Serious Failure Modes After EVAR Are Device Specific

OBJECTIVES

Type I and III endoleaks following endovascular aneurysm repair (EVAR) can lead to catastrophic events that require major re-interventions. We reviewed our experience with aortic endograft re-interventions for type I and III endoleaks and other serious failures among different devices.

METHODS

We retrospectively reviewed patients with a prior EVAR who underwent open conversion (OC) or major endovascular intervention (MEI) (re-lining, cuff/limb extension, parallel graft) for type I/III endoleaks at our institution from 2002 to 2019. Baseline characteristics, procedural details, re-interventions, and outcomes were collected.

RESULTS

A total of 229 patients (194 men) underwent re-interventions for type I and III endoleaks after EVAR (90 OC, 139 MEI) for devices implanted between 1997 and 2019. Average age at re-intervention was 78±8.5 years. A total of 135 (59%) were implanted at our institution, whereas 93 (41%) were referred. Median time to re-intervention was 4 years with 25% to 75% interquartile range (IQR) of 2.2-6.6 years. There was no significant difference in baseline demographics or type of re-interventions (OC/MEI) between device types. 42/229 (18%) presented with ruptured aneurysms, 20/229 (9%) were symptomatic, whereas the rest presented with asymptomatic radiographic findings. Type 1A endoleak was present in 146/229 (63.8%-72 with proximal migration), type IB in 46/229 (20.1%), type IIIA in 37/229 (16.6%), type IIIB in 15/229 (6.5%), and persistent aneurysm sac growth with no radiographic evidence of an endoleak in 6/229 (2.6%). Devices included most commercial products: AFX, Excluder, AneuRx, Ancure, Endurant, and Zenith. A smaller number of investigational devices accounted for the rest. Type 1A endoleak was the most common indication for re-intervention among all devices except for AFX and ancure devices, proximal migration was a frequent presentation with AneuRx. AFX devices more frequently presented with a type III and ancure devices more frequently presented with a type IB endoleak.

CONCLUSIONS

Serious failure modes after EVAR differ between endografts and occur throughout the follow-up period. This is important to guide targeted interrogation of surveillance studies and follow-up schedules, even for discontinued devices, as well as comparisons between various series and estimation of EVAR failure rates.

CLINICAL IMPACT

Surveillance after EVAR is critical for long term success of the repair, understanding of the differential modes of failure of every graft available is important in the longitudinal evaluation of these endografts. Equally important is the understanding of the modes of failure of legacy endografts that are no longer on the market but still being followed, in order to be able to tailor a surveillance regiemn and the evntual repair if needed.

Assessment of fitness for open repair in patients with infrarenal abdominal aortic aneurysms

OBJECTIVE

Endovascular aortic repair (EVAR) was originally designed as a treatment modality for patients with abdominal aortic aneurysms (AAAs) deemed unfit for open repair. However, the definition of "unfit for open repair" is largely subjective and heterogenous. The purpose of this study was to compare patients deemed unfit for open repair who underwent EVAR to a matched cohort who underwent open repair for infrarenal AAAs.

METHODS

The Vascular Quality Initiative of the Society for Vascular Surgery was queried for patients who underwent EVAR and open infrarenal AAA repair from 2003 to 2022. Patients that underwent EVAR were included if they were deemed unfit for open repair by the operating surgeon. EVAR patients deemed unfit because of a hostile abdomen were excluded. Patients in both the open and EVAR datasets were excluded if their repair was deemed non-elective or if they had prior aortic surgery. EVAR patients were matched to a cohort of open patients. The primary outcome for this study was 1-year mortality. Secondary outcomes included 30-day mortality, major adverse cardiac events, pulmonary complications, non-home discharge, reinterventions, and 5-year survival.

RESULTS

A total of 5310 EVAR patients were identified who were deemed unfit for open repair. Of those, 3028 EVAR patients (57.0%) were able to be matched 1:1 to a cohort of open patients. Open patients had higher rates of major adverse cardiac events (20.2% vs 4.4%; P < .001), pulmonary complications (12.8% vs 1.6%; P < .001), non-home discharges (28.5% vs 7.9%; P < .001), and 30-day mortality (4.5% vs 1.4%; P < .001). There were no differences in early survival, but open repair had better middle and late survival compared with EVAR over the course of 5 years. A total of 74 EVAR patients (2.4%) had reinterventions during the study period. EVAR patients that required interventions had higher 1-year (40.5% vs 7.3%; P < .001) and 5-year mortality (43.2% vs 14.1%; P < .001) compared with those that did not require reinterventions. EVAR patients who had reinterventions had higher 1-year (40.5% vs 6.3%; P < .001) and 5-year (43.2% vs 20.3%; P = .006) mortality compared with their matched open cohort.

CONCLUSIONS

Patients undergoing EVAR for AAAs who are deemed unfit for open repair have better perioperative morbidity and mortality compared with open repair. However, patients who had an open repair had better middle and late survival over the course of 5 years. The categorization of unfitness for open surgery may be inaccurate and re-evaluation of this terminology/concept should be undertaken.

Resonance Raman spectroscopy of twisted interfaces in turbostratic multilayer graphene

Turbostratic multilayer graphene presents a unique system with a large number of twisted interfaces with variable twist angles. In this work, we have systematically studied the laser excitation energy dependence of the Raman modes of turbostratic graphene. The combination of 4 different laser energies is shown to be important to reveal the twist angles ranging from 5∘to 30∘present at the same lateral position of the sample. Rotational or R-modes and D-like modes are observed, which directly arise from additional momentum transfer from the potential of corresponding superlattices. Trends in their dispersion and intensity are discussed. The resonant window for laser excitation indicates lowered positions of the van Hove singularities. Furthermore, an anomalous broadening factor of 0.17-0.265 eV is estimated for the resonance window when compared to the literature on isolated twisted bilayer graphene. Interestingly, a weak dependence of the R-modes on the laser wavelength is also observed. Finally, the dispersion of the 2D modes is also presented.

Room for improvement in patient compliance during peripheral vascular interventions

Introduction

For patients receiving Procedural Sedation and Analgesia (PSA), patient cooperation is crucial as patients remain continuously aware of operating room activity and can be asked to perform tasks such as prolonged breath-holds. This survey aimed to collect information on patient compliance with on-table instructions and its relation to periprocedural outcomes from surgeons nationwide performing peripheral vascular interventions (PVI) under PSA.

Methods

A 9-question online survey was sent to 383 vascular surgeons (including both vascular surgery attendings and trainees) across the United States through REDCap from August 30 to September 21, 2021, with responses closed on October 30, 2021. The survey response was analyzed with descriptive statistics.

Results

83 (21.6%) vascular surgeons responded to the survey, of which 67 (80.7%) were attending vascular surgeons and 16 (19.3%) were vascular surgery trainees. 41 (49.4%) respondents performed 11-20 PVI cases under PSA every month, while 31 (41.0%) respondents performed 1-10 PVI cases under PSA every month. 41 (49.4%) respondents reported that in 1-10% of their cases, additional contrast and/or radiation was administered because patient moved on the table or did not cooperate with breath holds; 25 (30.1%) reported that this occurred in 11-20% of their cases, 12 (14.5%) reported that this occurred in 21-50% of their cases and 4 (4.8%) reported that this occurred in over 50% of their cases. In such cases, the majority of respondents reported a 1-10% increase in contrast volume (59.0%), radiation dosage (62.7%), sedative/analgesia administration (46.3%) and procedural time (54.9%). Of cases being converted to general anesthesia due to inadequate patient cooperation, 35 (42.2%) respondents reported between 1-5 per month, and 3 (3.6%) respondents reported between 6-10 per month. Of cases being aborted due to inadequate patient cooperation, 25 (30.1%) respondents reported between 1-5 per month, and 1 (1.2%) respondents reported between 6-10 per month.

Conclusion

A significant fraction of PVI cases performed under PSA result in increased radiation and contrast exposure, sedative administration and procedural time due to inadequate patient cooperation. In certain cases, conversion to general anesthesia or case abortion is required. Further research should be performed to investigate strategies to minimize such adverse patient safety events.

Multi-institutional outcomes after femoropopliteal bypass in octogenarians

OBJECTIVES

Open lower extremity revascularization is controversial among octogenarians; however, the indications for surgical bypass are higher in the elderly population. The aim of the study was to compare postoperative outcomes between octogenarians and non-octogenarians following femoropopliteal bypass surgery.

METHODS

Our regional, multi-institutional database was queried for femoropopliteal bypass procedures performed between 1995 and 2020. Electronic medical records were individually reviewed for operative and postoperative data. Univariable and multivariable logistic regression were utilized to determine predictors of postoperative outcomes.

RESULTS

Among 1315 patients who underwent femoropopliteal bypass, 234 (17.8%) were octogenarians. Octogenarians more frequently underwent bypass for lower extremity tissue loss (48.7% vs 30.2%), whereas claudication was more common among non-octogenarians (24.0% vs 9.8%) (p < .001). Below-knee bypass target (72.2% vs 59.3%) and prosthetic conduit utilization (58.5% vs 43.7%) were more frequent in octogenarians (p < .001 each). Overall hospital length of stay was longer among patients > 80 years (median 6 days [interquartile range [IQR] 4-9] vs 5 days [IQR 4-8], p = .017). The overall 30-day (5.6% vs 1.5%) and one-year mortality rates (25.6% vs 7.9%) were higher among octogenarians (p < .001 each). On multivariable analysis, age greater than 80 years was found to be an independent risk factor for postoperative mortality (OR 3.79 [1.75-8.20], p = .0007).

CONCLUSIONS

Octogenarians undergoing bypass femoropopliteal bypass surgery have considerably worse postoperative outcomes, compared with non-octogenarians. These data may help inform elderly patients prior to undergoing open lower extremity revascularization.

Failure-to-Salvage After Femoropopliteal Bypass Surgery is Associated With Nonmodifiable Risk Factors

INTRODUCTION

Bypass graft failure and major amputation are among the worst complications after femoropopliteal bypass surgery. In this large multicenter analysis, we examined our incidence and risk factors for failure-to-salvage (FTS) following either bypass surgery or bypass graft failure.

METHODS

A regional multicenter database was retrospectively queried for all femoropopliteal bypass procedures performed between 2002 and 2021. Re-do bypasses were excluded. The primary outcome was FTS, defined as major ipsilateral limb amputation within 90 d following index bypass surgery or bypass graft failure. Bypass graft failure was defined as critical stenosis or occlusion of the bypass graft requiring reintervention. Graft rescue was defined as bypass graft failure without subsequent major ipsilateral limb amputation within 90 d. Multivariable logistic regression analysis was utilized to identify factors associated with bypass graft failure and FTS.

RESULTS

Over the study period, 1315 femoropopliteal bypass procedures were performed across five hospitals. There were 25 major amputations within 90 d of initial bypass. Bypass graft failure was diagnosed in an additional 503 (38.3%) patients. Mean time to graft failure was 619 d. On multivariable analysis, bypass for tissue loss (adjusted odds ratio [aOR] 1.38 [95% confidence interval (CI) 1.03-1.83], P = 0.03) was associated with graft failure. Of patients with graft failure, 33 had major amputation, leading to an overall FTS incidence of 4.4% (n = 58) over a mean follow-up period of 3.4 y. Patient demographics, medical comorbidities, and bypass conduits were similar between the FTS and graft rescue groups (n = NS each). The FTS group more frequently underwent bypass for tissue loss (51.7% versus 29.8%, P = 0.002), and an infrageniculate bypass target was more frequently utilized in FTS compared to graft rescue patients (81.0% versus 60.4%, P = 0.002). Anticoagulation (34.5% in FTS versus 37.7% in rescue) and dual antiplatelet therapy (15.5% versus 22.1%, respectively) were similar between groups (P = NS each). On multivariable analysis, factors associated with FTS included infrageniculate target (aOR 2.42 [95% CI 1.22-4.08], P = 0.01), black race (aOR 2.47 [95% CI 1.04-5.84], P = 0.04), and bypass for tissue loss (aOR 4.75 [95% CI 1.41-16.0], P = 0.01). Anticoagulation and dual antiplatelet therapy were not associated with loss of graft patency or FTS.

CONCLUSIONS

Failure-to-salvage after femoropopliteal bypass surgery is associated with nonmodifiable factors, and may represent progression of underlying disease. These data may help inform vascular surgeons in counseling patients with failing bypass grafts. Further investigation of care delivery factors improving likelihood of graft salvage may be warranted.

Prosthetic Conduit Use Does Not Adversely Impact Outcomes after Open Repair of Popliteal Artery Aneurysms

BACKGROUND

Single segment, greater saphenous vein (GSV) conduit is considered the optimal bypass conduit among patients undergoing bypass surgery for peripheral artery disease (PAD). While this data has been extrapolated to patients undergoing bypass for popliteal artery aneurysms (PAAs), the pathophysiology of PAA is inherently different when compared to PAD, and the impact of conduit type on long-term outcomes after open repair of PAA remains unclear.

METHODS

A multicenter database of five regional hospitals was retrospectively reviewed for all patients with PAA undergoing open surgical repair. Data were collected on demographic information, operative details, medications, and postoperative outcomes. Kaplan-Meier curves were used to compare freedom from major adverse limb events (MALE) following GSV versus prosthetic bypass. Cox proportional hazards model was used to identify patient-level characteristics associated with MALE, which was defined as major ipsilateral limb amputation or reintervention for graft patency.

RESULTS

From 1999 to 2020, a total of 101 patients with PAA underwent open exclusion and bypass surgery. Median follow-up period was 4.2 years (interquartile range, 1.3-7.4 years), and complete data were available for 99 (98.0%) patients. The majority of patients were male (99.0%) and Caucasian (93.9%). Only 11.1% of procedures were emergent, with the remainder (88.9%) being elective. All patients underwent medial exposure with a below-knee popliteal bypass target (100%). Bypass conduits included GSV (69.7%), prosthetic conduit (28.3%), and 2 (2.0%) alternative conduits (one spliced arm vein, one cryopreserved vein). Patients undergoing prosthetic bypass were older (72 vs. 66 years, P = 0.001) and had similar rates of medical comorbidities. Compared with the GSV group, patients with prosthetic conduits were more frequently placed on postoperative anticoagulation (60.7% vs. 23.2%, P < 0.001). Conduit type did not impact postoperative complication rates (P = NS each). MALE rates were low overall (19.2% at 2 years), and similar when stratified by conduit type (log rank P = 0.47). On multivariable analysis, emergent bypass was associated with MALE (hazard ratio [HR] 5.73, 95% confidence interval [CI] 2.07-15.85, P < 0.001). Prosthetic conduit usage (HR 1.00, 95% CI, 0.40-2.51, P = 0.99) and postoperative anticoagulation (HR 1.02, 95% CI 0.42-2.50, P = 0.97) were not associated with MALE.

CONCLUSIONS

Open repair of PAA is associated with excellent long-term outcomes. Prosthetic bypass is a comparable alternative to autogenous conduit for below-knee popliteal bypass targets, and lack of suitable GSV should not prohibit open surgical repair when indicated.

Incidence and Outcomes of Visceral Ischemia in Acute Aortic Occlusion

BACKGROUND

Acute aortic occlusion (AAO) is a morbid diagnosis in which mortality correlates with severity of ischemia on presentation. Visceral ischemia (VI) is challenging to diagnose and its presentation as a consequence of AAO is not well-studied. We aim to identify characteristics associated with VI in AAO to facilitate diagnosis.

METHODS

Patients diagnosed with AAO who underwent revascularization were identified retrospectively from institutional records (2006-2020). The primary outcome was the development of VI (intra-abdominal ischemia). Univariate analysis was used to compare demographic, exam, imaging, and intraoperative variables between patients with and without VI in the setting of AAO.

RESULTS

Ninety-one patients were included. The prevalence of VI was 20.9%. Preoperative comorbidities, time to revascularization, and operative approach did not differ between patients with and without VI. Patients with VI more frequently were transferred from outside institutions (100% vs. 53%, P = 0.02), presented with advanced acute limb ischemia (Rutherford III 36.9% vs. 7.5%, P < 0.01), and had elevated preoperative serum lactate (4.31 vs. 2.41 mmol/L, P < 0.01). VI patients had an increased occurrence of bilateral internal iliac artery (IIA) occlusion (47.4% vs. 18.1%, P = 0.01). Unilateral IIA occlusion, level of aortic occlusion, and patency of inferior mesenteric arteries were not associated with VI. Patients with VI had worse postoperative outcomes. In particular, VI conferred significant risk of mortality (odds ratio 5.45, P < 0.01).

CONCLUSIONS

Visceral ischemia is a common consequence of AAO. Elevated lactate, bilateral IIA occlusion, and advanced acute limb ischemia (ALI) should increase clinical suspicion for concomitant VI with AAO and may facilitate earlier diagnosis to improve outcomes.

Preoperative Anemia Is Associated With Postoperative Renal Failure After Elective Open Aortic Repair

INTRODUCTION

Preoperative anemia has been consistently shown to be a risk factor for acute kidney injury (AKI) after cardiac surgery. However, this association has not been examined in the open abdominal aortic aneurysm repair (OAR) population and is the subject of this analysis.

METHODS

Targeted Vascular Module from the American College of Surgeons National Surgical Quality Improvement Program was queried for patients undergoing OAR from 2013 to 2019. Anemia was defined according to World Health Organization Guidelines: Hematocrit<36% for women or <39% for men. Primary endpoint was 30-day AKI. Anemia's effect on AKI was determined using inverse probability weighted logistic regression.

RESULTS

There were 2275 OAR; mean age was 70.9 ± 8.2 y; 24.0% were women. Anemia was present in 498 (26.3%) patients; 165 (7.6%) had a hematocrit<33% and 8 (0.35%) had a hematocrit<24%. Differences in patient factor were nonsignificant after weighting. Any degree of postoperative AKI was more common in the anemia group (11.2% vs 5.1%; unweighted P < 0.001), as was AKI requiring hemodialysis (7.7% vs 3.2%; unweighted P < 0.001). In the weighted multivariable analysis, anemia was independently associated with postoperative AKI (odds ratio 1.51; 95% confidence interval: 1.01-2.26; P = 0.042) while controlling for age and operative factors. Patients with postoperative AKI were significantly more likely to die postoperatively than those without (26.1% vs 1.9%; <0.001).

CONCLUSIONS

Preoperative anemia was independently associated with post-OAR AKI after propensity weighting and controlling for operative factors. AKI is a major source of morbidity and mortality in these patients, and, if time permits, preoperative correction of anemia or its underlying cause should be considered in high-risk patients.

Preoperative Anemia is Associated with Poorer Postoperative Outcomes in Patients Undergoing Infrainguinal Bypass Surgery

BACKGROUND

Preoperative anemia is an important, modifiable risk factor among surgical patients. However, data are scarce on the impact of preoperative anemia on postoperative outcomes after infrainguinal bypass.

METHODS

In this multi-institutional analysis, data were retrospectively collected on all infrainguinal bypass procedures performed between 2010 and 2020. Patients were grouped by preoperative hemoglobin as per the National Cancer Institute anemia scale (mild, 10 g/dL-lower limit of normal; moderate, 8.0-9.9 g/dL; severe, 6.5-7.9 g/dL). Multivariable comparisons were performed using logistic regression analysis.

RESULTS

A total of 492 patients underwent bypass for peripheral artery disease over the 10-year study period. Median preoperative hemoglobin was 11.0 g/dL (interquartile range 9.5-12.7) and median follow-up was 1.7 years. Preoperative anemia was prevalent among bypass patients (mild 52.4% [n = 258], moderate 26.4% [n = 130], and severe 5.1% [n = 25]). Women were more likely to have moderate (49.2% [women] vs. 50.8% [men]) or severe anemia (52.0% [women] vs. 48.0% [men]) compared with normal hemoglobin (17.7% [women] vs. 82.3% [men]) (P < 0.001). Patients with preoperative anemia were more likely to present with tissue loss (22.8% [normal] vs. 47.7% [moderate] vs. 52.0% [severe], P = 0.01). Bypass target and conduit types were similar between groups. Anemic patients had longer median hospital length of stay compared with nonanemic patients (4 days [normal] vs. 5 days [mild] vs. 6 days [moderate] vs. 7 days [severe], P < 0.001). Postoperative mortality at 30 days was similar across anemia groups (2.5% [normal] vs. 4.6% [moderate] vs. 8.0% [severe], P = 0.23). On multivariable analysis, however, postoperative mortality was independently associated with severe anemia (odds ratio 7.5 [1.2-48.8], P = 0.04) and male gender (odds ratio 7.5 [1.2-26.4], P = 0.03).

CONCLUSIONS

Preoperative anemia is common among patients undergoing infrainguinal bypass surgery and is an independent risk factor for postoperative mortality. Future investigation is needed to determine whether correction of anemia improves postoperative outcomes in these high-risk patients.

Mortality differences by race over 20 years in individuals with peripheral artery disease

INTRODUCTION

Racial disparities exist in patients with peripheral artery disease (PAD), with Black individuals having worse PAD-specific outcomes. However, mortality risk in this population has been mixed. As such, we sought to evaluate all-cause mortality by race among individuals with PAD.

METHODS

We analyzed data from the National Health and Nutrition Examination Survey (NHANES). Baseline data were obtained from 1999 to 2004. Patients with PAD were grouped according to self-reported race. Multivariable Cox proportional hazards regression was performed to calculate adjusted hazard ratios (HR) by race. A separate analysis was performed to study the effect of burden of social determinants of health (SDoH) on all-cause mortality.

RESULTS

Of 647 individuals identified, 130 were Black and 323 were White. Black individuals had more premature PAD (30% vs 20%, p < 0.001) and a higher burden of SDoH compared to White individuals. Crude mortality rates were higher in Black individuals in the 40-49-year and 50-69-year age groups compared to White individuals (6.7% vs 6.1% and 8.8% vs 7.8%, respectively). Multivariable analysis demonstrated that Black individuals with both PAD and coronary artery disease (CAD) had a 30% higher hazard of death over 20 years compared to White individuals (HR = 1.3, 95% CI: 1.0-2.1). The cumulative burden of SDoH marginally (10-20%) increased the risk of all-cause mortality.

CONCLUSIONS

In a nationally representative sample, Black individuals with PAD and CAD had higher rates of mortality compared to their White counterparts. These findings add further proof to the ongoing racial disparities among Black individuals with PAD and highlight the necessity to identify ways to mitigate these differences.

Factors Influencing Hospital Readmission after Lower Extremity Bypass for Chronic Limb-Threatening Ischemia

Objectives: Unplanned hospital readmission is a leading source of hospital resource expenditure, and preventing readmission may improve both patient quality of life and healthcare costs. The factors influencing hospital readmission after lower extremity bypass (LEB) for chronic limb-threatening ischemia (CLTI) remain incompletely investigated. Methods: A regional, multi-institutional database was retrospectively reviewed for all patients who underwent LEB for CLTI between 1995 to 2020. The primary outcome was unplanned hospital readmission up to 30 days following bypass. Results: A total of 1315 patients underwent LEB across all institutions, of whom 843 (64.1%) underwent bypass for CLTI. The 30-day hospital readmission rate was 25.3%, and the leading causes of readmission were wound-related complications (51.6%). There was no difference in age, sex, or race between readmitted and non-readmitted patients. Conduit type and bypass target were also similar between groups. Readmitted patients more frequently underwent LEB for tissue loss (58.2% vs 50.2%, P = 0.042). On multivariable analysis, wound infection (odds ratio [OR] 9.1, 95% confidence interval [CI] 6.2-13.2, P < 0.001) and non-infectious wound complications (OR 2.0, 95% CI 1.0-3.9, P = 0.041) were independently associated with hospital readmission. Factors not associated with hospital readmission included patient age, conduit type, distal bypass target, and other medical comorbidities. Conclusions: One quarter of patients are readmitted within 30 days following lower extremity bypass for chronic limb-threatening ischemia. Efforts to mitigate wound infection and non-infectious wound complications may decrease rates of unplanned hospital readmission.

Impact of Rater Training on Residents Technical Skill Assessments: A Randomized Trial

OBJECTIVE

The ACS/APDS Resident Skills Curriculum's Objective Structured Assessment of Technical Skills (OSATS) consists of task-specific checklists and a global rating scale (GRS) completed by raters. Prior work demonstrated a need for rater training. This study evaluates the impact of a rater-training curriculum on scoring discrimination, consistency, and validity for handsewn bowel anastomosis (HBA) and vascular anastomosis (VA).

DESIGN/ METHODS

A rater training video model was developed, which included a GRS orientation and anchoring performances representing the range of potential scores. Faculty raters were randomized to rater training or no rater training and were asked to score videos of resident HBA/VA. Consensus scores were assigned to each video using a modified Delphi process (Gold Score). Trained and untrained scores were analyzed for discrimination and score spread and compared to the Gold Score for relative agreement.

RESULTS

Eight general and eight vascular surgery faculty were randomized to score 24 HBA/VA videos. Rater training increased rater discrimination and decreased rating scale shrinkage for both VA (mean trained score: 2.83, variance 1.88; mean untrained score: 3.1, variance 1.14, p = 0.007) and HBA (mean trained score: 3.52, variance 1.44; mean untrained score: 3.42, variance 0.96, p = 0.033). On validity analyses, a comparison between each rater group vs Gold Score revealed a moderate training impact for VA, trained κ=0.65 vs untrained κ=0.57 and no impact for HBA, R1 κ = 0.71 vs R2 κ = 0.73.

CONCLUSION

A rater-training curriculum improved raters' ability to differentiate performance levels and use a wider range of the scoring scale. However, despite rater training, there was persistent disagreement between faculty GRS scores with no groups reaching the agreement threshold for formative assessment. If technical skill exams are incorporated into high stakes assessments, consensus ratings via a standard setting process are likely a more valid option than individual faculty ratings.

Outcomes of Femoropopliteal Bypass for Lifestyle-Limiting Claudication in the Endovascular Era

INTRODUCTION

Outcomes after femoropopliteal bypass for intermittent claudication (IC) remain unclear in the endovascular era.

METHODS

A multi-institutional database was retrospectively queried for all femoropopliteal bypass procedures performed between 1995 and 2020. Demographics, operative details, and outcomes were documented. A statistical analysis included Kaplan-Meier curves and Cox proportional hazards ratios (HR).

RESULTS

A total of 282 patients underwent femoropopliteal bypass surgery for IC. Median age was 68 y (interquartile range, 61-73 y). Bypass conduits included great saphenous vein (GSV) (48.2%), prosthetic grafts (48.9%), and non-GSV autogenous grafts (2.8%). Distal bypass target was above-knee in 62.1% and below-knee in 37.9% of patients. The most common postoperative complications were wound infections (14.2%) followed by unplanned 30-d hospital readmissions (12.4%). Mortality rates were low at 0.4% (30 d) and 3.2% (1 y). Five-year primary patency rates trended highest for claudicants undergoing above-knee bypass with GSV conduit (log-rank P = 0.065). Five-year amputation-free survival rates were highest using GSV conduit regardless of distal bypass target (log-rank P = 0.017). On a multivariable analysis, age (HR 1.02 [1.00-1.04], P = 0.023) and active smoking (HR 1.48 [1.06-2.06], P = 0.021) were identified as risk factors for diminished primary graft patency. Risk factors for amputation-free survival included age (HR 1.03 [1.01-1.05], P < 0.001) and GSV conduit type (HR 0.65 [0.46-0.90], P = 0.011).

CONCLUSIONS

Femoropopliteal bypass among claudicants is associated with high rates of wound infection and hospital readmission. Active smoking portends worse outcomes in this population. These data may inform clinical decision-making regarding surgical intervention for claudication in the endovascular era.

Virtual Simulation of Intra-operative Decision-Making for Open Abdominal Aortic Aneurysm Repair: A Mixed Methods Analysis

OBJECTIVE

To create and pilot test a novel open abdominal aortic aneurysm (AAA) repair virtual simulation focused on intraoperative decision-making. To identify if the simulation replicated real-time intra-operative decision-making and discover how learners' respond to this type of simulation.

DESIGN

An explanatory sequential mixed methods study. We developed a step-by-step outline of major intra-operative decision points within a standard open AAA repair. Perioperative and intraoperative decision-making trees were developed and coded into an online virtual simulation. The simulation was piloted. Quantitative data was collected from the simulation platform. We then performed a qualitative thematic analysis on feedback from interviewed participants.

SETTING

Four academic general and vascular surgical training programs across the US.

PARTICIPANTS

Seventeen vascular and general surgery trainees and 6 vascular surgery faculty.

RESULTS

Participants spent on average 27 minutes (range: 8-45 minutes) interacting with the interface. 93% of participants reported feeling they were making real intraoperative decisions. 85% said it added to their knowledge base. 96% requested additional simulations. 22 interviews were completed: 241 primary codes were collapsed into 21 parent codes, and 6 emerging themes identified. Themes included the benefit of how (1) "Virtual Learning Could Standardize the Training Experience"; how (2) "Dealing with the Unexpected" as a trainee is an important part of surgical education growth, and that this (3) "Choose Your Own Adventure" virtual format simulates this intraoperative growth experience. Participants requested a (4) "Looping Feature Feedback Diagram" for future simulation iterations and highlighted that (5) "Fancier is Not Necessarily More Educational." Finally, many trainees wondered about (6) "The Attending Impact" from the simulation: if faculty would notice a difference between trainees who did vs did not utilize the simulation for case preparation.

CONCLUSIONS

Operative simulation training should focus on both technical skills and intra-operative decision-making, particularly "dealing with the unexpected." The learners' responses indicate that a low-fidelity, scalable, virtual platform can effectively deliver knowledge and allow for intra-operative decision-making practice in a remote learning environment.

Impact of Anticoagulation/Antiplatelet Therapy on Femoropopliteal Bypass Graft Outcomes

INTRODUCTION

Anticoagulant and antiplatelet (AC/AP) medications have been reported to improve bypass graft patency, however, the optimal AC/AP strategy remains unclear in the heterogenous peripheral artery disease population.

METHODS

A multi-institutional retrospective review utilizing the Research Patient Data Registry (RPDR) database from 1995-2020 was performed for all patients who underwent femoropopliteal bypass procedures. Electronic medical records were used to obtain demographic information, comorbidities, smoking status, operative details (bypass target), postoperative AC/AP medications, postoperative complications, and long-term outcomes were reviewed for the cohort. Cox proportional hazards model was used to determine independent risk factors for major adverse limb events (MALE) following bypass. MALE was defined as reintervention for patency or major amputation of index limb (above- or below-knee amputation).

RESULTS

A total of 1421 patients underwent femoropopliteal bypass between 1995-2020 throughout five institutions included in this study. Complete data was available for 1292/1421 (90.9%) patients. Indications for bypass included intermittent claudication (21.4%), rest pain (30.3%), tissue loss (33.5%), and non-atherosclerotic disease (14.8%). Distal bypass targets comprised above-knee (38.6%) and below-knee (61.4%) popliteal arteries. Patients were divided into six groups based on postoperative AC/AP use including none (n=57, 4.4%), mono-antiplatelet therapy (MAPT) (n=587, 45.4%), dual antiplatelet therapy (DAPT) (n=214, 16.6%), AC alone (n=73, 5.7%), AC+MAPT (n=319, 24.7%), and AC+DAPT (n=42, 3.3%). Postoperative bleeding complications were low for both hematoma (3.7%) and pseudoaneurysm (0.7%). There was no difference in bleeding complications across AC/AP groups (hematoma p=0.61, pseudoaneurysm p=0.31). After adjusting for patient factors, below-knee bypass target (HR 1.25 [1.04-1.52], p=0.019) and bypass for tissue loss (HR 1.40 [1.04-1.88], p=0.028) were independent predictors for MALE. Great saphenous vein conduit trended towards protection for MALE, compared with prosthetic grafts (HR 0.84 [0.70-1.01], p=0.06). No AC/AP regimen was associated with of MALE, even stratifying by above-knee and below-knee bypass cohorts. Median follow-up period was two years.

CONCLUSIONS

Among patients undergoing femoropopliteal bypass grafting, no combination of anticoagulation or antiplatelet medications was associated with improved graft patency, however, a below-knee target and tissue loss were associated with adverse limb events. Anticoagulation and antiplatelet regimen may be individualized post-bypass with regard to other concomitant medical comorbidities.

Distal Bypass Versus Infrageniculate Endovascular Intervention for Chronic Limb-Threatening Ischemia

Chronic limb-threatening ischemia (CLTI) carries a high risk of amputation and warrants urgent intervention. CLTI involving the infrageniculate vessels, in particular, carries a considerably higher risk of major limb amputation. Open surgical bypass is the historical gold standard for the treatment of tibial arterial disease; however, endovascular therapy provides an attractive alternative in this high-risk patient population. In this article, we review the existing literature regarding distal bypass and infrageniculate endovascular intervention in patients with CLTI.

Derivation and Validation of a Risk Score for Abdominal Compartment Syndrome after Endovascular Aneurysm Repair for Ruptured Abdominal Aortic Aneurysms

BACKGROUND

Abdominal compartment syndrome (ACoS) is a devastating complication after endovascular aneurysm repair for ruptured abdominal aortic aneurysms (rEVAR). This study sought to develop a risk score for ACoS to identify patients who would benefit from early decompressive laparotomy.

METHODS

Model derivation was performed with VQI data for rEVAR from 2013-2020. The primary outcome was evacuation of abdominal hematoma. Multivariable logistic regression was used to create and validate a scoring system to predict ACoS. The model was validated using institutional data for rEVAR from 1998-2019.

RESULTS

The derivation cohort included 2,310 patients with rEVAR. Abdominal hematoma evacuation occurred in 265 patients (11.5%). Factors associated with abdominal hematoma evacuation on multivariable analysis included transfer from an outside hospital, preoperative creatinine ≥1.4 mg/dl, preoperative systolic blood pressure ≤85 mmHg, preoperative altered mental status, ≥3.0 liters intraoperative crystalloid, and ≥4 units of red blood cells transfused intraoperatively. The validation cohort consisted of 67 rEVAR; ACoS occurred in 8 patients (11.9%). The c-statistic was 0.84 in the derivation and 0.87 in the validation cohort, while Hosmer-Lemeshow was p= 0.15 in the derivation and 0.84 in the validation cohorts, suggesting good model discrimination and calibration. Points were applied based on β-coefficients to produce a risk score ranging from -1 to 13. A cutoff of risk score ≥8 resulted in a sensitivity and specificity of 87.5% and 83.1% for detecting patients with ACoS, respectively. ACoS conveyed a significantly higher mortality in both the derivation (ACoS: 49.8% vs No ACoS: 17.8%; p<0.001) and validation cohorts (ACoS: 75.0% vs No ACoS: 15.2%; p<0.001).

CONCLUSION

In patients with equivocal signs/symptoms of ACoS, this scoring system can be used to guide surgeons on when to perform decompressive laparotomy prior to leaving the operating room for rEVAR. Patients with a risk score ≥8 would benefit from decompressive laparotomy at index rEVAR.

The Weekend Effect in Carotid Endarterectomy for Symptomatic Carotid Stenosis

BackgroundRecent studies report a limited window in which carotid endarterectomy (CEA) provides the greatest benefit for symptomatic carotid stenosis. Given the time-sensitive nature of CEA for symptomatic stenosis, it is important to understand whether patient outcomes are adversely affected by undergoing CEA over the weekend. Currently, it is unclear whether CEA is impacted by the "weekend effect" phenomenon. Methods A multi-institutional database was queried for all patients undergoing CEA for symptomatic carotid artery stenosis from 2015 to 2020 via ICD-9 codes. A total of 288 patients were identified during the study period. Univariate and multivariate analysis were used to compare outcomes based on weekend vs weekday surgery. Results A total of 261 patients (90.6%) underwent weekday CEA, as compared to 27 (9.4%) on the weekend. There were no differences in age, race, gender, or medical comorbidities between groups. Primary surgeon specialty was predominantly vascular surgery (77.0% weekday and 74.1% weekend) followed by neurosurgery (19.9% weekday and 25.9% weekend). Operative time was similar between groups (3.1 (weekday) vs 2.9 hr (weekend), P = .33) as well as estimated blood loss (100 vs 100 mL, P = .54). Hospital length of stay did not differ between groups (P = .69). Combined stroke and 30-day mortality rate was 2.0% on weekdays, compared to 3.7% on weekends (P = .75). On multivariate analysis, weekend surgery was not predictive of postoperative stroke or 30-day mortality (odds ratio .11 [95% CI: -1.57 to 1.85], P = .90). Conclusion In our multi-institutional experience, we did not identify a "weekend effect" in patients undergoing CEA for symptomatic carotid artery stenosis. Surgical revascularization should not be withheld on account of a weekend procedure in similar academic medical centers.

Pregnancy Conditions and Complications Associated with the Development of Varicose Veins

BACKGROUND

Pregnancy is a known risk factor for developing varicose veins (VV). However, pregnancy is often considered a homogeneous entity and few studies have examined if specific characteristics and complications of pregnancy may influence VV formation. This study sought to identify which pregnancy-specific factors are associated with the development of VV.

METHODS

All women who gave birth (live or still) between 1998-2020 within a multicenter healthcare system were retrospectively identified and followed through all hospital encounters (inpatient and outpatient). The primary outcome was VV, defined as any encounter with a primary diagnosis code for VV or procedure for VV. The study period for each woman was the time from the first to last encounter. Extended Cox regression modeling evaluated the association between VV and pregnancy-related factors as a time-varying covariates while controlling for patient comorbidities.

RESULTS

There were 156,622 women with a median follow-up of 8.3 years (IQR: 2.7-16.6 years) included. During this time, 225,758 deliveries occurred. The 10- and 20-year freedom from VV was 97.0% (95%CI: 96.8-97.1%) and 92.7% (95%CI: 92.4-93.0%), respectively, from the estimated start of first pregnancy. Overall, 4,028 (2.57%) developed VV during the follow-up period and 1,594 (1.02%) underwent a procedure for VV. After risk adjustment, increasing parity was significantly associated with VV, with each subsequent pregnancy increasing hazard of developing VV (parity=1: HR 1.78; 95%CI: 1.55-1.99; p<0.001; parity≥6: HR 4.83; 95%CI: 2.15-1.99-10.9; p<0.001), Other significant pregnancy factors included excessive weight gain in pregnancy (HR 1.44; 95%CI: 1.09-1.91; p=0.011), post-term pregnancy (HR 1.12; 95%CI: 1.02-1.21; p=0.021), preeclampsia (HR 0.79; 95%CI: 0.70-0.90; p<0.001), and postpartum transfusion of platelets, plasma, or cryoprecipitate (HR 2.05; 95%CI: 1.19-3.53; p=0.001).

CONCLUSION

Increasing parity, excessive weight gain in pregnancy, post-term pregnancy, and preeclampsia affect the development of VV after pregnancy. Though varicose veins after pregnancy are likely underreported and true incidence is unknown, women should be counseled about the impact of these factors on VV development after pregnancy.

Morbidity and mortality associated with open repair of visceral aneurysms

BACKGROUND

The Society for Vascular Surgery (SVS) recently published clinical practice guidelines on the management of visceral aneurysms. However, studies investigating the perioperative outcomes of open repair of visceral aneurysms have been limited to single-center experiences with variable results that span multiple decades. In the present study, we sought to detail the morbidity and mortality associated with open repair of visceral aneurysms using a national database in the contemporary era.

METHODS

National Surgical Quality Improvement Program data from 2013 to 2019 were queried for patients who had undergone open repair of visceral aneurysms, which had been classified as mesenteric, renal, or splenic using Current Procedural Terminology and International Classification of Diseases codes. The primary endpoint was the composite of major complications (cardiovascular, pulmonary, progressive renal failure, deep wound infection, return to operating room, sepsis) and 30-day mortality. Logistic regression was used to identify the predictors of the primary endpoint for nonruptured aneurysm cases.

RESULTS

Of the 304 aneurysms, 263 were nonruptured (137 mesenteric, 66 renal, 60 splenic) and 41 were ruptured (24 mesenteric, 1 renal, 16 splenic) and had undergone open repair. For those with nonruptured aneurysms, their mean age was 59.4 ± 14.7 years and 48.3% were women. For those with nonruptured aneurysms, the 30-day mortality was 1.9% and the major complication rate was 12.9%. A return to the operating room (5.3%) and prolonged ventilator support (3.8%) were especially common. As expected, rupture was associated with significantly greater mortality (22.0%; P < .001) and major complications (34.1%; P = .001). The use of postoperative transfusion was common in the elective group but was significantly greater in the ruptured group (24.3% vs 80.5%; P < .001). The predictors of the primary outcome for nonruptured aneurysms included male sex (odds ratio [OR], 2.93; 95% confidence interval [CI], 1.28-6.7; P = .011), anticoagulation (not discontinued before surgery) or bleeding disorder (OR, 4.52; 95% CI, 1.37-14.7; P = .012), and albumin <3.0 g/dL (OR, 4.66; 95% CI, 1.17-18.6; P = .029). Neither age nor aneurysm location were significant risk factors.

CONCLUSIONS

Open repair of visceral aneurysms was associated with acceptable morbidity and mortality, although these risks are significantly greater once ruptured. Male sex, bleeding risk, and low albumin were all risk factors for adverse events and should be considered for operative planning and postoperative care.

Comparison of enteric methane yield and diversity of ruminal methanogens in cattle and buffaloes fed on the same diet

An in vivo study was conducted to compare the enteric methane emissions and diversity of ruminal methanogens in cattle and buffaloes kept in the same environment and fed on the same diet. Six cattle and six buffaloes were fed on a similar diet comprising Napier (Pennisetum purpureum) green grass and concentrate in 70:30. After 90 days of feeding, the daily enteric methane emissions were quantified by using the SF6 technique and ruminal fluid samples from animals were collected for the diversity analysis. The daily enteric methane emissions were significantly greater in cattle as compared to buffaloes; however, methane yields were not different between the two species. Methanogens were ranked at different taxonomic levels against the Rumen and Intestinal Methanogen-Database. The archaeal communities in both host species were dominated by the phylum Euryarchaeota; however, Crenarchaeota represented <1% of the total archaea. Methanogens affiliated with Methanobacteriales were most prominent and their proportion did not differ between the two hosts. Methanomicrobiales and Methanomassillicoccales constituted the second largest group of methanogens in cattle and buffaloes, respectively. Methanocellales (Methanocella arvoryza) were exclusively detected in the buffaloes. At the species level, Methanobrevibacter gottschalkii had the highest abundance (55-57%) in both the host species. The relative abundance of Methanobrevibacter wolinii between the two hosts differed significantly. Methanosarcinales, the acetoclastic methanogens were significantly greater in cattle than the buffaloes. It is concluded that the ruminal methane yield in cattle and buffaloes fed on the same diet did not differ. With the diet used in this study, there was a limited influence (<3.5%) of the host on the structure of the ruminal archaea community at the species level. Therefore, the methane mitigation strategies developed in either of the hosts should be effective in the other. Further studies are warranted to reveal the conjunctive effect of diet and geographical locations with the host on ruminal archaea community composition.

Open Surgical Secondary Interventions are More Durable than Endovascular Interventions for Lower Extremity Bypass Stenosis or Occlusion

Objectives: Lower extremity bypasses often require secondary interventions to maintain patency. Our objectives were to characterize effectiveness of secondary interventions to maintain or restore bypass graft patency, and to compare outcomes of open and endovascular interventions. Methods: We reviewed patients who underwent lower extremity bypass at our institution from 2007 to 2010. We recorded the index bypass and subsequent ipsilateral interventions performed through 2018 or until loss of secondary patency. Patient, procedure, and anatomic data were collected. Endovascular intervention was compared with open/hybrid intervention. For outcome analysis, patency measures were defined relative to the time of the secondary intervention rather than the time of the index bypass. Results: 174 secondary interventions (56 open/hybrid, 118 endovascular; 42 for graft occlusion, and 132 for stenosis) treating 228 lesions in 97 bypasses were available for study. The index bypass was most commonly performed for tissue loss (71.1%), utilized a tibial artery target (57.7%), and used single-segment great saphenous vein (59.8%) rather than alternative vein (32.0%) or prosthetic (8.2%). A higher portion of open/hybrid interventions (51.8%) were done for graft occlusion than endovascular interventions (11.0%, P < .001). Mean follow-up for secondary interventions was 3.5 years. A multivariate Cox proportional hazards model identified female gender, prior MI, anticoagulation, occlusion, and endovascular intervention as predictors of loss of primary patency. Intervention for occlusion predicted poorer primary and secondary patency. Endovascular intervention was associated with poorer primary patency as compared to open intervention and a trend toward poorer secondary patency. Conclusions: Both open and endovascular secondary interventions on lower extremity bypasses are low-risk procedures that offer acceptable patency. Although more commonly performed in the setting of graft occlusion, open surgical interventions show improved durability compared to endovascular interventions. Some patients, including those with occluded grafts, may benefit from more liberal use of open surgical intervention to restore bypass patency.

Thermal transport across wrinkles in few-layer graphene stacks

Wrinkles significantly influence the physical properties of layered 2D materials, including graphene. In this work, we examined thermal transport across wrinkles in vertical assemblies of few-layer graphene crystallites using the Raman optothermal technique supported by finite-element analysis simulations. A high density of randomly oriented uniaxial wrinkles were frequently observed in the few-layer graphene stacks which were grown by chemical vapor deposition and transferred on Si/SiO₂ substrates. The thermal conductivity of unwrinkled regions was measured to be, κ ∼ 165 W m^-1 K^-1. Measurements at the wrinkle sites revealed local enhancement of thermal conductivity, with κ ∼ 225 W m^-1 K^-1. Furthermore, the total interface conductance of wrinkled regions decreased by more than an order of magnitude compared to that of the unwrinkled regions. The physical origin of these observations is discussed based on wrinkle mediated decoupling of the stacked crystallites and partial suspension of the film. Wrinkles are ubiquitous in layered 2D materials, and our work demonstrates their strong influence on thermal transport.

Improved outcomes of endovascular repair of thoracic aortic injuries at higher volume institutions

BACKGROUND

The use of thoracic endovascular aortic repair (TEVAR) has significantly improved the ability to treat traumatic aortic injuries (tTEVAR). We sought to determine whether a greater center volume correlated with better outcomes.

METHODS

Vascular Quality Initiative data of TEVAR (2011-2017) for trauma were used in the present analysis. Using the distribution of the annual case volume at the participating centers, the sample was stratified into three terciles. In-hospital mortality at high-volume centers (HVCs) and low-volume centers (LVCs) was compared after adjustment for risk factors established in our previous Vascular Quality Initiative-based risk model containing age, gender, renal impairment, left subclavian artery involvement, and select concomitant injuries.

RESULTS

A total of 619 tTEVAR cases were studied across 74 centers. HVCs (n = 184 cases) had performed ≥4.9 cases annually and LVCs (n = 220 cases) had performed ≤2.4 cases annually. Both crude mortality (4.4% vs 8.6%; P = .22) and adjusted odds of mortality (odds ratio, 0.44; 95% confidence interval, 0.18-1.09; P = .08) showed a trend toward better outcomes for tTEVAR performed at HVCs than at LVCs. The addition of center volume to our previous multivariate model significantly improved its discriminative ability (C-statistic, 0.90 vs 0.88; P = .02). The overall TEVAR volume (for all indications) was not associated with increased odds of mortality for tTEVAR (odds ratio, 0.46; 95% confidence interval, 0.17-1.20; P = .11), nor did it improve the model's discriminative ability.

CONCLUSIONS

Higher volume centers showed improved perioperative mortality after tTEVAR. The thoracic aortic trauma volume was more predictive than the overall TEVAR volume, suggesting that technical expertise is not the driving factor. Stable patients might benefit from transfer to a higher volume center before repair.

Complete Venous Ulceration Healing after Perforator Ablation Does Not Depend on Treatment Modality

BACKGROUND

Venous leg ulceration (VLU) represents the most advanced form of chronic venous insufficiency (CVI). Persistent VLU that fails to respond to noninvasive treatment requires a minimally invasive endovascular treatment, which may include chemical (ultrasound-guided foam sclerotherapy [UGFS]) and thermal ablation (endovenous laser therapy [EVLT] or radiofrequency ablation [RFA]) targeting incompetent veins. Current guidelines suggest ablation of incompetent perforating veins (IPVs) juxtaposed to active or healed VLU; however, the ideal treatment modality is unknown. We hypothesize that similar to incompetent superficial vein treatment options therapies, VLU healing will be equivalent across minimally invasive IPV treatment options.

METHODS

Using the Vascular Low Frequency Disease Consortium, adults with VLU across 11 medical centers were retrospectively reviewed (2013-2017). We included those who underwent IPV therapies. The primary outcome was complete ulcer healing over time compared with cumulative hazard curves, log-rank testing, and multivariable Cox proportional hazard regression. Secondary outcomes included number of subsequent procedures, which were compared using negative binomial regression.

RESULTS

Of the 832 adults with VLU, 158 (19%) were exclusively treated conservatively, and 232 (28%) underwent index treatment for IPV and constitute the full and final cohort. The mean age was 60 ± 14 years, 57% were men, and the mean ulcer area was 3.0 cm² (interquartile range, 1-6 cm²). Ninety-one (39%) were treated with EVLT, 127 (55%) RFA, and 14 (6%) UGFS. Patients treated with RFA were older (RFA 62 ± 14 years; EVLT 59 ± 14 years; UGFS 52 ± 9 years; P = 0.01), more likely to be men (RFA 68%, n = 86; EVLT 41%, n = 37; UGFS 64%, n = 9; P < 0.001), with a higher frequency of anticoagulation (RFA 36%, n = 46; EVLT 18%, n = 16; UGFS 14%, n = 2; P = 0.005). VLU did not significantly differ in size between groups (RFA 6.2 ± 8; EVLT 4.2 ± 5.4; UGFS 6.1 ± 8; P < 0.001). There were no differences in 1-year ulcer healing rates between groups (P = 0.18). The number of subsequent procedures did not differ by treatment modality (P = 0.47).

CONCLUSIONS

This multi-institutional retrospective study does not demonstrate any association of IPV treatment modality with differing rates of VLU healing or number of subsequent procedures.

Magnetic Stimulus Responsive DDS Based on Chitosan Microbeads Embedded with Magnetic Nanoparticles

In this paper, we have presented a novel Drug Delivery Substrate (DDS) that that is responsive to external stimuli of high-frequency alternating magnetic fields. The DDS is constituted of chitosan crosslinked with PEGDMA (polyethylene glycol dimethacrylate), loaded with Fe₃O₄ magnetic nanoparticles and vancomycin. In another experiment, a 19-hour elution was observed where three magnetic stimuli of 25 mT, 109.9 kHz were given for 60 min to the test samples. The stimuli were separated by several hours. After excitation span, it was observed that the stimulated samples released a significantly higher amount of vancomycin by as much as 21% compared to non-stimulated samples. In another study, preliminary results showing the effect of different PEGDMA chain lengths have been discussed. These results show evidence of a smart, controllable DDS that allows modulation of its normal passive antibiotic elution by applying external stimuli per personalized needs.

Acute Kidney Injury after Complex Endovascular Aneurysm Repair

Background:

Complex endovascular repair of abdominal aortic aneurysm carries higher perioperative morbidity than standard infrarenal endovascular repair.

Objective:

This study reviews the incidence and associated factors of acute kidney injury in complex aortic endovascular repair of juxtarenal, pararenal, and thoracoabdominal aortic aneurysms.

Methods:

A literature review was performed for all studies on the endovascular repair of juxtarenal, pararenal, and thoracoabdominal aneurysms that evaluated rates of acute kidney injury as an outcome. Outcomes were further analyzed by the level of anatomic complexity and method of repair.

Results:

52 studies met inclusion criteria, with a total of 5454 individuals undergoing repair from 2004 to 2017. The overall rate of acute kidney injury ranged widely from 0 to 41%, with a rate of hemodialysis from 0 to 19% (temporary) and 0 to 14% (permanent). Increasing anatomic complexity was associated with higher rates of acute kidney injury. Mode of endovascular repair, learning curve effect, and preoperative chronic renal insufficiency did not demonstrate any associations with the outcome.

Conclusion:

Published rates of acute kidney injury in complex aortic aneurysm repair vary widely with few definitively associated factors other than increasing anatomic complexity and operative time. Further study is needed for the identification of predictors related to postoperative acute kidney injury.

Risk factors for mortality after endovascular repair for blunt thoracic aortic injury

OBJECTIVE

Despite high use of endovascular repair, blunt thoracic aortic injury (BTAI) leads to significant mortality. We sought to identify risk factors and create a predictive model for mortality after thoracic endovascular aortic repair (TEVAR) based on available preoperative clinical data.

METHODS

We queried the Vascular Quality Initiative TEVAR dataset from April 2011 to November 2017 to identify patients with BTAI as the indication for repair. Patient characteristics, injury grade, timing of repair, and technical aspects including left subclavian artery (LSCA) involvement and coverage were evaluated. Logistic regression was used to identify univariable predictors of the primary outcome of in-hospital mortality. A multivariable model was constructed to predict in-hospital mortality after TEVAR for traumatic aortic injury. The model was tested as a prediction tool, internally validated using 10-fold cross-validation approach, externally validated using early and late split samples, and finally simplified into a scoring system.

RESULTS

We identified 633 TEVAR cases performed for blunt trauma. The majority of patients were male (73.9%) with median age of 39 years (interquartile range, 27-56 years). Although 18.6% documented zone 2 or proximal involvement, 28.1% documented involvement or treatment of the LSCA. 8.9% of repairs were performed for a grade 1 injury, with an increase from 6.4% in 2014 to 16.7% in 2017 (P = .04). The overall in-hospital mortality rate was 7.3%. Independent predictors of mortality were age 60 year or greater (odds ratio [OR], 11.33; 95% confidence interval [CI], 5.30-24.23; P < .001), creatinine 1.2 or greater (OR, 5.28; 95% CI, 2.46-11.34; P < .001), male gender (OR, 4.26; 95% CI, 1.53-11.84; P = .005), Injury Severity Score of greater than 30 (OR, 3.86; 95% CI, 1.74-8.57; P = .001), and LSCA involvement (OR, 2.25; 95% CI, 1.11-4.53; P = .02). The model predicted in-hospital mortality with a C-statistic of 0.86 (95% CI, 0.80-0.92), and a simplified model based on a point system had a similar C-statistic of 0.86 (95% CI, 0.80-0.92; P = .44).

CONCLUSIONS

TEVAR for BTAI is associated with a 7.3% in-hospital mortality in the Vascular Quality Initiative. Treatment of grade 1 injuries has increased significantly in recent years. Factors most strongly associated with mortality include age, male gender, renal impairment, LSCA involvement, and high ISS score. A simple point score model based on these variables robustly predicts in-hospital mortality and may assist in appropriate patient selection and risk stratification.

Nationwide trends in drug-coated balloon and drug-eluting stent utilization in the femoropopliteal arteries

OBJECTIVE

Drug-coated balloons (DCB) and drug-eluting stents (DES) have significantly altered treatment paradigms for femoropopliteal lesions. We aimed to describe changes in practice patterns as a result of the infusion of these technologies into the treatment of peripheral arterial disease.

METHODS

We queried the Vascular Quality Initiative registry from 2010 to 2017 for all peripheral vascular interventions involving the superficial femoral artery and/or the popliteal artery. Cases were divided into a PRE and a POST era with a cutoff of September 2016, when specific device identity was first recorded in Vascular Quality Initiative. For each artery, a primary treatment was identified as either plain balloon angioplasty, atherectomy, DCB, bare-metal stent, or DES. The relative distribution of primary treatments between the PRE and POST eras was evaluated, as were lesion characteristics associated with DCB and DES use and regional variability in the adoption of these new technologies.

RESULTS

Of 210,666 arteries in the dataset, 91,864 femoropopliteal arteries (across 74,842 procedures in 55,437 patients) were included. Each artery received 1.5 ± 0.6 treatments. Primary treatment use changed from 40% balloon angioplasty, 45% stenting, and 15% atherectomy in the PRE era to 22% plain balloon angioplasty, 26% bare-metal stent, 8% atherectomy, 37% DCB, and 8% DES in the POST era (P < .001). Forty-three percent of arteries received a drug-containing device as a primary or adjunctive therapy and 1.3% received both a DCB and DES in the POST era. DCB use as the primary treatment was highest in lesions with length 10.0 to 19.9 cm (42%), TransAtlantic InterSociety A, B, or C lesions (38%), and lesions with mild to no calcification (38%). DES use was highest in lesions with a length of 20 cm or more (12%), TransAtlantic InterSociety D lesions (13%), and lesions with moderate to severe calcification (9%). The range of use across 18 regions was 125 to 40% for DCB and 1% to 14% for DES. Regional variability was greater for DES (SD 4% vs mean 8%) than for DCB (SD 7% vs mean 29%).

CONCLUSIONS

There has been a rapid dissemination of DCB and DES technology in the femoropopliteal vessels, with nearly one-half of arteries receiving a drug-containing therapy in modern practice. DCBs are most used in medium length, minimally calcified lesions and DESs are most used in longer, more heavily calcified lesions. There is significant regional variability in adoption, especially with DES.