An Evaluation of Patient Characteristics Associated With Medical Disposition in the Surgical Treatment of Ankle Fractures.

The objective of this investigation was to evaluate patient characteristics associated with medical disposition in treatment of ankle fractures. The 2018 American College of Surgeons National Surgical Quality Improvement Program database was interrogated with data extracted related to the 6 current procedural terminology (CPT) codes available pertaining to ankle fractures: 27766, 27769, 27792, 27814, 27822, and 27823. The primary outcome analysis involved a comparison of patient characteristics and short-term adverse outcomes between those fractures repaired on an inpatient basis versus outpatient basis. A secondary analysis was then performed on patient characteristics and adverse short-term outcomes between those fractures treated on an inpatient basis who were discharged home versus elsewhere. Age (p < .001), race (p < .001), ethnicity (p < .001), body mass index (BMI) (p < .001), estimated probability of mortality (p < .001), estimated probability of morbidity (p < .001), CPT code of fracture designation (p < .001), functional status (p < .001), elective surgery designation (p < .001), American Society of Anesthesiologists class (p < .001), diabetes (p < .001), smoking status (p < .001), dyspnea (p < .001), COPD (p < .001), congestive heart failure (p < .001), hypertension (p < .001), dialysis (p < .001), cancer (p < .001), steroid use (p < .001), blood transfusion history (p < .001), and sepsis/systemic inflammatory response syndrome history (p < .001) were all independently associated with the ankle fracture repair being performed on an inpatient basis on regression analysis. Age (p < .001), race (p = .025), ethnicity (p < .001), BMI (p = .001), CPT code of fracture designation (p < .001), preoperative functional status (p < .001), and American Society of Anesthesiologists class (p < .001) were all independently associated with inpatient ankle fracture repairs being discharged to home following the procedure on regression analysis. The results of this investigation demonstrate that differences in patient demographic characteristics might contribute to medical decision-making as it relates to patient management and discharge disposition in the treatment of ankle fractures.

Flagellum couples cell shape to motility in Trypanosoma brucei.

In the unicellular parasite Trypanosoma brucei, the causative agent of human African sleeping sickness, complex swimming behavior is driven by a flagellum laterally attached to the long and slender cell body. Using microfluidic assays, we demonstrated that T. brucei can penetrate through an orifice smaller than its maximum diameter. Efficient motility and penetration depend on active flagellar beating. To understand how active beating of the flagellum affects the cell body, we genetically engineered T. brucei to produce anucleate cytoplasts (zoids and minis) with different flagellar attachment configurations and different swimming behaviors. We used cryo-electron tomography (cryo-ET) to visualize zoids and minis vitrified in different motility states. We showed that flagellar wave patterns reflective of their motility states are coupled to cytoskeleton deformation. Based on these observations, we propose a mechanism for how flagellum beating can deform the cell body via a flexible connection between the flagellar axoneme and the cell body. This mechanism may be critical for T. brucei to disseminate in its host through size-limiting barriers.

Co-Operative Vascular Intervention Disease (COVID) Team of Greater Philadelphia.

We established the Co-Operative Vascular Intervention Disease (COVID) Team of Greater Philadelphia because national guidelines may not apply to different geographic areas of the United States owing to varying penetrance of the virus. On April 10, 2020, a 10-question survey regarding issues and strategies dealing with COVID-19 was e-mailed to 58 vascular surgeons (VSs) in the Greater Philadelphia area. Fifty-four VSs in 18 surgical groups covering 28 hospitals responded. All groups accepted transfers because of continued availability of intensive care unit beds. Thirteen groups were asked to "redeploy" if the need arose to function outside of the usual duties of a VS. None imposed age restrictions regarding older VSs continuing clinical hospital work. The majority restricted noninvasive vascular laboratory studies to those studies for which findings might mandate intervention within 2 or 3 weeks, restricted dialysis access operations to urgent revisions of arteriovenous fistulas or grafts that were failing or had ulcerations, converted from in-person to telemedicine clinic interactions, and experienced moderate-severe anxiety or fear about personal COVID-19 exposure in the hospital. The majority of VSs in the Philadelphia area dramatically adjusted their clinical practices before the COVID-19 crisis reached peak levels experienced in other metropolitan areas.

Site of service influence on stent use for hemodialysis access interventions.

OBJECTIVE: With rising health care spending in the United States, the Centers for Medicare and Medicaid Services (CMS) in recent years attempted to use reimbursement rates to influence use of less expensive care sites for covered patients, such as ambulatory surgery centers (ASCs) and office-based laboratories (OBLs), in lieu of hospital service sites. It has been suggested that cost savings have not been realized because of more procedures being performed by physicians with ownership interests in nonhospital facilities. CMS adopted massive reimbursement changes for 2019 OBL and ASC-based procedures, which reduced dialysis access angioplasty reimbursement in the ASC setting by 50%, whereas facility reimbursement for stenting increased by 33% above prior levels. The clinical utility of adjunctive stenting in treating dialysis access stenosis remains controversial and highly discretionary. As a vascular group performing such procedures in both a hospital and nonhospital facility in which we have equity interest, we reviewed our use of stents in dialysis access procedures both in the hospital and in the ASC/OBL to determine whether site of service affected stent use. METHODS: A retrospective review of a prospectively maintained database was performed from 2014 to 2018. All patients undergoing dialysis access angiography with angioplasty and adjunctive stent placement at our OBL (later ASC) and our primary hospital were included in the study. RESULTS: There were 961 angioplasty or stent procedures performed for dialysis accesses between the two sites, 564 (58.7%) in the hospital setting and 397 (41.3%) at the OBL/ASC. There was a significant difference in race and age between the two sites, with younger, minority patients more frequently being treated in the hospital and older, white patients more likely to be treated in the ambulatory setting; 153 (27.1%) underwent adjunctive stent placement in the hospital and 127 (32.0%) in the ambulatory setting (P = .09). CONCLUSIONS: Whereas financial incentives have not yet had an appreciable influence on stent use for dialysis access within previous reimbursement paradigms, the dramatic changes recently adopted by CMS may well alter this dynamic and could lead to substantially higher overall costs without proven clinical advantage. Interventionalists may be incentivized to add stents when performing balloon angioplasty in ASCs. With high failure and reintervention rates and increasingly expensive adjuncts (drug-coated balloons and stents, covered stents), the cost implications of attempts to incentivize interventionalists toward a specific type of procedure or site of care are substantial, and unintended negative consequences are likely to occur.

Duplex Ultrasound for Diagnosis of Failing Stents Placed for Lower Extremity Arterial Occlusive Disease.

BACKGROUND: Noninvasive diagnostic testing may be beneficial to identify stenotic (failing) stents placed for occlusive lower extremity peripheral arterial disease (LEPAD), especially if subsequent intervention proves useful in maintaining prolonged stent patency. We previously documented the benefit of surveillance duplex ultrasound (DU) for peripheral covered stents (stent grafts). The purpose of this study was to evaluate whether DU can reliably diagnose failing bare metal stents placed in iliac, femoral, and popliteal arteries for LEPAD. METHODS: Between January 1, 2013, and December 31, 2016, 172 stents were placed for LEPAD in 119 arterial segments (1.4 stents/stenotic artery) in 110 patients who underwent one or more DU surveillance study documenting stent patency. Poststent DU surveillance was performed in our Intersocietal Accreditation Commission accredited noninvasive vascular lab at 1 week and then every 6 months. DU measured peak systolic velocities (PSVs) and ratio of adjacent PSVs (Vr) every 2.0 cm within the stent(s) and adjacent arteries. We retrospectively classified the following factors as "abnormal DU findings": focal PSVs >300 cm/s, uniform PSVs <45 cm/s, and Vr > 3.0. RESULTS: During average follow-up of 22 months (range, 1 week-48 months), all three of these DU criteria were "normal" in 62 (52%) of the 119 stented segments. Of the other 57 (48%) stented arterial segments that had one or more abnormal DU findings, 40 underwent prophylactic intervention, 12 patients did not undergo intervention and subsequently occluded (5 patient refusal, 4 surgeon-decision, 3 shortened surveillance interval), and 5 remained patent after mean follow-up of 7.2 months. Of the 12 arterial segments that occluded, 6 patients chose not to have further intervention, 4 failed additional endovascular intervention and required an arterial bypass, and 2 required amputation. Therefore, of the 17 stented arterial segments with one or more abnormal DU findings that did not undergo intervention, 12 (70%) went on to occlude versus 2 of 62 (3%) with normal DU findings demonstrating an odds ratio of 72.0 (95% CI 12.5-415.6, P < 0.0001). Of these 12 stented arterial segments with abnormal DU findings that occluded, 7 had uniform low PSVs alone, 3 had both abnormal PSV and Vr's, and 2 had abnormal Vr's alone. CONCLUSIONS: DU surveillance can predict LEPAD stent occlusion. While PSV >300 cm/sec alone is not a statistically significant predictor of stent failure, Vr > 3.0, and most importantly, uniform PSVs <45 cm/s throughout the stent were statistically reliable markers for predicting stent thrombosis, while the absence of any of these abnormalities strongly predicted stent patency.

Lateral femoral bypass for prosthetic arterial graft infections in the groin.

OBJECTIVE: Prosthetic arterial graft infections (PAGIs) in the groin pose significant challenges in terms of revascularization options and risk of limb loss as well as associated morbidities. Although obturator canal bypass (OCB) has been suggested for revascularization of the extremity in these cases, moderate success rates and technical challenges have limited widespread use. Our study analyzed lateral femoral bypass (LFB) as an alternative approach for the treatment of groin PAGIs. METHODS: This is a retrospective review of a prospectively maintained database of patients who underwent LFB for groin PAGIs at a single center from 2000 to 2017. Patients' data including demographics, comorbidities, perioperative complications, graft patency, and need for reintervention were used. Patients were observed after LFB with duplex ultrasound surveillance in an accredited noninvasive vascular laboratory every 3 months during the first year, followed by every 6 months for the second year and yearly thereafter. After isolation of the infected wound with sterile dressings, remote proximal and distal arterial exposure incisions were made. LFBs were tunneled under the inguinal ligament and lateral to the infected wound from an uninvolved inflow artery or bypass graft to an uninvolved outflow vessel. RESULTS: A total of 19 LFBs were performed in 16 patients (mean age, 69 ± 12.6 years). Three LFBs were performed urgently for acute bleeding. Choice of conduit included 6 (31.6%) autogenous vein grafts, 10 (52.6%) cadaveric grafts, 2 (10.5%) rifampin-soaked Dacron grafts, and 1 (5.3%) polytetrafluoroethylene graft. Average follow-up was 33 months (range, 0-103 months). Major adverse events occurring within 30 days of the operation included one (5.3%) death and one (5.3%) graft excision for pseudoaneurysm. Primary patency and primary assisted patency at 12 and 24 months were 73% and 83%, respectively. One patient required an amputation 17 months after surgery after failure of repeated revascularization attempts. Overall limb salvage was 93.8% during this follow-up period. CONCLUSIONS: In this series, LFB for management of groin PAGIs demonstrated higher patency and limb salvage rates compared with previous reports of OCB. Diligent postoperative duplex ultrasound surveillance is critical to the achievement of limb salvage and maintenance of graft patency. These results suggest that LFB, which is technically less complex than OCB, should be considered the first choice for revascularization in select cases of PAGIs involving the groin.

Patient satisfaction and chronic illness are predictors of postendovascular aneurysm repair surveillance compliance.

OBJECTIVE: Although lifelong surveillance is recommended by the Society for Vascular Surgery for patients undergoing endovascular aneurysm repair (EVAR) reported that compliance with long-term follow-up has been poor. We sought to identify factors that predict compliance with EVAR surveillance through analysis of patient variables and post-EVAR questionnaire results. METHODS: We analyzed 28 patient variables gathered from our computerized registry, patient charts, and phone questionnaires of patients who underwent EVAR between January 1, 2010, and December 31, 2014. These factors included patient demographics, education, postoperative complications, satisfaction with vascular surgery care, transportation mode, distance to our medical center, and living situation. Compliance was defined as a patient who underwent the most recent recommended follow-up surveillance study within the prescribed timeframe. Post-EVAR surveillance protocol consisted of office evaluation and duplex ultrasound examination performed in our accredited noninvasive vascular laboratory at 1 week, 6 months, then annually. Computed tomography angiography was obtained only if duplex ultrasound examination suggested endoleak, sac enlargement of more than 5 mm, or a failing limb. RESULTS: Of 144 patients who underwent EVAR during this time period, 89 patients (62%) were compliant with the most recent recommended follow-up study. One hundred two patients completed the questionnaire or their families did if patients died or were incapacitated. Of those, 80 were compliant with follow-up and 22 were not. Based on the questionnaires of these 102 patients, estimated compliance at 3 years after EVAR was 69.6 ± 6.0% based on Kaplan-Meier analysis. In the compliant vs noncompliant groups, the estimated 3-year survival rate was 93.2 ± 3.4% vs 52.4 ± 12.7%, respectively (P < .001), and the estimated 5-year survival rate was 83.1 ± 6.4% vs 34.4 ± 13.4%, respectively (P < .001), respectively. However, none of the mortalities observed in the noncompliant group were aneurysm related. Adverse neurologic events after EVAR demonstrated a trend predicting noncompliance after 5 years based on multivariate Cox regression analysis (hazard ratio [HR], 2.57; 95% confidence interval [CI], 0.95-6.90; P = .062). Patient dissatisfaction with their vascular surgeon and hospital care predicted noncompliance with recommended postoperative surveillance (HR, 5.0; 95% CI, 1.52-16.7; P = .008). College education or higher was associated with compliance (HR, 0.28; 95% CI, 0.06-1.23; P = .092). No other variables, including postoperative complications or distance from the hospital, predicted follow-up noncompliance. CONCLUSIONS: Patient satisfaction with their vascular surgeon and hospital experience predicted compliance with post-EVAR surveillance regardless of postoperative complications. Noncompliant patients had decreased survival, but mortality and surveillance noncompliance were likely due to disabling chronic disease.

Outcomes of Brachial Artery Access for Endovascular Interventions.

BACKGROUND: A percutaneous brachial artery (BA) approach is a suitable or even favorable alternative to femoral artery access when performing certain endovascular interventions. However, this approach may have a higher complication rate compared to femoral artery access. We analyzed our results using percutaneous BA approach for noncardiac endovascular interventions. METHODS: Between January 1, 2003 and December 31, 2017, BA access was used in 157 cases performed on 136 patients. The procedures included 102 (65%) therapeutic interventions and 55 (35%) diagnostic studies. The vessels studied or treated included lower extremity arteries (48), the aorta and iliac arteries (45), mesenteric arteries (45), failing arterial revascularizations (24), renal arteries (9), subclavian arteries (8), carotid arteries (2), and visceral aneurysms (2), or in conjunction with endovascular aneurysm repair (EVAR), fenestrated EVAR, or thoracic EVAR (8). More than 1 vessel was studied or treated in 34 cases. Sheath sizes included 5F in 38 (24%) cases, 6F in 93 (59%) cases, and 7F in 26 (17%) cases. Percutaneous puncture was utilized in 142 (90.4%) cases and planned surgical exposure with primary closure of the BA in 15 (9.6%) cases (10, 7F; 4, 6F; 1, 5F). Manual compression was used for hemostasis at the conclusion of all percutaneous cases. RESULTS: There were 2 (1.3%; 2/157 cases) deaths in the perioperative period, one due to myocardial infarction and the other from mesenteric ischemia. Access site complications occurred in 10.6% (15/142) of percutaneous cases, which required open surgical repair for bleeding (8) and BA thrombosis (7). There was an increased risk of complications with increasing sheath size in the percutaneous approach: 5.4% (2/37), 12.4% (11/89), and 12.5% (2/16) for 5F, 6F, and 7F sheaths, respectively (P = 0.49). None of the 15 patients who underwent surgical treatment suffered long-term vascular or neuropathic complications. CONCLUSIONS: In our experience, percutaneous BA access was associated with a 10% complication rate with an increased risk of complications associated with increasing sheath size. There was approximately the same incidence of bleeding as thrombosis. For patients who require 6 or 7F sheaths via a BA approach, we recommend more liberal use of open surgical exposure and primary BA repair.

Late type II endoleaks after endovascular aneurysm repair require intervention more frequently than early type II endoleaks.

OBJECTIVE: Type II endoleaks (T2ELs) are commonly observed after endovascular aneurysm repair (EVAR). We sought to determine whether time at onset of T2ELs correlated with the need to intervene based on sac expansion or rupture. METHODS: Between 1998 and 2015, 462 EVARs performed at our institution had duplex ultrasound surveillance in our accredited noninvasive vascular laboratory. Computed tomography and arteriography were reserved for abnormal duplex ultrasound findings. The need for intervention for T2ELs was classified according to time at onset after EVAR. Interventions for T2ELs were performed only for sac expansion >5 mm or rupture. We defined early-onset T2ELs as <1 year after EVAR and delayed or late onset as >1 year of follow-up. RESULTS: Of the 462 EVARs, 96 patients (21%) developed T2ELs after implantation. Of these, 65 (68%) had early and 31 (32%) had late onset (mean, 12 months; range, 1-112 months). Early T2ELs resolved without treatment in 75% (49/65) of cases compared with only 29% (9/31) of late T2ELs (P < .0001). Intervention was required for only 8% (5/65) of patients with early T2ELs (5 sac expansions, 0 ruptures) compared with 55% (17/31) for late T2ELs (16 sac expansions, 1 rupture; P < .0001). The remaining patients were observed for persistent T2ELs with no sac growth (17% [11/65] early vs 16% [5/31] late; P = .922). CONCLUSIONS: Less than one-third (29%) of T2ELs that develop after 1 year will resolve spontaneously and about half (55%) will require intervention for sac growth or rupture. T2ELs that develop >1 year after EVAR should be followed up with a more frequent surveillance protocol and perhaps with a lower threshold to intervene.

Low carotid stump pressure as a predictor for ischemic symptoms and as a marker for compromised cerebral reserve in octogenarians undergoing carotid endarterectomy.

BACKGROUND: Carotid artery occlusive disease can cause stroke by embolization, thrombosis, and hypoperfusion. The majority of strokes secondary to cervical carotid atherosclerosis are believed to be of embolic etiology. However, cerebral hypoperfusion could be an important factor in perioperative stroke. We retrospectively reviewed the stump pressure (SP) of carotid endarterectomy (CEA) of patients at Pennsylvania Hospital to identify whether physiologic perfusion differences account for differences in perioperative stroke rates, particularly in octogenarians. METHODS: We conducted a retrospective review of our prospectively maintained database for CEA performed between 1992 and 2015. SP was measured and recorded for 1190 patients. A low SP was defined as systolic pressure <50 mm Hg. Shunts were used only for patients under general anesthesia with SP <50 mm Hg, for awake patients with neurologic changes with carotid clamping, and in some patients with recent stroke. RESULTS: Symptomatic patients were more likely to have SP <50 mm Hg compared with asymptomatic patients (35.6% vs 26.2%; P = .0015). Patients having SP <50 mm Hg had a higher postoperative stroke rate compared with patients with SP >50 mm Hg (2.9% vs 0.9%; P = .0174). Octogenarians were more likely to have a lower SP compared with patients younger than 80 years (35.7% vs 27.7%; P = .0328). Symptomatic patients with low SP were at highest risk for perioperative stroke (6.4% vs 1.2%; P = .001) compared with patients without these factors. CONCLUSIONS: SP is a marker for decreased cerebrovascular reserve and along with symptomatic status identifies those at highest risk for periprocedural stroke with CEA. Whereas patients older than 80 years may benefit from carotid intervention, they are likely to be at somewhat elevated stroke risk because of higher prevalence of low SP, and shunting does not eliminate this risk.

Acute streptococcal meningitis presenting as bilateral conductive hearing loss.

Bacterial meningitis is a relatively uncommon condition encountered in the emergency department and the constellation of symptoms varies. Hearing loss has been well documented in the literature as a complication of the disease process, but not as the presenting complaint. We describe a case of a 59-year-old female who presented to the emergency department with sudden onset bilateral hearing loss who was found to have S. pneumonia meningitis bacterial meningitis. Even with advances in therapy, bacterial meningitis still carries a significant mortality rate. Early diagnosis and treatment is critical to achieving good outcomes.

The fate of endovascular aortic aneurysm repair after 5 years monitored with duplex ultrasound imaging.

BACKGROUND: Interventions for aortic aneurysm sac growth have been reported across multiple time points after endovascular aortic aneurysm repair (EVAR). We report the long-term outcomes of patients after EVAR monitored with duplex ultrasound (DUS) imaging with respect to the need for and type of intervention after 5 years. METHODS: We report a series of patients who were monitored with DUS imaging for a minimum of 5 years after EVAR. DUS imaging was performed in an accredited noninvasive vascular laboratory, and computed tomography angiography was only performed for abnormal DUS findings. RESULTS: There were 156 patients who underwent EVAR with follow-up >5 years (mean, 7.5 years; range, 5.1-14.5 years). Interventions for endoleak, graft limb stenosis, or thrombosis were performed in 44 patients (28%) at some time during follow-up. Of the 156 patients, 34 (22%) underwent their first intervention during the first 5 years (25 endoleaks, 9 limb stenoses, or occlusions). Four ruptures occurred, all in patients with their first intervention before 5 years. The remaining 10 patients (6%) underwent a first intervention >5 years after implantation: 3 for type I endoleak, 2 for type II endoleak with sac expansion, 2 for combined type I and II endoleaks 2 for type III endoleak, and 1 unknown type. CONCLUSIONS: Long-term follow-up of EVAR (mean, 7.5 years) revealed that approximately one in four patients will require intervention at some point during follow-up. First-time interventions were necessary in 22% of all patients in the first 5 years and in 6% of patients after 5 years, highlighting the need for continued graft surveillance beyond 5 years. All patients who had a first-time intervention after 5 years underwent an endoleak repair; none of these patients had a thrombosed limb or a rupture as a result of the endoleak.

Bovine carotid artery xenografts for hemodialysis access.

OBJECTIVE: Bovine carotid artery (BCA) grafts have been described as a possibly superior alternative to expanded polytetrafluoroethylene hemoaccess grafts. However, published experience remains limited, and patency rates for nonautogenous arteriovenous grafts remain unsatisfactory. We report herein the largest published experience with the current generation of BCA grafts for dialysis access and analyze subgroups to determine whether obesity, gender, or prior access surgery influences patency. METHODS: We retrospectively reviewed 134 BCA grafts (Artegraft, North Brunswick, NJ) implanted for hemodialysis access in the upper extremities of 126 patients between January 2012 and May 2015. Patients had a mean of 1.8 prior access operations. Primary, primary assisted, and secondary patency rates were calculated using the Kaplan-Meier method, and longitudinal infection risk was tabulated. Patency differences were calculated using the log-rank method. RESULTS: For the entire group, 1-year primary patency was 32%, primary assisted patency was 49%, and secondary patency was 78%. Ten of 133 grafts (7%) developed infection requiring graft excision between 1 and 9 months after implantation. There was no statistical difference between men and women in primary or secondary patency (P = .88, P = .69). There was no difference in primary patency or secondary patency for patients with body mass index >30 or <30 (P = .85, P = .54). Patients who had a BCA graft as their first access attempt had a higher primary and primary assisted patency than that of patients who had the graft placed after prior access failure (P = .039, P = .024). CONCLUSIONS: This represents the largest published series of BCA grafts for arteriovenous grafts in the modern era. The primary patency of BCA grafts in this series was lower than that reported in a smaller randomized study. However, primary assisted and secondary patency were similar. Infection rates in this series appear to be somewhat lower than polytetrafluoroethylene infection rates reported in the literature. BCA grafts are a satisfactory alternative to expanded polytetrafluoroethylene for hemodialysis access, but larger controlled studies are needed to determine whether superior primary patency previously reported is a reproducible finding.

Variability in 2-year training programs in vascular surgery based on results of an Association of Program Directors in Vascular Surgery survey.

OBJECTIVE: Although a great deal of attention has recently focused on 5-year integrated (0+5) training programs in vascular surgery, a paucity of data exists concerning variability of daily assignments in 2-year (5+2) vascular fellowships. METHODS: We polled Association of Program Directors in Vascular Surgery members with 2-year vascular fellowships to determine the number of days in a 5-day work week that first- and second-year fellows were assigned to open vascular operations, endovascular procedures (hospital vs nonhospital facility), arterial clinic, venous clinic, noninvasive vascular laboratory (NIVL), and research. RESULTS: Of the 103 program directors from 5+2 vascular training programs, 102 (99%) responded. The most common schedule for both first- and second-year fellows was performing both open and endovascular procedures in the hospital on the same day 4 days of the week and spending time in combined artery and vein clinic 1 day of the week. Program directors developed different schedules for each year of the 2-year fellowship in about half (55% [56]) of the programs. A small minority of programs devoted days to only open surgical cases (13% [13]), a separate venous clinic (17% [17]), or a separate arterial clinic (11% [11]) and performed endovascular procedures in a nonhospital facility (15% [15]). All but three programs had mandatory time in clinic both years. Approximately one-third (30% [31]) of programs designated time devoted to research, whereas the others expected fellows to find time on their own. Although passing the Registered Physician in Vascular Interpretation examination is required, there was devoted time in the NIVL in only 60% (61) of programs. CONCLUSIONS: Training assignments in terms of time spent performing open and endovascular procedures and participating in clinic, the NIVL, and research varied widely among Accreditation Council for Graduate Medical Education-accredited 5+2 vascular fellowships and did not always fulfill Accreditation Council for Graduate Medical Education guidelines. In the current era of emphasis on endovascular-based interventions, few programs devoted days to purely open surgical procedures. Endovascular experience in a nonhospital facility (where these procedures will likely become more common in the future), outpatient venous procedures, and designated time devoted to the NIVL and research were lacking in many programs. These results provide a valid data set for the Association of Program Directors in Vascular Surgery to consider establishing guidelines for training assignments in 5+2 vascular training programs.

Symmetry-free cryo-EM structures of the chaperonin TRiC along its ATPase-driven conformational cycle.

The eukaryotic group II chaperonin TRiC/CCT is a 16-subunit complex with eight distinct but similar subunits arranged in two stacked rings. Substrate folding inside the central chamber is triggered by ATP hydrolysis. We present five cryo-EM structures of TRiC in apo and nucleotide-induced states without imposing symmetry during the 3D reconstruction. These structures reveal the intra- and inter-ring subunit interaction pattern changes during the ATPase cycle. In the apo state, the subunit arrangement in each ring is highly asymmetric, whereas all nucleotide-containing states tend to be more symmetrical. We identify and structurally characterize an one-ring closed intermediate induced by ATP hydrolysis wherein the closed TRiC ring exhibits an observable chamber expansion. This likely represents the physiological substrate folding state. Our structural results suggest mechanisms for inter-ring-negative cooperativity, intra-ring-positive cooperativity, and protein-folding chamber closure of TRiC. Intriguingly, these mechanisms are different from other group I and II chaperonins despite their similar architecture.

Mechanism of folding chamber closure in a group II chaperonin.

Group II chaperonins are essential mediators of cellular protein folding in eukaryotes and archaea. These oligomeric protein machines, approximately 1 megadalton, consist of two back-to-back rings encompassing a central cavity that accommodates polypeptide substrates. Chaperonin-mediated protein folding is critically dependent on the closure of a built-in lid, which is triggered by ATP hydrolysis. The structural rearrangements and molecular events leading to lid closure are still unknown. Here we report four single particle cryo-electron microscopy (cryo-EM) structures of Mm-cpn, an archaeal group II chaperonin, in the nucleotide-free (open) and nucleotide-induced (closed) states. The 4.3 A resolution of the closed conformation allowed building of the first ever atomic model directly from the single particle cryo-EM density map, in which we were able to visualize the nucleotide and more than 70% of the side chains. The model of the open conformation was obtained by using the deformable elastic network modelling with the 8 A resolution open-state cryo-EM density restraints. Together, the open and closed structures show how local conformational changes triggered by ATP hydrolysis lead to an alteration of intersubunit contacts within and across the rings, ultimately causing a rocking motion that closes the ring. Our analyses show that there is an intricate and unforeseen set of interactions controlling allosteric communication and inter-ring signalling, driving the conformational cycle of group II chaperonins. Beyond this, we anticipate that our methodology of combining single particle cryo-EM and computational modelling will become a powerful tool in the determination of atomic details involved in the dynamic processes of macromolecular machines in solution.

Repair of aortoenteric fistula secondary to graft placement for middle aortic syndrome.

When an aortoenteric fistula (AEF) arises secondary to suprarenal or more proximal aortic repair, mortality and the complexity of the surgery increases. We present the first reported case to our knowledge of a secondary AEF arising 13 years after surgical repair of middle aortic syndrome. We performed the original surgery on a 22-year-old male who presented with hypertension and claudication by placing a Dacron prosthetic patch on the juxtarenal and infrarenal aorta, bilateral vein bypasses to the left and right renal artery, and a Dacron bypass to the proximal superior mesenteric artery. Thirteen years later, he presented with massive gastrointestinal bleeding and syncope. We performed a distal descending thoracic aortic rifampin-soaked bifurcated Dacron graft to the left renal artery and to a large meandering mesenteric artery followed by excision of all previous prosthetic graft and insertion of a rifampin-soaked tube graft from the distal descending thoracic aorta to the distal abdominal aorta with omental flap coverage. After a complicated postoperative course, he was discharged 2 months later and remains on dialysis at his 6-month postoperative follow-up without evidence of recurrent infection.

Duplex ultrasound diagnosis of failing stent grafts placed for occlusive disease.

OBJECTIVE: We previously showed that duplex ultrasound (DU) imaging is beneficial in the diagnosis of failing vein and prosthetic grafts performed for arterial occlusive disease. The purpose of this study was to evaluate whether DU imaging can reliably diagnose failing stent grafts (ie, covered stents) placed for arterial occlusive disease. METHODS: Between July 1, 2005, and June 30, 2013, we placed 142 stent grafts in 92 arterial segments (1.5 stent grafts/stenotic artery) for lower extremity occlusive disease in patients who also underwent at least one DU surveillance study documenting a patent stent graft. Stent grafts were placed in 29 iliac and 52 femoropopliteal arteries and in 11 failing infrainguinal bypass grafts. Stent grafts used were Viabahn (W. L. Gore and Associates Inc, Flagstaff, Ariz) in 116 (82%), Wallgraft (Boston Scientific, Natick, Mass) in 23 (16%), Fluency (C. R. Bard Inc, Tempe, Ariz) in 2 (1%), and iCast (Atrium, Hudson, NH) in 1 (1%). Mean follow-up was 16 months (range, 1 week-86 months). Postoperative DU surveillance was performed in our Intersocietal Accreditation Commission accredited noninvasive vascular laboratory at 1 week, then every 3 months the first year, and every 6 months thereafter. DU measured peak systolic velocities (PSVs) and velocity ratio of adjacent PSVs (Vr) every 5 cm within the stent graft and adjacent arteries. RESULTS: We retrospectively classified the following factors as "abnormal DU findings:" focal PSVs >300 cm/s, uniform PSVs <50 cm/s throughout the graft, and a Vr >3.0. Fifteen of 20 patients with one or more of these abnormal DU findings underwent prophylactic intervention (n = 8) or occluded without intervention (n = 7), whereas only two of 72 with normal DU findings occluded (P = .0001). Excluding the eight patients who underwent prophylactic intervention, seven of 12 patients with abnormal DU findings occluded without intervention vs two of 72 with normal DU findings (P = .0001). CONCLUSIONS: These findings suggest that follow-up DU surveillance can predict failure of stent grafts placed for lower extremity occlusive disease. Focal PSVs >300 cm/s, Vr >3.0, and most importantly, uniform PSVs <50 cm/s throughout the stent graft were statistically reliable markers for predicting stent graft thrombosis.