Analysis of the Learning Curve and Patient Outcomes of Endovascular Repair of Thoracoabdominal Aortic Aneurysms Using Fenestrated and Branched Stent Grafts: Prospective, Nonrandomized, Single-center Physician-sponsored Investigational Device Exemption Clinical Study.

OBJECTIVE: To evaluate the outcomes and learning curve of fenestrated and branched endovascular repair (F/BEVAR) of thoracoabdominal aneurysms. SUMMARY OF BACKGROUND DATA: Endovascular aneurysm repair has reduced morbidity and mortality compared with open surgical repair. However, application to thoracoabdominal aneurysm repair remains limited by procedural complexity and device availability. METHODS: Fifty patients treated in a prospective, nonrandomized, single-center Investigational Device Exemption (IDE) study between January 2014 and July 2017 were analyzed. Patients (mean age 75.6 ±â€Š7.5 years; mean aneurysm diameter 67.3 ±â€Š9.8 mm) underwent F/BEVAR of thoracoabdominal aneurysms (58% type IV; 42% type I-III) using custom-manufactured endografts. The experience was divided into 3 cohorts (Early: 1 to 17; Mid: 18 to 34; Late: 35 to 50) to evaluate learning curve effects on key process measures. RESULTS: F/BEVAR included 194 visceral arteries (average 3.9 per patient). Technical success was 99.5% (193/194 targeted arteries). Thirty-day major adverse events (MAEs) included 3 (6%) deaths, 1 (2%) new-onset dialysis, 3 (6%) paraparesis/paraplegia, and 2 (4%) strokes. One-year survival was 79 ±â€Š7%. Comparing the Early and Late groups revealed reductions in procedure time (452 ±â€Š74 vs 362 ±â€Š53 minutes; P = 0.0001), fluoroscopy time (130 ±â€Š40 vs 99 ±â€Š27 minutes; P = 0.016), contrast administration (157 ±â€Š73 vs 108 ±â€Š38 mL; P = 0.028), and estimated blood loss (EBL; 1003 ±â€Š933 vs 481 ±â€Š317 mL; P = 0.042). Intensive care unit (ICU) and total length of stay (LOS) decreased from 4 ±â€Š3 to 2 ±â€Š1 days and from 7 ±â€Š6 to 5 ±â€Š2 days, respectively, but was not statistically significant. CONCLUSIONS: Use of F/BEVAR for treatment of thoracoabdominal aneurysms is safe and effective. During this early experience, there was a significant improvement in key process measures reflecting improvements in technique and physician learning over time.

Assessing the Utility of Low-Cost Particulate Matter Sensors over a 12-Week Period in the Cuyama Valley of California.

The use of low-cost air quality sensors has proliferated among non-profits and citizen scientists, due to their portability, affordability, and ease of use. Researchers are examining the sensors for their potential use in a wide range of applications, including the examination of the spatial and temporal variability of particulate matter (PM). However, few studies have quantified the performance (e.g., accuracy, precision, and reliability) of the sensors under real-world conditions. This study examined the performance of two models of PM sensors, the AirBeam and the Alphasense Optical Particle Counter (OPC-N2), over a 12-week period in the Cuyama Valley of California, where PM concentrations are impacted by wind-blown dust events and regional transport. The sensor measurements were compared with observations from two well-characterized instruments: the GRIMM 11-R optical particle counter, and the Met One beta attenuation monitor (BAM). Both sensor models demonstrated a high degree of collocated precision (R² = 0.8-0.99), and a moderate degree of correlation against the reference instruments (R² = 0.6-0.76). Sensor measurements were influenced by the meteorological environment and the aerosol size distribution. Quantifying the performance of sensors in real-world conditions is a requisite step to ensuring that sensors will be used in ways commensurate with their data quality.

Outcomes and risk factors of cardiac arrest after vascular surgery procedures.

BACKGROUND: Despite increased awareness of the value of discussing patients' goals of care, advance directives, and code status as part of the surgical informed consent process, the actual outcomes and risks of cardiopulmonary resuscitation (CPR) remain poorly defined among some subsets of surgical patients. Thus, in an effort to generate an evidence base for communication about shared decision making and informed consent for vascular surgery patients and their surrogates, we defined the incidence, risks, and outcomes of postoperative cardiac arrest after primary vascular surgery procedures. METHODS: The 2007 to 2010 National Surgical Quality Improvement Program data were queried to develop a multi-institutional database of patients undergoing vascular surgery (N = 123,581). Univariate analyses and multivariate logistic regression were used to identify crude and adjusted risk factors for postoperative cardiac arrest requiring CPR and to assess outcomes. RESULTS: Postoperative cardiac arrest requiring CPR was seen in 1234 of 123,581 patients (1.0%) after vascular surgery at a mean of 7.2 ± 2 days. The 30-day mortality was 73.4% compared with 2.7% among patients who did not arrest (P < .001). Of CPR survivors, 102 (12.1%) were still hospitalized at 30 days. Patient variables that were most predictive of postoperative cardiac arrest included dependent functional status (odds ratio [OR], 2.9; 95% confidence interval [CI], 2.3-3.6; P < .001), dialysis dependence (OR, 2.7; 95% CI, 2.3-3.2; P < .001), emergent case (OR, 2.2; 95% CI, 1.9-2.5; P < .001), and preoperative ventilator dependence (OR, 2.0; 95% CI, 1.5-2.7; P < .001). Procedures associated with the highest risk included thoracic aortic surgery (OR, 6.9; 95% CI, 4.8-9.9; P < .001), open abdominal procedures (OR, 3.7; 95% CI, 3.1-4.4; P < .001), axillary-femoral bypass (OR, 2.1; 95% CI, 1.3-3.2; P = .001), and peripheral embolectomy (OR, 1.5; 95% CI, 1.2-1.9; P = .002). At least one major complication preceded cardiac arrest in 47.7% of patients including sepsis (23.5%), renal failure (14.5%), and myocardial infarction (12.1%). Patients with do not resuscitate orders were significantly less likely to undergo CPR (OR, 0.59; 95% CI, 0.39-0.93; P = .021). CONCLUSIONS: Patients undergoing vascular surgery who suffer a postoperative cardiac arrest frequently die in spite of receiving CPR; for those who survive, there is likely to be prolonged hospitalization and significant morbidity. These data provide an evidence base for discussing goals of care, advance directives, and code status with vascular surgery patients and their surrogates. Further research into how to best communicate risk, to elicit patient preferences, and to engage in shared decision making is needed.

An Atmospheric Constraint on the NO2 Dependence of Daytime Near-Surface Nitrous Acid (HONO).

Recent observations suggest a large and unknown daytime source of nitrous acid (HONO) to the atmosphere. Multiple mechanisms have been proposed, many of which involve chemistry that reduces nitrogen dioxide (NO2) on some time scale. To examine the NO2 dependence of the daytime HONO source, we compare weekday and weekend measurements of NO2 and HONO in two U.S. cities. We find that daytime HONO does not increase proportionally to increases in same-day NO2, i.e., the local NO2 concentration at that time and several hours earlier. We discuss various published HONO formation pathways in the context of this constraint.

Impact of "Do Not Resuscitate" Status on the Outcome of Major Vascular Surgical Procedures.

BACKGROUND: Patients with Do Not Resuscitate (DNR) orders may still be offered surgery that aims to prolong or improve quality of life. The widely accepted approach of "required reconsideration" mandates that patients and surgeons discuss perioperative risks and expected outcomes in the context of the patient's values and preferences. However, surgical outcomes in this patient population have not been well-defined. The objectives of this study are to assess outcomes in DNR patients undergoing major vascular procedures, and develop an evidence basis for informed, shared decision-making. METHODS: Patients undergoing common major vascular procedures were identified in the 2007-2010 National Surgical Quality Improvement Project databases. DNR patients were defined as those with an active DNR order within 30 days before surgery. Demographics, comorbidities, procedural details, and complications were compared with those without DNR orders. To isolate the impact of DNR status, multivariate regression and 1:1 propensity score matching were used to compare outcomes between DNR patients and a non-DNR cohort of comparably high-risk patients. RESULTS: Of 110,279 patients undergoing major vascular surgery, 1,565 (1.4%) had active DNR orders 30 days preceding surgery. DNR patients were more likely to be functionally dependent (69% vs. 15%; P < 0.0001), over 80 years of age (53% vs. 20%; P < 0.001), and suffer from a variety of cardiac, pulmonary, and systemic comorbidities. The most common procedures in DNR patients were major amputation (38.4%), lower extremity bypass (20%), and peripheral thromboembolectomy (11.7%). Unadjusted 30-day mortality was significantly higher among DNR patients (21% vs. 3.4%; P < 0.001). After 1:1 propensity score matching, with the 2 cohorts differing only with respect to DNR status, perioperative mortality remained significantly higher among DNR patients (21% vs. 13%; P < 0.01). There was a trend toward reduced cardiopulmonary resuscitation in patients with recent DNR (1.7% vs. 2.6%; P = 0.07). CONCLUSIONS: DNR patients are at high risk for major complications and mortality after vascular surgery procedures. Compared with a matched cohort of "high-risk" non-DNR patients, those with DNR orders suffered equivalent rates of postoperative morbidity, but markedly increased mortality. This suggests that DNR status, independent of comorbidities and perioperative complications, may increase the risk of "failure to rescue." These findings have implications not only for risk adjustment, but also provide an evidence basis for shared decision-making in challenging circumstances.

Comparative safety of endovascular and open surgical repair of abdominal aortic aneurysms in low-risk male patients.

OBJECTIVE: The prevalence of significant comorbidities among patients with abdominal aortic aneurysms (AAAs) has contributed to widespread enthusiasm for endovascular AAA repair (EVAR). However, the advantages of EVAR in patients at low risk for open surgical repair (OSR) remain unclear. The objective of this study was to assess perioperative outcomes of EVAR and OSR in low-risk patients. METHODS: Patients undergoing EVAR and OSR for infrarenal AAAs were identified in the 2007 to 2010 National Surgical Quality Improvement Program data sets. AAA-specific risk stratification, by the Medicare aneurysm scoring system, was used to create matched low-risk (score <3) cohorts. Perioperative morbidity and mortality were assessed by crude comparisons of matched groups and regression models. RESULTS: Of 11,753 elective patients undergoing EVAR, 4339 (37%) were deemed low risk (score <3). A matched cohort of 1576 low-risk patients was developed from a total of 3804 (41%) undergoing OSR. The low-risk cohorts included only male patients and those <75 years of age, without significant cardiac, pulmonary, or vascular comorbidities. Mean age in both low-risk groups was 67 ± 6 years (P = NS). EVAR patients had higher rates of obesity (40% vs 33%; P < .001), diabetes (16% vs 13%; P = .005), history of cardiac intervention (24% vs 19%; P < .001), cardiac surgery (23% vs 20%; P = .02), steroid use (4% vs 2%; P = .002), and bleeding disorders/anticoagulation (9% vs 6%; P = .001) compared with OSR patients. There were no other differences between the matched cohorts. EVAR was associated with reduced 30-day mortality (0.5% vs 1.5%; P < .01) and reduced rates of major complications, including the following: sepsis (0.7% vs 3.2%; P < .01), unplanned intubation (1.0 vs 5.4%; P < .001), pneumonia (0.8% vs 6.1%; P < .001), acute renal failure (0.4% vs 2.7%; P < .001), and early reoperation (3.7% vs 6.0%; P < .001). Furthermore, EVAR was associated with reduced perioperative morbidity across organ systems, including venous thromboembolism (0.1% vs 0.3%; P = .001), transfusion requirement of more than 4 units (2.0% vs 13.0%; P < .001), cardiac arrest (0.2 vs 0.8; P = .001), neurologic deficits (0.2% vs 0.5%; P = .032), and urinary tract infections (1.2% vs 2%; P = .02). CONCLUSIONS: Our results demonstrate that even among those male patients at low risk for OSR on the basis of comorbidities, EVAR is associated with reduced perioperative mortality and major complications. Whereas clinical decisions must account for safety and long-term effectiveness, the short-term benefit of EVAR is evident even among male patients at the lowest risk for OSR.

Determinants of outcome after endovascular therapy for critical limb ischemia with tissue loss.

BACKGROUND: In this study we examine outcomes of endovascular therapy for critical limb ischemia with tissue loss and identify risk factors for failure of endovascular therapy across a panel of outcome metrics. METHODS: A retrospective review (2006-2010) of patients undergoing endovascular therapy for critical limb ischemia with tissue loss provided data for multivariate models of overall survival, amputation-free survival, limb salvage (LS), and wound healing. RESULTS: One hundred six patients underwent endovascular therapy for Rutherford class 5 (88%) or class 6 (12%) ischemia with ulceration and/or gangrene of the heel (15%), forefoot (16%), toe(s) (43%), calf/ankle (11%), or multiple locations (15%). Sustained limb salvage at 1 year was 87%. One-year overall survival and amputation-free survival were 65% and 49%, respectively. Multivariate regression models identified independent risk factors for reduced primary patency: Rutherford 6 ischemia (P = 0.008; HR 4.7 [95% confidence interval 1.5-14.8]) and infrapopliteal intervention (P = 0.03; HR 2.58 [95% CI 1.08-6.14]). Rutherford class 6 ischemia was independently associated with reduced assisted patency (P = 0.004; HR 5.39 [95% CI 1.74-16.73]). Wound healing was adversely affected by diabetes (P = 0.02; HR 7.0 [95% CI 1.4-36.2]), continued smoking (P = 0.04; HR 5.3 [95% CI 1.1-26.3]), and patency loss (P = 0.04; HR 4.8 [95% CI 1.1-22.30]). Rutherford class 6 ischemia was independently associated with reduced limb salvage (P < 0.0001; HR 35.1 [95% CI 5.4-231.2]) and amputation-free survival (P = 0.007; HR 3.61 [95% CI 1.4-9.18]), in addition to COPD (P = 0.01; 3.58 [95% 1.28-9.55]). Independent predictors of poor overall survival included end-stage renal disease (P = 0.03; HR 2.99 [95% CI 1.1-8.05]), history of angina (P = 0.02; HR 5.08 [95% CI 1.28-20.29]), and COPD (P = 0.001; HR 3.77 [95% CI 1.76-8.34]). CONCLUSIONS: Both increasing severity of tissue loss as well as the presence of severe medical comorbidities are associated with poorer outcomes of endovascular therapy in these patients. Although sustained limb salvage in patients with tissue loss may be achieved with endovascular therapy, this is due to poor overall survival and a competing mortality hazard.

Endovascular repair of infrarenal focal aortic pathology with limited aortic coverage.

BACKGROUND: Endovascular abdominal aortic aneurysm repair (EVAR) for degenerative abdominal aortic aneurysm (AAA) requires complete aortic exclusion to prevent ongoing aneurysmal degeneration in a diseased aorta. Focal infrarenal aortic pathology, such as penetrating atherosclerotic ulcer (PAU), saccular aneurysm, and/or intramural hematoma (IMH) may not necessitate complete aortic coverage. Here, we review our experience with endovascular management of focal aortic pathology with limited aortic coverage. METHODS: A prospectively maintained institutional database of patients undergoing EVAR was retrospectively reviewed to identify all patients treated with a nonbifurcated device (Current Procedural Terminology code: 34,800). Patients without a diagnosis of PAU, saccular aneurysm, IMH, or iatrogenic pseudoaneurysm were excluded. Medical records and imaging studies were reviewed for confirmation of focal aortic pathology. Preoperative imaging and intraoperative details were reviewed. Outcome measures included technical success, symptom-free survival, and freedom from reintervention. RESULTS: Eight patients were identified who underwent repair of a focal aortic defect with an endovascular tube graft from 2004-2011. Six patients underwent surgery for 7 saccular pseudoaneurysms and 2 patients had iatrogenic infrarenal pseudoaneurysms. Six saccular aneurysms were associated with PAU. Seven patients (88%) were men; the median age was 76 years (range: 50-85 years). Four patients (50%) had symptoms attributable to their aneurysm (2 abdominal pain, 1 gastrointestinal symptoms, 1 lower extremity emboli). Aneurysm repair was classified as urgent in 2 patients (25%). Six patients (75%) required placement of a single aortic component, the other 2 patients (25%) required 2 components. All devices used were Zenith (Cook, Inc., Bloomington, IN) ancillary components. The median device diameter was 22 mm (range: 18-28 mm), while the median device length was 56.5 mm (range: 39-80 mm). The technical success rate was 100%. There were no early graft-related complications. All symptomatic patients experienced improvement or resolution of symptoms. In all cases, radiologic follow-up at 1 month showed stable or decreasing aneurysm size. No endoleaks were detected and no patients have required reintervention to date. CONCLUSIONS: The optimal management of many focal infrarenal aortic defects, particularly those that are incidentally discovered, remains unclear. Our experience with endovascular repair of focal aortic pathology with limited aortic coverage suggests this approach is technically feasible and associated with excellent early results.

Midterm outcomes after treatment of type II endoleaks associated with aneurysm sac expansion.

PURPOSE: To examine the outcomes following interventions for type II endoleaks in patients with aneurysm sac expansion after endovascular aneurysm repair (EVAR). METHODS: A retrospective review was conducted of all patients who underwent treatment for type II endoleak from July 2001 to September 2010 in a single center. In this time period, 29 (4.7%) patients (22 men; mean age 78.6 years, range 54-87) were identified as having a type II endoleak and enlargement of the aneurysm sac, meeting the criterion for treatment. All patients had at least one attempted percutaneous intervention. Patients were followed both clinically and radiographically, with computed tomographic angiography every 3 to 12 months, over a follow-up period that ranged from 1 to 10 years (mean 3.5). RESULTS: Forty-eight interventions were performed on the 29 patients. Of these, 15 (56%) patients underwent multiple (2-4) procedures. Of the 11 endoleaks with an isolated inferior mesenteric artery identified as the source, initial success for transarterial embolization at 2 years was 72%, with 2 of the failures having successful secondary interventions. For the 18 endoleaks with a lumbar source, the success of the initial intervention was 17% at 2 years; repeated embolization attempts produced a 40% secondary success rate. Seven (24%) patients had continued endoleak despite multiple treatment attempts; 3 ultimately required elective aortic graft explantation. There were no ruptures or deaths during the study period. In a comparison of type II endoleak patients who had stable aneurysm sacs and those who had persistent sac expansion, the only significant differences in preoperative anatomical characteristics were a lower prevalence of mural thrombus (p = 0.036) and longer right iliac arteries (p = 0.012) in the group with sac expansion. Independent predictors of type II endoleak were mural thrombus (p<0.001), patent lumbar arteries (p = 0.004), aneurysm length (p = 0.011), and iliac artery length (p = 0.004). CONCLUSION: This study demonstrates that most patients require multiple reinterventions to treat type II endoleaks; specifically, lumbar artery embolization carries a low midterm success rate.

Determining criteria for predicting stenosis with ultrasound duplex after endovascular intervention in infrainguinal lesions.

BACKGROUND: Studies examining duplex surveillance of lower extremity bypass grafts have defined a role for guiding graft re-intervention. The goal of this study is to determine the utility of duplex scanning to detect angiographic restenosis after endovascular therapy in patients with infrainguinal arterial disease. METHODS: A prospective registry including all patients treated for lower extremity atherosclerotic disease between February 2004 and September 2008 was established. Patients were followed up with duplex ultrasound at 1, 3, 6, 12 months, and then annually. Patients receiving repeat angiograms were identified and angiogram and duplex data were abstracted. Velocity ratios (Vr) were calculated for each lesion by dividing the peak velocity within the lesion by the peak velocity proximal to the lesion. Logarithmic regression and receiver operator characteristic (ROC) curve analyses were used. RESULTS: Repeat angiograms were performed on 345 lesions in 143 patients, and 254 lesions in 103 patients had a corresponding duplex ultrasound. Indications for the initial intervention were claudication (n = 62, 43.4%), rest pain (n = 23, 16.1%), and tissue loss (n = 58, 40.5%). A total of 178 superficial femoral artery (SFA) lesions, 59 popliteal lesions, and 17 tibial lesions were identified by surveillance duplex in 103 patients. In all, 70.5% of the intervened vessels that were studied were nonstented and the remaining 29.5% were stented. A total of 65% of the patients had diabetes. On determining correlations for peak systolic velocity (PSV) as measured by duplex ultrasound with degree of angiographic stenosis, strong correlation coefficients for SFA disease (R² = 0.84) and popliteal disease (R² = 0.88) were found. However, poor correlation was found in patients with tibial disease. When analyzing the lesions on the basis of Vr < 2.0, 11 of 86 (12.8%) had >70% angiographic stenosis. In lesions with ratios from 2 to 2.5, 12 of 13 (92.3%) had >70% angiographic stenosis and in lesions with ratios >2.5, 69 of 75 (92.0%) had >70% angiographic stenosis. ROC curve analysis showed that to detect ≥ 70% stenosis in the SFA, a PSV ≥ 204 cm/sec had a sensitivity of 97.6% and specificity of 94.7%. To detect ≥ 70% stenosis in the overall femoropopliteal region, a PSV ≥ 223 cm/sec had a sensitivity of 94.1% and specificity of 95.2%. CONCLUSIONS: Duplex ultrasound surveillance correlates to the degree of angiographic stenosis on the basis of PSV in the SFA and popliteal region. Correlation in the tibial vessels is poor. Vr > 2.0 appear to correlate to angiographic stenosis of > 70%. ROC analysis shows that PSV can have sufficiently high sensitivity and specificity to predict angiographic stenosis in the femoropopliteal region.

Assessing the perioperative safety of common femoral endarterectomy in the endovascular era.

INTRODUCTION: Common femoral endarterectomy (CFE) has historically been the preferred treatment for atherosclerotic lesions involving the common femoral artery. The objectives of this study are to delineate the safety of this open procedure in the endovascular era, establish contemporary benchmarks for morbidity and mortality after CFE, and identify the subgroup of patients at increased risk of postoperative adverse events. METHODS: Patients undergoing elective CFE in the 2007 to 2010 National Surgical Quality Improvement Project database were examined. Univariate analyses were used to identify the factors associated with major morbidity and mortality. Significant variables by univariate analysis were used to create multivariate logistic regression models for morbidity and mortality. RESULTS: A total of 1513 patients underwent elective CFE. The 30-day mortality rate was 1.5%. Postoperative morbidities included cardiac (1.0%), pulmonary (1.9%), renal (0.4%), urinary tract infection (1.7%), thromboembolic (0.5%), neurologic (0.4%), sepsis (2.7%), superficial (6.3%), and deep surgical site complications (2.0%). At least 1 complication, including major and minor, was seen in 7.9% of the patients. By multivariate analysis, partial- and total-dependent functional status (odds ratio [OR] 9.0, 95% confidence interval [CI] 2.8-28.4 and OR 21.3, 95% CI 3.3-139.4) and dyspnea at rest (OR 8.2, 95% 1.2-58.8) predicted mortality. Independent predictors of morbidity include steroid use (OR 2.4, 95% 1.4-4.1), diabetes (OR 1.8, 95% CI 1.3-2.4), and obesity (OR 1.6, 95% CI 1.1-2.4). DISCUSSION: Overall, CFE is tolerated well by the majority of patients with peripheral arterial disease. These results affirm the safety of CFE and can still be used as standard first-line therapy in most patients. Long-term results for endovascular interventions need to be studied to see whether high-risk patients that we identified for CFE would benefit more from an endovascular approach.