Arterial Network Research Articles

Link Travel Time Estimation for Arterial Networks Based on Sparse GPS Data and Considering Progressive Correlations

Understanding complicated city traffic patterns has been recognized as a critical goal by twenty-first-century urban planners and traffic management systems, resulting in a significant rise in the quantity and variety of traffic data gathered. For example, in a growing number of large cities, taxi firms have begun collecting metadata for each vehicle trip, such as origin, destination, and travel duration. Taxi data offer information on traffic patterns, allowing the study of urban flow – what will traffic look like between two sites on a particular day and time in the future? This paper proposes a method based on sparse GPS probe data, that focuses on allocating travel time data to the different links traveled between GPS observations. This model incorporates the progressive spatial correlations between the links in a network. The main goal of this work is to show how we can consider progressive spatial correlations and improve our results more realistically with a simple adjustment in the previously known parametric methods. For estimating arterial travel time, the methodology is applied to a case study for the partial network of New York City-based on the data collected from the taxicabs in New York City, providing the locations of origins, destinations, and travel times. The model estimates quarter-hourly averages of urban link travel times using OD trip data. This study proposes a more accurate approach for estimating link travel times, that fully utilizes the partial information received from taxi data in cities.

A new classification system for the anatomical variations of the human circle of Willis: A systematic review.

The circle of Willis (CoW) is an anastomotic arterial network located on the base of the brain. Studies have shown that it demonstrates considerable anatomical variation in humans. This systematic review aimed to identify and catalogue the described anatomical variations of the CoW in humans to create a new, comprehensive variation classification system. An electronic literature search of five databases identified 5899 studies. A two‐phase screening process was performed, and studies underwent quality assessment. A total of 42 studies were included in the review. Data were extracted and circles were reconstructed digitally using graphics software. The classification system contains 82 CoW variations in five continuous groups. Group one contains 24 circles with one or more hypoplastic segments only. Group two contains 11 circles with one or more absent segments only. Group three contains 6 circles with hypoplastic and absent segments only. Group four contains 26 circles with one or more accessory segments. Group five contains 15 circles with other types of anatomical variation. Within each group, circles were subcategorised according to the number or type of segments affected. An original coding system was created to simplify the description of anatomical variations of the CoW. The new classification system provides a comprehensive ontology of the described anatomical variations of the CoW in humans. When used with the coding system, it allows the description and categorisation of recorded and unrecorded variants identified in past and future studies. It is applicable to current clinical practice and the anatomical community, including human anatomy education and research.

Elastic Laminar Reorganization Occurs with Outward Diameter Expansion during Collateral Artery Growth and Requires Lysyl Oxidase for Stabilization.

When a large artery becomes occluded, hemodynamic changes stimulate remodeling of arterial networks to form collateral arteries in a process termed arteriogenesis. However, the structural changes necessary for collateral remodeling have not been defined. We hypothesize that deconstruction of the extracellular matrix is essential to remodel smaller arteries into effective collaterals. Using multiphoton microscopy, we analyzed collagen and elastin structure in maturing collateral arteries isolated from ischemic rat hindlimbs. Collateral arteries harvested at different timepoints showed progressive diameter expansion associated with striking rearrangement of internal elastic lamina (IEL) into a loose fibrous mesh, a pattern persisting at 8 weeks. Despite a 2.5-fold increase in luminal diameter, total elastin content remained unchanged in collaterals compared with control arteries. Among the collateral midzones, baseline elastic fiber content was low. Outward remodeling of these vessels with a 10–20 fold diameter increase was associated with fractures of the elastic fibers and evidence of increased wall tension, as demonstrated by the straightening of the adventitial collagen. Inhibition of lysyl oxidase (LOX) function with β-aminopropionitrile resulted in severe fragmentation or complete loss of continuity of the IEL in developing collaterals. Collateral artery development is associated with permanent redistribution of existing elastic fibers to accommodate diameter growth. We found no evidence of new elastic fiber formation. Stabilization of the arterial wall during outward remodeling is necessary and dependent on LOX activity.

Effect of Aneurysm and Patient Characteristics on Intracranial Aneurysm Wall Thickness.

Background: The circle of Willis is a network of arteries allowing blood supply to the brain. Bulging of these arteries leads to formation of intracranial aneurysm (IA). Subarachnoid hemorrhage (SAH) due to IA rupture is among the leading causes of disability in the western world. The formation and rupture of IAs is a complex pathological process not completely understood. In the present study, we have precisely measured aneurysmal wall thickness and its uniformity on histological sections and investigated for associations between IA wall thickness/uniformity and commonly admitted risk factors for IA rupture.Methods: Fifty-five aneurysm domes were obtained at the Geneva University Hospitals during microsurgery after clipping of the IA neck. Samples were embedded in paraffin, sectioned and stained with hematoxylin-eosin to measure IA wall thickness. The mean, minimum, and maximum wall thickness as well as thickness uniformity was measured for each IA. Clinical data related to IA characteristics (ruptured or unruptured, vascular location, maximum dome diameter, neck size, bottleneck factor, aspect and morphology), and patient characteristics [age, smoking, hypertension, sex, ethnicity, previous SAH, positive family history for IA/SAH, presence of multiple IAs and diagnosis of polycystic kidney disease (PKD)] were collected.Results: We found positive correlations between maximum dome diameter or neck size and IA wall thickness and thickness uniformity. PKD patients had thinner IA walls. No associations were found between smoking, hypertension, sex, IA multiplicity, rupture status or vascular location, and IA wall thickness. No correlation was found between patient age and IA wall thickness. The group of IAs with non-uniform wall thickness contained more ruptured IAs, women and patients harboring multiple IAs. Finally, PHASES and ELAPSS scores were positively correlated with higher IA wall heterogeneity.Conclusion: Among our patient and aneurysm characteristics of interest, maximum dome diameter, neck size and PKD were the three factors having the most significant impact on IA wall thickness and thickness uniformity. Moreover, wall thickness heterogeneity was more observed in ruptured IAs, in women and in patients with multiple IAs. Advanced medical imaging allowing in vivo measurement of IA wall thickness would certainly improve personalized management of the disease and patient care.

Angiosomes of the Ulnar Nerve at the Elbow: A Cadaver Trial Using Contrast-Enhanced Ultrasound.

Three major arteries supplying the ulnar nerve in the cubital tunnel are commonly known. However, their vascular territories (angiosomes) have not been described yet. Contrast-enhanced ultrasound was used to identify the angiosomes of posterior ulnar recurrent artery, inferior ulnar collateral artery and superior ulnar collateral artery in 20 fresh, non-frozen human body donors. The arteries were cannulated, and physiologic blood flow was simulated. Contrast agent was applied in each vessel in a randomized sequence, and the length of the contrast-enhancing ulnar nerve segment was measured by a radiologist blinded to the sequence. The angiosome of the posterior ulnar recurrent artery overlaps both other angiosomes. It fully covers the cubital tunnel in 63.6% of specimens. In addition, collateral flow via nerve and muscle branches of the arterial anastomotic network around the elbow (rete articulare cubiti) partly maintains the intra-neural blood flow in the absence of a vascular pedicle. The posterior ulnar recurrent artery is the dominant nutrient vessel of the ulnar nerve in the cubital tunnel. A potential watershed zone exists proximal to the Osborne ligament. Knowledge of these angiosomes may advance surgery of the ulnar nerve in the cubital tunnel.

The influence of human arterial network's frequency characteristics on a pulse wave delay estimation

The influence of human arterial network's frequency characteristics on a pulse wave delay estimation

Improve urban traffic efficiency with prohibiting left-turn policy

Enhancing traffic flow plays an important role in the traffic management of urban arterial networks. The policy of prohibiting left-turn (PLT) at selected highly demanded intersections has been adopted as an attempt to increase the efficiency at these intersections. In this paper, we study the impact of PLT by mathematical analysis and simulations based on the cellular automaton model. Using the flow-density relation, three system performance indexes are examined: the average trip completion rate, the average traffic flow, and the average velocity of vehicles. Different route guidance strategies, including the shortest path and the quickest path, are investigated. We show that when left turn is prohibited, vehicles are distributed more homogeneously in the road network, and the system performs better and reaches a higher capacity. We also derive a critical length of link, above which the benefit of PLT will decrease.

Endovascular treatment of tandemic occlusions in acute ischemic stroke

The observation of endovascular treatment of acute tandem occlusion of internal carotid artery (ICA), anterior cerebral artery (ACA) and middle cerebral artery (MCA) in combination with the thrombosis of the right ICA and the critical stenosis of the left vertebral artery is presented.Man, 61 years old. He was delivered to the Center of endovascular neuroradiology, NAMS of Ukraine on January 15, 2021 with an ischemic stroke clinic in the left internal carotid artery basin. He fell ill acutely ‒ against the background of complete well-being, sensorimotor aphasia and right-sided hemiplegia appeared. Upon admission on the NIHSS (National Institutes of Health Stroke Scale) ‒ 18 points. On the performed initial multispiral computed tomography of the brain according to ASPECTS (Alberta Stroke Program Early CT score) ‒ 8 points. In the endovascular operating room, cerebral angiography was performed, followed by surgery aimed at restoring cerebral blood flow. The time from the onset of the disease to the puncture was 330 minutes, the duration of the operation was 135 minutes, thus the time from the onset of the disease to reperfusion was 465 minutes. Angiography revealed acute thrombosis of the left ICA starting from the orifice, M1-segment of the left MCA and A2-segment of the left ACA. Partial compensation of the basin through the supra-block anastomosis (external carotid artery ‒ ICA), as well as from the vertebro-basilar system through the network of leptomeningeal arteries. Collaterals ‒ ACG 3. Thrombosis of the right ICA and critical stenosis (95 %) of the V1-segment of the left vertebral artery were also revealed. The operation was performed ‒ recanalization of thrombosis of the left ICA orifice followed by balloon angioplasty, thrombectomy from the MCA and ACA pools. The end result is eTICI 2c reperfusion. There were no complications during this operation. The patient was discharged the next day (transferred to the neurological department at the place of residence). Control multispiral computed tomography of the brain showed positive dynamics (ASPECTS ‒ 1 point).

The effect of certain pharmacological agents on the amount of circulating blood in animals

In recent years, in connection with the work of Barcroft'a, Wollheim'a and others, among clinicians, there has been an increased interest in the dynamics of blood circulation and the method of determining it. If earlier the center of gravity of the circulatory mechanism was reduced almost exclusively to the state of the central organ of the system - the heart, nowadays the clinic attaches no less importance to the active role in blood circulation to the state of the arterial and venous network and the amount of blood circulating in the vessels.

Comparison of algorithms for estimating blood flow velocities in cerebral arteries based on the transport information of contrast agent: An in silico study

While many algorithms have been proposed to estimate blood flow velocities based on the transport information of contrast agent acquired by digital subtraction angiography (DSA), most relevant studies focused on a single vessel, leaving a question open as to whether the algorithms would be suitable for estimating blood flow velocities in arterial systems with complex topological structures. In this study, a one-dimensional (1-D) modeling method was developed to simulate the transport of contrast agent in cerebral arterial networks with various anatomical variations or having occlusive disease, thereby generating an in silico database for examining the accuracies of some typical algorithms (i.e., time-of-center of gravity (TCG), shifted least-squares (SLS), and cross correlation (CC) algorithms) that estimate blood flow velocity based on the concentration-time curves (CTCs) of contrast agent. The results showed that the TCG algorithm had the best performance in estimating blood flow velocities in most cerebral arteries, with the accuracy being only mildly affected by anatomical variations of the cerebral arterial network. Nevertheless, the presence of a stenosis of moderate to high severity in the internal carotid artery could considerably impair the accuracy of the TCG algorithm in estimating blood flow velocities in some cerebral arteries where the transport of contrast agent was disturbed by strong collateral flows. In summary, the study suggests that the TCG algorithm may offer a promising means for estimating blood flow velocities based on CTCs of contrast agent monitored in cerebral arteries, provided that the shapes of CTCs are not highly distorted by collateral flows.

Structural Remodeling of the Extracellular Matrix in Arteriogenesis: A Review.

Lower extremity arterial occlusive disease (AOD) results in significant morbidity and mortality for the population, with up to 10% of patients ultimately requiring amputation. An alternative method for non-surgical revascularization which is yet to be fully understood is the optimization of the body's own natural collateral arterial network in a process known as arteriogenesis. Under conditions of conductance vessel stenosis or occlusion resulting in increased flow, shear forces, and pressure gradients within collaterals, positive remodeling occurs to increase the diameter and capacity of these vessels. The creation of a distal arteriovenous fistula (AVF) will drive increased arteriogenesis as compared to collateral formation with the occlusion of a conductance vessel alone by further increasing flow through these arterioles, demonstrating the capacity for arteriogenesis to form larger, more efficient collaterals beyond what is spontaneously achieved after arterial occlusion. Arteries rely on an extracellular matrix (ECM) composed of elastic fibers and collagens that provide stability under hemodynamic stress, and ECM remodeling is necessary to allow for increased diameter and flow conductance in mature arterial structures. When positive remodeling occurs, digestion of lamella and the internal elastic lamina (IEL) by matrix metalloproteinases (MMPs) and other elastases results in the rearrangement and thinning of elastic structures and may be replaced with disordered elastin synthesis without recovery of elastic function. This results in transmission of wall strain to collagen and potential for aneurysmal degeneration along collateral networks, as is seen in the pancreaticoduodenal artery (PDA) after celiac occlusion and inferior mesenteric artery (IMA) with concurrent celiac and superior mesenteric artery (SMA) occlusions. Further understanding into the development of collaterals is required to both better understand aneurysmal degeneration and optimize collateral formation in AOD.

Cerebral Vasculature Influences Blast-Induced Biomechanical Responses of Human Brain Tissue.

Multiple finite-element (FE) models to predict the biomechanical responses in the human brain resulting from the interaction with blast waves have established the importance of including the brain-surface convolutions, the major cerebral veins, and using non-linear brain-tissue properties to improve model accuracy. We hypothesize that inclusion of a more detailed network of cerebral veins and arteries can further enhance the model-predicted biomechanical responses and help identify correlates of blast-induced brain injury. To more comprehensively capture the biomechanical responses of human brain tissues to blast-wave exposure, we coupled a three-dimensional (3-D) detailed-vasculature human-head FE model, previously validated for blunt impact, with a 3-D shock-tube FE model. Using the coupled model, we computed the biomechanical responses of a human head facing an incoming blast wave for blast overpressures (BOPs) equivalent to 68, 83, and 104 kPa. We validated our FE model, which includes the detailed network of cerebral veins and arteries, the gyri and the sulci, and hyper-viscoelastic brain-tissue properties, by comparing the model-predicted intracranial pressure (ICP) values with previously collected data from shock-tube experiments performed on cadaver heads. In addition, to quantify the influence of including a more comprehensive network of brain vessels, we compared the biomechanical responses of our detailed-vasculature model with those of a reduced-vasculature model and a no-vasculature model for the same blast-loading conditions. For the three BOPs, the predicted ICP values matched well with the experimental results in the frontal lobe, with peak-pressure differences of 4–11% and phase-shift differences of 9–13%. As expected, incorporating the detailed cerebral vasculature did not influence the ICP, however, it redistributed the peak brain-tissue strains by as much as 30% and yielded peak strain differences of up to 7%. When compared to existing reduced-vasculature FE models that only include the major cerebral veins, our high-fidelity model redistributed the brain-tissue strains in most of the brain, highlighting the importance of including a detailed cerebral vessel network in human-head FE models to more comprehensively account for the biomechanical responses induced by blast exposure.

Revisited Arterial Supply of the Anterior Ear.

Since arterial supply of the anterior ear was described in 1992 by Park et al, various anatomical studies and surgical techniques have been published in the literatures. Although anatomic studies about the vascular pattern of the ear have been previously reported, most were incomplete to understand the vascular anatomy of the ear and its surgical outcomes. In this report, the authors defined further detailed vascular pattern of the arterial networks and of the main perforators of the anterior ear. The authors dissected in a total of 11 auricles that had been fixed in 10% formalin solution. Prior to dissection, a red latex solution was injected into the common carotid artery. The anteroauricular and postauricular skin was dissected to expose the arterial network under ×10 microscope magnification. There are 2 arterial networks in the anteroauricular surface of the ear: triangular-scapha fossa and concha network. In this study, triangular-scapha fossa network has 2 vascular patterns by a dominant arterial supply: the superficial temporal artery (STA) type (6/11, 54.5%) and the posterior auricular artery (PAA) type (5/11, 45.4%). The STA type is distributed by a subbranch of the ascending helical artery of the STA, whereas the dominant arterial supply of the PAA type is a perforator of the triangular fossa from the PAA. We describe an important inflow to the triangular-scapha fossa network as blood supply from the middle division of the PAA, which directly emerges from the posterior to the anterior surface over the cartilage border at midhelix. The detailed vascular anatomy of this report allows surgeons to perform surgical procedures safely and to develop various flaps in the field of the ear reconstruction.

Total Effective Vascular Compliance of a Global Mathematical Model for the Cardiovascular System

In this work, we determined the total effective vascular compliance of a global closed-loop model for the cardiovascular system by performing an infusion test of 500 mL of blood in four minutes. Our mathematical model includes a network of arteries and veins where blood flow is described by means of a one-dimensional nonlinear hyperbolic PDE system and zero-dimensional models for other cardiovascular compartments. Some mathematical modifications were introduced to better capture the physiology of the infusion test: (1) a physiological distribution of vascular compliance and total blood volume was implemented, (2) a nonlinear representation of venous resistances and compliances was introduced, and (3) main regulatory mechanisms triggered by the infusion test where incorporated into the model. By means of presented in silico experiment, we show that effective total vascular compliance is the result of the interaction between the assigned constant physical vascular compliance and the capacity of the cardiovascular system to adapt to new situations via regulatory mechanisms.

Successful experience of transcatheter arterial embolization for gonarthrosis in patients with severe pain syndrome and ineffectiveness of conservative therapy

Osteoarthritis is a common disease of the musculoskeletal system, the cause of pain, loss of joint function and, as a consequence, a factor in the disability of the population. The treatment strategy for patients with gonarthrosis is not fully defined, especially in patients with stage 1–2. One of the treatment options for such patients is transcatheter embolization of the hypervascular network of the popliteal arteries. The article presents a series of clinical cases of embolization of the popliteal artery branches. Retrograde percutaneous puncture and catheterization of the target femoral artery were performed under local anesthesia. Then, selective angiography of the popliteal artery was performed to identify the hypervascular vasculature of the knee joint. After revealing the target artery along the interventional guidewire, selective catheterization of the artery of the hypervascular vascular network was performed using a microcatheter. Transcatheter arterial embolization of the hypervascular vascular network in osteoarthritis of various origins and localization can be successfully applied as an alternative treatment if conservative therapy is ineffective and if there are contraindications to surgical treatment. It should be noted that further randomized multicenter studies and meta-analyzes are needed to introduce this treatment method into everyday clinical practice.

Effects of the Rho/Rho-Kinase Pathway on Perfusion Pressure in the Isolated-Perfused Rat Hind Limb Vascular Bed.

Background: Rho/ROCK signaling has been demonstrated to be involved in the vascular reactivity of many arterial networks. However, RhoA expression and the contribution of Rho/ROCK pathway to the control of perfusion pressure have not been investigated in the rat hind limb vascular bed as a skeletal muscle vascular network. Aims: To investigate the contribution of the Rho/ROCK pathway in the control of perfusion pressure in the isolated-perfused rat hind limb vascular bed.Study Design: Animal experimentation.Methods: Two Rho inhibitors (atorvastatin and C3 exoenzyme) and ROCK inhibitors (Y-27632 and fasudil) were tested on the phenylephrine-elevated perfusion pressure in the isolated-perfused rat hind limb vascular bed. Furthermore, we sought the expression of RhoA protein in the femoral, popliteal and saphenous arteries as well as quadriceps and gastrocnemius muscles by Western blotting.Results: The ROCK inhibitors Y-27632 and fasudil (both 10−8 to 10−5 M) induced substantial vasodilatations. The maximum vasodilatations induced by Y-27632 and fasudil (both at 10−5 M) were 84.0 ± 6.9% and 76.9 ± 6.9%, respectively (P = .091). Y-27632 was not more potent than fasudil, as the EC50 values for Y-27632 and fasudil were 0.7 ± 2.1 μM and 2.5 ± 2.4 μM, respectively (P = .177). Atorvastatin (10−7 to 10−4 M) and C3 exoenzyme (3 × 10−8 M) also produced vasodilatation (maximum vasodilatation; 20.3 ± 1.7% and 13.7 ± 3.6%, respectively). The EC50 value for atorvastatin was 94.9 ± 1.2 μM. The western blot analysis showed that the femoral, saphenous, and popliteal arteries, as well as the gastrocnemius and quadriceps muscles, express RhoA protein.Conclusion: The Rho/ROCK pathway contributes significantly to the control of perfusion pressure in the rat hind limb vascular bed.

Non-Target Embolization of the Glans Penis During Prostatic Artery Embolization

Prostatic artery embolization is becoming increasingly popular in the management of benign prostatic hyperplasia, particularly for patients with significant comorbidities that make them poor candidates for either general anaesthesia or surgical intervention. Penile tip necrosis as a complication following prostatic artery embolization is exceedingly rare, with only 4 cases previously reported in the world literature. It occurs as a result of the embolization material passing into and occluding collateral arterial networks such as those supplying the glans penis. This paper identifies 3 further cases of penile tip necrosis, outlines its natural history, and proposes management strategies, so that clinicians can better identify and treat this condition.

Relationship between cerebral aneurysms and variations in cerebral basal arterial network: a morphometric cross-sectional study in Computed Tomography Angiograms from a neurointerventional unit

ObjectiveSegments of cerebral basal arterial network (CBAN) dampen the peak pressure in blood flowing through these arteries, thus minimising the chances of development of cerebral aneurysms. The objective of this...

Estimating the effect of vehicle speeds on bicycle and pedestrian safety on the Georgia arterial roadway network

Cyclists and pedestrians account for a disproportionate amount of the world’s 1.3 million road deaths every year. This is a growing problem in the United Sates where bicyclist and pedestrian fatalities have increased steadily since 2009. A large body of research suggests vehicle speeds are a key contributing factor for crashes. However, few studies of bicycle or pedestrian crash probability incorporate detailed vehicle speed data.This study uses probe vehicle speed data to examine the impact of vehicle speeds on bicycle and pedestrian crashes on the state of Georgia’s network of major arterial roadways. The analysis examines 7000 road segments throughout the state in 2017. A Negative Binomial model relates annual crash and speed data on each segment. Models using speed percentiles (85th, 50th and 15th) are contrasted with models using speed differences (85th–50th and 50th–15th percentile). A small set of covariates are included: segment length, number of lanes, Average Annual Daily Traffic, and urbanicity.Results indicate that larger differences in high-end speed percentiles are positively associated with bicycle and pedestrian crash frequency on Georgia arterials. Furthermore, the coefficients on the high end of the speed distribution, measured by the difference in 85th and 50th percentile speeds, have greater magnitude and statistical significance than the low end of the distribution. This research shows a negative relationship between speed and crashes may be flawed, as it does not account for the distributions of speed.The findings in this study suggest that planners and engineers should identify areas with large speed distributions, especially at the high vehicle speeds, and work to reduce the fastest speeds on these roadways. To do so, differences in speed percentiles measured using probe vehicle speeds can be used to determine where high risk areas are located.

Dach1 Extends Artery Networks and Protects Against Cardiac Injury.

[Figure: see text].