Development and validation of a machine-learning prediction model to improve abdominal aortic aneurysm screening.

OBJECTIVE: Despite recommendations by the United States Preventive Services Task Force and the Society for Vascular Surgery, adoption of screening for abdominal aortic aneurysms (AAAs) remains low. One challenge is the low prevalence of AAAs in the unscreened population, and therefore a low detection rate for AAA screenings. We sought to use machine learning to identify factors associated with the presence of AAAs and create a model to identify individuals at highest risk for AAAs, with the aim of increasing the detection rate of AAA screenings. METHODS: A machine-learning model was trained using longitudinal medical records containing lab results, medications, and other data from our institutional database. A retrospective cohort study was performed identifying current or past smoking in patients aged 65 to 75 years and stratifying the patients by sex and smoking status as well as determining which patients had a confirmed diagnosis of AAA. The model was then adjusted to maximize fairness between sexes without significantly reducing precision and validated using six-fold cross validation. RESULTS: Validation of the algorithm on the single-center institutional data utilized 18,660 selected patients over 2 years and identified 314 AAAs. There were 41 factors identified in the medical record included in the machine-learning algorithm, with several factors never having been previously identified to be associated with AAAs. With an estimated 100 screening ultrasounds completed monthly, detection of AAAs is increased with a lift of 200% using the algorithm as compared with screening based on guidelines. The increased detection of AAAs in the model-selected individuals is statistically significant across all cutoff points. CONCLUSIONS: By utilizing a machine-learning model, we created a novel algorithm to detect patients who are at high risk for AAAs. By selecting individuals at greatest risk for targeted screening, this algorithm resulted in a 200% lift in the detection of AAAs when compared with standard screening guidelines. Using machine learning, we also identified several new factors associated with the presence of AAAs. This automated process has been integrated into our current workflows to improve screening rates and yield of high-risk individuals for AAAs.

Outcomes of Aortobifemoral Bypass Based on Configuration of the Proximal Anastomosis.

BACKGROUND: Aortobifemoral bypass (ABF) remains an important treatment modality in the revascularization of aortoiliac occlusive disease. Despite ABF being performed for decades, questions remain regarding the preferred technique for the proximal anastomosis, specifically whether an end-to-end (EE) or an end-to-side (ES) configuration is superior. The goal of this study was to compare the outcomes of ABF based on proximal configuration. METHODS: We queried the Vascular Quality Initiative registry for ABF procedures performed between 2009 and 2020. Univariate and multivariate logistic regression analyses were used to compare perioperative and 1-year outcomes between EE and ES configurations. RESULTS: Of the 6,782 patients (median [interquartile range] age, 60.0 [54-66 years]) who underwent ABF, 3,524 (52%) had an EE proximal anastomosis and 3,258 (48%) had an ES proximal anastomosis. Postoperatively, the ES cohort had a higher frequency of extubation in the operating room (80.3% vs. 77.4%; P < 0.01), lower change in renal function (8.8% vs. 11.5%; P < 0.01), and lower use of vasopressors (15.6% vs. 19.1%; P < 0.01), but higher rates of unanticipated return to the operating room (10.2% vs. 8.7%; P = 0.037) compared with the EE configuration. At 1-year follow-up, the ES cohort had a significantly lower primary graft patency rate (87.5% vs. 90.2%; P < 0.01) and higher rates of graft revision (4.8% vs. 3.1%; P < 0.01) and claudication symptoms (11.6% vs. 9.9%; P < 0.01). The ES configuration was significantly associated with a higher rate of 1-year major limb amputations in univariate (1.6% vs. 0.9%; P < 0.01) and multivariate (odds ratio, 1.95, confidence interval, 1.18-3.23, P=<0.01) analyses. CONCLUSIONS: While the ES cohort seemed to have less physiologic insult immediately postoperatively, the EE configuration appeared to have improved 1-year outcomes. To our knowledge, this study is one of the largest population-based studies comparing the outcomes of the proximal anastomotic configurations. Longer-term follow-up is needed to determine which configuration is optimal.

The Use of Paclitaxel-Coated Devices in the Treatment of Peripheral Arterial Disease is Not Associated With Increased Mortality or Amputations.

BACKGROUND: Strategies for the most effective treatment for peripheral arterial disease (PAD) remain controversial among clinicians. Several trials have shown improved primary patency of femoropopliteal interventions with the utilization of paclitaxel-coated balloons or stents compared to conventional balloons or stents. However, a 2018 meta-analysis suggested an increased mortality risk for patients receiving drug-coated balloons or stents (DCBS), resulting in an international pause in the use of DCBS. A 2021 meta-analysis by the same group suggested an increased risk of major amputation following DCBS use in peripheral arterial revascularization procedures. Here we report our long-term institutional outcomes comparing uncoated devices to DCBS. METHODS: A retrospective review of all patients who underwent peripheral arterial angioplasty, stenting, atherectomy, or a combination between 2011 and 2020 within a regional healthcare system was performed. Univariate, multivariate, and survival analyses were performed using standard statistical methods to assess the primary end points of overall survival, 5-year survival, and amputation-free survival. RESULTS: A total of 2,717 patients were identified, of whom 1,965 were treated with conventional uncoated devices and 752 were treated with DCBS. A univariate analysis showed that patients treated with non-DCBS had higher rates of overall mortality, major amputations, and mortality at 1, 3, and 5 years. A multivariable analysis demonstrated that the use of conventional devices, age, diabetes, chronic kidney disease, myocardial infarction, transient ischemic attack, warfarin use, and atrial fibrillation all significantly increased the risk of 5-year mortality, overall mortality, and combined mortality and/or amputation. CONCLUSIONS: DCBS are not associated with increased mortality or worse amputation-free survival in this real-world cohort of patients treated for PAD. Our data suggest that mortality is more closely linked with pre-existing patient comorbidities rather than device selection at the time of revascularization.

Expansion of Surgical Graduate Medical Education Training Programs: A Return on Investment Analysis.

BACKGROUND: The productivity of surgical departments is limited by the staffing of attending surgeons as well as surgical residents. Despite ongoing surgeon shortages, many health care organizations have been reluctant to expand training programs because of concerns about cost. We sought to determine the return on investment for the expansion of surgical training programs within our health system. METHODS: This study was completed as a retrospective review comparing two independent surgical departments at separate hospitals within a single integrated health system, including complete fiscal information from 2012 to 2019. Hospital A is a 594-bed hospital with large growth in its graduate surgical training programs over the study's period, whereas Hospital B is a 320-bed hospital where there was no expansion in surgical education initiatives. Case volumes, the number of full-time employees (FTE), and revenue data were obtained from our health systems business office. The number of surgical trainees, including general surgery residents and vascular surgery fellows, was provided by our office of Graduate Medical Education. The average yearly net revenue per surgeon was calculated for each training program and hospital location. RESULTS: Our results indicate a positive association between the number of surgical trainees and departmental net revenue, as well as the annual revenue generated per physician FTE. Each additional ancillary provider per physician FTE resulted in a positive impact of $112,552-$264,003 (R2 of 0.69 to 0.051). CONCLUSIONS: Regardless of hospital location or surgical specialty, our results demonstrate a positive association between the average net revenue generated per surgeon and the number of surgical trainees supporting the department. These findings are novel and provide evidence of a positive return on investment when surgical training programs are expanded.

The combined use of thoracic and abdominal aortic stent grafts for endovascular repair of wide neck abdominal aortic aneurysms in high risk patients.

INTRODUCTION: Treatment of abdominal aortic aneurysms (AAA) with large (28 mm to 34 mm) and wide diameter (> 35 mm) necks remains a challenge in patients who are high-risk candidates for open repair. While several case reports describe the use of a thoracic stent graft in conjunction with a traditional modular bifurcated stent graft, most patients do not have the aortic length to accommodate such a configuration. We present our experience utilizing a distal unibody bifurcated aortic stent graft (Endologix, Irvine, CA) in conjunction with a proximal thoracic aortic stent graft (Medtronic, Minneapolis, MN) to treat wide-necked non-ruptured AAAs in patients who were otherwise poor candidates for open or fenestrated repair. METHODS: A single center retrospective review of patients treated with a combination of a distal unibody bifurcated aortic stent graft and a proximal thoracic aortic stent graft extension from 2013 to 2019 was performed. Demographics, perioperative details and long-term outcomes were collected and summarized. Standard statistical methods were utilized. RESULTS: We identified 7 patients who underwent this procedure during the study interval. Of these, all 7 (100%) were male with an average age of 69.1 ± 5.1 years. Average Charlson Comorbidity Index was 5.0. Average pre-operative maximum aortic and neck diameters were 57.9 mm (± 5.8) and 37.4 mm (± 4.5) respectively. All patients underwent repair with a distal 28 mm diameter unibody bifurcated aortic stent graft and proximal extension with a thoracic aortic stent graft that ranged from 40 to 46 mm in diameter. Technical success was achieved in all 7 patients. There were no perioperative mortalities or aorta-related deaths. Follow up was a mean of 1.98 years with a mean survival of 4.75 years (± 0.86). One patient required an aneurysm-related intervention for a late type III endoleak. CONCLUSION: The combined use of thoracic and abdominal aortic stent grafts is a safe and effective endovascular method to treat high-risk surgical candidates with wide-necked AAAs.

Outcome of rectus femoris muscle flaps performed by vascular surgeons for the management of complex groin wounds after femoral artery reconstructions.

OBJECTIVE: Groin wound complications after femoral artery reconstructions are highly morbid and notoriously difficult to treat. Successful techniques include long-term antibiotic therapy, operative débridement, and muscle flap coverage. Historically, more complex muscle flap coverage, such as a rectus femoris muscle flap (RFF), has been performed by plastic and reconstructive surgeons. In this study, the experience of vascular surgeons performing RFF in the management of wound complications after femoral artery reconstructions is reported. METHODS: Clinical data between 2012 and 2018 were retrospectively analyzed. Data were summarized, and standard statistical analysis was performed. RESULTS: There were 23 patients who underwent 24 RFFs for coverage of complex groin wounds after femoral artery reconstructions. One of the 23 patients underwent bilateral RFFs. In this study cohort, patients had a median age of 67.5 years, and 79% (n = 19) were male. Median body mass index was 28.0 kg/m2, and 38% of patients were classified as obese on the basis of body mass index criteria. A history of tobacco use was present in 88%; however, only 29% were current smokers. Diabetes was present in 38% of patients and chronic kidney disease in 29%. Of the 24 RFFs, 14 (58%) were constructed in patients with reoperative groin surgery resulting in the need for muscle flap coverage. Femoral endarterectomy was the most common index procedure (46%), followed by infrainguinal leg bypass surgery (17%) and aortobifemoral bypass (17%). Grafts used during the original reconstruction included 12 bovine pericardial patches (50%), 6 Dacron grafts (25%), 4 PTFE grafts (17%), and 2 autogenous reconstructions (8%). Microbiology data identified 33% of patients (n = 8) to have gram-positive bacterial infections alone, 21% (n = 5) to have gram-negative infections alone, and 29% (n = 7) to have polymicrobial infections; 4 patients (13%) had negative intraoperative culture data. Median hospital stay after RFF was 8 days, and median follow-up time was 29.3 months. Major amputation was avoided in 20 of 24 limbs (83%) undergoing RFF. Eight patients underwent intentional graft or patch explantation (33%) before RFF, whereas 14 of the remaining 15 patients (93%) had successful salvage of the graft or patch after RFF. Two of the patients (13%) who underwent RFF with the intention of salvaging a prosthetic graft or patch required later graft excision. After RFF, 30-day and 1-year survival was 96% and 87%, respectively. CONCLUSIONS: RFF coverage of complex groin wounds after femoral artery reconstructions may safely be performed by vascular surgeons with excellent outcomes.

Outcomes of familial abdominal aortic aneurysm repair in the Vascular Quality Initiative.

OBJECTIVE: Recent investigations have reported increased rates of aneurysm-related complications after endovascular aneurysm repair (EVAR) in familial abdominal aortic aneurysm (fAAA) patients. The purpose of this study was to evaluate the outcomes of open aortic repair (OAR) and EVAR in sporadic AAA (spAAA) and fAAA patients in the Society for Vascular Surgery Vascular Quality Initiative. METHODS: This was a retrospective review of all AAA repairs in the Vascular Quality Initiative from 2003 to 2017. Patients' data were summarized, and standard statistical analysis was performed. Patients with known genetic syndromes and centers with long-term follow-up of <50% of patients were excluded. RESULTS: From 2003 to 2017, there were 1997 fAAA patients compared with 18,185 spAAA patients undergoing OAR and EVAR during the same study period. Compared with their spAAA counterparts, fAAA patients were younger (P < .001), were more likely to be living at home before surgery (P = .008), and demonstrated a lower incidence of coronary artery disease (P = .001) and hypertension (P = .039). Rates of smoking and end-stage renal disease did not differ between groups. However, fAAA patients were more likely to have aneurysmal degeneration of their iliac arteries (P < .001) and to undergo OAR (P < .001). When analyzing patients undergoing OAR, we found that fAAA patients were more likely to require concomitant renal bypass surgery (P = .012) but were extubated sooner (P = .005), received fewer blood transfusions (P < .001), and had a shorter length of stay (P = .018). Although individual complication rates did not differ between fAAA and spAAA groups after OAR, a composite end point of all early postoperative complications was decreased in fAAA patients (P = .020). When comparing fAAA and spAAA patients who underwent EVAR, we found a greater incidence of early lumbar branch endoleaks (type II) in fAAA patients; however, the rate of proximal type IA endoleaks (P = .279) and the rate of late reintervention for sac growth (P = .786), any endoleak (P = .439), or rupture (P = .649) did not differ between the groups. Whereas spAAA patients undergoing EVAR required longer postoperative intensive care unit stays (P < .001) and had a greater incidence of blood transfusions (P < .001), fAAA and spAAA patients had similar rates of postoperative complications (P = .510), 30-day mortality (P = .177), and long-term mortality (P = .259). CONCLUSIONS: This study shows that patients with a familial form of AAA do not have increased morbidity or mortality after AAA repair. Our findings suggest that EVAR and OAR are both safe and effective for fAAA patients. Further studies with longer follow-up are needed to best care for this unique cohort of patients.

Outcomes of endovascular treatments for in-stent restenosis in patients with mesenteric atherosclerotic disease.

OBJECTIVE: Mesenteric angioplasty and stenting (MAS) has surpassed open revascularization as the treatment of choice for mesenteric ischemia. Despite the lower perioperative mortality associated with MAS, the need for reintervention is not infrequent. The purpose of this study was to review the outcomes of patients treated for mesenteric artery in-stent restenosis (MAISR). METHODS: Clinical data from a single center between 2004 and 2017 were retrospectively analyzed. Standard statistical analysis including Kaplan-Meier estimate for time-dependent outcomes, χ2 test for categorical variables, and two-sample t-test for continuous variables was performed. Primary end points included stent patency and reintervention rate. Secondary end points included mortality and morbidity. RESULTS: During the study period, 91 patients underwent primary MAS. In total, 113 mesenteric vessels were treated with 20 covered stents and 93 bare-metal stents. Overall primary patency was 69% at 2 years. At 2 years, primary patency was 83% for covered stents compared with 65% for bare-metal stents (P = .17). Of these 91 primary MAS patients, 27 (30%) were treated for MAISR (32 vessels). Two covered stent patients developed significant restenosis (11%) compared with 25 (34%) bare-metal stent patients (P = .02). The mean age of patients requiring reintervention was 69 years (36% male), with the majority having a history of tobacco use (85%), hypertension (75%), and hyperlipidemia (78%). Fourteen reintervention patients (52%) presented with recurrent symptoms, 10 (37%) had asymptomatic restenosis, and 3 (11%) developed intestinal ischemia. Twelve patients (44%) underwent reintervention with balloon angioplasty alone and 15 (56%) underwent repeated stent placement. Of the 15 patients who had repeated stent placement, 7 patients had covered stents placed. The 30-day mortality rate after reintervention for mesenteric stent restenosis was 0%. Postoperative complications occurred in 15% of patients (myocardial infarction, 4%; reversible kidney injury, 4%; and bowel ischemia requiring surgical exploration, 7%). There was no difference in the perioperative morbidity in comparing symptomatic and asymptomatic patients undergoing reintervention. Mean follow-up after mesenteric reintervention was 31 months, with one-third of patients (n = 9) requiring another reintervention because of either recurrence of symptoms or asymptomatic high-grade restenosis. Assisted primary patency at 2 years was 92% after reintervention with balloon angioplasty and 87% for repeated stent placement, with no statistically significant difference between the groups (P = .66). CONCLUSIONS: Treatment of MAISR is associated with low mortality and acceptable morbidity. The initial use of covered stents may reduce the need for reintervention.

Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci.

RATIONALE: Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA. OBJECTIVE: To identify additional AAA risk loci using data from all available genome-wide association studies. METHODS AND RESULTS: Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9. CONCLUSIONS: The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease.

Long-term comparative effectiveness of carotid stenting versus carotid endarterectomy in a large tertiary care vascular surgery practice.

OBJECTIVE: Carotid interventional trials have strict inclusion and exclusion criteria that make translation of their results to the real-world population challenging. Furthermore, the specialty of the operating surgeon and the role of clinical decision-making are not well studied. This study compares the effectiveness of carotid endarterectomy (CEA) vs carotid artery stenting (CAS) in a real-world setting when the procedure is performed by fellowship-trained vascular surgeons. METHODS: A retrospective study was conducted of all consecutive patients undergoing CEA and CAS performed by vascular surgeons in a large rural tertiary health care system from 2004 to 2014. Postoperative outcomes of stroke, acute myocardial infarction (AMI), and death were analyzed at 30 days and during the long term (median follow-up of 5.5 years for CEA and 4.8 years for CAS). Standard statistical analysis was performed. Differences in long-term outcomes were expressed as cumulative incidence functions for nondeath outcomes (stroke and AMI), which account for the high death rate in this population of vascular patients, and as Kaplan-Meier curves for death itself. RESULTS: From January 1, 2004, through December 31, 2014, there were 2331 carotid interventions performed (CEA, 1853; CAS, 478), all by fellowship-trained vascular surgeons. The average age of the patients was 71 years, and 63% were male, with more men in the CAS group (61.5% vs 67.8%; P = .011). Preoperatively, 30% of patients were symptomatic, and 77% of patients had high-grade stenosis in the 70% to 99% range. CEA patients were more likely to have preoperative hypertension (89.7% vs 86.2%; P = .029) and were less likely to have a history of cardiovascular disease (53.4% vs 59.4%; P = .018). There were no significant differences in 30-day outcomes between CEA and CAS (stroke, 1.1% vs 1.3% [P = .743]; AMI, 2.2% vs 1.7% [P = .474]; death, 0.7% vs 0.6% [P = .859]) or long-term outcomes (stroke, 6.8% vs 7.7% [P = .321]; AMI, 22.7% vs 21.0% [P = .886]; death, 28.4% vs 28.2% [P = .122]). CONCLUSIONS: The short- and long-term outcomes after CEA vs CAS are similar when the procedure is performed in a real-world setting by fellowship-trained vascular surgeons.

Patency and limb salvage after femoral endarterectomy and iliac stenting are not affected by severity of iliac disease.

OBJECTIVE: The hybrid procedure of femoral endarterectomy and iliac artery stenting (FEIS) has been used as an alternative to traditional open surgical repair of iliofemoral arterial occlusive disease, but whether the severity of the iliac disease component affects long-term results is not well understood. METHODS: This was a retrospective cohort study of patients undergoing FEIS at Geisinger Health System from January 1, 2004, through December 31, 2013, for the treatment of symptomatic iliofemoral atherosclerotic occlusive disease. The cohort was stratified according to the severity of the iliac occlusive disease component into patients with mild iliac disease (group 1) and patients with severe iliac disease (group 2). RESULTS: Between January 1, 2004, and December 31, 2013, 99 patients underwent 111 total FEIS procedures. The mean age of the cohort was 67.4 years. Men composed 61% of patients. Indications for surgery were claudication (41%), ischemic rest pain (36%), and tissue loss (23%). At 5 years of follow-up, there was no difference in primary patency (73% in group 1 vs 68% in group 2 [P = .67]) and limb salvage (90% in group 1 vs 92% in group 2 [P = .51]). There was a trend toward higher overall mortality in group 2 patients vs group 1 patients (53% vs 81%; P = .08), but this did not reach statistical significance. Univariate analysis did not identify any device-related or anatomic factors predictive of patency. CONCLUSIONS: When combined iliofemoral arterial occlusive disease is treated with FEIS, the severity of the iliac disease component does not affect long-term patency or limb salvage.

Value of delayed duplex ultrasound assessment after endothermal ablation of the great saphenous vein.

OBJECTIVE: Endothermal ablation (ETA) of the great saphenous vein (GSV) is associated with a small but definite risk of endothermal heat-induced thrombosis (EHIT) extending into the common femoral vein. Follow-up duplex ultrasound imaging to detect EHIT after ETA is considered standard of care, although the exact timing of duplex ultrasound imaging to detect EHIT after ETA remains unclear. We hypothesized that an additional duplex ultrasound assessment 1 week after ETA would not identify a significant number of patients with EHIT and would significantly increase health care costs. METHODS: This was a retrospective review of consecutive ETA GSV procedures from 2007 to 2014. All patients were evaluated with duplex ultrasound imaging on postprocedure day 1, and 79% of patients underwent a second ultrasound assessment 1 week postprocedure. EHIT was considered present when proximal GSV closure progressed to level ≥4, based on a six-tier classification system. RESULTS: From January 1, 2007, until December 31, 2014, 842 patients underwent GSV ETA. Patients with EHIT were more likely to have had a prior deep venous thrombosis (DVT; P = .002) and a larger GSV (P = .006). Forty-three procedures (5.1%) were classified as having EHIT requiring anticoagulation, based on a level ≥4 proximal closure level. Of the 43 patients with EHIT, 20 (47%) were found on the initial ultrasound assessment performed 24 hours postprocedure, but 19 patients (44%) with EHIT would not have been identified with a single postoperative ultrasound scan performed 24 hours after intervention. These 19 patients had a level ≤3 closure level at the duplex ultrasound scan performed 24 hours postprocedure and progressed to EHIT on the delayed duplex ultrasound scan. Lastly, thrombotic complications in four patients (9%), representing three late DVT and one DVT/pulmonary embolism presenting to another hospital, would not have been identified regardless of the postoperative surveillance strategy. Maximum GSV diameter was the only significant predictor of progression to EHIT on multivariate analysis (P = .007). Based on 2014 United States dollars, the two-ultrasound surveillance paradigm is associated with health care charges of $31,109 per identified delayed venous thromboembolism event. CONCLUSIONS: Delayed duplex ultrasound assessment after ETA of the GSV comes with associated health care costs but does yield a significant number of patients with progression to EHIT. Better understanding of the timing, risk factors, and significance of EHIT is needed to cost-effectively care for patients after ETA for varicose veins.

Patients with familial abdominal aortic aneurysms are at increased risk for endoleak and secondary intervention following elective endovascular aneurysm repair.

OBJECTIVE: A recent investigation has documented an increased risk of aneurysm-related complications after endovascular aneurysm repair (EVAR) of familial abdominal aortic aneurysms (fAAAs). We hypothesized that fAAA patients are not at increased risk for complications following open AAA repair or EVAR when compared with sporadic abdominal aortic aneurysm (spAAA) patients. To this end, we performed a single institution retrospective review. METHODS: Epidemiologic data were collected through the electronic medical record. Family history data were obtained from a questionnaire administered at the initial vascular surgery consultation. Major adverse events were defined as myocardial infarction, respiratory failure, renal failure, bowel ischemia, limb ischemia, multisystem organ failure, intracranial hemorrhage, paraplegia, hemorrhage, or death. Endoleaks were classified in accordance with the standardized reporting practices of the Society for Vascular Surgery. AAA-related complications were defined as the need for a secondary intervention due to endoleak, limb ischemia, or postimplantation rupture. RESULTS: A total of 392 patients with complete clinical data underwent elective AAA repair from 2004 to 2014. Of these 392 patients, 89 (23%) were classified as fAAA patients and 303 (77%) were classified as spAAA patients. With the exception of increased rates of chronic obstructive pulmonary disease (P = .0009) and pack-years smoked (P = .03) in spAAA patients, demographics did not differ. Sixty-two percent (n = 55) of fAAA patients and 68% (n = 205) of spAAA patients underwent EVAR (P = .30). fAAA patients did not incur any significant difference in major adverse events following open AAA repair (fAAA, 9% vs spAAA, 11%; P = .75). Additionally, fAAA patients did not incur any significant difference in major adverse events following EVAR (fAAA, 4% vs spAAA, 5%; P = .70). Patients with fAAA did have a significantly increased rate of endoleak (fAAA, 24% vs spAAA, 12%; P = .03) and secondary intervention following EVAR (fAAA, 21% vs spAAA, 12%; P = .04). CONCLUSIONS: The current study shows that patients with fAAA do not have increased perioperative morbidity following open or endovascular AAA repair. However, patients with fAAA do have an increased risk of endoleak and secondary intervention following EVAR. These findings suggest that EVAR and open AAA repair are both safe and effective for fAAA patients. The increased rate of endoleak and secondary intervention in patients with fAAA suggests that this subpopulation may benefit from closer post-EVAR surveillance or open surgical repair in good risk patients.

Proinflammatory role of stem cells in abdominal aortic aneurysms.

OBJECTIVE: The pathogenesis of abdominal aortic aneurysm (AAA) formation includes inflammation, vascular smooth muscle cell apoptosis, extracellular matrix degradation, and oxidative stress. That multipotent stem cells have an important role in cardiovascular health and disease has been well established, but the role of stem cells in aortic structural deterioration is poorly defined. We sought to describe the presence of stem cells in human AAA tissue and also investigated the differentiation of stem cells within the aneurysmal aorta. METHODS: Infrarenal aortic wall specimens were collected from patients (n = 7) undergoing open AAA surgical repair. Nonaneurysmal infrarenal aortic control samples (n = 4) were collected at autopsies. Using immunohistochemistry, we compared the abundance of Stro1-positive ((+)), c-kit(+), and CD34(+) cells in aortic tissue. Using double-immunofluorescence staining, we evaluated stem cell differentiation into smooth muscle cells (SM22), fibroblasts (FSP1), and macrophages (CD68). We then investigated the colocalization of CD68(+) cells with the cellular marker of proliferation Ki67. RESULTS: The media and adventitia of infrarenal AAA samples both demonstrated a significantly greater number of c-kit(+) and CD34(+) cells compared with matched control nonaneurysmal aortic tissues; however, the abundance of Stro1(+) cells was not significantly different between the groups. Using double-immunofluorescence staining, we identified that AAA stem cells express the macrophage marker CD68 but not the smooth muscle cell marker SM22 or the fibroblast marker FSP1. CD68(+) cells within the aortic wall colocalized with the cellular marker of proliferation Ki67. CONCLUSIONS: Stem cells are significantly elevated in infrarenal AAA tissue compared with matched control aortic tissue. Our data also demonstrate that AAA stem cells express macrophage surface antigens but not smooth muscle cell or fibroblast markers. Furthermore, CD68(+) cells within the aortic wall colocalized with the cellular marker of proliferation Ki67. These finding suggest an inflammatory/immune role of stem cells during AAA pathogenesis and raise the possibility of localized replenishment therapy within the aneurysm wall.

The potential role of DNA methylation in abdominal aortic aneurysms.

Abdominal aortic aneurysm (AAA) is a complex disorder that has a significant impact on the aging population. While both genetic and environmental risk factors have been implicated in AAA formation, the precise genetic markers involved and the factors influencing their expression remain an area of ongoing investigation. DNA methylation has been previously used to study gene silencing in other inflammatory disorders and since AAA has an extensive inflammatory component, we sought to examine the genome-wide DNA methylation profiles in mononuclear blood cells of AAA cases and matched non-AAA controls. To this end, we collected blood samples and isolated mononuclear cells for DNA and RNA extraction from four all male groups: AAA smokers (n = 11), AAA non-smokers (n = 9), control smokers (n = 10) and control non-smokers (n = 11). Methylation data were obtained using the Illumina 450k Human Methylation Bead Chip and analyzed using the R language and multiple Bioconductor packages. Principal component analysis and linear analysis of CpG island subsets identified four regions with significant differences in methylation with respect to AAA: kelch-like family member 35 (KLHL35), calponin 2 (CNN2), serpin peptidase inhibitor clade B (ovalbumin) member 9 (SERPINB9), and adenylate cyclase 10 pseudogene 1 (ADCY10P1). Follow-up studies included RT-PCR and immunostaining for CNN2 and SERPINB9. These findings are novel and suggest DNA methylation may play a role in AAA pathobiology.

Ultrasound-guided percutaneous thrombin injection of iatrogenic upper extremity pseudoaneurysms.

OBJECTIVE: The objective of this study was to evaluate the safety and efficacy of ultrasound-guided thrombin injection (TI) for the treatment of upper extremity iatrogenic pseudoaneurysms (PAs) after percutaneous upper extremity arterial access. METHODS: This is a retrospective single-institution study from January 2009 to December 2012. All patients with clinical suspicion of an upper extremity PA after arterial puncture underwent duplex examination. Patients with and without PAs were compared to identify risk factors for development of PAs. Outcomes were analyzed in those patients with PAs that were treated with TI. RESULTS: Between January 1, 2009, and December 31, 2012, there were 61 upper extremity arterial duplex examinations performed for a clinical suspicion of an upper extremity PA. Eighteen ultrasound examinations (29.5%) demonstrated an iatrogenic upper extremity PA (13 brachial and five radial). Those patients with an upper extremity PA were more likely to have a history of hypertension, atrial fibrillation, and chronic kidney disease. Sheath size, preprocedural antiplatelet therapy, periprocedural anticoagulation regimen, service specialty performing the procedure, and procedure type did not influence the development of PA. Of 18 patients with PA, 14 were treated with TI with an overall success rate of 86%. There was one PA that failed to thrombose with TI, and there was one native brachial artery thrombosis requiring emergent surgical intervention. Outpatient clinical follow-up in the successfully treated patients demonstrated no recurrences at an average follow-up of 8 months. CONCLUSIONS: Ultrasound-guided percutaneous TI appears safe and effective for the treatment of iatrogenic brachial and radial artery PAs.

Endoleak visualized with carbon dioxide angiography during endovascular aneurysm repair using the Endurant stent-graft.

PURPOSE: To make interventionists aware of the potential for type IV endoleak on completion carbon dioxide (CO2) angiography during endovascular aneurysm repair (EVAR) using the Endurant stent-graft. CASE REPORT: A 74-year-old man with chronic kidney disease underwent EVAR with an Endurant stent-graft using CO2 angiography to guide graft placement. Completion CO2 angiography demonstrated immediate accumulation of CO2 in the aneurysm sac suggestive of an endoleak, but confirmatory angiography with conventional iodinated contrast showed no evidence of an endoleak. We speculate that this is a type IV endoleak, and graft porosity may be responsible. CONCLUSION: Interventionists should be alerted to the possibility of visualizing these endoleaks through Endurant stent-grafts under CO2 angiography. Further work should be done to elucidate the exact mechanism of the endoleak.

Coronary stent migration to aorta with successful recovery during aortobifemoral bypass.

We present with full and proper consent of the patient, the case of a 64-year-old man with severe peripheral arterial disease and a known chronic infrarenal aortic occlusion causing severe short-distance claudication. Preoperative computed tomography angiography was significant for a new "cylindrical" calcified lesion. During the elective surgery, the lesion was confirmed to be a coronary stent. The coronary stent was confirmed to be from the patient's prior percutaneous coronary intervention to the left anterior descending artery 1 year prior. The stent was removed without complications by the surgical team. To the best of our knowledge, this is the first such case to be described in current literature. This patient is currently alive, and a revision of his left anterior descending artery intervention was found to be unwarranted on repeat coronary angiography.