PTA. All routine HD patients at one teaching hospital participated in this study including ankle-brachial index (ABI) examinations and serum oxidative stress markers. The serum oxidative stress markers (high-sensitivity C-reactive protein (hs-CRP), matrix metalloproteinase-2 (MMP-2), MMP-9, homocysteine, asymmetrical dimethylarginine (ADMA), nitrate oxidase (NO), tumour necrosis factor-α (TNF-α), monocyte chemotactic protein 1 (MCP-1), interleukin-1β (IL-1β), and transforming growth factor-β (TGF-β)) were measured using immunosorbent assays in 159 HD patients (83 men and 76 women; mean age: 65 ± 12 years). The participants met the following criteria: (1) received regular HD treatment for at least 6 months, without clinical evidence of acute or chronic inflammation, recent myocardial infarction, unstable angina or circulatory congestion; and (2) received an arteriovenous fistula (AVF)/arteriovenous graft (AVG: polytetrafluoroethylene, PTFE) as the current VA for more than 6 months, without interventions within the last 6 months. All the participants were followed up clinically for up to 12 months to estimate the amount of primary thrombotic occlusion and VA dysfunction demanding PTA. During the 12-month observation, 24 patients (15.1%) had primary thrombotic occlusion of VAs. Another 24 patients (15.1%) required PTA because of clinical dysfunction of access. Additionally, during the follow-up period, restenosis occurred in 12 patients (50% of 24 patients). The access types of arteriovenous grafts (AVGs) and a diagnosis of peripheral arterial occlusive disease (PAOD) were two strong predictors for acute thrombotic events of VA (hazard ratio (HR): 16.93 vs. 2.35; p < 0.001 vs. 0.047). Comparing dysfunctional with non-dysfunctional VAs, up to 27.7% of patients with high levels of ADMA (>0.6207 μM, N = 65) received required PTA compared with 4.4% of those with low levels (≤0.6207 μM; N = 90; p < 0.001). In multivariate analysis, the plasma baseline levels of ADMA independently conferred nearly 4.55 times the risk of primary stenotic dysfunction of HD VA (HR: 4.55; 95% confidence interval: 1.20 to 17.26; p = 0.026). In conclusion, our findings suggest the role of ADMA in the development of symptomatic VA dysfunction. Additionally, PAOD severity can be used in clinical practice to predict whether acute thrombotic occlusion of VA will easily occur in HD patients.

Vessel Enlargement in Development and Pathophysiology

From developmental stages until adulthood, the circulatory system remodels in response to changes in blood flow in order to maintain vascular homeostasis. Remodeling processes can be driven by de novo formation of vessels or angiogenesis, and by the restructuration of already existing vessels, such as vessel enlargement and regression. Notably, vessel enlargement can occur as fast as in few hours in response to changes in flow and pressure. The high plasticity and responsiveness of blood vessels rely on endothelial cells. Changes within the bloodstream, such as increasing shear stress in a narrowing vessel or lowering blood flow in redundant vessels, are sensed by endothelial cells and activate downstream signaling cascades, promoting behavioral changes in the involved cells. This way, endothelial cells can reorganize themselves to restore normal circulation levels within the vessel. However, the dysregulation of such processes can entail severe pathological circumstances with disturbances affecting diverse organs, such as human hereditary telangiectasias. There are different pathways through which endothelial cells react to promote vessel enlargement and mechanisms may differ depending on whether remodeling occurs in the adult or in developmental models. Understanding the molecular mechanisms involved in the fast-adapting processes governing vessel enlargement can open the door to a new set of therapeutical approaches to be applied in occlusive vascular diseases. Therefore, we have outlined here the latest advances in the study of vessel enlargement in physiology and pathology, with a special insight in the pathways involved in its regulation.

The relationship between intracranial arterial dolichoectasia and intracranial atherosclerosis

OBJECTIVE

We aimed to investigate the relationship between intracranial arterial dolichoectasia (IADE) and intracranial atherosclerosis (ICAS).

METHODS

Patients with acute ischemic stroke were screened via the Nanjing Stroke Registry Program. Patients were diagnosed with IADE (diameter, height of bifurcation, and laterality of basilar artery) based on magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) results. Intracranial atherosclerosis was defined as a ≥50 % diameter reduction in internal carotid artery, middle cerebral artery, posterior cerebral artery, or anterior cerebral artery on MRA, computed tomography angiography, or digital subtraction angiography. We also evaluated the presence and degree of white matter changes and lacuna infarctions on MRI.

RESULTS

Of the 469 enrolled patients, 61 (13 %) had IADE. Patients with IADE were older (64.1 ± 9.9 vs. 59.6 ± 11.4 years, P = 0.004) and had a higher prevalence of hypertension (78.7 % vs. 61.0 %, P = 0.008) than patients without IADE. Patients with ICAS were older (62.6±10.5 vs 58.1±11.6 years, P < 0.001), had higher prevalence of hypertension (72.9 % vs. 55.0 %, P < 0.001) and a previous history of stroke (21.6 % vs. 9.2 %, P < 0.001), had higher levels of serum low-density lipoprotein cholesterol (2.57±0.82 vs. 2.31±0.86mmol/l P = 0.002), and had high counts of white blood cells (7.90±3.29 vs 7.10±2.44, P = 0.004). No association was detected between IADE and extracranial carotid atherosclerosis [odds ratio (OR)=0.618; 95 % confidence interval (CI), 0.280-1.367; P = 0.235]. After adjusting for age, sex, hypertension, and ischemic heart disease, patients with IADE had a lower ICAS rate than that in those without IADE (OR 0.417, 95 % CI, 0.213-0.816, P = 0.011). Unlike patients with ICAS, patients with IADE were more likely to have infratentorial stroke lesions (OR=2.952, 95 % CI, 1.207-7.223, P = 0.018), multi-lacuna (OR=2.142, 95 % CI, 1.158-3.964, P = 0.015), and white matter changes (OR = 2.782; 95 % CI, 1.522-5.085, P = 0.001).

CONCLUSIONS

IADE was associated with advanced age, hypertension, multi-lacuna, and white matter changes but was not associated with ICAS.

Time-dependent and site-dependent morphological changes in rupture-prone arteries: ovariectomized rat intracranial aneurysm model

OBJECTIVE

The pathogenesis of intracranial aneurysm rupture remains unclear. Because it is difficult to study the time course of human aneurysms and most unruptured aneurysms are stable, animal models are used to investigate the characteristics of intracranial aneurysms. The authors have newly established a rat intracranial aneurysm rupture model that features site-specific ruptured and unruptured aneurysms. In the present study the authors examined the time course of changes in the vascular morphology to clarify the mechanisms leading to rupture.

METHODS

Ten-week-old female Sprague-Dawley rats were subjected to hemodynamic changes, hypertension, and ovariectomy. Morphological changes in rupture-prone intracranial arteries were examined under a scanning electron microscope and the association with vascular degradation molecules was investigated.

RESULTS

At 2-6 weeks after aneurysm induction, morphological changes and rupture were mainly observed at the posterior cerebral artery; at 7-12 weeks they were seen at the anterior Willis circle including the anterior communicating artery. No aneurysms at the anterior cerebral artery-olfactory artery bifurcation ruptured, suggesting that the inception of morphological changes is site dependent. On week 6, the messenger RNA level of matrix metalloproteinase-9, interleukin-1β, and the ratio of matrix metalloproteinase-9 to the tissue inhibitor of metalloproteinase-2 was significantly higher at the posterior cerebral artery, but not at the anterior communicating artery, of rats with aneurysms than in sham-operated rats. These findings suggest that aneurysm rupture is attributable to significant morphological changes and an increase in degradation molecules.

CONCLUSIONS

Time-dependent and site-dependent morphological changes and the level of degradation molecules may be indicative of the vulnerability of aneurysms to rupture.

Preliminary study on the separation of specular reflection and backscattering components using synthetic aperture beamforming

PURPOSE

In the early stages of atherosclerosis, the luminal surface of the arterial wall becomes rough due to injury and detachment of endothelial cells. This roughening can potentially be estimated with ultrasound since the electrical echo signal from the transducer is sensitive to both the angle of incidence to an extended surface as well as the roughness of the surface. Specifically, as the roughness of an interface increases, specular reflection is substituted by scattering. We propose a method that attempts separation of reflection and backscattering components in the received echo signals.

METHOD

Assuming the predominant propagation directions of the reflected and scattered waves can be somewhat controlled by the emitted sound field, separation of those components was attempted using synthetic aperture imaging with a transmit beam, focused at a point more distant than the imaging depth. Specifically, two dedicated beamforming processes were used for generation of reflection-emphasized and backscattering-emphasized images.

RESULT

Experimental verifications on a phantom using an ultrasound system with a limited number of active transmit-receive channels yielded a difference between these two images of 8 dB. The results further showed a similar (slightly improved) lateral spatial resolution size of 0.41 mm for the backscattering-emphasized image compared with conventional B-mode imaging (0.47 mm).

CONCLUSION

A new technique for separation of the reflection and backscattering components using synthetic aperture beamforming with a transmit beam featuring a large focal distance was proposed. The technique demonstrated a partial separation of the reflection and backscattering components, which potentially may be used to estimate surface roughness.

Association between Intracranial Arterial Dolichoectasia and Cerebral Small Vessel Disease and Its Underlying Mechanisms

Intracranial arterial dolichoectasia (IADE), also known as dilatative arteriopathy of the brain vessels, refers to an increase in the length and diameter of at least one intracranial artery, and accounts for approximately 12% of all patients with stroke. However, the association of IADE with stroke is usually unclear. Cerebral small vessel disease (CSVD) is characterized by pathological changes in the small vessels. Clinically, patients with CSVD can be asymptomatic or present with stroke or cognitive decline. In the past 20 years, a series of studies have strongly promoted an understanding of the association between IADE and CSVD from clinical and pathological perspectives. It has been proposed that IADE and CSVD may be attributed to abnormal vascular remodeling driven by an abnormal matrix metalloproteinase/tissue inhibitor of metalloproteinase pathway. Also, IAD-Erelated hemodynamic changes may result in initiation or progression of CSVD. Additionally, genetic factors are implicated in the pathogenesis of IADE and CSVD. Patients with Fabry’s disease and late-onset Pompe’s disease are prone to developing concomitant IADE and CSVD, and patients with collagen IV alpha 1 or 2 gene (COL4A1/COL4A2) and forkhead box C1 (FOXC1) variants present with IADE and CSVD. Race, strain, familial status, and vascular risk factors may be involved in the pathogenesis of IADE and CSVD. As well, experiments in mice have pointed to genetic strain as a predisposing factor for IADE and CSVD. However, there have been few direct genetic studies aimed towards determining the association between IADE and CSVD. In the future, more clinical and basic research studies are needed to elucidate the causal relationship between IADE and CSVD and the related molecular and genetic mechanisms.

Modified high-resolution wavenumber analysis for detection of pulse wave velocity using coefficient of variation of arterial wall acceleration waveforms

PURPOSE

In high-resolution wavenumber analysis for detection of pulse wave velocity (PWV), phase information of analytic signals is used to estimate the wavenumber. However, the phase information could be affected by the adjacent signals in the temporal direction. Therefore, we propose a modified high-resolution wavenumber analysis technique using real acceleration waveforms of the arterial wall.

METHOD

In the modified wavenumber analysis, we propose a new evaluation function that corresponds to the inverse of the squared coefficient of variation. The accuracy of estimation of PWV was investigated by performing simulations, and the feasibility was also examined in an in vivo experiment.

RESULTS

In the simulation experiments, the estimation accuracy using the proposed method was comparable to that using the previous method using phase information. However, when the pulse wave included the reflection components, the PWV estimated using the proposed method was more stable than that estimated using the previous method. Also, in the in vivo experiments, at opening of the aortic valve, the velocity estimated by the proposed method was almost equal to that estimated by the previous method (previous: 2.97 ± 1.2 m/s, proposed: 4.82 ± 1.4 m/s). Meanwhile, when the reflection components were present, the estimated PWV values yielded by the previous and proposed methods were - 1.13 and - 3.50 ± 0.9 m/s, respectively. The PWVs at those two time points estimated by the previous method were quite different, and the PWV estimate was considered to be more affected by the reflected waves.

CONCLUSION

The results of the simulations and in vivo experiments indicated that the modified high-resolution wavenumber analysis method was less affected by the reflected waves and more accurate in estimation of PWVs of both the forward and reflected waves.

Potential Therapeutic Strategies for Intracranial Aneurysms Targeting Aneurysm Pathogenesis

Subarachnoid hemorrhage resulting from intracranial aneurysms (IAs) is associated with high rates of morbidity and mortality. Although trigger mechanisms in the pathogenesis of IAs have not been fully elucidated, accumulating evidence has demonstrated that inflammation acts as a critical contributor to aneurysm pathogenesis. IAs is initiated by disruption and dysfunction of endothelial cells (ECs) caused by abnormal wall shear stress (WSS). Subsequently, vascular inflammation can trigger a series of biochemical reactions resulting in vascular smooth muscle cell (VSMC) apoptosis and migration, accompanied by inflammatory cell infiltration, secretion of various cytokines, and inflammatory factors. These changes result in degradation of vascular wall, leading to the progression and eventual rupture of IAs. Increasing our knowledge of the pathogenesis of these lesions will offer physicians new options for prevention and treatment. In this study, we review aneurysmal pathogenesis to seek for safe, effective, and non-invasive therapeutic strategies.

A 5-Year Follow-up of Intracranial Arterial Dolichoectasia: A Case Report and Review of Literature

A patient with multiple dolichoectasia of the intracranial cerebral artery was followed sequentially with clinical and radiological progression of disease in the past 5 years. The patient was treated in multiple stages in the past 5 years with the endovascular and microsurgical clipping method. The maximum diameter of each major intracranial artery segment was recorded and compared in the follow-up year. The progression in size of the dolichoectatic segment was observed in spite of surgical intervention. In review diagnostic criteria, etiopathogenesis and treatment options have been discussed.

Influence of Relative Residence Time on Side-Wall Aneurysm Inception

BACKGROUND

Relative residence time (RRT) is a marker of disturbed blood flow, marked by low magnitude and high oscillatory wall shear stress (WSS). The relation between solute residence time in proximity to the vascular endothelium and the atherosclerotic process is well appreciated in the literature.

OBJECTIVE

To assess the influence of RRT on side-wall aneurysm inception to better understand the role of atherosclerosis in aneurysm formation.

METHODS

Fourteen side-wall internal carotid artery aneurysms from the Aneurisk repository which met criteria for parent vessel reconstruction were reconstructed with Vascular Modeling Toolkit. Computational fluid dynamics analysis was carried out in Fluent. RRT was calculated in MATLAB (The MathWorks Inc, Natick, Massachusetts). We analyzed the results for correlations, defined as presence or absence of local elevations in RRT in specific regions of vasculature.

RESULTS

RRT was concluded to be negatively correlated with aneurysm inception in this study of side-wall internal carotid artery aneurysms, with 12/14 cases yielding the absence of local RRT elevations within or in close proximity of the removed ostium. Subsequent analysis of WSS showed that 11 of 14 aneurysms were formed in an atheroprotective environment, with only 1 of 14 formed in an atherogenic environment. Two models were found to be of indeterminate environment.

CONCLUSION

Atherogenesis and atherosclerosis have long been thought to be a major inciting factor responsible for the formation of aneurysms in the cerebral vasculature. We propose that inception of side-wall aneurysms occurs in hemodynamic environments that promote an atheroprotective endothelial phenotype and that the atheroprotective phenotype is therefore aneurysmogenic.

Physical exercises decreases thrombus and neointima formation in atherosclerotic mice

The practice of physical exercise is highly indicated to prevent cardiovascular diseases and is directly related to the improvement of endothelial function and the regulation of arterial blood pressure. The objective of this study was to analyze the effect of physical exercise in vascular remodeling after FeCl₃ chemically induced arterial injury on atherosclerotic mice. To analyze the effect of exercises on thrombus formation, LDL receptor-deficient mice were fed for 6 weeks with a high-fat diet and performed or not physical exercises for 2 weeks before the arterial injury. To verify endothelium recovery the animals were exercised or not 2 weeks before the injury, and 3 weeks after it, when the vessels were analyzed. In this work, we observed that physical exercises done only before arterial injury reduced thrombosis time, protected the endothelial layer, promoted the recruitment of CD34 positive progenitor cells, increased the level of eNOS and gelatinases activities and decreased the number of inflammatory cells in the vessel, but do not avoid the growth of neointima. Otherwise exercises done before and continued after injury, increased gelatinase activities, reduced lipid deposition in the aortic arch and prevented neointima formation. Thus, we could conclude that physical exercises are done before and continued after endothelial injury stimulate endothelial recovery by promoting endothelial cell growth, matrix remodeling and decreasing inflammation in the vessel wall.

The Optimality Principle Decreases Hemodynamic Stresses for Aneurysm Initiation at Anterior Cerebral Artery Bifurcations

OBJECTIVE

To investigate hemodynamic stresses on anterior cerebral artery bifurcation apex and possible mechanism of the optimality principle in protecting bifurcation wall from supercharged hemodynamic stresses.

METHODS

Three-dimensional angiographic datasets of 122 patients with anterior communicating artery (Acom) aneurysms, 21 patients with non-Acom aneurysms, and 220 control subjects with no aneurysms were used. Radii of parent (r0) and daughter branches (r1 and r2) were measured, and bifurcations obeying the optimality principle required optimal caliber control of r0n = r1n + r2n, with the junction exponent n approximating 3. Radius ratio = r03/(r13 + r23) and n were compared between aneurysmal and control bifurcations. Blood flow was simulated for analysis of hemodynamic stresses.

RESULTS

Acom bifurcations in subjects without Acom aneurysms displayed optimal caliber radius, with mean radius ratio of 0.99 and n of 3.25, whereas Acom aneurysmal bifurcations had significantly lower radius ratio, 0.62 (P < 0.05), but higher n, 4.23 (P < 0.05). Peak wall shear stress and corresponding total pressure were significantly smaller for bifurcations obeying than disobeying the optimality principle (P < 0.001 and P < 0.05, respectively). Total pressures in the direct impinging center, peak wall shear stress distance, and anterior cerebral artery bifurcation angle all were significantly smaller for bifurcations obeying than disobeying the optimality principle (P < 0.05 and P < 0.001, respectively).

CONCLUSIONS

Normal anterior cerebral artery bifurcations obey the optimality principle whereas bifurcations with Acom aneurysms do not. Disobeying the optimality principle presents significantly enhanced hemodynamic stresses to possibly damage the bifurcation wall for aneurysm initiation.

Long-Term Effects of the Abdominal Aortic Aneurysm Model in Rabbits Prepared by Pancreatic Elastase Combined With Angiotensin II

OBJECTIVE:

This study aimed to observe the effect of pancreatic elastase combined with angiotensin II on a stable rabbit abdominal aortic aneurysm model.

METHODS:

A total of 20 male New Zealand rabbits were randomly divided into groups A and B, with 10 rabbits per group. The rabbits in group A were given an intraperitoneal perfusion of pancreatic elastase, and the rabbits in group B were given continuous pumping of angiotensin II in addition to the operation of group A. Before the operation and at 2, 4, and 16 weeks postoperation, vascular color Doppler ultrasonography was performed, and blood samples were collected to measure the serum matrix metalloproteinase 9 (MMP9) and MMP2 levels. At 16 weeks postoperation, all rabbits in both groups were killed, and hematoxylin and eosin, Elastic-van-Gieson, Masson's, and immunohistochemical staining were performed for the vessel specimens.

RESULTS:

At 2 weeks postoperation, the aneurysm formation rates of the 2 groups were both 100%, and the average expansion rates of the aneurysm diameters were 85% and 93%, respectively; these differences were not significant ( P = .150 and P = .280, respectively). At 4 weeks postoperation, the aneurysm formation rates of the 2 groups were 71.4% and 100%, and the average expansion rates of the aneurysm diameter were 68% and 99%, respectively; the differences between the groups were significant ( P = .031 and P = .022, respectively). At 16 weeks postoperation, the aneurysm formation rates of the 2 groups were 14.3% and 100%, and the average expansion rates of the aneurysm diameter were 12% and 108%, respectively; the differences between the groups were significant ( P = .026 and P = .014, respectively).

CONCLUSION:

Compared to the abdominal aortic aneurysm modeling method in rabbits based on pancreatic elastase alone, the abdominal aortic aneurysm modeling method in rabbits using pancreatic elastase combined with angiotensin II maintained the morphology of the abdominal aortic aneurysm for a longer time, showing an important application value for the long-term observation of changes in abdominal aortic aneurysms.

Rabbit aortic aneurysm model with enlarging diameter capable of better mimicking human aortic aneurysm disease

The self-healing phenomenon can be found in the elastase-induced abdominal aortic aneurysm (AAA) model, and an enlarging AAA model was successfully induced by coarctation. Unfortunately, aortic coarctation in these enlarging models is generally not found in human AAA disease. This study aimed to create an experiment model of enlarging AAA in rabbits to better mimic human aortic aneurysm disease. Eighty-four male New Zealand white rabbits were randomly divided into three equal groups: two aneurysm groups (A and B) and a SHAM group. Aneurysm group rabbits underwent extrinsic aortic stenosis below the right renal artery and received a 10-minute incubation of 60 μl elastase (1 unit/μl). Absorbable suture was used in Group A and nonabsorbable cotton thread was used in Group B. A sham operation was performed in the SHAM group. Aortic diameter was measured after 1, 3, 7, and 15 weeks; thereafter animals were sacrificed for histopathological, immunohistochemical and quantitative studies. Two rabbits died at 29 and 48 days, respectively, after operation in Group B. All aneurysms formed and enlarged progressively by 3 weeks in the Aneurysm groups. However, diameter enlargement in Group A was significantly lower than that in Group B at 7 weeks. Aneurysm groups developed intimal hyperplasia; intima-media thickness (IMT) increased significantly by week 7, and aortic media thickness and intima-media ratio (IMR) increased significantly by week 15. Marked destruction of elastin fibers and smooth muscle cells (SMCs) occurred 1 week later and increased progressively thereafter. Intimal hyperplasia and SMCs content in Group A increased significantly by week 15 compared with Group B. Aneurysm groups exhibited strong expression of matrix metalloproteinases 2 and 9 and RAM11 by week 1, and decreased progressively thereafter. In conclusion, this novel rabbit AAA model enlarges progressively without coarctation and is capable of better mimicking human aortic aneurysm disease.

Early growth response factor-1 DNA enzyme 1 inhibits the formation of abdominal aortic aneurysm in rats

The aim of the present study was to characterize the effects of early growth response factor-1 DNA enzyme (EDRz) in a rat abdominal aortic aneurysm (AAA) model to determine the mechanism by which EDRz inhibits AAA and affects the formation of AAA by regulating the activity of matrix metalloproteinase (MMP)-2 and MMP-9. EDRz was transfected into the abdominal aorta of rats using the jetPRIME transfection reagent following infusion with elastase. Fluorescent microscopy, hematoxylin and eosin staining, ultrastructural analysis, reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemical analysis were performed to characterize the response to EDRz. The EDRz group showed minimal aneurysm formation when compared with the control group, with significantly lower aortic diameter expansion (2.5±0.1 vs. 3.5±0.1 mm; P<0.05). Early growth response factor 1 (Egr-1) mRNA and protein levels were significantly decreased in the EDRz group, as expected. The decrease in Egr-1 was accompanied by decreases in the mRNA and protein levels of MMP-2 and MMP-9 (P<0.05). Transfection of the Egr-1 specific synthetic DNA enzyme EDRz significantly reduced AAA following elastase infusion in rats, at least in part due to the decreased expression of downstream MMP-2 and MMP-9.

Ischemic stroke due to intracranial arterial dolichoectasia coexisting with spontaneous dissection of the basilar artery: A case report

INTRODUCTION

We present a rarely seen case of cerebral infarction due to intracranial dolichoectasia coexisting with spontaneous dissection of the basilar artery. A definition of dolichoectasia, its pathology, and imaging findings, as well as the clinical management and prognosis are briefly reviewed.

CONCLUSION

We discuss in general terms the diagnosis of basilar artery dissection and its probable relationship with the occurrence of dolichoectasia.

S-shaped versus conventional straight skin incision: Impact on primary functional maturation, stenosis and thrombosis of autogenous radiocephalic arteriovenous fistula: Impact of incision on maturation, stenosis & failure of RCAVF. Study design: Prospective observational comparative

Introduction

The objective of this study is to test the null hypothesis that an S-shaped surgical incision versus conventional (straight) skin incision in the creation of autogenous radiocephalic arteriovenous fistulas (RCAVFs) have no impact on the primary end-point of primary functional maturation and secondary end points of stenosis and thrombosis.

Methods

A prospective observational comparative consecutive study with intention-to-treat on individuals undergoing only radiocephalic arteriovenous fistula (RCAVFs) over a period of 12 months was conducted. Variables on patient's demographics, comorbidities, anesthesia type, mean arterial blood pressure, thrill, laterality, cephalic vein and radial artery diameter were collated. The test of probability was assessed through Chi-Square, Kaplan-Meier survival estimator and Log-Rank analysis.

Results

Total of n = 83 individuals with median age of 67 years (IQR, 20–89) and male predominance 83% during this period were subjected to RCAVF formation. Total of n = 45 patients in straight skin incision were compared to n = 38 individuals in S-shaped group. Despite equal prevalence of demographics, comorbidities, anesthesia type, mean arterial blood pressure (MAP), thrill, laterality, cephalic vein and radial artery diameter (p > 0.05) higher incidence of juxta-anastomotic stenosis was noted in the straight skin incision group (p = 0.029) in comparative and survival analysis (Log-Rank, p = 0.036). The maturation of the entire cohort was 69% (S-shaped 76% vs. straight group 62%) (p > 0.05).

Conclusion

The outcome of this study demonstrates that S-shaped surgical skin incision is associated with a lower incidence of stenosis in comparison to straight incision type in RCAVF formation.

•

S-shaped skin incision is an alternative to the conventional skin incision for creation of radiocephalic arteriovenous fistula (RCAVF).

•

This approach permits better exposure for both vessels and minimise the need for extensive mobilisation of cephalic vein.

•

S-shaped skin incision is associated with lower incidence of stenosis within the maturation period.

Intracranial Arterial Dolichoectasia

An increased diameter (ectasis) and/or long and tortuous course (dolichosis) of at least one cerebral artery define intracranial arterial dolichoectasia (IADE). IADE could be detected incidentally or may give rise to an array of neurological complications including ischemic stroke, intracranial hemorrhage, or compression of surrounding neural structures. The basilar artery is preferentially affected and has been studied in more detail, mainly due to the presence of accepted diagnostic criteria proposed by Smoker and colleagues in 1986 (1). Criteria for the diagnoses of dolichoectasia in other cerebral arteries have been suggested. However, they lack validation across studies. The prevalence of IADE is approximately 0.08–6.5% in the general population, while in patients with stroke, the prevalence ranges from 3 to 17%. Variations among case series depend on the characteristics of the studied population, diagnostic tests used, and diagnostic criteria applied. In rare instances, an underlying hereditary condition, connective tissue disorder, or infection predispose to the development of IADE. However, most cases are sporadic and associated with traditional vascular risk factors including advanced age, male gender, and arterial hypertension. The link between this dilative arteriopathy and other vascular abnormalities, such as abdominal aortic aneurysm, coronary artery ectasia, and cerebral small vessel disease, suggests the underlying diffuse vascular process. Further understanding is needed on the physiopathology of IADE and how to prevent its progression and clinical complications.

Hemodynamic modeling of leukocyte and erythrocyte transport and interactions in intracranial aneurysms by a multiphase approach

Hemodynamics has been recognized as an important factor in the development, growth, and rupture of cerebral aneurysms, and investigated by computational fluid dynamics techniques using a single phase approach. However, flow-dependent cell transport and interactions are usually ignored in single phase models, in which blood is usually treated as a single phase Newtonian fluid. For getting better insight into the underlying pathology of intracranial aneurysm, cell transport and interactions should be covered in hemodynamic studies. In the present study, a multiphase hemodynamic model incorporating cell transport and interactions was developed, in which blood was modeled as multiphase fluid having a continuous phase (plasma) and two particulate phases (erythrocytes and leukocytes). The model showed good agreement with experimental data and observations in the literature, and was applied to four patient-specific aneurysms in a pulsatile manner. Leukocyte accumulations were predicted at locations with flow disturbance and low wall shear stress. The concentrations of leukocyte at accumulation sites were found to exceed 200 to 500% of normal physiological level on three unstable aneurysms, including two ruptured aneurysms and a growing aneurysm where accumulation was observed near a daughter sac and a secondary aneurysm. This suggested that aneurysms with complex secondary flow patterns could be prone to leukocyte accumulation on the wall. As this is the first study to characterize cell transport and interactions in aneurysm hemodynamics, our model can serve as a foundation for future intracranial aneurysm models.

Future research directions to improve fistula maturation and reduce access failure

With the increasing prevalence of end-stage renal disease, there is a growing need for hemodialysis. Arteriovenous fistulae (AVF) are the preferred type of vascular access for hemodialysis, but maturation and failure continue to present significant barriers to successful fistula use. AVF maturation integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes in the setting of uremia, systemic inflammation, oxidative stress, and pre-existent vascular pathology. AVF can fail due to both failure to mature adequately to support hemodialysis and development of neointimal hyperplasia that narrows the AVF lumen, typically near the fistula anastomosis. Failure due to neointimal hyperplasia involves vascular cell activation and migration and extracellular matrix remodeling with complex interactions of growth factors, adhesion molecules, inflammatory mediators, and chemokines, all of which result in maladaptive remodeling. Different strategies have been proposed to prevent and treat AVF failure based on current understanding of the modes and pathology of access failure; these approaches range from appropriate patient selection and use of alternative surgical strategies for fistula creation, to the use of novel interventional techniques or drugs to treat failing fistulae. Effective treatments to prevent or treat AVF failure require a multidisciplinary approach involving nephrologists, vascular surgeons, and interventional radiologists, careful patient selection, and the use of tailored systemic or localized interventions to improve patient-specific outcomes. This review provides contemporary information on the underlying mechanisms of AVF maturation and failure and discusses the broad spectrum of options that can be tailored for specific therapy.

Metalloproteinases and Brain Arterial Remodeling Among Individuals With and Those Without HIV Infection

BACKGROUND

 This study tests the hypothesis that increased elastolytic activity is associated differentially with dolichoectasia in individuals with and those without human immunodeficiency virus (HIV) infection.

METHODS

 Large arteries from 84 autopsied brains from HIV-positive individuals and 78 autopsied brains from HIV-negative individuals were stained for metalloproteinase 2 (MMP-2), MMP-3, MMP-9, tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2, CD68, and caspase 3. Average pixel intensity was automatically obtained and categorized as high, moderate, or low. Dolichoectasia was defined as a lumen to wall ratio ≥95th percentile.

RESULTS

 High MMP-9 staining alone (P = .001) or coexistent with low TIMP-2 staining was associated with dolichoectasia only in HIV-negative individuals (P = <.001). In HIV-positive individuals, MMP-9 was associated with dolichoectasia only when coexpressed with caspase 3 (P = .01). Thinning of the media was associated with CD68 staining (P = <.001) in HIV-negative individuals, while caspase 3 was associated with a thinner media only in HIV-positive individuals (P = .01). Media thickness modified the association between lumen to wall ratio and MMP expression.

CONCLUSIONS

 A role for MMP/TIMP balance in dolichoectasia appears more prominent in HIV-negative individuals, while apoptosis, mediated by caspase 3, is the most important determinant of media thinning in HIV-infected individuals. Furthermore, apoptosis and media thickness appear to mediate the effects of MMP in the HIV-infected population.

Collateral Growth in the Peripheral Circulation: A Review

Arterial occlusive diseases are a major cause of morbidity and death in the United States. The enlargement of pre-existing vessels, which bypass the site of arterial occlusion, provide a natural way for the body to compensate for such obstructions. Individuals differ in their capacity to develop collateral vessels. In recent years much attention has been focused upon therapy to promote collateral development, primarily using individual growth factors. Such studies have had mixed results. Persistent controversies exist regarding the initiating stimuli, the processes involved in enlargement, the specific vessels that should be targeted, and the most appropriate terminology. Consequently, it is now recognized that more research is needed to extend our knowledge of the complex process of collateral growth. This basic science review addresses five questions essential in understanding current problems in collateral growth research and the development of therapeutic interventions.

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats

Background

Hyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear.

Methods

Thirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed.

Results

During a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6–8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake.

Conclusions

We first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0634-3) contains supplementary material, which is available to authorized users.