Modified Harborview Risk Score improves ease in predicting mortality after ruptured abdominal aortic aneurysm repair.

OBJECTIVE: The Harborview Risk Score (HRS) is a simple, accurate 4-point preoperative risk scoring system used to predict 30-day mortality following ruptured abdominal aortic aneurysm (rAAA) repair. The HRS assigns 1 point for each of the following: age >76 years, pH <7.2, creatinine >2 mg/dL, and any episode of severe hypotension (systolic blood pressure <70 mmHg). One potential limitation of this risk scoring system is that arterial blood gas (ABG) analysis is required to determine arterial pH. Because ABG analysis is not routinely performed prior to patient transfer or rAAA repair, we sought to determine if the HRS could be modified by replacing pH with the international normalized ratio (INR), a factor that has been previously shown to have a strong and independent association with 30-day death after rAAA repair. METHODS: A retrospective review of all rAAA repairs done at a single academic medical center between January 2002 and December 2018 was performed. Our traditional HRS was compared with a modified score, in which pH <7.2 was replaced with INR >1.8. Patients were included if they underwent rAAA repair (open or endovascular), and if they had preoperative laboratory values available to calculate both the traditional and modified HRS. RESULTS: During the 17-year study period, 360 of 391 repairs met inclusion criteria. Observed 30-day mortality using the modified scoring system was 17% (18/106) for a score of 0 points, 43% (53/122) for 1 point, 54% (52/96) for 2 points, 84% (27/32) for 3 points, and 100% (4/4) for 4 points. Receiver operating characteristic analysis revealed similar ability of the two scoring systems to predict 30-day death: there was no significant difference in the area under the curve (AUC) comparing the traditional (AUC = 0.74) and modified (AUC = 0.72) HRS (P = .3). CONCLUSIONS: Although previously validated among a modern cohort of patients with rAAA, our traditional 4-point risk score is limited in real-world use by the need for an ABG. Substituting INR for pH improves the usefulness of our risk scoring system without compromising accuracy in predicting 30-day mortality after rAAA repair.

Modified Harborview Risk Score accurately predicts mortality for patients with ruptured abdominal aortic aneurysm.

OBJECTIVE: The modified Harborview Risk Score (HRS) is a simple measure initially derived from a single institutional dataset used to predict ruptured abdominal aortic aneurysm (rAAA) repair survival preoperatively using basic labs and vital signs collected upon presentation. However, validation of this widely applicable scoring system has not been performed. This study aims to validate this scoring system using a large multi-institutional database. METHODS: All patients who underwent repair of an rAAA from 2011 to 2018 in the National Surgical Quality Improvement Program (NSQIP) and at a single academic medical center were included. The modified HRS was calculated by assigning 1 point for each of the following: age >76 years, creatinine >2 mg/dL, international normalized ratio >1.8, and any systolic blood pressure less than 70 mmHg. Assessment of the prediction model was then completed. Using a primary outcome measure of 30-day mortality, the receiver operating characteristic area under the curve was calculated. The discrimination between datasets was compared using a Delong test. Mortality rates for each score were compared between datasets using the Pearson χ2 test. Comparative analysis for patients with a score of 4 was limited due to a small sample size. RESULTS: A total of 1536 patients were identified using NSQIP, and 163 patients were assessed in the institutional dataset. There were 518 patients with a score of 0 (455 NSQIP, 63 institutional), 676 patients with a score of 1 (617 NSQIP, 59 institutional), 391 patients with a score of 2 (364 NSQIP, 27 institutional), 106 with a score of 3 (93 NSQIP, 13 institutional), and 8 patients with a score of 4 (7 NSQIP, 1 institutional). No difference was found in the receiver operating characteristic area under the curves between datasets (P = .78). Thirty-day mortality was 10% NSQIP vs 22% institutional for a score of 0; 28% NSQIP vs 36% institutional for a score of 1; 41% NSQIP vs 44% institutional for a score of 2; 45% NSQIP vs 69% institutional for a score of 3; and 57% NSQIP vs 100% institutional for a score of 4. Score 0 was the only score with a significant mortality rate difference between datasets (P = .01). CONCLUSIONS: The modified HRS is confirmed to be broadly applicable as a clinical decision-making tool for patients presenting with rAAAs. Therefore, this easily applicable model should be applied for all patients presenting with rAAAs to assist with provider and patient decision-making prior to proceeding with repair.

Dynamic Imaging is the Ideal Modality for the Diagnosis of Popliteal Artery Entrapment Syndrome.

BACKGROUND: Popliteal Artery Entrapment Syndrome (PAES) is a rare vascular condition with significant equipoise on how to properly diagnose and evaluate relevant imaging. This can lead to misdiagnosis and delay in surgical management. The objective of this study is to describe and compare distinct imaging features of dynamic versus static images to help determine the ideal imaging modality for diagnosis of PAES. METHODS: This is a retrospective review of patients referred for PAES at a single institution. We reviewed noninvasive imaging studies, diagnostic arteriograms, and cross-sectional images which include computed tomography angiography (CTA) or magnetic resonance angiography (MRA). For each affected and unaffected extremity, the characteristic collaterals for PAES were named and measured on arteriogram using Picture Archiving and Communication Software. Available cross-sectional images were also analyzed and compared with arteriogram and intraoperative findings during surgical exploration. RESULTS: There were 23 patients referred for PAES who underwent diagnostic evaluation and surgical management between 2013 and 2022. All patients had a duplex ultrasound that revealed a mean popliteal peak systolic velocity of 78 cm/sec at rest. With forced plantar flexion, the peak systolic velocity increased to a mean 175 cm/sec. A total of 12 extremities had complete loss of flow with provocation during duplex ultrasound. All patients underwent diagnostic angiography of 46 extremities. All limbs with PAES (n = 35) exhibited complete popliteal artery occlusion during angiography with forced plantar flexion. Distinct angiographic findings on resting images included a well-developed medial sural artery in 100% of limbs with PAES with a mean diameter of 2.7 mm. In limbs without PAES, only 80% had a visualized medial sural artery on arteriogram with a mean diameter of 2.0 mm (P = 0.1). A lateral sural artery was seen in 85% of affected extremities (mean diameter of 1.8 mm), while an anterior tibial recurrent artery was seen in 59% of affected extremities (mean diameter of 1.3 mm). In unaffected limbs, there were no visible lateral sural or anterior tibial recurrent arteries. The mean contrast used with diagnostic arteriograms was 58 milliliters (range 10-100 milliliters). Axial imaging was available for 9 affected extremities. Five had a previous MRA with only 1 being truly positive for arterial compression. Four extremities had previous CTA with 3 being falsely negative despite having type 3 PAES discovered during surgical exploration. CONCLUSIONS: Dynamic imaging with angiography provides immediate surgeon feedback by visualizing popliteal artery compression and enlarged sural collaterals during resting arteriography. The medial sural collateral is enlarged in patients with PAES and often the lateral sural and anterior tibial recurrent arteries can be visualized as well. CTA and MRA are associated with high false-negative rates, and therefore cause delays in diagnosis and surgical management of PAES. Dynamic imaging should, therefore, be the gold standard for the diagnosis of PAES.

Initial experience with the Terumo aortic Treo device for fenestrated endovascular aneurysm repair.

OBJECTIVE: The Terumo aortic (TA) Treo device (Terumo, Somerset, NJ) is an endograft with unique features that lends itself to fenestrated endovascular aneurysm repair (FEVAR), including a low device profile, a wide amplitude stent design, and an increased interstent distance. We have described our initial experience with the Treo device for FEVAR to treat short neck and juxtarenal abdominal aortic aneurysms. METHODS: As part of an ongoing physician-sponsored investigational device exemption clinical trial (ClinicalTrials.gov identifier, NCT01538056), subjects were prospectively enrolled and underwent elective FEVAR using a variety of devices. Demographic and procedural details were collected. The data from subjects treated specifically with the Treo device from November 3, 2016 to May 2, 2019 were collected and analyzed. RESULTS: Of a cohort of 161 patients who had undergone elective FEVAR, 46 had been treated with the TA Treo device. Most patients were men (70%), with a mean age of 75 years and high rates of hypertension (74%), hyperlipidemia (83%), coronary artery disease (33%), and chronic obstructive pulmonary disease (33%). The mean aneurysm size was 66 mm, the mean preoperative infrarenal neck length was 5 mm, and the mean final seal zone length was 45 mm. The average hospital and intensive care unit lengths of stay were 2.4 and 1.5 days, respectively. A total of 129 fenestrations were created for 44 superior mesenteric and 85 renal arteries (2.8 fenestrations per patient). Technical success, defined as successful implantation of the device with all target vessels preserved, was 98% (45 of 46), with only one renal artery not successfully preserved. The mean follow-up period was 598 days. During the study period, 18 endoleaks were detected (17 type II and 1 type III), with one patient with a type III endoleak requiring reintervention. Three subjects had died within 30 days, one of intracranial hemorrhage, one of respiratory failure, and one of ischemic colitis. The graft modification times for the TA Treo were significantly shorter (43 minutes) than those for other commercially available devices (Cook Zenith, 55 minutes; Medtronic Endurant, 54 minutes; P < .0001). CONCLUSIONS: Our institution has reported exclusive worldwide experience using the TA Treo device for FEVAR. This device provides for a highly efficient and technically successful procedure for most patients. The procedural and fluoroscopy times were low even in the setting of high complexity. The technical success rates and simplification of the FEVAR procedure have made this approach a preferred technique for most patients at our institution.

Preoperative risk score accuracy confirmed in a modern ruptured abdominal aortic aneurysm experience.

OBJECTIVE: Various risk score calculators used to predict 30-day mortality after treatment of ruptured abdominal aortic aneurysms (rAAAs) have produced mixed results regarding their usefulness and reproducibility. We prospectively validated the accuracy of our preoperative scoring system in a modern cohort of patients with rAAAs. METHODS: A retrospective review of all patients wiith rAAAs who had presented to a single academic center from January 2002 to December 2018 was performed. The patients were divided into three cohorts according to when the institutional practice changes had occurred: the pre-endovascular aneurysm repair (EVAR) era (January 2002 to July 2007), the pre-Harbor View risk score era (August 2007 to October 2013), and the modern era (November 2013 to December 2018). The primary outcome measure was 30-day mortality. Our preoperative risk score assigns 1 point for each of the following: age >76 years, pH <7.2, creatinine >2 mg/dL, and any episode of hypotension (systolic blood pressure <70 mm Hg). The previously reported mortality from a retrospective analysis of the first two cohorts was 22% for 1 point, 69% for 2 points, 78% for 3 points, and 100% for 4 points. The goal of the present study was to prospectively validate the Harborview scoring system in the modern era. RESULTS: During the 17-year study period, 417 patients with rAAAs were treated at our institution. Of the 118 patients treated in the modern era, 45 (38.1%) had undergone open aneurysm repair (OAR), 61 (51.7%) had undergone EVAR, and 12 (10.2%) had received comfort measures only. Excluding the 12 patients without aneurysm repair, we found a statistically significant linear trend between the preoperative risk score and subsequent 30-day mortality for all patients combined (P < .0001), for OAR patients alone (P = .0003), and for EVAR patients alone (P < .0001). After adjustment for the Harborview risk score, the 30-day mortality was 41.3% vs 31.6% after OAR vs EVAR, respectively (P = .2). For all repairs, the 30-day mortality was 14.6% for a score of 0, 35.7% for a score of 1, 68.4% for a score of 2, and 100% for a score of 3 or 4. CONCLUSIONS: Our results, representing one of the largest modern series of rAAAs treated at a single institution, have confirmed the accuracy of a simple 4-point preoperative risk score in predicting 30-day mortality in the modern rAAA patient. Such tools should be used when discussing the treatment options with referring physicians, patients, and their family members to help guide transfer and treatment decision-making.

Intraoperative consultation of vascular surgeons is increasing at a major American trauma center.

OBJECTIVE: Vascular surgeons are often called to aid other surgical specialties for complex exposure, hemorrhage control, or revascularization. The evolving role of the vascular surgeon in the management of intraoperative emergencies involving trauma patients remains undefined. The primary aims of this study included determining the prevalence of intraoperative vascular consultation in trauma, describing how these interactions have changed over time, and characterizing the outcomes achieved by vascular surgeons in these settings. We hypothesized that growing endovascular capabilities of vascular surgeons have resulted in an increased involvement of vascular surgery faculty in the management of the trauma patient over time. METHODS: A retrospective review of all operative cases at a single level I trauma center where a vascular surgeon was involved, but not listed as the primary surgeon, between 2002 and 2017 was performed. Cases were abstracted using Horizon Surgical Manager, a documentation system used in our operating room to track staff present, the type of case, and use. All elective cases were excluded. RESULTS: Of the 256 patients initially identified, 22 were excluded owing to the elective or joint nature of the procedure, leaving 234 emergent operative vascular consultations. Over the 15-year study period, a 529% increase in the number of vascular surgery consultations was seen, with 65% (n = 152) being intraoperative consultations requiring an immediate response. Trauma surgery (n = 103 [44%]) and orthopedic surgery (n = 94 [40%]) were the most common consulting specialties, with both demonstrating a trend of increasing consultations over time (general surgery, 1400%; orthopedic surgery, 220%). Indications for consultation were extremity malperfusion, hemorrhage, and concern for arterial injury. The average operative time for the vascular component of the procedures was 2.4 hours. Of patients presenting with ischemia, revascularization was successful in 94% (n = 116). Hemorrhage was controlled in 99% (n = 122). In-hospital mortality was relatively low at 7% (n = 17). Overall, despite the increase in intraoperative vascular consultations over time, a concomitant increase in the proportion of procedures done using endovascular techniques was not seen. CONCLUSIONS: Vascular surgeons are essential team members at a level I trauma center. Vascular consultation in this setting is often unplanned and often requires immediate intervention. The number of intraoperative vascular consultations is increasing and cannot be attributed solely to an increase in endovascular hemorrhage control, and instead may reflect the declining experience of trauma surgeons with vascular trauma. When consulted, vascular surgeons are effective in quickly gaining control of the situation to provide exposure, hemorrhage control, or revascularization.

The Impact of a Limb Preservation Service on the Incidence of Major Amputations for All Indications at a Level I Trauma Center.

BACKGROUND: Multidisciplinary limb preservation services (LPS) have improved the care of patients with limb-threatening vascular disease. However, the impact of an LPS on major amputations for nonvascular etiologies is unknown. We sought to characterize the trends in major amputations performed at a level I trauma center following the institution of an LPS. METHODS: A retrospective review of all patients undergoing amputation at a level I trauma center from January 2009 to December 2018 was performed. Patients were divided into 2 cohorts: those undergoing amputation pre-LPS (2009-2013) and post-LPS (2014-2018). Major amputations were defined as any amputation at or proximal to the below-knee level. Indications for amputation included chronic limb-threatening ischemia (CLTI), acute limb ischemia (ALI), trauma, infection, and revision amputations. RESULTS: During the study period, 609 major amputations were performed, 490 pre-LPS and 119 post-LPS, representing a 76% reduction. Reductions were seen for every indication, including trauma (95%), ALI (90%), chronic infection (83%), revision (79%), CLTI (68%), and acute infection (62%). CONCLUSIONS: Although previous work has validated the role of an LPS in advanced vascular disease, its value extends beyond vascular disease alone. The drastic reductions seen in the number of amputations performed for a variety of indications, including trauma and diabetic foot infections, further validate the use of a multidisciplinary LPS.

Reevaluating the Need for Routine Coverage of the Left Subclavian Artery in Thoracic Blunt Aortic Injury.

BACKGROUND: Thoracic endovascular aortic repair (TEVAR) is the treatment of choice for thoracic blunt aortic injury (TBAI). A 20 mm proximal seal zone is recommended based on aneurysmal disease literature which often results in coverage of the left subclavian artery (LSA). The aim of this study was to analyze our experience with TEVAR for TBAI and evaluate whether 20 mm is required to achieve successful remodeling. METHODS: This is a single-center, retrospective study of all consecutive patients who received a TEVAR for treatment of moderate and severe TBAI between April 2014 and November 2018. Three-dimensional software reconstruction was used for computed tomography (CT) scan centerline measurements. Outcomes included technical success, need for reinterventions, and immediate and long-term aortic-related complications. RESULTS: Sixty-one patients underwent TEVAR for TBAI during the study period. Twenty-eight (46%) patients underwent LSA coverage with an average distance from the LSA to the injury of 6.4 mm (0-15.1 mm). Of the 33 (54%) patients who did not undergo coverage of the LSA, 22 patients (66%) had less than 20 mm of proximal seal zone. The mean distance from the LSA to injury in this group was 16.6 mm (7.9-29.5 mm). None of the patients with LSA coverage developed ischemic symptoms, and an average decrease in left arm systolic blood pressure of 24.8 mm Hg (0-62 mm Hg) was noted versus the right arm. There was no aortic-related mortality in either group. Follow-up CT scans revealed excellent remodeling. CONCLUSIONS: Immediate outcomes of TEVAR for TBAI with LSA coverage are well tolerated; however, the long-term sequela of LSA coverage is unknown. Exclusion of the injury and excellent remodeling appear to occur with less than 20 mm of proximal seal, and perhaps more attention should be made to preservation of the LSA.

Emerging practice patterns in vascular surgery during the COVID-19 pandemic.

OBJECTIVE: Ever since the first positive test was identified on January 21, 2020, Washington State has been on the frontlines of the coronavirus disease 2019 (COVID-19) pandemic. Using information obtained from Italian surgeons in Milan and given the concerns regarding the increasing case numbers in Washington State, we implemented new vascular surgery guidelines, which canceled all nonemergent surgical procedures and involved significant changes to our inpatient and outpatient workflow. The consequences of these decisions are not yet understood. METHODS: The vascular surgery division at Harborview Medical Center immediately instituted new vascular surgery COVID-19 practice guidelines on March 17, 2020. Subsequent clinic, operative, and consultation volume data were collected for the next 4 weeks and compared with the historical averages. The Washington State case and death numbers and University of Washington Medical Center (UW Medicine) hospital case volumes were collected from publicly available sources. RESULTS: Since March 10, 2020, the number of confirmed positive COVID-19 cases within the UW Medicine system has increased 1867%, with floor and intensive care unit bed usage increasing by 120% and 215%, respectively. After instituting our new COVID-19 guidelines, our average weekly clinical volume decreased by 96.5% (from 43.1 patients to 1.5 patients per week), our average weekly surgical volume decreased by 71.7% (from 15 cases to 4.25 cases per week), and our inpatient consultation volume decreased to 1.81 consultations daily; 60% of the consultations were completed as telemedicine "e-consults" in which the patient was never evaluated in-person. The trainee surgical volume has also decreased by 86.4% for the vascular surgery fellow and 84.8% for the integrated resident. CONCLUSIONS: The COVID-19 pandemic has changed every aspect of "normal" vascular surgical practice in a large academic institution. New practice guidelines effectively reduced operating room usage and decreased staff and trainee exposure to potential infection, with the changes to clinic volume not resulting in an immediate increase in emergency department or inpatient consultations or acute surgical emergencies. These changes, although preserving resources, have also reduced trainee exposure and operative volume significantly, which requires new modes of education delivery. The lessons learned during the COVID-19 pandemic, if analyzed, will help us prepare for the next crisis.

Re-evaluating the safety and effectiveness of the 0.9 ankle-brachial index threshold in penetrating lower extremity trauma.

OBJECTIVE: Current guidelines recommend additional imaging when the ankle-brachial index (ABI) is ≤0.9 after extremity trauma; however, the accuracy of this 0.9 threshold compared with other values has not been evaluated. The primary aim of this study was to compare the safety and effectiveness of various ABI thresholds in predicting lower extremity vascular injuries after penetrating trauma. We hypothesized that a lower ABI threshold can be used safely to avoid unnecessary imaging. METHODS: A retrospective cohort study was performed at a single level I trauma center from January 2015 to December 2017. All patients who presented with penetrating lower extremity trauma and who underwent computed tomography angiography (CTA) were reviewed. Patients taken directly to the operating room without first undergoing CTA or those without documented ABIs were excluded. Demographic information, clinical features of presentation, interventions performed, and outcomes were recorded. P values were obtained using the Kolmogorov-Smirnov test, and a receiver operating characteristic curve was created to compare various ABI thresholds. RESULTS: A total of 47 patients (81% male), with a mean age of 29 years (range, 14-59 years), met inclusion criteria. Of the 17 limbs (36%) with a vascular abnormality seen on CTA, 6 (35%) required an intervention. The distribution of ABIs in injured limbs requiring revascularization was significantly lower (P = .006) than in those that did not require intervention. An ABI threshold of 0.7 is most accurate, with the highest combined sensitivity (83%) and specificity (91%) for detecting vascular injuries requiring revascularization. In addition, the negative predictive value was no different between a threshold of 0.7 (98%) and a threshold of 0.9 (97%), with both thresholds missing one vascular injury (pseudoaneurysm) requiring repair. CONCLUSIONS: The ABI remains reliable in distinguishing between limbs with and limbs without vascular injury requiring revascularization after penetrating lower extremity trauma. A lower threshold can safely be used without compromising the negative predictive value of a screening ABI. Applying a threshold of 0.7 to our cohort would have avoided 51% (24) of the CTA studies performed without missing additional vascular injuries requiring repair.

Lowering the Ankle-Brachial Index Threshold in Blunt Lower Extremity Trauma May Prevent Unnecessary Imaging.

BACKGROUND: Current algorithms for the management of blunt lower extremity trauma recommend additional imaging in patients presenting with soft signs of vascular injury and an ankle-brachial index (ABI) less than 0.9. The aim of this study is to analyze lower extremity computed tomography angiographies (CTAs) to determine the incidence and characteristics of patients sustaining vascular injury from blunt lower extremity trauma. We hypothesized that a lower ABI threshold can avoid unnecessary imaging without missing clinically significant vascular injury. METHODS: A single-center, retrospective review of all consecutive patients who presented to a level 1 trauma center with blunt lower extremity trauma and underwent a CTA from January 2015 to December 2017 was conducted. Baseline demographics, clinical features, and outcomes were recorded. Patients without documented ABIs were excluded. A receiver operating characteristic curve was used to define the ABI threshold. RESULTS: One hundred twenty-five patients (133 injured limbs) met inclusion criteria. The mean age was 44 years (range 9-96), and 74% of the patients were male. A vascular abnormality was identified on CTA in 65 limbs (48.9%), of which only 8 (12%) required intervention. The ABIs in these 8 injured limbs were between 0 and 0.6. An ABI threshold of 0.6 maximized the balance between sensitivity (100%) and specificity (87%) and missed no injuries requiring revascularization. CONCLUSIONS: The ABI remains useful in evaluating blunt lower extremity trauma. A lower ABI threshold in patients presenting with soft signs of vascular injury after blunt trauma may avoid unnecessary imaging without missing vascular injuries requiring intervention. Further prospective studies are needed to validate the safety and effectiveness of a lower ABI threshold.

Safety of transfer, type of procedure, and factors predictive of limb salvage in a modern series of acute limb ischemia.

OBJECTIVE: The primary objective was to evaluate the safety of transfer, type of procedure, and factors associated with limb salvage in patients with acute limb ischemia (ALI) treated at a quaternary referral center. METHODS: A retrospective review of all patients with ALI secondary to thrombotic or embolic occlusion at a quaternary referral hospital from 2013 to 2016 was conducted. Patients were transferred from throughout Washington and Alaska by ambulance, helicopter, or fixed-wing modes of transportation. Demographics, transport and operative timing, Rutherford classification, level of occlusion, procedural information, and fasciotomy characteristics were reviewed. Outcomes measured included limb salvage rates, discharge disposition, and mortality. RESULTS: One hundred twelve patients with ALI were identified, with 82% due to thrombosis and 18% due to arterial embolization. Fifty-seven percent of patients were transferred from a referring hospital with low mean transfer times (1.9 hours for embolic, 2.7 hours for thrombotic). Although the initial operative strategy varied according to the etiology, with 50% of thrombotic occlusions treated with endovascular therapies and 80% of embolic occlusions treated with open thrombectomy, the rates of limb salvage did not vary based on operative approach (92% endovascular first, 90% open first). Further, limb salvage rates were identical between transferred and nontransferred patients (77%). Limb salvage was successful in 91% of patients with Rutherford class 1 and 2 disease, but only 8% in patients with Rutherford class 3 disease. In-hospital and 30-day mortality rates were not different based on ischemic etiology (5%), although patients with Rutherford class 3 disease had significantly higher mortality rates (15%) compared with patients with class 1 (6%), class 2a (6%), and class 2b (2%) disease. Fasciotomy was performed in 29% of patients, with 59% of fasciotomy wounds closed primarily. Predictors of amputation include multiple attempts at limb salvage, higher Rutherford class, multilevel occlusion, more proximal levels of occlusion, and nonviable muscle seen after fasciotomy, with ischemic times trending toward higher amputation rates without statistical significance. There was no difference in discharge disposition based on ischemic etiology. CONCLUSIONS: The modern treatment of patients with ALI is effective, with high rates of limb salvage and low mortality regardless of transfer status, etiology, or initial operation performed. In situations where compartment syndrome is unclear, fasciotomy should not be withheld because it provides valuable predictive information regarding limb salvage.

APOE3, but not APOE4, bone marrow transplantation mitigates behavioral and pathological changes in a mouse model of Alzheimer disease.

Apolipoprotein E4 (APOE4) genotype is the strongest genetic risk factor for late-onset Alzheimer disease and confers a proinflammatory, neurotoxic phenotype to microglia. Here, we tested the hypothesis that bone marrow cell APOE genotype modulates pathological progression in experimental Alzheimer disease. We performed bone marrow transplants (BMT) from green fluorescent protein-expressing human APOE3/3 or APOE4/4 donor mice into lethally irradiated 5-month-old APPswe/PS1ΔE9 mice. Eight months later, APOE4/4 BMT-recipient APPswe/PS1ΔE9 mice had significantly impaired spatial working memory and increased detergent-soluble and plaque Aß compared with APOE3/3 BMT-recipient APPswe/PS1ΔE9 mice. BMT-derived microglia engraftment was significantly reduced in APOE4/4 recipients, who also had correspondingly less cerebral apoE. Gene expression analysis in cerebral cortex of APOE3/3 BMT recipients showed reduced expression of tumor necrosis factor-α and macrophage migration inhibitory factor (both neurotoxic cytokines) and elevated immunomodulatory IL-10 expression in APOE3/3 recipients compared with those that received APOE4/4 bone marrow. This was not due to detectable APOE-specific differences in expression of microglial major histocompatibility complex class II, C-C chemokine receptor (CCR) type 1, CCR2, CX3C chemokine receptor 1 (CX3CR1), or C5a anaphylatoxin chemotactic receptor (C5aR). Together, these findings suggest that BMT-derived APOE3-expressing cells are superior to those that express APOE4 in their ability to mitigate the behavioral and neuropathological changes in experimental Alzheimer disease.

Surgical release of anterior tibial artery entrapment with associated popliteal artery entrapment.

Popliteal artery entrapment syndrome (PAES) is compression of the popliteal artery from embryologic myotendinous variation or calf muscle hypertrophy. PAES necessitates prompt diagnosis and complete release of the entrapped vasculature for symptom relief and to prevent chronic cumulative vascular damage. Our patient is a 27-year-old female referred for progressive bilateral claudication. Workup was consistent with bilateral PAES with preoperative imaging notable for an atypically proximal origin of the anterior tibial artery, which was also encased anterior to the popliteus muscle. Preoperative angiogram confirmed the diagnosis, and complete surgical release resolved symptoms by 4 months postoperatively.

Ablation of the microglial protein DOCK2 reduces amyloid burden in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) neuropathology is characterized by innate immune activation primarily through prostaglandin E2 (PGE2) signaling. Dedicator of cytokinesis 2 (DOCK2) is a guanyl nucleotide exchange factor expressed exclusively in microglia in the brain and is regulated by PGE2 receptor EP2. DOCK2 modulates microglia cytokine secretion, phagocytosis, and paracrine neurotoxicity. EP2 ablation in experimental AD results in reduced oxidative damage and amyloid beta (Aß) burden. This discovery led us to hypothesize that genetic ablation of DOCK2 would replicate the anti-Aß effects of loss of EP2 in experimental AD. To test this hypothesis, we crossed mice that lacked DOCK2 (DOCK2-/-), were hemizygous for DOCK2 (DOCK2+/-), or that expressed two DOCK2 genes (DOCK2+/+) with APPswe-PS1Δe9 mice (a model of AD). While we found no DOCK2-dependent differences in cortex or in hippocampal microglia density or morphology in APPswe-PS1Δe9 mice, cerebral cortical and hippocampal Aß plaque area and size were significantly reduced in 10-month-old APPswe-PS1Δe9/DOCK2-/- mice compared with APPswe-PS1Δe9/DOCK2+/+ controls. DOCK2 hemizygous APPswe-PS1Δe9 mice had intermediate Aß plaque levels. Interestingly, soluble Aß42 was not significantly different among the three genotypes, suggesting the effects were mediated specifically in fibrillar Aß. In combination with earlier cell culture results, our in vivo results presented here suggest DOCK2 contributes to Aß plaque burden via regulation of microglial innate immune function and may represent a novel therapeutic target for AD.

Bilateral internal iliac branch device with ipsilateral deployment.

Iliac branch endograft devices offer an elegant solution to preserve perfusion to the internal iliac artery when treating aortoiliac aneurysms; however, they are difficult to perform when bilateral access is not available owing to aortoiliac anatomy or previous endovascular aortic aneurysm repair. We present a technique to perform iliac branch endograft deployment from ipsilateral access in a patient with a prior EVAR endovascular aortic aneurysm repair, obviating the need for a difficult up-and-over access.

Axillary Artery Pseudoaneurysm After Revision Plate Osteosynthesis of a Midshaft Clavicle Fracture Nonunion: A Case Report.

CASE: A patient with history of nonunion repair of traumatic midshaft clavicle fracture was referred to our orthopaedic trauma clinic for new-onset shoulder pain and paresthesias involving the ipsilateral arm. Computed tomography angiography revealed an axillary artery pseudoaneurysm adjacent to the instrumentation and recurrent nonunion of the fracture site. The patient underwent coil embolization of the pseudoaneurysm and nonunion repair. CONCLUSION: This case demonstrates that iatrogenic neurovascular injury during clavicle fracture nonunion repairs can present in a delayed fashion requiring more thorough clinical and imaging evaluation to achieve successful treatment.

Suppressed retinal degeneration in aged wild type and APPswe/PS1ΔE9 mice by bone marrow transplantation.

Alzheimer's disease (AD) is an age-related condition characterized by accumulation of neurotoxic amyloid ß peptides (Aß) in brain and retina. Because bone marrow transplantation (BMT) results in decreased cerebral Aß in experimental AD, we hypothesized that BMT would mitigate retinal neurotoxicity through decreased retinal Aß. To test this, we performed BMT in APPswe/PS1ΔE9 double transgenic mice using green fluorescent protein expressing wild type (wt) mice as marrow donors. We first examined retinas from control, non-transplanted, aged AD mice and found a two-fold increase in microglia compared with wt mice, prominent inner retinal Aß and paired helical filament-tau, and decreased retinal ganglion cell layer neurons. BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels. Aß and paired helical filament-tau were reduced (61.0% and 44.1% respectively) in BMT-recipient AD mice, which had 20.8% more retinal ganglion cell layer neurons than non-transplanted AD controls. Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls. Quantitation of retinal ganglion cell layer neurons in young mice confirmed age-related retinal degeneration was mitigated by BMT. We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons. Thus, BMT is neuroprotective in age-related as well as AD-related retinal degeneration, and may be a result of alterations in innate immune function and oxidative stress in BMT recipient mice.