A systematic review and meta-analysis of sirolimus-eluting stents for treatment of below-the-knee arterial disease.

OBJECTIVE: We performed a systematic review and meta-analysis to analyze the efficacy and safety of sirolimus-eluting stents (SESs) in the treatment of below-the-knee (BTK) arterial disease. METHODS: An electronic literature search was conducted from inception to July 24, 2021. Retrospective, prospective, and randomized studies that had used SESs to treat BTK arterial disease and had reported the primary patency, technical success, target lesion revascularization, and/or mortality were included. Meta-analyses of the proportions were conducted to derive pooled summary statistics of the outcomes. Where Kaplan-Meier curves were provided for primary patency, a meta-analysis of the individual patient data was conducted via a graphic reconstruction tool to estimate primary patency at various follow-up points. For studies comparing SESs and bare metal stents (BMSs), a two-stage meta-analysis was performed to compare the 6-month primary patency of SESs vs BMSs. RESULTS: Ten studies across 13 publications, including 995 patients, were retrieved for analysis. In the meta-analysis of proportions, across six studies (n = 339 patients), the pooled 6-month primary patency was 87.3% (95% confidence interval [CI], 81.6%-92.1%). Across seven studies (n = 283 patients), the pooled 6-month mortality was 5.4% (95% CI, 1.4%-11.2%). An individual patient data analysis of three studies (n = 282 patients) yielded a primary patency rate of 95.2% (95% CI, 92.7%-97.8%), 82.8% (95% CI, 78.3%-87.6%), 79.8% (95% CI, 75.0%-85.0%), and 79.8% (95% CI, 75.0%-85.0%) at 6, 12, 18, and 24 months, respectively. The 12-month target lesion revascularization rate across four studies (n = 324 patients) was 9.6% (95% CI, 6.4%-13.4%). In the two-stage meta-analysis of 6-month primary patency across three studies (n = 168 patients), the use of SESs was significantly favored over BMSs (risk ratio, 1.28; 95% CI, 1.12-1.46; P < .001). CONCLUSIONS: The overall evidence suggests that the use of SESs appears to be safe and offers favorable outcomes for BTK arterial disease compared with BMSs.

The Effect of Obesity on Outcomes After Arteriovenous Fistulae Creation: A Systematic Review.

BACKGROUND: Establishing reliable vascular access is critical for hemodialysis in end-stage renal disease (ESRD). In recent years, the global health burden of ESRD has grown, matched by a rise in prevalence of obesity. Currently, more and more arteriovenous fistulae (AVFs) are being created for obese patients with ESRD. This is a growing concern as creating arteriovenous (AV) access in obese ESRD patients can be more challenging and may be associated with poorer outcomes. METHODS: We performed a literature search with multiple electronic databases. We included studies that compared outcomes after autogenous upper extremity AVF creation between obese and nonobese patients. The relevant outcomes were postoperative complications, outcomes related to maturation, outcomes related to patency, and outcomes related to reintervention. RESULTS: We included 13 studies with a total of 305,037 patients. We found a significant association between obesity and poorer early and late AVF maturation. Obesity was also strongly associated with lower primary patency rates and a higher need for reintervention. CONCLUSIONS: This systematic review found that higher body mass index and obesity are associated with poorer AVF maturation outcomes, poorer primary patency, and higher reintervention rates.

Percutaneous decannulation of venoarterial extracorporeal membrane oxygenation using the Manta vascular closure device: A systematic review and meta-analysis.

OBJECTIVES: To perform a systematic review and meta-analysis of the techniques and outcomes associated with percutaneous decannulation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) using the Manta vascular closure device. BACKGROUND: Peripheral VA-ECMO can be used to treat critically ill patients with conditions such as refractory cardiogenic shock. After percutaneous implantation of VA-ECMO, VA-ECMO can also be decannulated completely percutaneously by using a vascular closure device. The Manta vascular closure device is a dedicated device used in the closure of large-bore arteriotomies by sandwiching the arteriotomy with an intra-arterial toggle and an extraluminal collagen plug. METHODS: We performed a thorough literature search using various electronic databases. We included studies that reported outcomes after peripheral femorofemoral VA-ECMO decannulation with the Manta vascular closure device. We performed a meta-analysis of proportions on outcome measures, including technical success, bleeding complications, vascular complications, wound complications, major amputation, and procedural-related deaths. RESULTS: We included seven studies with a total of 116 patients. The overall technical success of percutaneous decannulation of VA-ECMO with the Manta vascular closure device was 93.7%. The overall incidence of bleeding, vascular and wound complications was 1.7%, 13.8%, and 3.4%, respectively. No patient required lower limb amputation or died due to VA-ECMO decannulation. CONCLUSION: Percutaneous decannulation with the Manta vascular closure device is an effective and safe procedure that should be considered in suitable patients on VA-ECMO.

National Rates of Lower Extremity Amputation in People With and Without Diabetes in a Multi-Ethnic Asian Population: a Ten Year Study in Singapore.

OBJECTIVE: Population level data from Asia on amputation rates in people with and without diabetes are extremely limited. Hence it is unclear how the rising diabetes prevalence in Asia has affected the amputation burden. The present study examined national amputation rates in people with and without diabetes in Singapore from 2008 to 2017 in the context of increasing diabetes prevalence and health system changes. METHODS: This was a retrospective observational study using national population data for ages 16 - 100 years obtained from the Ministry of Health Singapore administrative datasets. Age sex standardised major and toe/ray amputation rates per 100 000 people with diabetes and per 100 000 people without diabetes were calculated. Rates were calculated overall and in each ethnic group (Chinese, Malay, Indian, Others), with trends over time calculated using joinpoint trend analysis. In addition, age specific rates, relative risk (RR) of amputation in diabetics compared with non-diabetics and proportion of amputations in the population attributable to diabetes were also calculated. RESULTS: Between 2008 and 2017, the database included 3.6 million unique individuals, of whom 75% were Chinese, 8.6% Malay, 7.9% Indian, and 8.4% Others. Of those, 413 486 (11%) had diabetes. Major amputation rates in people with diabetes remained stable (2008: 99.5/100 000; 2017: 95.0/100 000 people with diabetes, p = .91) as did toe/ray amputation rates. Rates in people without diabetes were substantially lower, with major amputation rates decreasing significantly (2008: 3.0/100 000; 2017: 2.1/100 000 people without diabetes, 3% annual reduction, p = .048). Diabetes related amputation rates were highest in Malays and lowest in Chinese. Diabetes related major amputation rates declined significantly among Chinese (3.1% annual reduction, p < .038). While the RR for amputations in diabetes remained stable, the proportion of major amputations attributable to diabetes increased from 63.6% in 2008 to 81.7% in 2017 (3% annual increase, p = .003). CONCLUSION: Diabetes related major and toe/ray amputation rates have remained stable but relatively high in Singapore compared with other countries, and the proportion of amputations attributable to diabetes has increased over time. More research is needed to understand the aetiopathological, sociocultural, and health system factors that may underlie the continued high rates of diabetes related amputations in this population.

Lobar versus Sublobar Resection in the Elderly for Early Lung Cancer: A Meta-Analysis.

OBJECTIVES: We performed a systematic review and meta-analysis of outcomes of lobectomy versus sublobar resection in elderly patients (≥65) with stage 1 nonsmall cell lung carcinoma (NSCLC). METHODS: We searched for relevant articles using a set of inclusion and exclusion criteria. Meta-analytic techniques were applied. RESULTS: Twelve studies (n = 5834) were chosen. Our results indicate that in the elderly, lobectomy for stage 1 NSCLC confers a survival advantage over sublobar resection. Lobectomy patients had a lower risk of death within 5 years and lower odds of local cancer recurrence. Our results show that lobectomy had a better 5-year cancer-specific survival and 5-year disease-free survival that trended toward significance. The sublobar resection group showed better 30-day operative mortality that trended toward significance. Subgroup analysis of stage 1A cancer demonstrated no difference in 5-year overall survival rates. However, for stage 1B tumors 5-year overall survival favored lobectomy. CONCLUSION: Lobectomy for stage 1 NSCLC in elderly patients is superior to sublobar resection in terms of survival and cancer recurrence and should be afforded where possible. For stage 1A tumors, sublobar resection is noninferior and may be considered. Further randomized controlled trials in this topic is required.

Partial Versus Complete Thymectomy in Non-Myasthenic Patients With Thymoma: A Systematic Review and Meta-Analysis of Clinical Outcomes.

OBJECTIVE: The optimal extent of surgical resection for non-myasthenic patients with thymoma is controversial. The objective of this meta-analysis was to compare complete to partial thymectomy in non-myasthenic patients for oncological and postoperative clinical outcomes. METHODS: We performed a PubMed and EMBASE search (from inception to January 2020) for English-language studies directly comparing partial thymectomy (thymomectomy) to complete thymectomy for thymoma resection. Clinical endpoints studied included overall and disease-free survival, Masaoka and World Health Organization staging, adjuvant therapy, postoperative complications, postoperative drainage, length of hospital stay, thymoma-related deaths, postresection development of myasthenia gravis, incomplete resection, and recurrence. Random effects meta-analyses across all clinical endpoints was done. RESULTS: There was no statistically significant difference between the two approaches with regard to recurrence (odds ratio [OR], 1.22; 95% confidence interval [CI], 0.78-1.92), completeness of resection (OR, 1.17; 95% CI, 0.66-2.10), adjuvant therapy (OR, 0.71; 95% CI, 0.40-1.26), or thymoma-related deaths (OR, 0.76; 95% CI, 0.12-4.66). There was a statistically significant decrease in postoperative complications (OR, 0.61; 95% CI, 0.39-0.97), drainage (mean difference [MD], -0.99; 95% CI, -1.98 to -0.01), and length of hospital length (MD, -1.88; 95% CI, -3.39 to -0.36) with partial thymectomy. CONCLUSIONS: The evidence appeared to suggest that partial thymectomy is oncologically equivalent to complete thymectomy for non-myasthenic patients with early-stage thymoma. There is an additional advantage of reduced postoperative complications and decreased length of hospital stay with partial thymectomy.

Diabetes-related lower extremity complications in a multi-ethnic Asian population: a 10 year observational study in Singapore.

AIMS/HYPOTHESIS: Diabetes progression and complication risk are different in Asian people compared with those of European ancestry. In this study, we sought to understand the epidemiology of diabetes-related lower extremity complications (DRLECs: symptomatic peripheral arterial disease, ulceration, infection, gangrene) and amputations in a multi-ethnic Asian population. METHODS: This was a retrospective observational study using data obtained from one of three integrated public healthcare clusters in Singapore. The population consisted of individuals with incident type 2 diabetes who were of Chinese, Malay, Indian or Other ethnicity. We examined incidence, time to event and risk factors of DRLECs and amputation. RESULTS: Between 2007 and 2017, of the 156,593 individuals with incident type 2 diabetes, 20,744 developed a DRLEC, of whom 1208 underwent amputation. Age- and sex-standardised incidence of first DRLEC and first amputation was 28.29/1000 person-years of diabetes and 8.18/1000 person-years of DRLEC, respectively. Incidence of both was highest in individuals of Malay ethnicity (DRLEC, 36.09/1000 person-years of diabetes; amputation, 12.96/1000 person-years of DRLEC). Median time from diabetes diagnosis in the public healthcare system to first DRLEC was 30.5 months for those without subsequent amputation and 10.9 months for those with subsequent amputation. Median time from DRLEC to first amputation was 2.3 months. Older age (p < 0.001), male sex (p < 0.001), Malay ethnicity (p < 0.001), Indian ethnicity (p = 0.014), chronic comorbidities (nephropathy [p < 0.001], heart disease [p < 0.001], stroke [p < 0.001], retinopathy [p < 0.001], neuropathy [p < 0.001]), poorer or missing HbA1c (p < 0.001), lower (p < 0.001) or missing (p = 0.002) eGFR, greater or missing BMI (p < 0.001), missing LDL-cholesterol (p < 0.001) at diagnosis, and ever-smoking (p < 0.001) were associated with higher hazard of DRLEC. Retinopathy (p < 0.001), peripheral vascular disease (p < 0.001), poorer HbA1c (p < 0.001), higher (p = 0.009) or missing (p < 0.001) LDL-cholesterol and missing BMI (p = 0.008) were associated with higher hazard of amputation in those with DRLEC. Indian ethnicity (p = 0.007) was associated with significantly lower hazard of amputation. CONCLUSIONS/INTERPRETATION: This study has revealed important ethnic differences in risk of diabetes-related lower limb complications, with Malays most likely to progress to DRLEC. Greater research efforts are needed to understand the aetiopathological and sociocultural processes that contribute to the higher risk of lower extremity complications among these ethnic groups.

A scoping review of vascular surgery education in the medical school curriculum.

OBJECTIVE: Despite the high burden of vascular disease that is assessed, investigated, and managed by generalists, no specific medical school curriculum is in use for vascular surgery (VS). In the present scoping review, we aimed to map the available evidence on the provision of VS education in the medical school curriculum worldwide. METHODS: The present review was conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analysis) extension for scoping reviews. The inclusion criterion was reported research studies on VS education in the medical curriculum. RESULTS: A total of 20 studies were included. Three main themes were identified. VS was perceived as an essential part of the general medical student curriculum by VS applicants. Exposure to VS varied considerably, and students generally expressed a need for an increase in VS coverage. The most important positive determinants when choosing VS as a career were having a VS mentor, the technical aspects of VS, and participation in a VS rotation. Frequently cited deterrents were the long training time and demanding lifestyle potentially compromising family life. CONCLUSIONS: The present scoping review has provided a starting point to better understand the provision of VS education in medical schools across the world. Our review has demonstrated the variability in VS exposure at medical school and described students' sentiments toward VS. We have highlighted the need to determine whether the current curricula are adequate from the perspective of multiple stakeholders (eg, vascular surgeons, educators, general practitioners, a variety of specialists) with a crucial role in the treatment of patients with vascular conditions.

A systematic review of brachial artery ligation as a safe and feasible option in the management of arteriovenous dialysis access infection.

OBJECTIVE: Creation of good long-term arteriovenous access is essential in patients requiring hemodialysis for end-stage renal failure. However, arteriovenous grafts or fistulae can be complicated by infection that may require emergency surgery. For infections that involve the brachial artery anastomosis, or if total graft explantation is indicated, brachial artery repair or reconstruction is often required. An alternative management strategy would be brachial artery ligation (BAL). We performed a systematic review to evaluate the outcomes of BAL that has been performed for infected arteriovenous grafts or fistulae. METHODS: A thorough literature search was conducted using various electronic databases. We included articles that reported outcomes of BAL performed for infected arteriovenous grafts or fistulae. The primary outcome was the incidence of upper limb ischemia after BAL. Secondary outcomes were the need for urgent revascularization, need for upper limb amputation, and incidence of postoperative neurological deficit after BAL. RESULTS: A total of five studies with a total of 125 patients were included in our systematic review. BAL was performed for infected arteriovenous grafts or fistulae for all studies. Follow-up period ranged from 1 to 27 months. The incidence of upper limb ischemia after BAL was low. Only a single study reported three patients who developed upper limb ischemia. Two patients required urgent revascularization, and one patient required forearm amputation after proximal ligation. All studies reported clearance of infection with no recurrence. CONCLUSIONS: Distal BAL may be performed safely for patients with infected arteriovenous fistulae or grafts with low risk of upper limb ischemia, postoperative neurological deficit, and recurrent infection.

Anticoagulation After Isolated Mitral Valve Repair: A Systematic Review and Meta-Analysis of Clinical Outcomes.

Recommendations from international guidelines on optimal thromboprophylaxis after mitral repair are controversial and based on underpowered observational studies. This study aimed to evaluate the prophylactic use of warfarin after isolated mitral valve repair (MVr). A PubMed, EMBASE and Scopus search for studies in English on postoperative thromboprophylaxis for isolated MVr published to February 2020 was performed. The analysis excluded all studies with combined operations, mitral valve replacement and preoperative or postoperative atrial fibrillation. Clinical endpoints that were studied were thromboembolic events, bleeding complications and mortality. Random effects meta-analyses of the effect of postoperative warfarin use as compared with no warfarin use across all clinical endpoints was conducted. Warfarin use did not confer benefit in terms of thromboembolic prophylaxis after isolated MVr in patients without atrial fibrillation (OR, 0.97; 95% CI, 0.72-1.31). At the same time, it did not increase the risk of bleeding complications (OR, 1.10; 95% CI, 0.53-2.30) or affect overall survival during the follow-up period of the included studies (OR, 1.06; 95% CI, 0.28-4.05). To conclude, warfarin use is not necessary for patients after isolated MVr who remain in sinus rhythm. Recommendations from international guidelines may need to be revisited for this group of patients.

Vascular Complications of Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Regression Analysis.

OBJECTIVES: Perform a systematic review and meta-analysis of vascular complications associated with extracorporeal membrane oxygenation and identify prognostic and predictive factors. DATA SOURCES: Systematic search for publications reporting vascular complications on extracorporeal membrane oxygenation, published from 1972 to January 31, 2020, was conducted via PubMed, Scopus, and Embase. STUDY SELECTION: Of 4,076 references screened, 47 studies with 6,583 patients were included in final analyses. Studies with fewer than 10 patients were excluded. DATA EXTRACTION: Relevant data, including demographics, comorbidities, extracorporeal membrane oxygenation and cannulation characteristics, occurrence rates of early and late vascular complications, patient outcomes, and use of distal perfusion cannula, were extracted from selected articles into an excel sheet specifically designed for this review. DATA SYNTHESIS: Random-effects meta-analyses and meta-regression analyses were undertaken. Overall pooled estimate of vascular complications in our meta-analysis was 29.5% (95% CI, 23.6-35.9%). Two-thousand three-hundred forty-seven vascular complications in 6,124 venoarterial extracorporeal membrane oxygenation patients compared with 95 in 459 venovenous extracorporeal membrane oxygenation patients (odds ratio, 2.35; 95% CI, 1.87-2.96; p < 0.0001) were analyzed. Successful weaning off extracorporeal membrane oxygenation occurred in 60.6% of pooled patients; 46.2% were eventually discharged. Pooled prevalences of vascular complications like significant bleeding, limb ischemia, and cannula site bleeding were 15.4% (95% CI, 8.6-23.7%), 12.6% (95% CI, 10.0-15.5%), and 12.6% (95% CI, 9.6-18.5%), respectively. Meta-analysis showed that the use of distal perfusion cannula was associated with lower odds of limb ischemia (odds ratio, 1.93; 95% CI, 1.17-2.47; p = 0.03) Meta-regression showed that male sex, smoking, advanced age, and comorbidities contributed to higher in-hospital mortality, while distal perfusion cannula was protective. CONCLUSIONS: Nearly a third of patients on extracorporeal membrane oxygenation develop vascular complications; elderly males with comorbidities appear vulnerable. The use of distal perfusion cannulas caused significant reduction in limb ischemia and mortality.

A systematic review of the impact of preoperative exercise for patients with abdominal aortic aneurysm.

BACKGROUND: Abdominal aortic aneurysm (AAA) surgery carries significant risk of morbidity and mortality. Preoperative exercise may improve the physical fitness capacity of patients with AAA as well as postoperative outcomes. METHODS: A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. An electronic search was performed on MEDLINE, Embase, and Cochrane Library for relevant studies. A methodologic assessment of included studies was conducted using the Physiotherapy Evidence Database (PEDro) scale. RESULTS: Seven studies (six randomized controlled trials and one retrospective cohort study) were included. The overall quality of studies was assessed to range from fair to good. Three studies included AAA patients without indication for surgery, whereas four other studies included AAA patients awaiting surgical repair. One study implemented an inspiratory muscle training program; five studies implemented a continuous moderate-intensity exercise regimen; one study implemented a high-intensity interval training program. Overall compliance with the exercise regimen was high (94% in those not waiting for surgery; 75.8% to 82.3% in those waiting for surgery). In patients not awaiting surgery, preoperative exercise may improve physical fitness parameters including ventilatory threshold (P = .016 at 12 weeks; P = .09 at 12 months) and anaerobic threshold (10% increase; P = .007) but not peak oxygen consumption (P = .183 at 12 weeks; P = .29 at 12 months). In patients awaiting surgery, one study demonstrated a statistically significant improvement in peak oxygen consumption (difference, 1.6 mL/kg/min; P = .004) and anaerobic threshold (difference, 1.9 mL/kg/min; P = .012) for patients who exercised. In terms of postoperative outcomes, exercise may reduce the risk of cardiac, renal, and respiratory complications, although only in those who undergo open surgery. Only patients who underwent endovascular repair had a shorter length of hospital stay when preoperative exercise was conducted. CONCLUSIONS: Despite the encouraging evidence of preoperative exercise for AAA patients, it remains premature to recommend it as a preoperative intervention. Given the heterogeneity of reported outcomes, future studies should consider conducting well-designed randomized controlled trials with standardized reporting outcomes and definitions.

Experience from a Singapore tertiary hospital with restructuring of a vascular surgery practice in response to national and institutional policies during the COVID-19 pandemic.

Singapore was one of the first countries to be affected by COVID-19, with the index patient diagnosed on January 23, 2020. For 2 weeks in February, we had the highest number of COVID-19 cases behind China. In this article, we summarize the key national and institutional policies that were implemented in response to COVID-19. We also describe in detail, with relevant data, how our vascular surgery practice has changed because of these policies and COVID-19. We show that with a segregated team model, the vascular surgery unit can still function while reducing risk of cross-contamination. We explain the various strategies adopted to reduce outpatient and inpatient volume. We provide a detailed breakdown of the type of vascular surgical cases that were performed during the COVID-19 pandemic and compare it with preceding months. We discuss our operating room and personal protective equipment protocols in managing a COVID-19 patient and share how we continue surgical training amid the pandemic. We also discuss the challenges we might face in the future as COVID-19 regresses.

Managing central venous access during a health care crisis.

OBJECTIVE: During the COVID-19 pandemic, central venous access line teams were implemented at many hospitals throughout the world to provide access for critically ill patients. The objective of this study was to describe the structure, practice patterns, and outcomes of these vascular access teams during the COVID-19 pandemic. METHODS: We conducted a cross-sectional, self-reported study of central venous access line teams in hospitals afflicted with the COVID-19 pandemic. To participate in the study, hospitals were required to meet one of the following criteria: development of a formal plan for a central venous access line team during the pandemic; implementation of a central venous access line team during the pandemic; placement of central venous access by a designated practice group during the pandemic as part of routine clinical practice; or management of an iatrogenic complication related to central venous access in a patient with COVID-19. RESULTS: Participants from 60 hospitals in 13 countries contributed data to the study. Central venous line teams were most commonly composed of vascular surgery and general surgery attending physicians and trainees. Twenty sites had 2657 lines placed by their central venous access line team or designated practice group. During that time, there were 11 (0.4%) iatrogenic complications associated with central venous access procedures performed by the line team or group at those 20 sites. Triple lumen catheters, Cordis (Santa Clara, Calif) catheters, and nontunneled hemodialysis catheters were the most common types of central venous lines placed by the teams. Eight (14%) sites reported experience in placing central venous lines in prone, ventilated patients with COVID-19. A dedicated line cart was used by 35 (59%) of the hospitals. Less than 50% (24 [41%]) of the participating sites reported managing thrombosed central lines in COVID-19 patients. Twenty-three of the sites managed 48 iatrogenic complications in patients with COVID-19 (including complications caused by providers outside of the line team or designated practice group). CONCLUSIONS: Implementation of a dedicated central venous access line team during a pandemic or other health care crisis is a way by which physicians trained in central venous access can contribute their expertise to a stressed health care system. A line team composed of physicians with vascular skill sets provides relief to resource-constrained intensive care unit, ward, and emergency medicine teams with a low rate of iatrogenic complications relative to historical reports. We recommend that a plan for central venous access line team implementation be in place for future health care crises.

Computational Fluid Dynamics Modeling of Hemodynamic Parameters in the Human Diseased Aorta: A Systematic Review.

BACKGROUND: The analysis of the correlation between blood flow and aortic pathology through computational fluid dynamics (CFD) shows promise in predicting disease progression, the effect of operative intervention, and guiding patient treatment. However, to date, there has not been a comprehensive systematic review of the published literature describing CFD in aortic diseases and their treatment. METHODS: This review includes 136 published articles which have investigated the application of CFD in all types of aortic disease (aneurysms, dissections, and coarctation). We took into account case studies of both, treated or untreated pathology, investigated with CFD. We also graded all studies using an author-defined Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach based on the validation method used for the CFD results. RESULTS: There are no randomized controlled trials assessing the efficacy of CFD as applied to aortic pathology, treated or untreated. Although a large number of observational studies are available, those using clinical imaging tools as independent validation of the calculated CFD results exist in far smaller numbers. Only 21% of all studies used clinical imaging as a tool to validate the CFD results and these were graded as high-quality studies. CONCLUSIONS: Contemporary evidence shows that CFD can provide additional hemodynamic parameters such as wall shear stress, vorticity, disturbed laminar flow, and recirculation regions in untreated and treated aortic disease. These have the potential to predict the progression of aortic disease, the effect of operative intervention, and ultimately help guide the choice and timing of treatment to the benefit of patients and clinicians alike.

Risk factors for distal stent graft-induced new entry in type B aortic dissections: Systematic review and meta-analysis.

BACKGROUND: After the use of thoracic endovascular aortic repair in the management of type B aortic dissection (TBAD), there has been increasing recognition of the phenomenon of stent graft-induced new entry (SINE) as a late complication of thoracic endovascular aortic repair, with risk factors for SINE identified. We performed a meta-analysis of contemporary studies to establish the risk factors for distal SINE (dSINE). METHODS: A systematic search of the literature was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to investigate the risk factors for dSINE. Data from population-cohort and case-control studies were extracted to compute a conventional meta-analysis by combining the odds ratio using the generic inverse variance function on RevMan 5.3. Furthermore, a meta-analysis of proportions using the Freeman-Tukey double arcsine transformation was performed to compare the incidence of acute and chronic TBAD. RESULTS: Seventeen studies assessing the data of 3962 patients met the eligibility requirements and were included in the review. The pooled proportion of dSINE in TBAD cases treated with thoracic endovascular aortic repair is 10.1%. The relative risk of incidence of dSINE in chronic TBAD compared to acute TBAD is 3.12. The chronicity of TBAD and excessive distal oversizing ratio was demonstrated to be positively associated with dSINE with odds ratios of 2.25 and 2.06, respectively. Stent grafts with connecting bars were also positively associated with dSINE, but this lacked statistical significance. CONCLUSIONS: This meta-analysis demonstrated that chronic TBAD and an excessive distal oversizing ratio are both positively and independently associated with the incidence of dSINE tears in TBAD. This should be taken into consideration when planning interventions in these patient cohorts.

A systematic review and meta-analysis of surgical versus endovascular thrombectomy of thrombosed arteriovenous grafts in hemodialysis patients.

BACKGROUND: The major pitfall of arteriovenous grafts (AVGs) for hemodialysis patients is thrombosis and occlusion. Prompt intervention with either surgical or endovascular therapy to salvage the vascular access is crucial in maintaining effective hemodialysis. The purpose of this systematic review and meta-analysis was to assess and compare the efficacy of open surgical vs wholly endovascular therapy for the treatment of thrombosed AVGs. METHODS: This review was conducted according to the PRISMA guidelines. Relative risks **(RRs) and pooled proportions for both primary and secondary outcomes were calculated. RESULTS: A total of eight randomized, controlled trials and two retrospective cohort studies were included, comprising 806 (63%) and 466 (37%) participants in the surgical and wholly endovascular treatment arms respectively. There were no significant differences between endovascular and surgical therapy in the 30-, 60-, and 90-day primary nonpatency rates. However, endovascular therapy reported a significantly higher 1-year primary nonpatency rate (rate ratio [RR], 1.22; 95% confidence interval [CI], 1.13-1.33; P < .01) and the 2-year primary nonpatency rate (RR, 1.26; 95% CI, 1.10-1.45; P < .01) as compared with surgical therapy. Similarly, the endovascular arm had a higher pooled proportion of primary nonpatency of 87.7% (95% CI, 81.5%-92.9%; P = .297), as compared with the surgical arm (72.1%; 95% CI, 66.4%-77.4%; P = .289). In terms of secondary nonpatency rates, there were no significant differences between endovascular and surgical procedures at 30, 60, and 90 days. Endovascular procedures reported a significantly higher technical failure rate as compared with surgical thrombectomy (RR, 1.58; 95% CI, 1.06-2.37; P = .03). There was no significant difference in terms of minor and major complications. CONCLUSIONS: Our data suggest that, for thrombectomy of AVGs, wholly endovascular therapy seems to be inferior to open surgery plus adjuncts based on the long-term patency and technical failure rates. However, further research in the form of a well-conducted randomized trial is warranted to establish a firmer conclusion.

A systematic review and meta-regression analysis of nonoperative management of blunt traumatic thoracic aortic injury in 2897 patients.

BACKGROUND: Thoracic endovascular aortic repair has transformed the management of blunt traumatic thoracic aortic injuries (BTTAI). Recent studies have suggested that the nonoperative management (NOM) of BTTAI may be a viable alternative. We investigated the NOM of BTTAI by conducting a systematic review and meta-analysis of the mortality proportions and incidence of complications. METHODS: We searched PubMed through June 22, 2017, and referenced lists of included studies without language restriction, with the assistance of a trained librarian. We included studies that reported the NOM of BTTAI (≥5 participants). Two authors independently screened titles, abstracts, and performed data extraction. Pooled prevalence of mortality (aortic related, in hospital) were obtained based on binomial distribution with Freeman-Tukey double-arcsine transformation and continuity correction. The random-effects model was used for all analyses to account for variation between studies. Meta-regression was performed to explore sources of heterogeneity, including Injury Severity Score, age, and gender. RESULTS: We included 35 studies comprising 2897 participants. The pooled prevalence of all-cause in-patient mortality in the overall, grade I, grade II, grade III, and grade IV populations are as follows: 29.0% (95% confidence interval [CI], 19.3%-39.6%; I2 = 95%; P < .01), 6.8% (95% CI, 0.6%-19.3%; I2 = 52%; P = .03), 0% (95% CI, 0%-2.0%; I2 = 0%; P = .81), 29.2% (95% CI, 17%-42.5%; I2 = 3%; P = .41), and 87.4% (95% CI, 16.4%-100%; I2 = 48%; P = .14), respectively. The combined incidence of aortic-related in-patient mortality in the overall, grade I, grade II, and grade III populations are: 2.4% (95% CI, 0.4%-5.5%; I2 = 60%; P < .01), 0.93% (95% CI, 0%-14.2%; I2 = 65%; P < .01), 0% (95% CI, 0%-1.8%; I2 = 0%; P = .99), and 0.13% (95% CI, 0%-6.4%; I2 = 14%; P = .33), respectively. The total proportion of postdischarge aortic-related mortality is 0% (95% CI, 0%-0.5%; I2 = 0%; P = .91). Meta-regression showed a decreased risk of in-hospital mortality as age increases (ß = .99; 95% CI, 0.98-1.00), an increased risk of in-hospital mortality with a higher Injury Severity Score (ß = 1.02; 95% CI, 1.00-1.04), and a decreased risk of in-hospital mortality among male patients (ß = .54; 95% CI, 0.3-0.90). CONCLUSIONS: This study provides, to our knowledge, the most up-to-date pooled estimate of mortality rates after the NOM of BTTAI. However, its interpretation is limited by the paucity of data and substantial quantitative heterogeneity. If patients are to be managed nonoperatively, we would recommend the judicious use of active surveillance in a select group of patients in the short, mid, and long term.

The association between diabetes and thoracic aortic aneurysms.

OBJECTIVE: The negative correlation between diabetes mellitus (DM) and abdominal aortic aneurysms (AAAs) is well described. The etiologic similarities and differences between AAAs and thoracic aortic aneurysms (TAAs) have also been documented. We aimed to evaluate the relationship between DM and TAA by performing a meta-analysis of contemporary clinical studies. METHODS: A systematic search of the literature was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to investigate the relationship of DM and TAA. Data from population cohort and case-control studies were extracted and computed together to determine a pooled unadjusted odds ratio (OR) with corresponding 95% confidence intervals (CIs) using random-effects meta-analysis. RESULTS: Five population cohort studies and five case-control studies involving 1,006,360 patients met eligibility requirement and were included. Unadjusted pooled analysis of all 10 studies demonstrated an inverse association of DM with TAA (OR, 0.77; 95% CI, 0.61-0.98). Primary analysis of the five cohort studies demonstrated a statistically significant negative association between DM and TAA (OR, 0.70; 95% CI, 0.59-0.84). However, primary analysis of the five case-control studies demonstrated a negative association between DM and TAA (OR, 0.86; 95% CI, 0.50-1.47) with no statistical significance. CONCLUSIONS: This meta-analysis demonstrated a statistically significant inverse association between DM and TAA, similar to that of AAA. Further research is required into the potentially protective mechanisms that DM may confer and whether there is biologic plausibility to exploit these mechanisms further to prevent aneurysm expansion and rupture.

Forecasting aortic aneurysm rupture: A systematic review of seasonal and atmospheric associations.

BACKGROUND: Abdominal aortic aneurysms (AAAs) represent a significant burden of disease worldwide, and their rupture, without treatment, has an invariably high mortality rate. Whereas some risk factors for ruptured AAAs (rAAAs) are well established, such as hypertension, smoking, and female sex, the impact of seasonal and meteorologic variables is less clear. We systematically reviewed the literature to determine whether these variables are associated with rAAA. METHODS: Review methods were according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We calculated pooled proportions and incidence rate ratios (IRRs) for the different months and seasons. Funnel plots were constructed to assess for publication bias. Given the poor methodologic quality of included studies, a sensitivity analysis was performed on better-quality studies, which scored 6 and above of 9 in the author-modified Newcastle-Ottawa Scale. RESULTS: The pooled proportion of rAAA was highest in the autumn season (incidence rate, 26.6%; 95% confidence interval [CI], 25.6%-27.7%; I2 = 15.4%), followed by winter (incidence rate, 26.2%; 95% CI, 24.1%-28.2%; I2 = 72.4%), and lowest in summer (incidence rate, 21.1%; 95% CI, 19.3%-23.0%; I2 = 70.4%). The IRRs of rAAA were -6.9% (95% CI, -9.8% to -3.9%), -19.5% (95% CI, -22% to -16.8%), +10.5% (95% CI, 7.2%-13.9%), and +18.1% (95% CI, 15%-22%) in spring, summer, autumn, and winter compared with the remaining seasons, respectively (all P < .0001), thus affirming existence of seasonal variation. The pooled proportion of rAAA was highest in December (incidence rate, 8.9%; 95% CI, 7.1%-10.9%; I2 = 54.5%) but lowest in July (incidence rate, 5.7%; 95% CI, 4.2%-7.3%; I2 = 54.5%). The IRR was significantly the highest in January (IRR, 1.14; 95% CI, 1.01-1.29; P = .031) but lowest in July (IRR, 0.75; 95% CI, 0.65-0.87; P < .0001). There is also some evidence for a possible association with atmospheric pressure. Associations with temperature and daylight hours, however, are at best speculative. CONCLUSIONS: Autumn and winter are significantly associated with a higher incidence of rAAAs, and autumn is associated with the highest rupture incidence of all the seasons. However, the inability to appropriately control for other confounding factors known to increase the risk of AAA rupture precludes any additional recommendations to alter current provision of vascular services on the basis of these data.