Ipsilateral Vessel Research Articles

In-hospital recurrent stroke in ipsilateral carotid web patients undergoing thrombectomy.

Carotid artery web is a possible cause of ischemic stroke, especially in young patients who lack conventional risk factors. The immediate and long-term outcomes are not well studied. We aimed to determine the association between an ipsilateral carotid web and in-hospital stroke recurrence. We analyzed data from adult patients admitted with an acute anterior circulation large vessel occlusion at a Comprehensive Stroke Center between July 2015 and March 2023. The primary outcome was in-hospital stroke recurrence and secondary outcome was in-hospital recurrent LVO. Multivariable logistic regression was performed to examine the association between ipsilateral carotid web and recurrent ischemic stroke and recurrent LVO. Of the 1463 patients with anterior circulation large vessel occlusion, 27 (1.8%) had an ipsilateral carotid artery web. Patients with carotid web were younger (median age (IQR), 60 years (53-67 years) versus 74 years (62-84 years), P < 0.01) and less likely to be Caucasian (60% vs. 80%, p = 0.014). Of the 27 patients with carotid web, 18 (70%) had no identifiable competing stroke mechanism. When compared to patients without ipsilateral carotid web, those with an ipsilateral carotid web had a higher risk of recurrent ischemic stroke (adjusted RR: 4.38, 95% CI: 1.38-13.85) and recurrent ipsilateral large vessel occlusion (adjusted RR: 4.49, 95% CI: 1.41-14.21). Carotid webs are an under recognized cause of acute large vessel occlusion and are associated with higher risk of early recurrence. Studies are needed to validate our findings and test early revascularization strategies in patients with symptomatic carotid artery webs.

Common carotid artery dissection from sportive choking

Tandem occlusions of the anterior circulation refer to the simultaneous presence of a cervical carotid artery occlusion or high-grade stenosis and an ipsilateral large vessel occlusion involving the intracranial internal carotid artery, M1 or proximal M2 middle cerebral artery. Whilst carotid occlusion usually results from progressive atherosclerotic disease, in younger individuals it may arise secondary to a dissection for which there are multiple aetiologies, with trauma being an important cause in patients having a relevant history. We present a rare case of traumatic left common carotid artery dissection in a young professional Jiu-Jitsu fighter presenting with delayed stroke symptoms and angiographic findings of a tandem occlusion. This case was successfully managed with endovascular clot retrieval and antiplatelet medication.

Change in Peak Systolic Velocity Estimation in Internal Carotid Artery Following Contralateral Near Occlusive Carotid Endarterectomy

Carotid artery stenosis (CAS) is one of the main causes of stroke, as the internal carotid artery (ICA) is a major source of cerebral blood supply. A common surgical intervention for CAS is carotid endarterectomy (CEA), which carries a high risk of stroke and mortality. CEA is indicated for 50% to 99% stenosis in symptomatic patients and 60% to 99% stenosis in asymptomatic patients. Carotid duplex ultrasound is frequently used to estimate peak systolic velocity (PSV), end diastolic velocity (EDV), and ICA/common carotid artery (CCA) ratio to determine the extent of stenosis. This does not account for other factors that can artificially change PSV and EDV, such as a contralateral carotid artery near occlusion with >90% stenosis. Although >70% contralateral stenosis has been previously studied, limited research exists on the impact of ICA near occlusions. We hypothesize that the degree of stenosis in an ipsilateral patent vessel can be more accurately estimated by examining the change in PSV pre- vs post-CEA of the contralateral ICA near occlusion. A retrospective study was conducted on 239 patients, at least 18 years of age, who underwent standard, routine carotid duplex ultrasound at a single institution. Patients who qualified for the study had bilateral carotid stenosis with ICA near occlusive disease on at least one side and underwent CEA. Near occlusion was determined by either a carotid duplex ultrasound >70% with one of the following criteria: PSV >400, EDV >140, or ratio of ICA/CCA >6, or a carotid computed tomography angiography showing near occlusion interpreted by a physician. Preoperative duplex velocities contralateral to the CEA were recorded and compared postoperatively. Interestingly, in the presence of contralateral >50% ICA stenosis, the PSV, EDV, and ICA/CCA ratio in the unoperated artery increased significantly following contralateral CEA (P < .001). In greater than 70% contralateral ICA occlusion, PSV, EDV, and ICA/CCA ratio increased to a greater extent compared with >50% contralateral ICA stenosis (P < .001). In detecting ≥70% stenosis of the patent vessel pre-CEA, PSV ≥250 cm/s had 87.2% sensitivity. In predicting ≥70% stenosis of the patent vessel pre-CEA, PSV >300 cm/s had 96.0% sensitivity. The present study deviates from the current theoretical model and shows that ultrasound PSV, EDV, ICA/CCA ratios can be significantly elevated in the patent vessel pre-CEA and post-CEA of the contralateral ICA near occlusion. This study provides novel insight into customized duplex ultrasound criteria for estimation of stenosis and to avoid unnecessary high-risk surgery.

Abstract WP163: Relationship Between Three-dimensional Arterial Tortuosity And Difficulty Of Guide Catheter Access During Endovascular Reperfusion Therapy

Introduction: Few studies have investigated the tortuosity of great vessels only in the longitudinal direction during endovascular reperfusion therapy. This study evaluated the tortuosity of the great vessels in the perpendicular and longitudinal directions by using novel reference line and how it affects procedural difficulty. Methods: We retrospectively reviewed the medical records of 294 patients with large vessel occlusion. Features of the anatomy of the ipsilateral great vessels were investigated by preintervention CT angiography. The reference line used to evaluate tortuosity was defined as a line from the origin of each ipsilateral great vessel to the entrance of the external auditory canal (AE-line). Coronal and sagittal angles were calculated using the AE-line and the most curved point of each ipsilateral great vessel. The right side of the reference line was negative and the left side was positive, and similarly, the ventral side of the reference line was negative and the dorsal side of the reference line was positive. Patients were divided into three groups with a threshold of -20° and 20° based on sagittal and coronal angles on the both sides, and finally into nine groups. (Figure) Reference group was set to Group 5. Procedural difficulty was determined by whether or not the internal carotid artery could be accessed within 10 min. Results: On the left side, compared with the reference group, the odds ratio [OR] (95% confidence interval [CI]) for the procedural difficulty in the Group 9 was 9.020 (2.85-28.5; p&lt;0.001). On the right side, the ORs (95% CI) for the procedural difficulty in the Group 2, Group 3, and Group 9 were 21.700 (2.200-215.000; p=0.008), 29.000 (1.770-475.000; p=0.018), and 65.200 (8.010-532.000; p&lt;0.001), respectively. Conclusion: There was a strong correlation between difficulty in guide catheter placement in the internal carotid artery and three-dimensional tortuosity when using the AE-line as a reference.

Recurrence of Cryptogenic (ESUS) Strokes in the First Year: Predictors and Outcome-A South Indian Study.

Around 9-25% of ischemic strokes are embolic stroke of undetermined source (ESUS) with an annual recurrence risk of 4.5-5%. Regarding ESUS, studies from India are limited. Here, we studied the prevalence of cryptogenic ESUS among stroke subtypes, recurrence risk and outcome at 1 year, and their predictors. We performed a single-center study of ambispective nature. Patients above 18 years of age with a diagnosis of cryptogenic (ESUS) strokes from January 1, 2017, to December 31, 2020 (4 years), with a 1-year follow-up were recruited in our study. All the patients underwent neuroimaging computerised tomography/magnetic resonance tomography (CT/MRI) with angiography, electrocardiogram (ECG), transthoracic echo (TTE), and rhythm monitoring. Functional outcome was measured using the modified Rankin scale with scores 0-2 taken as good outcome. We had 234 (11.21% of total ischemic strokes) subjects satisfying the criteria for ESUS over the study period with a mean age of 58.2 ± 12.8 years. 46 patients had a history of stroke/transient ischemic attack (TIA) at admission. 9.4% had a recurrent event at 1 year. The most important neuroimaging predictor of recurrent strokes was multiple embolic followed by superficial watershed pattern. Around 10% had more than one marker of atrial cardiopathy positive. While the risk factors, coronary artery disease (CAD), and neuroimaging pattern showed an association with recurrent events at 1 year on bivariate analysis, only the latter two remained significant on multivariate analysis. Our cohort of ESUS had a higher annual recurrence risk than reported before. Though vascular risk factors and ipsilateral vessel abnormalities were more in the recurrent ESUS group, it did not significantly affect the recurrence risk at 1 year. CAD and multiple embolic patterns on imaging showed an association with recurrent strokes, suggesting a possible cardiac substrate in our ESUS population as well.

Natural History of Cerebrovascular Flow in Cervical Arterial Dissection Using Quantitative Magnetic Resonance Angiography

The degree to which cervical arterial dissection (CAD) limits cerebral blood flow and the change in flow over time is not well characterized. This study is the first to evaluate blood flow using quantitative magnetic resonance angiography (QMRA) in this patient population. A retrospective chart review was completed in patients CAD between 2009 and 2019. Inclusion criteria were adults with dissection of internal carotid artery or vertebral artery, who underwent QMRA. Cases were reviewed for presentation, management, and imaging findings. Patients treated endovascularly were excluded. Flow index was calculated using ipsilateral vessel flow divided by contralateral flow. A total of 36 patients were included, mean age 44.8 +/- 11.1 years. 21 patients (51.2%) had internal carotid artery (ICA) dissections, 19 (46.3%) with vertebral artery (VA) dissections, and 1 with both. 6 patients (14.6%) had bilateral or multiple vessels involved. Although flow tended to improve over time in the affected vessel, patients with the lowest flow index on presentation continued to have low flow at follow-up (p<0.001). In addition, cerebral blood flow was shown to be associated with the degree of vessel narrowing, particularly in the ICA (p<0.001, R=0.891, R 2 =0.794), although this effect was not significant in the VA (p=0.237). This study represents the first to assess vessel flow in CAD using QMRA and to describe its patterns over time. Flow tended to improve in all patients over time in the dissected vessel, although patients with low flow on presentation continued to have low flow at follow-up.

Endovascular Treatment for Aneurysms Located in the Posterior Communicating Artery (PCoA) by the Swinging-Tail Technique: A Technical Note.

Purposes: A stent-assisted coil (SAC) is a safe and effective treatment modality for some complex intracranial aneurysms, especially for wide neck aneurysms. However, some wide neck aneurysms with a tough angle and located in the posterior communicating artery (PCoA) are challenging to treat with a SAC. This study aimed to examine and discuss the swinging-tail technique for treating wide neck aneurysms located in the PCoA using a SAC by Prof. Lv. Materials and Methods: We retrospectively reviewed our institutional clinical database and identified nine patients with neck aneurysms located in the PCoA, and these patients underwent the swinging-tail technique by Prof. Lv, which is a novel technique of releasing a stent, from June 2016 to September 2021. Results: In this study, nine patients underwent SAC treatment using the swinging-tail technique by Prof. Lv. Aneurysmal complete occlusion was observed in every patient without any complications, as shown by immediate postoperative angiography. Additionally, the modified Rankin scale was monitored for clinical outcomes in the follow-up. One patient died postoperatively due to severe SAH with an intraventricular hemorrhage. Four of nine patients underwent imaging follow-up, demonstrating the complete occlusion of aneurysms; eight patients underwent clinical follow-up and achieved a favorable clinical outcome (modified Rankin scale score: 0–2). Conclusion: The SAC treatment for wide neck aneurysms located in the PCoA can be challenging for operators because of the specific location, resulting in inadequate vessel wall apposition by antegrade stenting via the ipsilateral vessel. In this circumstance, the swinging-tail technique may be a feasible and effective choice.

Impact of Vessel Narrowing and Changes in Blood Flow on the Development of Ischemia in Cervical Arterial Dissection Using Quantitative Magnetic Resonance Angiography

Background Up to 3% of all ischemic strokes are secondary to dissections; however, cerebral hemodynamic patterns in cervical arterial dissection and their association with cerebral ischemia are unknown. This study represents the first to assess blood flow using quantitative magnetic resonance angiography in patients with cervical arterial dissection and their presentation with ischemia. Methods Retrospective chart review was completed in patients with cervical arterial dissection between 2009 and 2019. Inclusion criteria were adults with dissection of internal carotid artery or vertebral artery who underwent baseline magnetic resonance imaging (MRI) and quantitative magnetic resonance angiography. Cases were reviewed for presentation, management, and imaging findings. Flow index was calculated using ipsilateral vessel flow divided by contralateral flow. Results A total of 37 patients with a mean age of 45.95±11.95 years were included. Of the patients, 19 (51.2%) had internal carotid artery dissections, 17 (45.9%) with vertebral artery dissections, and 1 with both. Patients with ischemia on MRI demonstrated lower flow in the ipsilateral vessel when compared with those patients without ischemia ( P =0.003). Using the flow index in receiver operating characteristic analysis to predict ischemia on MRI yielded an area under the curve of 0.833 ( P =0.002); receiver operating characteristic analysis of the percent of total flow for ischemia on MRI found an area under the curve of 0.895 ( P =0.000), and receiver operating characteristic analysis of percent vessel narrowing calculated an area under the curve of 0.887 ( P =0.000). Multivariate analysis identified vessel narrowing as significantly associated with ischemia on MRI ( P =0.03). Conclusion This study represents the first to evaluate blood flow in patients with cervical arterial dissection using quantitative magnetic resonance angiography and its relationship with cerebral ischemia. Patients with lower flow as a result of dissection appear to be at higher risk of ischemia on presentation, emphasizing the role of hemodynamics in underlying pathophysiology, and vessel narrowing appears paramount in the association with developing ischemia.

Selective endovascular treatment of cervical arterial dissection using quantitative magnetic resonance angiography.

The role of endovascular treatment in cervical artery dissection (CAD) is equivocal. This study compared cerebral blood flow in CAD between medically and endovascularly treated patients using quantitative magnetic resonance angiography (QMRA). Retrospective chart review was completed for patients with CAD. Inclusion criteria were adults (>18 years) with diagnosis of dissection of the internal carotid artery or vertebral artery who received QMRA. The cases were reviewed for clinical presentation, diagnosis, management, and imaging, and in particular, patients who underwent endovascular treatment were evaluated. Forty-one patients were included, 46.3% female and mean age 46.0+/- 11.9 years. 21 patients (51.2%) had contralateral (ICA) dissections while 19 (46.3%) had vertebral artery (VA) dissections, and 1 had both involved. Five patients underwent stenting, angioplasty, or both. Baseline characteristics between patients who underwent medical versus endovascular treatment were similar, although patients undergoing stenting/angioplasty were more likely to have diabetes (p = 0.015) and prior anticoagulation use (p = 0.007). All endovascular patients demonstrated ischemia on MRI versus 53.1% of those undergoing medical management (p = 0.047). Comparing ipsilateral vessel flow over time in these two patient groups showed those who underwent stenting or angioplasty had lower baseline flows, albeit non-significant (p = 0.629). Patients who underwent endovascular treatment had lower distal flow compared to the medical management group. This study represents the first to assess vessel flow using QMRA in patients who underwent endovascular treatment of CAD. In combination with progressive symptoms, QMRA may serve as a useful adjunct in the selection of patients for endovascular intervention in arterial dissections.

Abstract WMP62: Assessment Of Cerebral Hemodynamic Patterns In Cervical Arterial Dissection Using Quantitative Magnetic Resonance Angiography

Background: Cervical arterial dissection accounts for 2-3% of all ischemic strokes. The pathophysiologic mechanism of the ensuing neurological sequelae is largely attributed to embolic phenomenon. The degree to which the dissection may limit cerebral blood flow and its relationship to symptoms is currently not well characterized. This study is the first to evaluate and quantify blood flow using quantitative magnetic resonance angiography (QMRA) in this patient population. Methods: A retrospective chart review was completed in patients at this institution with cervical arterial dissection between August 31, 2009, to September 1, 2019. Inclusion criteria were adults (≥18 years) with diagnosis of dissection of the common carotid artery, internal carotid artery, or vertebral artery, who received QMRA neuroimaging. The cases were reviewed for clinical presentation, diagnosis, management strategy, and radiologic imaging finding. Flow index was calculated using the ipsilateral vessel flow divided by the contralateral flow. Statistical analyses were completed using SPSS software (Version 27, IBM Corporation, Armonk, NY). Results: A total of 41 patients were included in this study, 53.7% male and 46.3% female, with mean age 46.0 +/- 11.9 years. Twenty-one patients (51.2%) had ICA dissections while 19 patients (46.3%) had VA dissections, and 1 patient had both ICA and VA vessels affected. Patients with ischemia on MRI demonstrated lower flow in the ipsilateral vessel when compared to those patients without ischemia on MRI at diagnosis and follow-up (p=0.003). Although flow improved over time, patients continued to remain stratified: patients with the lowest index on presentation tended to continue to have low flow in the ipsilateral vessel (p=0.000). Using the flow index in ROC analysis to predict ischemia on MRI yielded an area under the curve of 0.833 (p=0.002); ROC analysis of the percent of total flow for ischemia on MRI found an AUC of 0.895 (p=0.000). Conclusion: This study represents the first to assess vessel flow in patients with cervical arterial dissection using QMRA. Patients with lower flow as a result of dissection appear to be at higher risk of ischemia on presentation, emphasizing the role of hemodynamics in the underlying pathophysiology.

Impact of Aortic Arch Anatomy on Technical Performance and Clinical Outcomes in Patients with Acute Ischemic Stroke.

Arterial access is a technical consideration of mechanical thrombectomy that may affect procedural time, but few studies exist detailing the relationship of anatomy to procedural times and patient outcomes. We sought to investigate the respective impact of aortic arch and carotid artery anatomy on endovascular procedural times in patients with large-vessel occlusion. We retrospectively reviewed imaging and medical records of 207 patients from 2 academic institutions who underwent mechanical thrombectomy for anterior circulation large-vessel occlusion from January 2015 to July 2018. Preintervention CTAs were assessed to measure features of the aortic arch and ipsilateral great vessel anatomy. These included the cranial-to-caudal distance from the origin of the innominate artery to the top of the aortic arch and the takeoff angle of the respective great vessel from the arch. mRS scores were calculated from rehabilitation and other outpatient documentation. We performed bootstrap, stepwise regressions to model groin puncture to reperfusion time and binary mRS outcomes (good outcome, mRS ≤ 2). From our linear regression for groin puncture to reperfusion time, we found a significant association of the great vessel takeoff angle (P = .002) and caudal distance from the origin of the innominate artery to the top of the aortic arch (P = .05). Regression analysis for the binary mRS revealed a significant association with groin puncture to reperfusion time (P < .001). These results demonstrate that patients with larger takeoff angles and extreme aortic arches have an association with longer procedural times as approached from transfemoral access routes.

Association of Primary Anesthesia Type with Postoperative Adverse Events After Transcarotid Artery Revascularization

The literature remains sparse regarding the influence of primary anesthesia type (monitored anesthesia care [MAC] v general anesthesia) on 30-day adverse events after transcarotid artery revascularization (TCAR). The objective of this study was to report the association of primary anesthesia type with 30-day adverse events after TCAR. Retrospective cohort analysis of the American College of Surgeons National Surgical Quality Improvement Program Registry from 2012-2016. Multi-institutional. The final analysis included 625 patients who underwent TCAR. The primary exposure was anesthesia type, categorized as MAC (defined as regional anesthesia, local anesthesia, or MAC) or general anesthesia. The primary endpoint was 30-day mortality. Secondary 30-day endpoints included pulmonary, renal, and cardiac complications; sepsis; deep venous thrombosis; stroke; blood transfusion; embolism/thrombosis of ipsilateral carotid vessel; and redo surgery. The prevalence of MAC was 73.4%. A 93% decrease was observed in the odds of 30-day mortality (p = 0.003) in patients who received MAC. Mean (standard deviation) hospital stay (2.99 [5.92] d v 4.30 [9.15] d; p = 0.037) and case duration (88.45 [39.48] min v 105.85 [63.77] min; p < 0.001) were shorter among patients who received MAC. The odds of pulmonary complications (odds ratio 0.19, 95% confidence interval 0.05-0.65; p = 0.009) were significantly lower in the MAC group. No other differences in secondary endpoints were found between the anesthesia type cohorts. The majority of studies on this topic pertain to carotid endarterectomy patients, and this retrospective analysis sheds light on outcomes after TCAR. Overall, the authors urge additional risk stratification and preprocedural optimization to carefully select patients who may undergo MAC.

Abstract TP541: CT Angiography Leptomeningeal Collateral Assessment for Vasospasm in Patients With Aneurysmal Subarachnoid Hemorrhage

Introduction: Although leptomeningeal collaterals in acute large vessel occlusion have been well studied with respect to core infarct volume and risk of hemorrhagic conversion, their association with vasospasm in the setting of subarachnoid hemorrhage is less clear. Our purpose is to investigate the utility of leptomeningeal collateral scoring on CTA of patients presenting with aneurysmal subarachnoid hemorrhage (aSAH). Methods: IRB-approved retrospective review of 122 consecutive patients with angiographic vasospasm after surgical or endovascular repair of ruptured intracranial aneurysm. A 5-point grading scale was adapted from Christoforidis et al. to compare leptomeningeal collateral scores on CTA with digital subtraction agiography (DSA) at presentation. An independent chart review was performed to correlate imaging with clinical markers of symptomatic vasospasm and delayed cerebral ischemia. Results: Of the 122 initial patients with vasospasm, 16 demonstrated unilateral high-grade M1 stenosis in the absence of a second ipsilateral large vessel stenosis, 11 of which (68.8%) developed cerebral infarction secondary to vasospasm. Leptomeningeal collateral scoring on CTA at presentation agreed with DSA scores in half of patients (n=8), underestimated collaterals by 1 point in 7 patients, and overestimated their presence by 1 point in a single case. Conclusion: Characterization of leptomeningeal collaterals in patients with aSAH may better predict subsequent vasospasm and cerebral ischemia. Our initial findings in cases of isolated severe M1 vasospasm highlight the potential value of collateral scoring on CTA at presentation. Collateral scoring on CTA correlates with DSA in half of cases, however further work is indicated to elucidate the technical factors contributing to 1-point underestimation in the other half cases. Christoforidis, G.A., et al., Predictors of hemorrhage following intra-arterial thrombolysis for acute ischemic stroke: the role of pial collateral formation. AJNR Am J Neuroradiol, 2009. 30 (1): p. 165-70.

Are morphologic features of recent small subcortical infarcts related to specific etiologic aspects?

Background:Recent small subcortical infarcts (RSSIs) mostly result from the occlusion of a single, small, brain artery due to intrinsic cerebral small-vessel disease (CSVD). Some RSSIs may be attributable to other causes such as cardiac embolism or large-artery disease, and their association with coexisting CSVD and vascular risk factors may vary with morphological magnetic resonance imaging (MRI) features.Methods:We retrospectively identified all inpatients with a single symptomatic MRI-confirmed RSSI between 2008 and 2013. RSSIs were rated for size, shape, location (i.e. anterior: basal ganglia and centrum semiovale posterior cerebral circulation: thalamus and pons) and MRI signs of concomitant CSVD. In a further step, clinical data, including detailed diagnostic workup and vascular risk factors, were analyzed with regard to RSSI features.Results:Among 335 RSSI patients (mean age 71.1 ± 12.1 years), 131 (39%) RSSIs were >15 mm in axial diameter and 66 (20%) were tubular shaped. Atrial fibrillation (AF) was present in 44 (13.1%) and an ipsilateral vessel stenosis > 50% in 30 (9%) patients. Arterial hypertension and CSVD MRI markers were more frequent in patients with anterior-circulation RSSIs, whereas diabetes was more prevalent in posterior-circulation RSSIs. Larger RSSIs occurred more frequently in the basal ganglia and pons, and the latter were associated with signs of large-artery atherosclerosis. Patients with concomitant AF had no specific MRI profile.Conclusion:Our findings suggest the contribution of different pathophysiological mechanisms to the occurrence of RSSIs in the anterior and posterior cerebral circulation. While there appears to be some general association of larger infarcts in the pons with large-artery disease, we found no pattern suggestive of AF in RSSIs.

Clinical examination and non-invasive screening tests in the diagnosis of peripheral artery disease in people with diabetes-related foot ulceration.

Peripheral artery disease is common in people with diabetes-related foot ulceration and is a risk factor for amputation. The best method for the detection or exclusion of peripheral artery disease is unknown. This study investigated the utility of clinical examination and non-invasive bedside tests in screening for peripheral artery disease in diabetes-related foot ulceration. Some 60 people presenting with new-onset ulceration participated. Accuracy of pulses, ankle pressure, toe pressure, toe-brachial index (TBI), ankle-brachial pressure index (ABPI), pole test at ankle, transcutaneous oxygen pressure and distal tibial waveform on ultrasound were examined. The gold standard diagnostic test used was > 50% stenosis in any artery or monophasic flow distal to calcification in any ipsilateral vessel on duplex ultrasound. The negative and positive likelihood ratios of pedal pulse assessment (0.75, 1.38) and the other clinical assessment tools were poor. The negative and positive likelihood ratios of ABPI (0.53, 1.69), transcutaneous oxygen pressure (1.10, 0.81) and ankle pressure (0.67, 2.25) were unsatisfactory. The lowest negative likelihood ratios were for tibial waveform assessment (0.15) and TBI (0.24). The highest positive likelihood ratios were for toe pressure (17.55) and pole test at the ankle (10.29) but the negative likelihood ratios were poor at 0.56 and 0.74. Pulse assessment and ABPI have limited utility in the detection of peripheral artery disease in people with diabetes foot ulceration. TBI and distal tibial waveforms are useful for selecting those needing diagnostic testing.

Robotic kidney autotransplantation in a porcine model: a procedure-specific training platform for the simulation of robotic intracorporeal vascular anastomosis.

Robotic-assisted kidney transplantation (RKT) with the Da Vinci (Intuitive, USA) platform has been recently developed to improve outcomes by decreasing surgical site complications and morbidity, especially in obese patients. This potential paradigm shift in the surgical technique of kidney transplantation is performed in only a few centers. For wider adoption of this high stake complex operation, we aimed to develop a procedure-specific simulation platform in a porcine model for the training of robotic intracorporeal vascular anastomosis and evaluating vascular anastomoses patency. This paper describes the requirements and steps developed for the above training purpose. Over a series of four animal ethics' approved experiments, the technique of robotic-assisted laparoscopic autotransplantation of the kidney was developed in Amsterdam live pigs (60-70kg). The surgery was based around the vascular anastomosis technique described by Menon et al. This non-survival porcine training model is targeted at transplant surgeons with robotic surgery experience. Under general anesthesia, each pig was placed in lateral decubitus position with the placement of one robotic camera port, two robotic 8mm ports and one assistant port. Robotic docking over the pig posteriorly was performed. The training platform involved the following procedural steps. First, ipsilateral iliac vessel dissection was performed. Second, robotic-assisted laparoscopic donor nephrectomy was performed with in situ perfusion of the kidney with cold Hartmann's solution prior to complete division of the hilar vessels, ureter and kidney mobilization. Thirdly, the kidney was either kept in situ for orthotopic autotransplantation or mobilized to the pelvis and orientated for the vascular anastomosis, which was performed end to end or end to side after vessel loop clamping of the iliac vessels, respectively, using 6/0 Gore-Tex sutures. Following autotransplantation and release of vessel loops, perfusion of the graft was assessed using intraoperative indocyanine green imaging and monitoring urine output after unclamping. This training platform demonstrates adequate face and content validity. With practice, arterial anastomotic time could be improved, showing its construct validity. This porcine training model can be useful in providing training for robotic intracorporeal vascular anastomosis and may facilitate confident translation into a transplant human recipient.

Abstract WMP21: The Delayed Vessel Sign in Multiphase CT Angiography: Facilitating the Rapid On-table Confirmation of Acute Ischaemic Stroke

Objective: The “delayed vessel sign” refers to the presence of relative unilateral delayed enhancement of a vessel or vessels in the anterior circulation on delayed phases of a multiphase CTA (MPCTA) distal to the point of vessel occlusion. We aimed to determine if educating radiologists on the “delayed vessel sign” would improve sensitivity, confidence and speed in the detection of distal anterior circulation vessel occlusions in the suspected stroke patient. Methods: Non-contrast CT (NCCT) and MPCTA studies of 53 individual patients, who presented with signs/symptoms of acute anterior circulation stroke, were retrospectively selected by an independent radiologist. 15 cases without a vessel occlusion, 15 cases with a M1 occlusion and 23 cases with a distal anterior circulation (A2/M2/M3) occlusion were included. Initially, NCCT and single phase CTA (SPCTA) studies were independently interpreted by four observers (two neuroradiologists, two radiology trainees) and observers’ confidence (scale 1-5), speed and sensitivity of detection were recorded. Observers were then educated on the “delayed vessel sign” and each study was re-examined after an interval of at least 14 days. Results: There was a significant improvement in the sensitivity of detection of distal anterior circulation vessel occlusions on MPCTA compared to SPCTA (p=0.0003) and this was also true for M1 occlusions (p=0.045). Overall confidence was 4.0 for SPCTA and 4.88 with MPCTA (p&lt;0.0001). Average time taken to interpret each case on SPCTA was 85.5s and decreased to 40.1s with MPCTA (p&lt;0.0001). Conclusion: The “delayed vessel sign” is a reliable indicator of ipsilateral vessel occlusion, and is particularly useful in cases involving distal MCA branches where the occlusion is not easily identified on the initial angiographic phase. We have found this sign facilitates the rapid on-table confirmation of acute ischemic stroke, even when small vessels are involved and the clinical diagnosis is uncertain.

New Optimal Needle Entry Angle for Cervical Transforaminal Epidural Steroid Injections: A Retrospective Study.

Objective: A cervical epidural steroid injection is one of the most commonly performed interventions to manage chronic neck pain and cervical radiculopathy. Despite its many severe complications, cervical transforaminal epidural steroid injection (CTFESI) is a clinically necessary modality for managing neck pain and cervical radiculopathy. We aimed in this study to find a safer optimal needle entry angle to decrease the chance of an accidental vertebral artery (VA) puncture even with a proper needle entry angle and to visualize the target of the needle tip.Methods: This retrospective study included 312 patients with neck pain or cervical radiculopathy who had undergone magnetic resonance imaging scans for diagnosis and treatment. The first line was drawn from the midpoint of the two articular pillars and passed through the exact midline of the spinous process. The second line was drawn parallel to the ventral lamina line (conventional transforaminal approach line, CTAL). The third line was drawn parallel to the ventral margin at the midpoint of the superior articular process's ventral border (new transforaminal approach line, NTAL). The angle of intersection between the midline and CTAL versus with NTAL were measured from both sides (right and left) at C5-6, C6-7, and C7-T1 levels. Also, the distance of CTAL and NTAL from VA were measured from both sides at each level. We examined whether the CTAL and NTAL would penetrate the ipsilateral VA, internal carotid artery (ICA), and internal jugular vein (IJV).Results: There were significant differences between CTAL and NTAL angles at all levels (P < 0.001). There were significant differences between the distance of CTAL and NTAL from VA at all levels (P < 0.001). There were also significant differences between the observed frequency of CTAL and NTAL that would penetrate the major ipsilateral vessel (VA, ICA, and IJV) on all levels and sides (P < 0.001~0.030).Conclusion: The angle of NTAL (approximately 70°) is safer than the angle of CTAL (approximately 50°) when considering vascular injuries to vessels, such as the VA, ICA, and IJV.

Endovascular Treatment of Tandem Common Carotid Artery Origin and Distal Intracranial Occlusion in Acute Ischemic Stroke

Tandem occlusion resulting in acute ischemic stroke is associated with high morbidity and mortality and a poor response to thrombolytic therapy. The use of endovascular strategies for tandem stroke cases results in an improved outcome for this subgroup of patients. We present 2 cases with a pattern of tandem occlusion consisting of proximal obstruction at the origin of the common carotid artery (CCA) with concomitant intracranial occlusion treated by endovascular techniques. The 2 patients presented each with occlusion at the left CCA origin and ipsilateral intracranial vessel (left middle cerebral artery and carotid terminus, respectively). A transfemoral anterograde approach was used to deliver a balloon-mounted stent across the proximal CCA origin occlusion to gain access to the distal cerebral vasculature. Subsequently, a stent retriever assisted mechanical aspiration thrombectomy was used to revascularize the intracranial occlusion. Complete revascularization with Thrombolysis in Cerebral Infarction scores of 2b and improvement in neurologic deficits occurred in both cases. Good clinical outcome was achieved for both patients at 3-month follow-up. An anterograde transfemoral approach should be considered in cases of tandem occlusion of the proximal CCA and middle cerebral artery.

Selective α1-adrenergic blockade disturbs the regional distribution of cerebral blood flow during static handgrip exercise.

Handgrip-induced increases in blood flow through the contralateral artery that supplies the cortical representation of the arm have been hypothesized as a consequence of neurovascular coupling and a resultant metabolic attenuation of sympathetic cerebral vasoconstriction. In contrast, sympathetic restraint, in theory, inhibits changes in perfusion of the cerebral ipsilateral blood vessels. To confirm whether sympathetic nerve activity modulates cerebral blood flow distribution during static handgrip (SHG) exercise, beat-to-beat contra- and ipsilateral internal carotid artery blood flow (ICA; Doppler) and mean arterial pressure (MAP; Finometer) were simultaneously assessed in nine healthy men (27 ± 5 yr), both at rest and during a 2-min SHG bout (30% maximal voluntary contraction), under two experimental conditions: 1) control and 2) α1-adrenergic receptor blockade. End-tidal carbon dioxide (rebreathing system) was clamped throughout the study. SHG induced increases in MAP (+31.4 ± 10.7 mmHg, P < 0.05) and contralateral ICA blood flow (+80.9 ± 62.5 ml/min, P < 0.05), while no changes were observed in the ipsilateral vessel (-9.8 ± 39.3 ml/min, P > 0.05). The reduction in ipsilateral ICA vascular conductance (VC) was greater compared with contralateral ICA (contralateral: -0.8 ± 0.8 vs. ipsilateral: -2.6 ± 1.3 ml·min(-1)·mmHg(-1), P < 0.05). Prazosin was effective to induce α1-blockade since phenylephrine-induced increases in MAP were greatly reduced (P < 0.05). Under α1-adrenergic receptor blockade, SHG evoked smaller MAP responses (+19.4 ± 9.2, P < 0.05) but similar increases in ICAs blood flow (contralateral: +58.4 ± 21.5 vs. ipsilateral: +54.3 ± 46.2 ml/min, P > 0.05) and decreases in VC (contralateral: -0.4 ± 0.7 vs. ipsilateral: -0.4 ± 1.0 ml·min(-1)·mmHg(-1), P > 0.05). These findings indicate a role of sympathetic nerve activity in the regulation of cerebral blood flow distribution during SHG.