[Fluid-solid coupling model and analysis on pulse wave propagation properties of iliac artery].

In this work, we investigated the influence of the bifurcation geometry of the iliac artery on the propagation properties of the pulse wave, and applied software to establish the straight bifurcation and curved bifurcation bi-directional fluid-solid coupling finite element analysis models based on the iliac artery, and compared and analyzed the influence of the bifurcation angle of the blood vessel on the propagation characteristics of the pulse wave. It was found that the bifurcation geometry had a significant effect on the pulse wave propagation in the iliac arteries, and the pressure and velocity pulse wave amplitudes predicted by these two models had a good agreement with that before the vessel bifurcation in a cardiac cycle. The curvilinear bifurcation model predicted the pulse wave amplitude to be lower and the pressure drop to be smaller after the bifurcation, which was more in line with the actual situation of the human body. In addition, the bifurcation point is accompanied by the stress concentration phenomenon in the vessel wall, and there is a transient increase in the velocity pulse waveform amplitude, which was consistent with the fact that the bifurcation site is prone to phenomena such as arterial stenosis and hardening. The preliminary results of this paper will provide some reference for the use of pulse waveforms in the diagnosis of arterial diseases.

Effect of aortic bifurcation geometry on pressure and peak wall stress in abdominal aorta: Fluid-structure interaction study.

BACKGROUND AND OBJECTIVE: Geometry of aorto-iliac bifurcation may affect pressure and wall stress in aorta and thus potentially serve as a predictor of abdominal aortic aneurysm (AAA), similarly to hypertension. METHODS: Effect of aorto-iliac bifurcation geometry was investigated via parametric analysis based on two-way weakly coupled fluid-structure interaction simulations. The arterial wall was modelled as isotropic hyperelastic monolayer, and non-Newtonian behaviour was introduced for the fluid. Realistic boundary conditions of the pulsatile blood flow were used on the basis of experiments in literature and their time shift was tailored to the pulse wave velocity in the model to obtain physiological wave shapes. Eighteen idealized and one patient-specific geometries of human aortic tree with common iliac and renal arteries were considered with different angles between abdominal aorta (AA) and both iliac arteries and different area ratios (AR) of iliac and aortic luminal cross sections. RESULTS: Peak wall stress (PWS) and systolic blood pressure (SBP) were insensitive to the aorto-iliac angles but sensitive to the AR: when AR decreased by 50%, the PWS and SBP increased by up to 18.4% and 18.8%, respectively. CONCLUSIONS: Lower AR (as a result of the iliac stenosis or aging), rather than the aorto-iliac angles increases the BP in the AA and may be thus a risk factor for the AAA development.

Optimal Wire Myography Normalization for the Rat Dorsal Penile, Internal Pudendal and Internal Iliac Arteries.

In functional arterial studies using wire myography, the determination of a vessel's standardized normalization factor (factor k) is an essential step to ensure optimal contraction and relaxation by the arteries when stimulated with their respective vasoactive agents and to obtain reproducible results. The optimal factor k for several arteries have been determined, however, the optimal initial tension and factor k for the arteries involved in erection remains unknown. Hence, in the present study we set out to determine the optimal factor k for the internal iliac artery, proximal and distal internal pudendal artery (IPA), and dorsal penile artery. After isolating, harvesting, and mounting the arteries from male Sprague-Dawley rats on a multi wire myograph, we tested arterial responsivity to high K+-stimulation when the factor k was set at 0.7, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1, and 1.2 to determine the factor k setting that results in the greatest K+-induced active force production for each vessel type. The data showed the optimal factor k is 0.90-0.95 for the dorsal penile, distal internal pudendal and internal iliac arteries while it is 0.85-0.90 for proximal internal pudendal artery. These optimal values corresponded to initial passive tension settings of 1.10±0.16 - 1.46±0.23, 1.28±0.20 - 1.69±0.34, 1.03±0.27 - 1.33±0.31, and 1.33±0.31 - 1.77±0.43 mN/mm for the dorsal penile, distal IP, proximal IP, and internal iliac arteries, respectively.

Mechanical characterization of 3D printed mimic of human artery affected by atherosclerotic plaque through numerical and experimental methods.

This paper proposes a novel experimental investigation based on 3D printing to validate numerical models for biomechanics simulations. Soft elastomeric materials have been used in Polyjet multi-material 3D printer to mimicking arteries affected by atherosclerotic plaque. The nonlinear mechanical properties of five digital materials are characterized and used as an input for finite element (FE) modeling. Pressurized air is applied to the internal cavity of the printed model to reproduce the internal blood pressure in the artery. Digital Imaging Correlation is adopted to measure the displacement and deformation. A 1D linear higher-order FE model based on the Carrera Unified Formulation is compared to 3D nonlinear FE solutions.

Platelets Do Not Alter Flow-Mediated Dilation or Arterial Conduction in vivo.

The aim of this study was to investigate whether platelets contribute to shear stress and vascular conductance in the iliac vascular bed in vivo. Flow-mediated dilation of pig iliac was induced by downstream injection of acetylcholine (50 µg), and separately, conductance (ΔF/ΔP) was calculated. This was carried out before and after removal of 1 L of arterial blood in 240 mL increments, and each 240 mL was spun in a centrifuge (1,500 rcf for 7 min); platelet-rich plasma was replaced with equal volume of heparinised saline and reinjected. The circulating platelet count fell from 369 × 109/L (n = 5) to 165 × 109/L (p = 0.01; n = 4; Student's unpaired t). An increase in flow led to an increase in the iliac diameter by 0.49 ± 0.03 mm (mean ± SEM) before platelet reduction and 0.55 ± 0.05 mm after (p = 0.36, Student's paired t, n = 5); the change in arterial conductance was also not significantly affected by platelet reduction, control: 1.44 ± 0.34 mL/min/mm Hg, after platelet reduction: 1.39 ± 0.04 mm (p = 0.55, Student's paired t, n = 4). Therefore, platelets do not contribute to shear stress or conductance in vivo.

Acute Hemodynamic Improvement by Thermal Vasodilation inside the Abdominal and Iliac Arterial Segments of Young Sedentary Individuals.

OBJECTIVE: To study the hemodynamic response to lower leg heating intervention (LLHI) inside the abdominal and iliac arterial segments (AIAS) of young sedentary individuals. METHODS: A Doppler measurement of blood flow was conducted for 5 young sedentary adults with LLHI. Heating durations of 0, 20, and 40 min were considered. A lumped parameter model (LPM) was used to ascertain the hemodynamic mechanism. The hemodynamics were determined via numerical approaches. RESULTS: Ultrasonography revealed that the blood flow waveform shifted upwards under LLHI; in particular, the mean flow increased significantly (p < 0.05) with increasing heating duration. The LPM showed that its mechanism depends on the reduction in afterload resistance, not on the inertia of blood flow and arterial compliance. The time-averaged wall shear stress, time-averaged production rate of nitric oxide, and helicity in the external iliac arteries increased more significantly than in other segments as the heating duration increased, while the oscillation shear index (OSI) and relative residence time (RRT) in the AIAS declined with increasing heating duration. There was a more obvious helicity response in the bilateral external iliac arteries than the OSI and RRT responses. CONCLUSION: LLHI can effectively induce a positive hemodynamic environment in the AIAS of young sedentary individuals.

Braylin induces a potent vasorelaxation, involving distinct mechanisms in superior mesenteric and iliac arteries of rats.

Arterial hypertension is a risk factor for various cardiovascular and renal diseases, representing a major public health challenge. Although a wide range of treatment options are available for blood pressure control, many hypertensive individuals remain with uncontrolled hypertension. Thus, the search for new substances with antihypertensive potential becomes necessary. Coumarins, a group of polyphenolic compounds derived from plants, have attracted intense interest due to their diverse pharmacological properties, like potent antihypertensive activities. Braylin (6-methoxyseselin) is a coumarin identified in the Zanthoxylum tingoassuiba species, described as a phosphodiesterase-4 (PDE4) inhibitor. Although different coumarin compounds have been described as potent antihypertensive agents, the activity of braylin on the cardiovascular system has yet to be investigated. To investigate the vasorelaxation properties of braylin and its possible mechanisms of action, we performed in vitro studies using superior mesenteric arteries and the iliac arteries isolated from rats. In this study, we demonstrated, for the first time, that braylin induces potent vasorelaxation, involving distinct mechanisms from two different arteries, isolated from rats. A possible inhibition of phosphodiesterase, altering the cyclic adenosine monophosphate (cAMP)/cAMP-dependent protein kinase (PKA) pathway, may be correlated with the biological action of braylin in the mesenteric vessel, while in the iliac artery, the biological action of braylin may be correlated with increase of cyclic guanosine monophosphate (cGMP), followed by BKCa, Kir, and Kv channel activation. Together, these results provide evidence that braylin can represent a potential therapeutic use in preventing and treating cardiovascular diseases.

Kidney transplantation from living donor with monolateral renal artery fibromuscular dysplasia using a cryopreserved iliac graft for arterial reconstruction: a case report and review of the literature.

BACKGROUND: Aging and mortality of patients on waiting lists for kidney transplantation have increased, as a result of the shortage of organs available all over the world. Living donor grafts represent a significant source to maintain the donor pool, and resorting successfully to allografts with arterial disease has become a necessity. The incidence of renal artery fibromuscular dysplasia (FMD) in potential living renal donors is reported to be 2-6%, and up to 4% of them present concurrent extra-renal involvement. CASE PRESENTATION: We present a case of renal transplantation using a kidney from a living donor with monolateral FMD. Resection of the affected arterial segment and its subsequent replacement with a cryopreserved iliac artery graft from a deceased donor were performed. No intraoperative nor post-operative complications were reported. The allograft function promptly resumed, with satisfying creatinine clearance, and adequate patency of the vascular anastomoses was detected by Doppler ultrasounds. CONCLUSION: Literature lacks clear guidelines on the eligibility of potential living renal donors with asymptomatic FMD. Preliminary assessment of the FMD living donor should always rule out any extra-renal involvement. Whenever possible, resection and reconstruction of the affected arterial segment should be taken into consideration as this condition may progress after implantation.

The Effect of Different Thawing Rates on Cryopreserved Human Iliac Arteries Allograft's Structural Damage and Mechanical Properties.

INTRODUCTION: The rate of thawing of cryopreserved human iliac arteries allografts (CHIAA) directly affects the severeness of structural changes that occur during this process. METHOD: The experiment was performed on ten CHIAA. The 10% dimethylsulphoxide in 6% hydroxyethyl starch solution was used as the cryoprotectant; all CHIAA were cooled at a controlled rate and stored in the vapor phase of liquid nitrogen (-194°C). Two thawing protocols were tested: (1) placing the CHIAA in a water bath at 37°C, and (2) the CHIAA were thawed in a controlled environment at 5°C. All samples underwent analysis under a scanning electron microscope. Testing of the mechanical properties of the CHIAA was evaluated on a custom-built single axis strain testing machine. Longitudinal and circumferential samples were prepared from each tested CHIAA. RESULTS: Ultrastructural analysis revealed that all five CHIAA thawed during the thawing protocol 1 which showed significantly more damage to the subendothelial structures when compared to the samples thawed in protocol 2. Mechanical properties: Thawing protocol 1-longitudinal UTS 2, 53 ± 0, 47 MPa at relative strain 1, 27 ± 0, 12 and circumferential UTS 1, 94 ± 0, 27 MPa at relative strain 1, 33 ± 0, 09. Thawing protocol 2-longitudinal ultimate tensile strain (UTS) 2, 42 ± 0, 34 MPa at relative strain 1, 32 ± 0, 09 and circumferential UTS 1, 98 ± 0, 26 MPa at relative strain 1, 29 ± 0, 07. Comparing UTS showed no statistical difference between thawing methods. CONCLUSION: Despite the significant differences in structural changes of presented thawing protocols, the ultimate tensile strain showed no statistical difference between thawing methods.

Mechanism of Membrane Depolarization Involved in α1A-Adrenoceptor-Mediated Contraction in Rat Tail and Iliac Arteries.

Our previous studies have shown that phenylephrine-induced contraction of cutaneous arteries is primarily mediated via α1A-adrenoceptors, but not α1D-adrenoceptors that generally mediate vascular contraction, and that the larger part of the contraction is induced in a voltage-dependent Ca2+ channel (VDCC)-independent manner. Here, we investigated the mechanism underlying the smaller part of the α1A-adrenoceptor-mediated contraction, i.e., VDCC-dependent one, in cutaneous arteries. Isometric contraction was measured with wire myograph in endothelium-denuded tail and iliac arterial rings isolated from male Wistar rats. LOE908 (10 µM), a cation channel blocker, partially inhibited the contraction induced by phenylephrine in tail and iliac arteries. Nifedipine (10 µM) further suppressed the phenylephrine-induced contraction that remained in the presence of LOE908 (10 µM) in iliac arteries but barely in tail arteries, suggesting that phenylephrine-induced depolarization in tail arteries is due to the activation of LOE908-sensitive cation channels. In iliac arteries, the contraction induced by A-61603, a specific α1A-adrenoceptor agonist, was also partially inhibited by LOE908 (10 µM); however, nifedipine had little effect on the A-61603-induced contraction that remained in the presence of LOE908 (10 µM), suggesting that depolarization mediated via α1A-adrenoceptors is due to the activation of LOE908-sensitive cation channels even in iliac arteries. These results suggest that membrane depolarization mediated via α1Α-adrenoceptors is caused by cation influx through LOE908-sensitive cation channels. Less contribution of VDCC to phenylephrine-induced contraction in tail arteries compared to in iliac arteries is likely due to that α1Α-adrenoceptor-mediated activation of VDCC is caused only by depolarization via cation influx through LOE908-sensitive cation channels.

Berberine restored nitrergic and adrenergic function in mesenteric and iliac arteries from streptozotocin-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Perivascular neuropathy was reported to involve in the vascular disorders associated with diabetes. The dried rhizomes of Coptis chinensis Franch. (Latin name: Coptidis Rhizoma; common name: Huang Lian in China), used frequently in Traditional Chinese medicine to treat diabetes (Xiaoke), have been confirmed to possess beneficial effects on diabetic peripheral neuropathy by modern clinical and pharmacological studies. Berberine (BBR), the main effective component of Huang Lian in the treatment of diabetes, is reported to ameliorate diabetic central and peripheral neuropathy. However, the effects of BBR on nerve function of mesenteric and iliac arteries are unclear. AIM OF THE STUDY: To investigate the effects of BBR on the diabetes-induced changes in nitrergic and adrenergic function in mesenteric and iliac arteries. MATERIALS AND METHODS: In this study, the animals were randomized into three groups: control rats, diabetic rats, and diabetic rats gavaged with BBR. We established diabetic rat model using intraperitoneal injection of streptozotocin (STZ, 55 mg kg-1). Two weeks after model establishment, those in the BBR-treated groups were gavaged with berberine chloride (Sichuan Xieli Fharmaceutical. Co., Ltd; 200 mg·kg-1·day-1) diluted in distilled water for another 2 weeks. The superior mesenteric artery and iliac artery were excised. Electric field stimulation (EFS) was used to induce arterial vasoconstriction and explore (1) the diabetes-induced changes in neurogenic function of the superior mesenteric artery and iliac artery; (2) the effects of BBR on neurovascular dysfunction in the early stage of STZ-induced diabetic rats. Nitric oxide (NO) and noradrenaline (NA) released from the nitrergic and adrenergic nerves were quantified using fluorescence assays and ELISA, respectively. RESULTS: EFS induced frequency-dependent vasoconstrictions in both superior mesenteric and iliac artery, and the contractile responses of arteries were abolished by 0.1 µmol·L-1 tetrodotoxin (TTX), or inhibited by 1 µmol·L-1 phentolamine or increased by 0.1 mmol·L-1 Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME). In superior mesenteric artery, but not in iliac artery, the changes of contractile responses with L-NAME were significantly decreased in diabetic rats, and NO release was less also. In contrast, in iliac artery of diabetic rats, but not in superior mesenteric artery, the changes of contractile responses with phentolamine were increased, and NA release was increased significantly. All these changes in diabetic rats on both superior mesenteric artery and iliac artery were reversed by treated with BBR. CONCLUSIONS: In the STZ-induced early diabetic rats, neural control of mesenteric and iliac vasomotor tone are altered differently. The diminished nitrergic nerve in superior mesenteric artery and enhanced adrenergic nerve in iliac artery both contributed to increased vasocontrictor responses. All these changes in diabetic rats were reversed by BBR, suggesting a novel mechanism of BBR in balance of neural regulation of vascular tone.

Heparan sulphate and hyaluronic acid components of the glycocalyx do not play a role in flow-mediated dilation of the iliac in the anaesthetized pig.

The shear-stress sensor function of vascular glycocalyx heparan sulphate and hyaluronic acid was investigated in vivo by assessing flow-mediated dilation before and after their removal. Heparinase III exposure (100 mU·mL-1 for 20 min;n = 6) did not significantly affect flow-mediated dilation of the iliac, from 0.42 ± 0.08 mm (mean ± SEM) to 0.34 ± 0.07 mm after (P = 0.12; paired Student's t test) for a statistically similar increase in shear stress; 18.24 ± 4.2 N·m-2 for the control and 15.8 ± 3.6 N·m-2 for the heparinase III experiment (P = 0.18). Hyaluronidase exposure (0.14-1.4 mg·mL-1 for 20 min; n = 8) also did not significantly reduce flow-mediated dilation of the iliac, which averaged 0.39 ± 0.08 mm before and 0.38 ± 0.09 mm after (P = 0.11) for a statistically similar increase in shear stress; 11.90 ± 3.20 N·m-2 for the control and 9.8 ± 3.33 N·m-2 for the hyaluronidase experiment (P = 0.88). Removal of both heparan sulphate and hyaluronic acid was confirmed using immunohistochemistry. Neither the heparan sulphate nor the hyaluronic acid components of the glycocalyx mediate shear-stress-induced vasodilation in conduit arteries in vivo.

Exploring magnetohydrodynamic voltage distributions in the human body: Preliminary results.

BACKGROUND: The aim of this study was to noninvasively measure regional contributions of vasculature in the human body using magnetohydrodynamic voltages (VMHD) obtained from electrocardiogram (ECG) recordings performed inside MRI's static magnetic field (B0). Integrating the regional VMHD over the Swave-Twave segment of the cardiac cycle (Vsegment) provides a non-invasive method for measuring regional blood volumes, which can be rapidly obtained during MRI without incurring additional cost. METHODS: VMHD was extracted from 12-lead ECG traces acquired during gradual introduction into a 3T MRI. Regional contributions were computed utilizing weights based on B0's strength at specified distances from isocenter. Vsegment mapping was performed in six subjects and validated against MR angiograms (MRA). RESULTS: Fluctuations in Vsegment, which presented as positive trace deflections, were found to be associated with aortic-arch flow in the thoracic cavity, the main branches of the abdominal aorta, and the bifurcation of the common iliac artery. The largest fluctuation corresponded to the location where the aortic arch was approximately orthogonal to B0. The smallest fluctuations corresponded to areas of vasculature that were parallel to B0. Significant correlations (specifically, Spearman's ranked correlation coefficients of 0.96 and 0.97 for abdominal and thoracic cavities, respectively) were found between the MRA and Vsegment maps (p < 0.001). CONCLUSIONS: A novel non-invasive method to extract regional blood volumes from ECGs was developed and shown to be a rapid means to quantify peripheral and abdominal blood volumes.

Use of Bilateral Cook Zenith Iliac Branch Devices to Preserve Internal Iliac Artery Flow During Endovascular Aneurysm Repair.

OBJECTIVES: Iliac branch devices (IBD) have become a widespread option to preserve antegrade internal iliac artery (IIA) flow during endovascular aneurysm repair (EVAR). Reported experience with bilateral implantation of IBDs is limited. This study aimed to describe the indications, technical options, and outcomes with the use of bilateral IBDs. METHODS: All patients undergoing elective implantation of bilateral Cook Zenith IBD between January 2010 and September 2017 in a single centre were included. Bilateral IBD was indicated in physically active, anatomically suitable patients and those with previous or concomitant surgery for a thoraco-abdominal aortic aneurysm or impaired collateral circulation to the IIA. Data were collected prospectively. RESULTS: Twenty-nine patients (29 male, mean age 64.1 ± 10 years) were included. Of the 58 IBDs, 48 (83%) were implanted in one procedure and 10 (17%) in two procedures (mean time between procedures 30.4 ± 9 months). Nineteen patients (65%) had a previous or simultaneous EVAR and the remaining 10 (35%) a previous or simultaneous complex aortic repair. Mean CIA diameter was 35.2 ± 8 mm. Technical success was achieved in 55 of the 58 IBDs (95%) with no mortality. Axillary artery access was used in 13 (38%) procedures. During follow up, four (7%) IIA branches occluded (1 bilateral occlusion and 2 unilateral). Estimated IIA branch patency at one and three years was 97.8% ± 2% and 88.5% ± 7%, respectively. All patients with late IIA occlusion remained asymptomatic. Re-intervention was needed in four patients (14%): two bridging stent graft extensions for type Ib endoleak, one relining of the external iliac artery because of mural in-stent thrombus and one femoro-femoral crossover bypass to treat an external iliac limb occlusion. CONCLUSIONS: Bilateral implantation of IBDs is a safe and effective technique to preserve IIA flow in selected patients with suitable anatomy, showing similar technical success and mid-term outcomes to the unilateral use of the device.

α1A-Adrenoceptors, but not α1B- or α1D-adrenoceptors, contribute to enhanced contractile response to phenylephrine in cooling conditions in the rat tail artery.

Cutaneous arteries show enhanced contraction in response to cooling, which is suggested to be mediated via α2C-adrenoceptors. We have previously shown that α1-adrenoceptors are also involved in the enhanced contraction in cooling conditions. In the present study, we aimed to identify the α1-adrenoceptor subtype involved in the response. Phenylephrine-induced contraction was enhanced by cooling to 24 °C in isolated rat tail arteries but suppressed in iliac arteries and aorta. At 37 °C, RS100329 (3 nM), an α1A-adrenoceptor antagonist, shifted the concentration-response curve of phenylephrine to the right in tail and iliac arteries, but not in aorta, while BMY7378 (10 nM), an α1D-adrenoceptor antagonist, shifted them to the right in aorta and iliac arteries, but not in tail arteries. At 24 °C, RS100329 (3 nM) shifted the concentration-response curve of phenylephrine to the right and decreased the maximum contraction in tail arteries. The inhibitory effects of RS100329 (3 nM) were more pronounced at 24 °C, compared to at 37 °C, implying larger contribution of α1A-adrenoceptors at 24 °C. In tail arteries, the maximum contraction of A-61603, an α1A-adrenoceptor agonist, was larger at 24 °C than at 37 °C. In contrast, in iliac arteries, the maximum contraction of A-61603 was smaller and its EC50 was smaller at 24 °C than at 37 °C. Under the condition where α1D-adrenoceptors were blocked, phenylephrine-induced contraction of iliac arteries was rather enhanced by cooling to 24 °C. These results suggest that α1A-adrenoceptors contribute to the enhanced contraction of cutaneous arteries in cooling conditions.

Hemodynamic performance within crossed stent grafts: computational and experimental study on the effect of cross position and angle.

BACKGROUND AND AIMS: The crossed limbs stent graft technique is regularly employed to treat abdominal aortic aneurysm patients with unfavorable aneurysm necks or widely splayed common iliac arteries. This article numerically evaluates the hemodynamic performance of the crossed limbs strategy by analyzing numerical simulations and conducting experiments using two series of idealized bifurcated stent grafts with different cross angles and cross positions. RESULTS: Results demonstrated that the absolute helicity at outlets decreased with increased cross angles and increased with decreased cross positions. The time-averaged wall shear stress remained approximately unchanged, whereas the oscillating shear index and relative resident time decreased slightly when the cross angle increased and cross position decreased in iliac grafts. Additionally, both numerical and in vitro experimental results indicate the displacement force acting on the stent graft gradually increased as cross angles increased and cross positions decreased. Results further indicated that strip areas with a high oscillating shear index and high relative resident time, which may be vulnerable to thrombosis formation, exist along the outer surface of the iliac artery grafts. CONCLUSION: Given this information, the optimal crossed limbs configuration may contain a small cross angle and low cross position; however, low cross positions may increase the risk of migration.

The Investigation and Management of Iliac Artery Endofibrosis: Lessons Learned from a Case Series.

OBJECTIVE/BACKGROUND: The objective was to summarise the lessons learned, and evolution in local practice over the last 7 years, in the investigation and surgical management of iliac artery endofibrosis. METHODS: This was a retrospective case series. A case note review of consecutive patients investigated for suspected iliac artery endofibrosis by a single surgeon, over a 7 year period, was undertaken. Included were cases of first presentation and those who had previously undergone intervention. RESULTS: Some 63 patients were referred with suspected endofibrosis in the period 2011-17, four of whom had previously undergone surgery for the condition. After investigation of both limbs, 50 symptomatic limbs in 46 patients had a confirmed diagnosis; amongst those 46 patients, iliac artery endofibrosis was found in a further six asymptomatic, contralateral limbs. Individuals were diagnosed at a median age of 36 years (range 18-52 years) and typically presented with thigh claudication, foot numbness, and limb weakness on exercise. The median delay to diagnosis was 3 years (range 0-14 years). Complete external iliac artery occlusion was a feature in three cases. Overall, 27 limbs in 25 patients underwent operative repair; a further five limbs in four patients underwent operative repair at other centres internationally. There were three post-operative superficial wound infections (11%) and one below knee deep vein thrombosis (4%). Symptoms resolved in 23 cases (85%) with a median follow up of 2.1 years (range 65 days-5.7 years). Of the four limbs developing recurrent symptoms, two had undergone surgery for an occluded external iliac artery. CONCLUSION: Surgical repair in the medium term appears effective in resolving symptoms in most patients. Further investigation is needed to establish the durability of surgery and to delineate the natural history of the disease.

Differential contribution of calcium channels to α1-adrenoceptor-mediated contraction is responsible for diverse responses to cooling between rat tail and iliac arteries.

Our previous studies have shown that α1-adrenoceptors, in addition to α2-adrenoceptors, are involved in enhanced contraction of cutaneous blood vessels during cooling. The present study aimed to elucidate the mechanism underlying it. In tail and iliac arteries isolated from rats, isometric contraction was measured using a myograph and the phosphorylation level of myosin phosphatase target subunit 1 (MYPT1) was quantified by western blotting. The phenylephrine-induced contraction was enhanced by cooling to 24 °C in tail arteries, but was suppressed in iliac arteries. Endothelium denudation or treatment with iberiotoxin enhanced the phenylephrine-induced contraction in tail arteries at 37 °C; however, neither affected the contraction at 24 °C. The phenylephrine-induced contraction at 37 °C was largely suppressed by nifedipine in iliac arteries, but only slightly in tail arteries. The Rho kinase inhibitor H-1152 largely suppressed the phenylephrine-induced contraction at 24 °C, but only slightly at 37 °C, in both arteries. The phosphorylation level of MYPT1 at Thr855 in tail arteries was increased by the cooling. Taken together, these results suggest the following mechanism in regard to cooling-induced enhancement of α1-adrenoceptor-mediated contraction in tail arteries: Cooling enhances the contraction of tail arteries via α1-adrenoceptor stimulation by reducing endothelium-dependent, large-conductance Ca2+-activated K+ channel-mediated relaxation and by inducing Rho kinase-mediated Ca2+ sensitization, although the latter occurs even in iliac arteries. A smaller contribution of voltage-dependent Ca2+ channels, which are largely suppressed by cooling, to α1-adrenoceptor-mediated contraction in tail arteries seems to be more crucially involved in the appearance of the enhanced contractile response to cooling.

The arteriolar glycocalyx plays a role in the regulation of blood flow in the iliac of the anaesthetised pig.

The role of the glycocalyx of arterial resistance vessels in regulating blood flow in vivo is not fully understood. Therefore, the effect of glycocalyx damage using two separate compounds, hyaluronidase and N-Formylmethionyl-leucyl-phenylalanine (fMLP), was evaluated in the iliac artery vascular bed of the anaesthetised pig. Blood flow and pressure were measured in the iliac, an adjustable snare was applied to the iliac above the pressure and flow measurement site to induce step decreases (3 occlusions at 3-4 min intervals were performed for each infusion) in blood flow, and hence iliac pressure, and vascular conductance (flow/pressure) was calculated. Saline, hyaluronidase (14 and 28 microg/ml/min), and fMLP (1 microM/min) were infused separately, downstream of the adjustable snare and their effect on arterial conductance assessed. Hyaluronidase at the higher infusion rate and fMLP both caused a reduction in arterial conductance, and hence an increase in blood flow resistance. In conclusion, the results show that glycocalyx damage causes an increase in resistance to blood flow in the iliac artery vascular bed.

Analysis of non-Newtonian effects within an aorta-iliac bifurcation region.

The geometry of the arteries at or near arterial bifurcation influences the blood flow field, which is an important factor affecting arteriogenesis. The blood can act sometimes as a non-Newtonian fluid. However, many studies have argued that for large and medium arteries, the blood flow can be considered to be Newtonian. In this work a comprehensive investigation of non-Newtonian effects on the blood fluid dynamic behavior in an aorta-iliac bifurcation is presented. The aorta-iliac geometry is reconstructed with references to the values reported in Shah et al. (1978); the 3D geometrical model consists of three filleted cylinders of different diameters. Governing equations with the appropriate boundary conditions are solved with a finite-element code. Different rheological models are used for the blood flow through the lumen and detailed comparisons are presented for the aorta-iliac bifurcation. Results are presented in terms of the velocity profiles in the bifurcation zone and Wall Shear Stress (WSS) for different sides of the bifurcation both for male and female geometries, showing that the Newtonian fluid assumption can be made without any particular loss in terms of accuracy with respect to the other more complex rheological models.