Hemodynamic Characteristics of a Tortuous Microvessel Using High-Fidelity Red Blood Cell Resolved Simulations.

OBJECTIVE: Tortuous microvessels are characteristic of microvascular remodeling associated with numerous physiological and pathological scenarios. Three-dimensional (3D) hemodynamics in tortuous microvessels influenced by red blood cells (RBCs), however, are largely unknown, and important questions remain. Is blood viscosity influenced by vessel tortuosity? How do RBC dynamics affect wall shear stress (WSS) patterns and the near-wall cell-free layer (CFL) over a range of conditions? The objective of this work was to parameterize hemodynamic characteristics unique to a tortuous microvessel. METHODS: RBC-resolved simulations were performed using an immersed boundary method-based 3D fluid dynamics solver. A representative tortuous microvessel was selected from a stimulated angiogenic network obtained from imaging of the rat mesentery and digitally reconstructed for the simulations. The representative microvessel was a venule with a diameter of approximately 20 µm. The model assumes a constant diameter along the vessel length and does not consider variations due to endothelial cell shapes or the endothelial surface layer. RESULTS: Microvessel tortuosity was observed to increase blood apparent viscosity compared to a straight tube by up to 26%. WSS spatial variations in high curvature regions reached 23.6 dyne/cm2 over the vessel cross-section. The magnitudes of WSS and CFL thickness variations due to tortuosity were strongly influenced by shear rate and negligibly influenced by tube hematocrit levels. CONCLUSIONS: New findings from this work reveal unique tortuosity-dependent hemodynamic characteristics over a range of conditions. The results provide new thought-provoking information to better understand the contribution of tortuous vessels in physiological and pathological processes and help improve reduced-order models.

Nail fold capillaroscopy in leprosy: Unveiling the microvascular changes.

BACKGROUND: Leprosy, a chronic infectious disease, is associated with various nail changes. Its etiopathogenesis is multifaceted, with microvascular damage being crucial. Nail fold capillaroscopy (NFC) emerges as a novel tool for detecting early vascular deficits in leprosy. The study aimed to assess and provide a complete clinical characterization of NFC changes in leprosy patients. METHODS: It is an observational cross-sectional study, done over a period of 1.5 year (January 2021 to august 2022) in a tertiary care hospital, encompassing 60 patients diagnosed with leprosy (18-60 years). After obtaining informed consent; detailed history, complete cutaneous and neurological examinations were conducted. All fingernails and toenails were examined for clinical changes. Subsequently, onychoscopy was performed using USB type of video-dermatoscope (Model AM7115MZT Dino-lite), a non-invasive tool. This was followed by NFC which was done for all fingernails and images were recorded by single operator, which were then assessed for quantitative and qualitive changes and statistical analysis was conducted using SPSS v20, with mean capillary density compared using Student's t-test, morphological change frequencies assessed by proportions, and group comparisons made using Chi-square or Fischer exact tests, with a significance threshold of p < 0.05. RESULTS: Among the 60 patients, 39 were in the lepromatous group, which included both borderline lepromatous (BL) and lepromatous leprosy (LL) patients, and 17 were in the tuberculoid group, which included borderline tuberculoid (BT) leprosy patients; 23.3 % had Type 1 reactions, and 18.3 % had Type 2 reactions. Nail fold capillaroscopy (NFC) showed microvasculature changes in 93.3 % of patients. The average capillary density was 6.8 ± 1.5 capillaries per mm, with the lepromatous group having a lower density (6.5 ± 1.09) compared to the tuberculoid group (7.0 ± 0.86). The most common NFC changes in the tuberculoid group were tortuous capillaries (70 %), capillary dropouts, and dilated capillaries (both 64.7 %). In the lepromatous group, capillary dropouts (82 %) were most frequent, followed by tortuous (69 %), receding (69 %), and dilated capillaries (66 %). A dilated and prominent subpapillary plexus was more common in the lepromatous group (35 %, p = 0.04). Patients with trophic changes in the lepromatous group had more capillary dropouts and bizarre capillaries. Capillary dropouts, dilated capillaries, and visible subpapillary venous plexus were more prevalent in patients with Type 2 reactions. CONCLUSION: NFC changes are prevalent in both tuberculoid and lepromatous leprosy, which may be an indicator of peripheral vascular compromise and trophic changes, especially in lepromatous leprosy. NFC can be an auxiliary tool for detecting microvascular abnormalities in leprosy patients.

The "Pre-Rotating Dilator Technique" for Optimal Endograft Orientation in Complex Endovascular Aortic Repair.

PURPOSE: To describe a novel technique for optimal orientation and accurate deployment of aortic endografts during complex endovascular aortic repair (cEVAR). TECHNIQUE: After establishing the femoral access in the standard fashion, a long large-bore dilator is inserted before the cEVAR delivery system. The dilator is advanced beyond the renovisceral segment noticing the degree of axial rotation. The endograft markers are verified with fluoroscopy outside the patient in the standard way. Thereafter, the cEVAR delivery system is pre-emptively rotated by the same degree in the opposite direction than the dilator showed upon insertion. The endograft is then advanced into position with the markers ending with the markers roughly in position. Minor adjustments are done before and during deployment if needed as per standard technique. CONCLUSION: The use of long, large-bore dilator before the introduction of the aortic graft allows to proactively minimize the risk of endograft misalignment and malrotation especially in cases with challenging anatomies in both the visceral and iliac segments. This can potentially be used in all cases because it minimizes the manipulation of the delivery system and potentially increases the accuracy of endograft deployment. CLINICAL IMPACT: This report describes a novel technique involving the use of a long large-bore dilator to predict the degree of rotation of the cEVAR delivery system during insertion and thereby enabling a pre-emptive compensation. This facilitates the precise orientation of the main aortic endograft with an easier alignment of any branches and/or fenestrations to their respective target arteries. This approach holds the potential to mitigate several of the difficulties commonly encountered with current cEVAR solutions, especially the challenges posed by small and tortuous access and severe angulation in the iliac and visceral aortic segment.

Esophagogastroduodenoscopy findings that do no not explain dysphagia are associated with underutilization of high-resolution manometry.

In patients with dysphagia that is not explained by upper endoscopy, high-resolution esophageal manometry (HRM) is the next logical step in diagnostic testing. This study investigated predictors of failure to refer for HRM after an upper endoscopy that was performed for but did not explain dysphagia. This was a retrospective cohort study of patients >18 years of age who underwent esophagogastroduodenoscopy (EGD) for dysphagia from 2015 to 2021. Patients with EGD findings that explained dysphagia (e.g. esophageal mass, eosinophilic esophagitis, Schatzki ring, etc.) were excluded from the main analyses. The primary outcome was failure to refer for HRM within 1 year of the index non-diagnostic EGD. We also investigated delayed referral for HRM, defined as HRM performed after the median. Multivariable logistic regression modeling was used to identify risk factors that independently predicted failure to refer for HRM, conditioned on the providing endoscopist. Among 2132 patients who underwent EGD for dysphagia, 1240 (58.2%) did not have findings to explain dysphagia on the index EGD. Of these 1240 patients, 148 (11.9%) underwent HRM within 1 year of index EGD. Endoscopic findings (e.g. hiatal hernia, tortuous esophagus, Barrett's esophagus, surgically altered anatomy not involving the gastroesophageal junction, and esophageal varices) perceived to explain dysphagia were independently associated with failure to refer for HRM (adjusted odds ratio 0.45, 95% confidence interval 0.25-0.80). Of the 148 patients who underwent HRM within 1 year of index EGD, 29.7% were diagnosed with a disorder of esophagogastric junction outflow, 17.6% with a disorder of peristalsis, and 2.0% with both disorders of esophagogastric outflow and peristalsis. The diagnosis made by HRM was similar among those who had incidental EGD findings that were non-diagnostic for dysphagia compared with those who had completely normal EGD findings. Demographic factors including race/ethnicity, insurance type, and income were not associated with failure to refer for HRM or delayed HRM. Patients with dysphagia and endoscopic findings unrelated to dysphagia have a similar prevalence of esophageal motility disorders to those with normal endoscopic examinations, yet these patients are less likely to undergo HRM. Provider education is indicated to increase HRM referral in these patients.

Populus D-type cyclin gene PsnCYCD1;1 accelerates cell division and participates in secondary growth of vascular bundles.

Plant growth and development rely heavily on cyclins, which comprise an important class of cell division regulators. D-type cyclins (CYCDs) are responsible for the rate-limiting step of G1 cells. In the plant kingdom, despite the importance of CYCDs in herbaceous plants, there is little knowledge of these proteins in perennial woody plants. Here, the gene of a nucleus-localized cyclin, PsnCYCD1;1, was cloned from Populus simonii × P. nigra. PsnCYCD1;1 was highly expressed in tissues with active cell division, especially the leaf buds, and could be induced by sucrose and phytohormones. Moreover, overexpression of PsnCYCD1;1 in poplar could stimulate cell division, resulting in the generation of small cells and causing severe morphological changes in the vascular bundles, resulting in 'S'-shaped tortuous stems and curled leaves. Furthermore, transcriptomic analysis revealed that endogenous genes related to cell division and vascular cambium development were significantly up-regulated in the transgenic plants. In addition, using yeast two-hybrid and bimolecular fluorescence complementation assays PsnCDKA1, PsnICK3, and PsnICK5 were identified as proteins interacting with PsnCYCD1;1. Our study demonstrates that PsnCYCD1;1 accelerates plant cell division and participates in secondary growth of vascular bundles in poplar.

Approach to tortuous vena saphena magna with insufficiency: Foam scleroterapy.

OBJECTIVE: This study aimed to investigate the efficacy of foam sclerotherapy in the treatment of tortuous Great Saphenous Vein (GSV) insufficiency. METHODS: In this prospective non-randomized study 62 patients with tortuous GSV insufficiency were included. All patients were delivered sclerosant agent in the form of foam into the GSV through a cannula above the knee level. Characteristics of patients, diameter of veins, reflux grades, Venous Clinical Severity Score (VCSS) and Clinical, Etiological, Anatomical, Pathological (CEAP) scores, concentration of sclerosant agent, complications and follow-up results were recorded. RESULTS: Foam sclerotheraphy was performed with 100% technical success in all patients at operative room. There were no allergic reactions or neurological complications during and after the operations. Ecchymosis was the most common complication with 37.1% frequency. . VCSS scores significantly decreased from 6.43% to 2.53%, during follow-up from initial admission to sixth months, respectively (P<0.05).In the first month parameters, successful occlusion rate was 88.7%, whereas its rate was 82.3% in sixth month. Recanalization rate significantly increased from 11.3% to 17.7% during follow-up from first to sixth months, respectively (P<0.05). CONCLUSIONS: Due to its low complication rate, low cost, acceptable total occlusion rate and reproducibility; Foam sclerotherapy can be considered a reliable treatment for patients with tortuous GSV insufficiency.

The chromosome-level genome provides insight into the molecular mechanism underlying the tortuous-branch phenotype of Prunus mume.

Plant with naturally twisted branches is referred to as a tortuous-branch plant, which have extremely high ornamental value due to their zigzag shape and the natural twisting of their branches. Prunus mume is an important woody ornamental plant. However, the molecular mechanism underlying this unique trait in Prunus genus is unknown. Here, we present a chromosome-level genome assembly of the cultivated P. mume var. tortuosa created using Oxford Nanopore combined with Hi-C scaffolding, which resulted in a 237.8 Mb genome assembly being anchored onto eight pseudochromosomes. Molecular dating indicated that P. mume is the most recently differentiated species in Prunus. Genes associated with cell division, development and plant hormones play essential roles in the formation of tortuous branch trait. A putative regulatory pathway for the tortuous branch trait was constructed based on gene expression levels. Furthermore, after transferring candidate PmCYCD genes into Arabidopsis thaliana, we found that seedlings overexpressing these genes exhibited curled rosette leaves. Our results provide insights into the evolutionary history of recently differentiated species in Prunus genus, the molecular basis of stem morphology, and the molecular mechanism underlying the tortuous branch trait and highlight the utility of multi-omics in deciphering the properties of P. mume plant architecture.

Right transradial coronary angiography in the setting of tortuous brachiocephalic/thoracic aorta ("elephant head"): Impact on fluoroscopy time and contrast use.

OBJECTIVES: Assess the impact on fluoroscopy time and contrast use in patients with tortuous brachiocephalic/thoracic aortas undergoing right transradial coronary angiography (RTCA) and provide strategies to manage. BACKGROUND: Unfavorable anatomy with severe brachiocephalic/thoracic tortuosity, referred to as an "elephant head," remains a significant obstacle for RTCA. METHODS: We reviewed the coronary angiograms of patients who underwent RTCA and had tortuous aortas. Angiography was attempted first using a universal catheter (Tiger) and switched to a left coronary specific catheter (Judkins Left [JL]) if challenging. Fluoroscopy time, contrast volume, and greatest distance from the patient's midline to the catheter in the aorta were recorded. RESULTS: Forty-nine patients (62.6 ± 12.0 years, 69.4% male) were included. Fifteen (30.6%) patients underwent successful angiography with a Tiger catheter; 34 (69.4%) patients required switching to JL catheter. The average distance of Tiger catheters to the midline of the spine was 0.78 ± 0.41 cm versus 1.28 ± 0.44 cm (p = .001) in JL catheters. Tiger catheter use resulted in less fluoroscopy time (6.48 ± 4.73 min) and contrast use (58.87 ± 43.53 ml) than in cases switched to JL (13.26 ± 10.76 min [p = .026]; 86.5 ± 69.95 ml [(p = .017]). CONCLUSIONS: For patients undergoing RTCA with significant brachiocephalic/thoracic aorta tortuosity, "elephant head," a Tiger catheter can be used efficiently for curvatures <1 cm from the middle of the spine. We propose that for curvatures >1 cm, operators should consider immediately switching to a JL catheter.

Renal denervation in a patient with a highly tortuous renal artery using a guide extension catheter: a case report.

BACKGROUND: Catheter-based renal denervation (RDN) has been introduced to treat resistant hypertension. Although the technology of RDN has been largely improved, denervation of tortuous renal arteries remains challenging. CASE PRESENTATION: This is a case report of a 49-year-old man with drug resistant hypertension. The patient was selected for RDN after ruling out possible causes of secondary hypertension. Computed tomography angiography showed a highly tortuous left renal artery. An Iberis multielectrode ablation catheter failed to reach the target vessel with a regular guiding catheter. A 5-French extension catheter was introduced into the proximal segment of the main left renal artery to provide extra support force, which enabled successful ablation of the highly tortuous left renal artery. His ambulatory blood pressure was significantly decreased at 1 month follow-up. CONCLUSIONS: It is feasible and effective to use a guide extension catheter for denervation of highly tortuous renal arteries. The present study provides a useful method to ablate tortuous and angled renal arteries and branches.

The rotational atherectomy with a guide extension catheter for calcified and tortuous lesions in left anterior descending artery: a case report.

BACKGROUND: The interventional treatment of calcified lesions with severe tortuosity in the left anterior descending artery (LAD) was challenging and the report of rotational atherectomy with mother-and-child technique has been scarce. CASE PRESENTATION: An 84-year-old woman was hospitalized for non-ST-segment acute coronary syndrome. Coronary angiography revealed a calcified nodule in the LAD. During rotational atherectomy of the calcified and tortuous lesion in the proximal LAD, eccentric cutting due to wire bias nearly caused perforation. The burr seemed to protrude from the contrast media during angiography. Intravascular ultrasound imaging revealed that extremely eccentric ablation almost reached the adventitia. We successfully ablated the distal calcified nodule by preventing proximal overcutting of the tortuous lesion with support from a guide extension catheter, i.e., the mother-and-child technique, followed by the deployment of the drug-eluting stent. The patient was discharged without chest symptoms and no symptom recurred during 12-month follow-up. CONCLUSION: This case demonstrated that safe ablation of a calcified nodule located distal to a tortuous and calcified lesion in the proximal LAD with the mother-and-child technique.

Internal carotid artery anomaly in oropharynx as a rare cause of sore throat.

BACKGROUND: Anomaly of internal carotid artery (ICA) is a very rare variation. In almost all the cases, the anomaly was on the right side. This right-sided predominance may be attributed to anatomical influences and factors affecting blood pressure. CASE REPORT: A 67-years-old man presented to ear, nose and throat (ENT) outpatient clinic in Al Wakra Hospital complain of sore throat, there was associated medical co-morbidities (diabetic, hypertensive, hyperlipidemia and coronary artery diseases). ENT examination showed a pulsating, bulging mass on the right posterolateral oropharyngeal wall with normal mucosal covering. CT scan with contrast showed aberrant course of the right ICA which is coursing medially in prevertebral space and right posterolateral hypopharyngeal wall over a length of approximately 1.7 cm, making an acute U-turn before resuming the normal course and its distal aspects, only a thin layer of mucosa noted over the aberrant course of ICA. CONCLUSION: Anomaly of ICA must be kept in mind in the evaluation of patients with sore throat associated with oropharyngeal mass especially in old-aged patients with atherosclerotic diseases.

Abnormal Vascular Phenotypes Associated with the Timing of Interruption of Retinal Vascular Development in Rats.

Pathological angiogenesis is a leading cause of blindness in several retinal diseases. The key driving factor inducing pathological angiogenesis is the pronounced hypoxia leading to a marked, increased production of vascular endothelial growth factor (VEGF). The aim of this study was to determine whether the abnormal vascular growth occurs in a manner dependent on the degree of the vascular defects. Vascular defects of two different degrees were created in the retina by subcutaneously treating neonatal rats with the VEGF receptor (VEGFR) tyrosine kinase inhibitor KRN633 on postnatal day (P) 4 and P5 (P4/5) or P7 and P8 (P7/8). The structure of the retinal vasculature changes was examined immunohistochemically. Prevention of vascular growth and regression of some preformed capillaries were observed on the next day, after completion of each treatment (i.e., P6 and P9). The vascular regrowth occurred as a result of eliminating the inhibitory effect on the VEGFR signaling pathway. KRN633 (P4/5)-treated rats exhibited a retinal vasculature with aggressive intravitreal neovascularization on P21. On the other hand, the appearance of tortuous arteries is a representative vascular pathological feature in retinas of KRN633 (P7/8)-treated groups. These results suggest that an interruption of the retinal vascular development at different time points induces different vascular pathological features in the retina. Pharmacological agents targeting the VEGF signaling pathway are useful for creating an abnormal retinal vasculature with various pathological features in order to evaluate the efficacy of anti-angiogenic compounds.

Impact of three-dimensional tortuous pore structure on polyethersulfone membrane morphology and mass transfer properties from a manufacturing perspective.

We examined typical commercial poly(ethersulfone) (PESf) hemodialysis and hemoconcentration membranes successfully used in manufacturing, and employed scanning probe microscope (SPM) to achieve a structural observation of the pores in the inner membrane surfaces, as well as measure the pore diameters and their distribution, verifying the relationship between the typical mass transfer properties. We focused on the differences between the PESf membranes which were expected to further improve the advanced pore structure control and functional design for various medical uses. The three-dimensional tortuous capillary pores on the inner surface of hollow fiber hemodialysis and hemoconcentrator membranes were investigated using dynamic force microscopy (DFM), and the pore diameter and distribution were measured through a line analysis. Compared with PUREMA-A, PES-Sα hemodialysis membranes have smaller three-dimensional tortuous capillary pore diameters and pore areas, as well as a smaller pore diameter distribution and pore area distribution, which make the accurate measurements of the pore diameter using FE-SEM impossible. These PESf membranes are almost the same in pure water permeability, but greatly differ in pore diameter and pore diameter distribution. By comparing and verifying as above, we may gain insight into the flexibility, versatility, and superior structural and functional controllability of PESf membrane pore structures, which could advance the development of pore structure control. Pending issues include the fact that, using a line analysis software of SPM devices, it is very difficult to measure hundred pores which clearly reflects the poor quality of pore size distributions obtained in this study, measurement accuracy must be improved further.

Tortuous Microvessels Contribute to Wound Healing via Sprouting Angiogenesis.

OBJECTIVE: Wound healing is accompanied by neoangiogenesis, and new vessels are thought to originate primarily from the microcirculation; however, how these vessels form and resolve during wound healing is poorly understood. Here, we investigated properties of the smallest capillaries during wound healing to determine their spatial organization and the kinetics of formation and resolution. APPROACH AND RESULTS: We used intravital imaging and high-resolution microscopy to identify a new type of vessel in wounds, called tortuous microvessels. Longitudinal studies showed that tortuous microvessels increased in frequency after injury, normalized as the wound healed, and were closely associated with the wound site. Tortuous microvessels had aberrant cell shapes, increased permeability, and distinct interactions with circulating microspheres, suggesting altered flow dynamics. Moreover, tortuous microvessels disproportionately contributed to wound angiogenesis by sprouting exuberantly and significantly more frequently than nearby normal capillaries. CONCLUSIONS: A new type of transient wound vessel, tortuous microvessels, sprout dynamically and disproportionately contribute to wound-healing neoangiogenesis, likely as a result of altered properties downstream of flow disturbances. These new findings suggest entry points for therapeutic intervention.

Aminated polyacrylonitrile nanofibers with immobilized gold-silver core-shell nanoparticles for use in a colorimetric test strip for copper(II).

The authors describe colorimetric test strips by using electrospun nanofiber membranes (NFMs) carrying gold/silver core/shell nanoparticles (Au/Ag NPs). The Au/Ag NPs were immobilized on aminated porous polyacrylonitrile NFMs to obtain test strips with a tortuous porous structure and a large surface area (38.6 m2 g-1). The color of the resultant NFMs, measured at a wavelength of 420 nm, is red-shifted when exposed to copper ions (Cu2+) with a color change from yellow to pink to colorless. The effect is due to leaching Au/Ag NPs from the NFMs in the presence of ammonium chloride, thiosulfate and Cu2+ upon which soluble thiosulfate complexes of Ag+, Au3+ and Cu2+ are formed. The effect can be readily seen with bare eyes. Under optimized conditions, this method has a low limit of detection (50 nM at S/N = 3), a fast assay time (3 min), good specificity, and excellent reversibility. The colorimetric test strip was successfully applied to the analysis of Cu2+ in drinking water sample. Graphical abstract Schematic of the preparation of test strips for Cu2+ by immobilizing Au/Ag core-shell nanoparticles on aminated polyacrylonitrile nanofibers.

Double micro-guide-wire technique to facilitate microcatheter navigation through tortuous intracranial vasculature.

We report a case in which navigation of the micro catheter (Headway 027) with the conventional single microwire technique became impossible because of the difficult intracranial vascular anatomy. In order to achieve access, we used two Terumo 012 inches micro guide-wires with a 45° angle inside a single micro catheter. The manoeuver was easy and can be reproduced in specific and challenging cases.

Initial experience with a multiple parallel guidewire support system for complex tortuous aortic arch navigation and great vessel catheterization: technical note.

The ability to traverse an anatomically challenging and complex arch is paramount to the success of any neuroendovascular procedure. With age, the aortic arch becomes elongated, calcified, and less compliant. The authors present the initial experience with a multiple parallel guidewire system (ZigiWire Mode 3) for catheterization through a complex tortuous aortic arch to access extracranial vessels. The ZigiWire is an organized guidewire system that uses consecutive delivery of 3 small-diameter (0.014-inch) guidewires that are progressively advanced in parallel to secure support-wire access. The authors have found it useful in situations in which traditional methods for great-vessel access have failed. Moreover, the progressive construction of a large wire from smaller wires prevents "kickback" force from a single larger guidewire, allowing stable distal access. The authors have been able to advance different diagnostic and guide catheters over the ZigiWire. This guidewire has allowed them to successfully complete neuroendovascular procedures in patients who were previously considered unsuitable for the procedure because of tortuous vascular access.

Vertebral artery loops in surgical perspective.

PURPOSE: Vertebral artery loop is a congenital or acquired anomaly. Vertebral artery loops are incidentally diagnosed during evaluation of neck problems and trauma. We aimed to present the incidence of VA loops using magnetic resonance angiography in consecutive patients and discuss epidemiological data including the gender, age, location, signs and symptoms, treatment approaches and outcomes of VA loops via analyzing literature. METHODS: In the first leg of our two-legged study, consecutive patients were evaluated using magnetic resonance angiography to detect any medial loop of vertebral arteries. The study period was from October 2015 to March 2016. In the second leg, academic databases about medial loop of vertebral artery were screened. Case reports, case series, abstracts and references of relevant literature were searched manually to avoid any missing cases. RESULTS: We evaluated 239 consecutive patients using magnetic resonance angiography. Twenty-one patients were excluded from the study due to inadequate image acquisition, aplastic vertebral artery and/or concomitant vertebral artery stenosis. Medial loop of V2 vertebral artery was observed in 13 patients (5.9 %): 9 with left, 2 with right and 2 with bilateral medial V2 loop. Patients with medial V2 loop were significantly older than patients with straight vertebral arteries (70.30 vs. 62.36, p = 0.028). In the literature analysis, VA loops were more commonly observed at V2 segment (90.5 %). Vertebral artery loops were mostly diagnosed at the 5th and 6th decades of life predominantly in females. The most common signs and symptoms were radiculopathy and/or neck pain, and signs and symptoms of vertebrobasilar insufficiency. CONCLUSIONS: Concise pre-operative evaluation of the vertebral arteries is essential to avoid the injury of undiagnosed VA loops during surgery, which might result in catastrophic circumstances. Further evaluation of the vertebral arteries using MR angiography is required, especially in elder age, before cervical spine surgeries.

Pseudoaneurysm formation caused by the withdrawal of a Trevo ProVue stent at a tortuous cerebral vessel: a case report.

This is the first report on the mechanism of pseudoaneurysm formation after withdrawal of a stent retriever. A 79-year-old woman developed cardiogenic embolization of the distal middle cerebral artery (M2). The deployed stent retriever bent because of vessel tortuosity. After withdrawal of the stent with strong resistance, complete revascularization was achieved, but an extravasation was detected at the site. Eight hours after disappearance of the extravasation, re-bleeding occurred with aneurysm-like pooling of contrast media. Direct surgical observation confirmed a pseudoaneurysm formation. The pseudoaneurysm was likely formed by avulsion of a fine vessel during withdrawal of the stent retriever at a tortuous vessel.