Limited Flow Research Articles

Countercurrent Flow Limitation in a Pipeline with an Orifice

Countercurrent flow limitation (CCFL) refers to an important class of gravity-induced hydrodynamic processes that impose a serious restriction on the operation of gas–liquid two-phase systems. In a nuclear power plant, CCFL may occur in the liquid level measurement system where an orifice is applied in the pipeline, which may introduce error into the level measurement system. CCFL can occur in horizontal, vertical, inclined, and even much more complicated geometric patterns, and the hot-leg channel flow passage has been widely investigated; however, a pipeline with variable cross-sections, including an orifice, has not yet been investigated. An experimental investigation has been conducted in order to identify the phenomenon, pattern, and mechanism of CCFL onset in this type of geometry. Both visual and quantified experiments were carried out. A high-speed camera was applied to capture the flow pattern. Visual experiments were implemented at atmospheric pressure, while quantified pressurizer experiments were implemented at higher pressures. It was determined that if the condensate drainage is low and the liquid level is also low, with a stable stratified flow upstream of the orifice, there is no oscillation of the differential pressure. However, at higher condensate drainage levels, when the liquid level increases, a stratified wavy flow occurs. One of these waves can suddenly rise upstream of the orifice to choke it, which subsequently gives rise to differential pressure across the orifice, with periodic variation. This pattern alternately features stratified flow, stratified wavy flow, and slug flow, which indicates the occurrence of CCFL. The CCFL occurring under these experimental conditions can be expressed as a Wallis type correlation, where the coefficients m and C are 0.682 and 0.601, respectively.

Low-Energy Clay–Cement Slurries Find Application as Waterproofing Membranes for Limiting the Migration of Contaminants—Case Studies in Poland

The purpose of this review was to present clay–cement suspensions that are mainly used in the construction and renovation of hydrotechnical facilities and flood protection. We present the characteristics of clay–cement slurries that are used in waterproofing barriers. One of their significant components are clays of different types and origins. Examples of kaolin-type and smectite-type clays, which are associated minerals, as balanced components of suspensions are presented. As mentioned, before the hydration process, barriers are suspended, and the main test methods are rheometric measurements. Their rheological parameters, extremely important from the point of view of injection mechanics, are shown. The higher the flow limit and faster the reconstruction of thixotropic structures, the higher the energy input of the injection processes. After the hydration process, it is important to form agglomerates and seal the barrier; therefore, we present a summary of the strength results, filtration coefficients and microscopic images of the resulting structures. Additional properties of such barriers in terms of limiting contaminant migration are indicated. One of the aspects affecting the use of liquid slurries is their application methods; thus, a summary of low-energy slurry injection methods is also presented.

Elektrikli Araçlarda Kullanılan Paralel ve Seri Kanallı Soğutma Plakalarının Performanslarının HAD Yöntemi ile Karşılaştırılması

In a cold plate low thermal resistance thus high heat transfer rate and also low pressure drop is desired. In this study, performances of three liquid cold plates with different configurations are investigated for the thermal regulation of li-ion battery cells in electric vehicle applications. The outer dimensions of the cold plates are kept identical in order to use the cold plates in the same battery module under series, parallel and series-parallel configurations. The performances of the cold plates are investigated by using Computational Fluid Dynamic (CFD) tools. ANSYS Fluent commercial software is used to calculate the flowfield and the thermal field inside the cold plates for various flowrates. The performances of the cold plates are obtained by 3D simulations that solve Navier-Stokes, energy and continuity equations in a steady manner. The flow is assumed to be laminar for all the cases since calculated Reynolds number stay in laminar flow limits. The results show that the pressure drop of the coolant liquid of parallel flow arrangement is significantly lower than the serial arrangement. However, high thermal resistance and low uniformity of the temperature through the cold plate is observed compared to the serial case, as expected. As a result, series-parallel configuration results show that the trade-off between pressure drop and heat transfer rate can be optimized by applying a serpentine shape while keeping the flow arrangement as parallel as possible and increasing the length of the cross channels.

Diagnosing Sport-Related Flow Limitations in the Iliac Arteries Using Near-Infrared Spectroscopy.

Background: A flow limitation in the iliac arteries (FLIA) in endurance athletes is notoriously difficult to diagnose with the currently available diagnostic tools. At present, a commonly used diagnostic measure is a decrease in ankle brachial index with flex hips (ABIFlexed) following a maximal effort exercise test. Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures skeletal muscle oxygenation as reflected by the balance of O2 delivery from microvascular blood flow and O2 uptake by metabolic activity. Therefore, NIRS potentially serves as a novel technique for diagnosing FLIA. The purpose of this study is to compare the diagnostic accuracy of NIRS-derived absolute, amplitude, and kinetic variables in legs during and after a maximal exercise test with ABIFlexed. Methods: ABIFlexed and NIRS were studied in 33 healthy subjects and 201 patients with FLIA diagnosed with echo-Doppler. Results: After maximal exercise, NIRS kinetic variables, such as the half value time and mean response time, resulted in a range of 0.921 to 0.939 AUC for the diagnosis of FLIA when combined with ABIFlexed. Conversely, ABIFlexed measurements alone conferred significantly worse test characteristics (AUC 0.717, p < 0.001). Conclusions: NIRS may serve as a diagnostic adjunct in patients with possible FLIA.

Expiratory flow limitation during exercise: why does it 'suck' so much?

Expiratory flow limitation during exercise: why does it 'suck' so much?

Ice Age effects on genetic divergence of the American crocodile (Crocodylus acutus) in Panama: reconstructing limits of gene flow and environmental ranges: a reply to O'Dea et al.

O'Dea et al. (2022) (Pleistocene sea level changes and crocodile population histories on the isthmus of panama: a comment on Avila-Cervantes et al. (2020). Evolution, 76(11), 2778-2783. https://doi.org/10.1111/evo.14610) question our hypothesis that sea-level changes during the past glaciation played a role in restricting gene flow between Pacific and Caribbean Crocodylus acutus in Panama. They argue that an error in sea-level high-stand reconstruction during the last interglacial period (118-130 ka) does not support our hypothesis. Although they are correct in our high-stand reconstruction error, overlooked the point in that we were presenting a model of restricted gene flow across the Panamanian Isthmus during low sea levels. We review the assumptions of gene demographic methods, emphasizing that we were focusing on times of genetic divergence. We expand here why gene flow between these coastal populations could have been restricted during the last glacial maximum (19-26.5 ka) and the 50,000 years preceding it when sea levels were lower than today. O'Dea et al. suggest local climates may have played larger roles than sea levels. We demonstrate that paleoclimate estimates for the past 3.3 Ma in Panama are within the bounds of extant C. acutus. The importance of Ice Age Sea-level dynamics on Neotropical species was likely profound and should be incorporated into evolutionary studies of these taxa.

Mechanical mechanism to induce inspiratory flow limitation in obstructive sleep apnea patients revealed from in-vitro studies

Inspiratory flow limitation means that when the flowrate reaches a certain value, it no longer increases, or even decreases, which is called negative effort dependence flow limitation, even if the inspiration effort is increased. This occurs often in obstructive sleep apnea patients, but its mechanism remains unclear. To reveal the mechanism of inspiratory flow limitation, we constructed a unique partially collapsible in-vitro upper airway model of obstructive sleep apnea patients to observe the change of airway resistance with inspiratory driving pressure. The important findings demonstrate that with the increase of inspiratory effort, the driving pressure increases faster than the airway resistance in the early stages, and then the reverse occurs as the airway becomes narrower. The airway collapse caused by the transmural pressure can lead to a rapid increase in downstream resistance with the increase of inspiratory effort, which is the key reason causing the flow reduction and the formation of typical negative effort dependence flow limitation. The mechanical mechanism revealed in this study will lead to fully new insights into the study and treatment of obstructive sleep apnea.

Paracentral acute middle maculopathy secondary to retinal artery macroaneurysm elucidates anatomy and physiology of retinal capillary plexus

AbstractPurpose: To report a novel case of Paracentral Acute Middle Maculopathy (PAMM) Secondary to Retinal Artery Macroaneurysm.Methods: A case report.Results: A 72‐year‐old lady presented with three‐month history of sudden onset left paracentral scotoma. Her medical history include hypertension and hyperlipidemia. Visual acuity was 6/7.5 and 6/45 in the right and left eye respectively. Anterior segment examination and intraocular pressures were unremarkable. A ruptured retinal arterial macroaneurysm (RAM) was seen along the second‐order artery along the inferotemporal arcade with a small area of deep‐retinal whitening along the distal branches of the artery. Corresponding optical coherence tomography showed a round superficial retinal hyperreflective lesion consistent with RAM and hyperreflective band involving the outer plexiform layer (OPL), inner nuclear layer (INL) and inner plexiform layer (IPL) consistent with PAMM. Confocal scanning laser ophthalmoscopy video fluorescein angiogram (FA) demonstrated a ruptured and hemorrhagic RAM with significantly delayed distal filling of the artery, with resultant PAMM in an area supplied by the tributary arterioles of the affected artery.Conclusions: Oxygen consumption is highest at the metabolically active middle retinal layer. The inner and middle retinal layers are supplied by the superficial capillary plexus in the ganglion cell layer, intermediate capillary plexus (ICP) in the INL‐IPL boundary and deep capillary plexus (DCP) in the INL‐OPL boundary. Rupture and partial thrombosis of the RAM resulted in mechanical narrowing of the vessel lumen and severe flow limitation, which was further exacerbated by her history of hypertension and hyperlipidemia. This was consistent with the FA findings of delayed filling in the distal parts of the artery. Flow limitation results in decreased blood supply to the retinal capillary plexuses, further decreasing perfusion pressure, causing most disruption to the delicately balanced ICP and DCP blood supply of the middle retinal layer. Middle retinal infarction occurs most readily and presents as PAMM in our patient. In conclusion, we described a novel case of PAMM secondary to a ruptured and partially thrombosed RAM which clearly elucidates the anatomy and physiology of retinal capillary plexuses.

Metody obliczeń wytrzymałości zmęczeniowej części maszyn

Regardless of the operating conditions, a load acts on the parts of a machine in different directions. These loads in particular determine the required strength and resistance of parts and determine the study and selection of appropriate strength, resistance parameters for the parts. This can be determined by their impact on oilfield equipment and machine parts. Testing is done to determine the static flexibility, flow limit, tensile strength relative to flexibility, strength period limit, and plastic deformation coefficient. In some cases, when the limits of wear of machine parts are equal, elements with a larger coefficient of deformation are more convenient. These regularities should be used in those cases when it is possible to apply the methods of fracture mechanics or when there are direct experimental data on the development of fatigue cracks, which make it possible to carry out a probabilistic assessment of the durability of structural elements at the stage of crack growth and to substantiate the corresponding limitations on the service life of products. For the safety margins of machine parts, the starting points are as follows: longitudinal bending stress in the sleeve of a solid machine part made of a plastic material cannot damage the part. The length of the first crack can be taken to be equal to several millimetres, which is determined by the capabilities of the simplest means of observation, and by the fact that in some cases even a crack of such length can be critical from the point of view of a potential brittle fracture. In this regard, the fatigue resistance characteristics used in such a calculation should correspond to the point at which the first macroscopic crack appears.

Finite-Time Distributed Flow Balancing

We consider a flow network that is described by a digraph, each edge of which can admit a flow within a certain interval, with nonnegative end points that correspond to lower and upper flow limits. We propose and analyze a distributed iterative algorithm for solving, in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">finite time</i> , the so-called feasible circulation problem, which consists of computing flows that are <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">admissible</i> (i.e., within the given intervals at each edge) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">balanced</i> (i.e., the total in-flow equals the total out-flow at each node). The algorithm assumes a communication topology that allows bidirectional message exchanges between pairs of nodes that are physically connected (i.e., nodes that share a directed edge in the physical topology) and is shown to converge to a feasible and balanced solution as long as the necessary and sufficient circulation conditions are satisfied with strict inequality. In case, the initial flows and flow limits are commensurable (i.e., they are integer multiples of a given constant), then the proposed algorithm reduces to a previously proposed finite-time balancing algorithm, for which we provide an explicit bound on the number of steps required for termination.

An approximate analytical solution for transient gas flows in a vertically fractured well of finite fracture conductivity

An analytical solution in physical variable space is presented for transient gas flows during constant-rate production from a vertically-fractured well in an infinite homogeneous reservoir with finite fracture conductivity. The solution is based on the short-time asymptotic solution and a new approximate transient elliptical flow solution, which covers transient flows from the bilinear flow regime to the pseudo-radial flow regime. The solution covers the well-known asymptotic solutions in both short- and long-time limits of bilinear and pseudo-radial flows. The analytical model provides a practical and reliable engineering tool to evaluate the fractured reservoir properties, which can be programmed using a spreadsheet.

Scheduling Method for Aggregated Photovoltaic-Battery Systems Considering Information Notified by Distribution System Operator

In recent years, the aggregation business has gained a lot of attention in Japan. Aggregators will make contracts with customers with photovoltaic (PV) power systems and battery energy storage systems (BESSs) including electric vehicles (EVs) to participate in electricity markets. Aggregators might have to pay electricity supply-demand imbalance charges when generated and consumed energies contracted at the day-ahead supply-demand market are different from those at the current day operation due to distribution network constraints such as voltage and power flow limitations. Therefore, the information on network constraints is very important for aggregators to determine their day-ahead schedules. In this paper, we evaluated the relationship between aggregator supply-demand schedules and the distribution system operation. It was assumed that the reverse power flow limitations due to network constraints are notified to the aggregators by distribution system operator (DSO). Two cases of the aggregators' schedules of PV systems and stationary BESSs were compared in the simulations. In addition, aggregator strategies for making adequate schedules were evaluated.

Responses of Bilevel Ventilators to Unintentional Leak: A Bench Study.

The impact of leaks has mainly been assessed in bench models using continuous leak patterns which did not reflect real-life leakage. We aimed to assess the impact of the pattern and intensity of unintentional leakage (UL) using several respiratory models. An active artificial lung (ASL 5000) was connected to three bilevel-ventilators set in pressure mode; the experiments were carried out with three lung mechanics (COPD, OHS and NMD) with and without upper airway obstruction. Triggering delay, work of breathing, pressure rise time, inspiratory pressure, tidal volume, cycling delay and the asynchrony index were measured at 0, 6, 24 and 36 L/min of UL. We generated continuous and inspiratory UL. Compared to 0 L/min of UL, triggering delays were significantly higher with 36 L/min of UL (+27 ms) and pressure rise times were longer (+71 ms). Cycling delays increased from -4 [-250-169] ms to 150 [-173-207] ms at, respectively 0 L/min and 36 L/min of UL and work of breathing increased from 0.15 [0.12-0.29] J/L to 0.19 [0.16-0.36] J/L. Inspiratory leakage pattern significantly increased triggering delays (+35 ms) and cycling delays (+263 ms) but decreased delivered pressure (-0.94 cmH2O) compared to continuous leakage pattern. Simulated upper airway obstruction significantly increased triggering delay (+199 ms), cycling delays (+371 ms), and decreased tidal volume (-407 mL) and pressure rise times (-56 ms). The pattern of leakage impacted more the device performances than the magnitude of the leakage per se. Flow limitation negatively reduced all ventilator performances.

Blood shifts between body compartments during submaximal exercise with induced expiratory flow limitation in healthy humans.

External expiratory flow limitation (EFLe) can be applied in healthy subjects to mimic the effects of chronic obstructive pulmonary disease during exercise. At maximal exercise intensity, EFLe leads to exercise intolerance owing to respiratory pump dysfunction limiting venous return. We quantified blood shifts between body compartments to determine whether such effects can be observed during submaximal exercise, when the load on the respiratory system is milder. Ten healthy men (25.2±3.2 years of age, 177.3±5.4cm in height and weighing 67.4±5.8kg) exercised at 100W (∼40% of maximal oxygen uptake) while breathing spontaneously (CTRL) or with EFLe. We measured respiratory dynamics with optoelectronic plethysmography, oesophageal (Pes ) and gastric (Pga ) pressures with balloon catheters, and blood shifting between body compartments with double body plethysmography. During exercise, EFLe resulted in the following changes: (i) greater intrabreath blood shifts between the trunk and the extremities [518±221 (EFLe) vs. 224±60ml (CTRL); P<0.001] associated with lower Pes during inspiration (r=0.53, P<0.001) and higher Pga during expiration (r=0.29, P<0.024); and (ii) a progressive pooling of blood in the trunk over time (∼700ml after 3min of exercise; P<0.05), explained by a predominant effect of lower inspiratory Pes (r=0.54, P<0.001) over that of increased Pga . It follows that during submaximal exercise, EFLe amplifies the respiratory pump mechanism, with a prevailing contribution from lower inspiratory Pes over increased expiratory Pga , drawing blood into the trunk. Whether these results can be replicated in chronic obstructive pulmonary disease patients remains to be determined. KEY POINTS: External expiratory flow limitation (EFLe) can be applied in healthy subjects to mimic the effects of chronic obstructive pulmonary disease and safely study the mechanisms of exercise intolerance associated with the disease. At maximal exercise intensity with EFLe, exercise intolerance results from high expiratory pressures altering the respiratory pump mechanism and limiting venous return. We used double body plethysmography to quantify blood shifting between the trunk and the extremities and to examine whether the same effects occur with EFLe at submaximal exercise intensity, where the increase in expiratory pressures is milder. Our data show that during submaximal exercise, EFLe amplifies the respiratory pump mechanism, each breath producing greater blood displacements between the trunk and the extremities, with a prevailing effect from lower inspiratory intrathoracic pressure progressively drawing blood into the trunk. These results help us to understand the haemodynamic effects of respiratory pressures during submaximal exercise with expiratory flow restriction.

Diffusion parameters of flows in stable multi-class queueing networks

We consider open multi-class queueing networks with general arrival processes, general processing time sequences and Bernoulli routing. The network is assumed to be operating under an arbitrary work-conserving scheduling policy that makes the system stable. We study the variability of flows within the network. Computable expressions for quantifying flow variability have previously been discussed in the literature. However, in this paper, we shed more light on such analysis to justify the use of these expressions in the asymptotic analysis of network flows. Toward that end, we find a simple diffusion limit for the inter-class flows and establish the relation to asymptotic (co-)variance rates.

Microfluidic vortex focusing for high throughput synthesis of size-tunable liposomes

Control over vesicle size during nanoscale liposome synthesis is critical for defining the pharmaceutical properties of liposomal nanomedicines. Microfluidic technologies capable of size-tunable liposome generation have been widely explored, but scaling these microfluidic platforms for high production throughput without sacrificing size control has proven challenging. Here we describe a microfluidic-enabled process in which highly vortical flow is established around an axisymmetric stream of solvated lipids, simultaneously focusing the lipids while inducing rapid convective and diffusive mixing through application of the vortical flow field. By adjusting the individual buffer and lipid flow rates within the system, the microfluidic vortex focusing technique is capable of generating liposomes with precisely controlled size and low size variance, and may be operated up to the laminar flow limit for high throughput vesicle production. The reliable formation of liposomes as small as 27 nm and mass production rates over 20 g/h is demonstrated, offering a path toward production-scale liposome synthesis using a single continuous-flow vortex focusing device.

Symptoms of sleep disordered breathing: Association with the apnea-hypopnea index and somatic arousal

We investigated the association of typical symptoms of obstructive sleep apnea with a measure of daytime somatic arousal and with the apnea-hypopnea index. We extended the finding of an association between sleepiness, fatigue and somatic arousal previously reported in a US sleep apnea population to a German sleep apnea population (n = 374) and to other typical sleep apnea symptoms, insomnia, anxiety, daytime alertness and non-restorative sleep.Somatic arousal was measured using the body sensation questionnaire (BSQ). Correlations of apnea-hypopnea index and BSQ were computed with values of polysomnographic variables derived from overnight sleep studies and with severity of OSA symptoms.Apnea-hypopnea index and BSQ scores showed only a small negative correlation with each other; each correlated independently with the Epworth Sleepiness Scale score. Controlling for BSQ score, the apnea-hypopnea index was found to affect sleepiness only when it exceeded 50/h.Severity of all other sleep apnea symptoms did not increase with increasing apnea-hypopnea index. In contrast, severity of all symptoms of sleep apnea increased consistently with increasing BSQ scores. Thus, autonomic stress associated with obstructive sleep apnea may be the driving force behind sleep apnea symptoms rather than the sleep fragmentation associated with obstructive sleep apnea severity (apnea-hypopnea index).These findings support previously reported correlations by Gold and associates between the levels of somatic arousal, sleepiness and fatigue. Using the apnea-hypopnea index and BSQ together renders a more comprehensive assessment of sleep apnea than apnea-hypopnea index alone, which appears to impact only on sleepiness and only when it exceeds 50/h. More work is needed to elucidate the source of the chronic stress, which appears to arise endogenously in affected individuals, likely as a function of sleep disordered breathing, such as snoring/inspiratory flow limitation.

An experimental study on the effect of liquid properties on the counter-current flow limitation (CCFL) during gas/liquid counter-current two-phase flow in a 1/30 scaled-down of Pressurized Water Reactor (PWR) hot leg geometry

To promote the safety of the nuclear reactors, numerous authors have carried out investigations of gas/liquid counter-current two-phase flow in order to understand the characteristics during the inception of flooding or CCFL. The present work covers an experimental and analytical study on the effect of liquid properties on CCFL characteristics in a complex geometry representing 1/30 scaled-down version of a German-Konvoi PWR hot leg. The obtained results reveal that the gas velocity to initiate the flooding monotonically decreases with the increase of the liquid velocity. At high liquid flow rates, it is noticed that with the increase of glycerol percentage, the gas flow rate needed to initiate the flooding significantly decrease due to either the increase in liquid viscosity or the decrease in corresponding surface tension. Here under the same flow condition, the flooding is initiated faster by the higher glycerol percentage. Moreover, instead of the well-known Wallis superficial velocity, the Kutateladze-type parameter or a combination of the Wallis parameter and liquid property numbers by Zapke & Kröger (1996) which were previously proposed by numerous authors to investigate the effects of liquid properties on CCFL characteristics, a modified non-dimensional Wallis parameter combined with the inverse viscosity number introduced by Ma et al. (2020) is found herein to more accurately correlate the present experimental data. Through a dimensional similarity analysis, a new empirical correlation reveals that the liquid Froude number is the greatest determinant of CCFL characteristics with respect to the effect of the liquid properties.

O055 Flow limitation and sleepiness in individuals without sleep apnea

Abstract Introduction Moderate-Severe Obstructive Sleep Apnea (OSA, AHI&amp;gt;15) disturbs sleep through frequent bouts of apnea and is associated with daytime sleepiness. However, many individuals without moderate or severe OSA (i.e. AHI≤15) also report sleepiness. We propose that sleepiness may be a consequence of substantial flow limitation, even in the absence of overt reductions in airflow (apnea/hypopnea). Methods 2060 participants from the MESA sleep cohort were analysed using our validated method to estimate frequency of certain flow limitation from the airflow signal. Individuals with Epworth Sleepiness Scale ≥11 points were considered ‘sleepy’. Logistic regression was conducted to investigate the association between sleepiness (binary dependent variable) and frequency of flow limitation (continuous) in individuals without moderate-to-severe OSA AHI≤15. Models were adjusted for age, sex, race, BMI and self-reported sleep duration. Results N=832 individuals with AHI≤15 were included in primary models: The odds ratio (OR) for flow limitation predicting sleepiness was 2.14 (CI 1.27-3.61, per 2SD increase in flow limitation frequency i.e. +11% of sleep) and 2.08 (1.19-3.64) when adjusted for AHI. No association between flow limitation and sleepiness was observed in moderate-severe OSA (AHI&amp;gt;15, OR=1.01, 0.7-1.46). Discussion In individuals with few scored respiratory events (non-OSA and mild-OSA), increased flow limitation frequency by 2 SD (11% of sleep) is associated with a 2-fold increase in risk for sleepiness. Increasing flow limited breaths by 11% increases the odds for being sleepy equivalent to 1.2 hrs less sleep. Flow limitation may be an independent target for ameliorating sleepiness even in the absence of OSA.

Surgical shortening of lengthened iliac arteries in endurance athletes: Short-term and long-term satisfaction

ObjectiveEndurance athletes are prone to develop flow limitations in iliac arteries (FLIA). Especially in cyclists and ice speed skaters, excessive hemodynamic loading coupled with hip hyperflexion may cause kinking in lengthened iliac arteries necessitating surgical correction. This study investigated the short-term (≤1.5 years) and long-term (≥5 years) satisfaction of operative shortening of the iliac artery in endurance athletes. MethodsAll patients who were diagnosed and operated for FLIA owing to lengthened and kinked iliac arteries between 1997 and 2015 in one center were analyzed. Short-term follow-up consisted of an incremental maximal cycling test, ankle-brachial index with flexed hips, echo-Doppler examination with peak systolic velocity measurements and contrast-enhanced magnetic resonance angiography before and 6 to 18 months after surgery. Both short- and long-term satisfaction were assessed using questionnaires. ResultsA total of 83 patients (90 operated legs; 96.7% males; median age of 34 years at the time of surgery; interquartile range [IQR], 29-47) were analyzed. In the short-term, 87.5% reported symptom reduction with an 86.4% overall satisfaction rate. Symptom-free cycling improved from 272 ± 84 W to 384 ± 101 W (P < .001), whereas the maximal workload increased from 419 ± 72 W to 428 ± 67 W (P = .01). The ankle-brachial index with flexed hips increased from 0.55 (IQR, 0.45-0.65) to 0.62 (IQR, 0.52-0.74; P = .008), and the peak systolic velocity measured with hips flexed decreased from 2.50 m/s (IQR, 1.77-3.13 m/s) to 1.57 m/s (IQR, 1.20-2.04 m/s; P < .001). After a median of 12 years (IQR, 9.0-15.4 years), symptoms were still decreased in 84.1% of patients with an 81.2% overall satisfaction rate (79.5% response rate). Three patients needed a reintervention (recurrent FLIA, n = 2; failure, n = 1). ConclusionsOperative shortening of a lengthened and kinked iliac artery causing FLIA is successful both in the short- and long-term.