Duplex ultrasound derived maximal systolic acceleration can be a reliable and rapid alternative to ankle brachial pressure indices for the diabetic population with lower extremity arterial disease; a prospective, observational cohort study.

Objectives: Ankle brachial pressure index (ABPI) is limited for diabetic patients. This can have costly impacts upon patient's quality of life along with healthcare budgets, with diabetic care equating to approximately 10% of NHS expenditure.11 We aimed to determine whether ultrasound waveform parameters are an alternative for quantifying lower extremity peripheral arterial disease (PAD) where ABPI is unreliable. Design: This was a prospective, observational study. Waveform parameters, systolic rise time (SRT), maximal systolic acceleration (AccMax) and peak systolic velocity (PSV) were recorded at ankle and compared to the ABPI and an aorta-ankle duplex ultrasound scan (DUS) as gold standard. Setting: Measurements were obtained by a Clinical Vascular Scientist at the Royal Free Hospital. Participants: Participants (≥18yrs) with known PAD, but without previous vascular intervention were allocated to non-diabetic control (n = 24) and diabetic test groups (n = 22). Outcome measures: The primary outcome measure was the correlation of novel ultrasound derived indices to PAD severity. The secondary outcome was the efficacy of this correlation in the diabetic population. Results: AccMax was most powerful in detecting PAD in both groups when compared to ABPI in the controls (r = 0.805; p < 0.01) and to DUS in control and test groups (r = -0.633 to -0.643; p < 0.01). In the test group, PSV did not consistently quantify PAD. SRT measurements were inconclusive throughout. Conclusion: AccMax is a rapid alternative tool for diagnosing PAD in diabetic patients. With further research, this simple test may prove useful for monitoring PAD progression in patients unsuitable for ABPI, reducing the need for lengthy repeat duplex scans.

Sex-related trends in mortality after elective abdominal aortic aneurysm surgery between 2002 and 2013 at National Health Service hospitals in England: less benefit for women compared with men.

AIMS: To quantify the difference in long-term survival and cardiovascular morbidity between women and men undergoing elective abdominal aortic aneurysm (AAA) repair at National Health Service hospitals in England. METHODS AND RESULTS: Patients having elective repair of AAA were reviewed using the Hospital Episode Statistics and Office for National Statistics (ONS) datasets. The primary outcome measure was 30-day mortality and the secondary outcomes were 1-year, 5-year, and aortic-related mortality and post-operative complication rates. We used logistic regression and survival models to assess risk factors on the primary and secondary outcomes. Between 1 April 2002 and 31 March 2013, a total of 31 090 patients (4795 women and 26 295 men) underwent open AAA repair. Between 1 January 2006 and 31 March 2013, a total of 16 777 patients (2036 women and 14 741 men) underwent endovascular aneurysm repair (EVAR). All-cause and aortic-related mortalities at 30 days, 1 year, and 5 years were all higher in women, despite a lower prevalence of pre-operative cardiovascular risk factors. Female sex was a significant independent risk factor for 30-day mortality in both open repair [odds ratio (OR) 1.39; 95% confidence interval (CI) 1.25-1.56; P < 0.001] and EVAR (OR 1.57; 95% CI 1.23-2.00; P < 0.001) groups. Based on an all-cause long-term survival model, conditional on 30-day survival, the estimated hazard for women in the open repair group was significantly (P = 0.006) higher than men, but the sex difference was not significant in the EVAR group (P = 0.356). In the open repair group, women had significantly (P < 0.001) higher cumulative incidence probabilities for both aortic-related mortality and other-cause mortality. In the EVAR group, women had significantly (P < 0.001) higher mean cumulative incidence probabilities for the aortic-related mortality compared with men, but not for the other-cause mortality (P = 0.235). CONCLUSION: Women undergoing elective AAA repair at National Health Service hospitals in England had increased short- and long-term mortality and post-operative morbidity compared with men. These findings can be used to improve pre-operative counselling for women undergoing AAA repair, and highlight the need for female-specific pre-, peri-, and post-operative management strategies.

A sutureless aortic stent-graft based on a nitinol scaffold bonded to a compliant nanocomposite polymer is durable for 10 years in a simulated in vitro model.

PURPOSE: To physiologically test the durability of a sutureless aortic stent-graft based on nitinol bonded to polyhedral oligomeric silsesquioxane (POSS) and poly(carbonate-urea) urethane (PCU) for 10 years according to Food and Drug Administration guidelines. METHODS: Aortic stent-grafts (n = 4) were tested in 37°C distilled water using simulated in vivo hydrodynamic pulse loading. After 400 million cycles, surface topography was assessed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Dynamic compliance was measured using a pulsatile flow phantom. Mechanical and elastic properties were determined by stress-strain studies and elastic deformation tests. Dynamic scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to assess thermal resistance. Comparison was made with a zero-cycled control. RESULTS: All stent-grafts successfully completed accelerated pulsatile fatigue at 94±14-mmHg pulse pressure. SEM images confirmed uniform surface topography without any fractures. FTIR showed increased intensity of -NHCO- bonds, but there was no significant sign of biodegradation. Tensile stress of fatigue-tested polymer compared favorably with the zero-cycled control at 50% to 500% strain (p = 0.69). At a mean pressure range of 60 to 120 mmHg, overall compliance of the fatigue-tested grafts was 3.48±1.27%mmHg(-1)×10(-2) with no significant difference compared to control (3.26±0.65%mmHg(-1)×10(-2); p = 0.47). DSC and TMA showed comparable thermotropic transition. CONCLUSION: Simulated physiological in vivo hydrodynamic loading has no significant degradative effect on an innovative sutureless stent-graft made from POSS-PCU nanocomposite polymer. Sutureless technology incorporating nitinol stents proved to be robust, with no separation over an accelerated 10-year cycle, which may allow development of durable stent-grafts with better compliance.

Knee length versus thigh length graduated compression stockings for prevention of deep vein thrombosis in postoperative surgical patients.

BACKGROUND: Graduated compression stockings (GCS) are a valuable means of thromboprophylaxis in hospitalised postoperative surgical patients. But it is still unclear whether knee length graduated compression stockings (KL) or thigh length (TL) stockings are more effective. OBJECTIVES: The aim of this review was to systematically analyse the randomised, controlled trials that have evaluated the effectiveness of KL versus TL GCS as a thromboprophylaxis tool in hospitalised patients undergoing various types of surgery. SEARCH METHODS: The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched February 2012) and CENTRAL (2012, Issue 1). The authors searched MEDLINE and EMBASE (until 27 February 2012) and they also searched the reference lists of relevant articles to identify additional trials. SELECTION CRITERIA: Randomised controlled trials published in any language on KL versus TL GCS used as a thromboprophylaxis tool in hospitalised patients of any age and either gender. DATA COLLECTION AND ANALYSIS: Data extraction was undertaken independently by two review authors using data extraction sheets and confirmed by the third review author. MAIN RESULTS: Three studies, with a combined total of 496 patients, matched the inclusion criteria for this review. All three included studies evaluated the role of KL and TL in thromboprophylaxis among a group of postoperative patients. These studies showed no significant difference in the ability of the two modalities of leg compression to reduce the incidence of deep vein thrombosis in postoperative patients. In both the fixed-effect model (odds ratio (OR) 1.55, 95% confidence interval (CI) 0.78 to 3.07, P = 0.21) and random-effects model (OR 1.32, 95% CI 0.43 to 4.06, P = 0.63) KL graduated compression stockings were as effective as TL stockings in thromboprophylaxis. However, there was significant heterogeneity (Tau(2) = 0.50; Chi(2) = 4.12, df = 2 (P = 0.13); I(2) = 51%) among trials. Results of this review may be considered weak because there was significant heterogeneity among included trials resulting from inadequate randomisation techniques, allocation concealment, power calculations and the absence of intention-to-treat analysis. AUTHORS' CONCLUSIONS: This review found that there is insufficient high quality evidence to determine whether or not KL and TL GCS differ in their effectiveness in terms of reducing the incidence of deep vein thrombosis (DVT) in hospitalised patients.  A major multicentre RCT is required to address this issue. In the meantime, the decision on which type of stocking to use in clinical practice is likely to be influenced by factors such as patient compliance, ease of use and cost implications.

Remote ischaemic preconditioning versus no remote ischaemic preconditioning for vascular and endovascular surgical procedures.

BACKGROUND: Despite advances in perioperative care, elective major vascular surgical procedures carry a significant risk of morbidity and mortality. Remote ischaemic preconditioning is initiated by brief, non-lethal periods of ischaemia in a vascular bed different from the one which will be subjected to ischaemic insult during surgery. It has the potential to provide local tissue protection from further prolonged periods of ischaemia. OBJECTIVES: The aim of this review was to compare the outcomes from vascular and endovascular surgical procedures with and without the use of remote ischaemic preconditioning. SEARCH METHODS: The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (June 2011) and CENTRAL (2011, Issue 2). The authors searched MEDLINE via PubMed (July 2011), EMBASE (June 2011), and Science Citation Index Expanded (July 2011). SELECTION CRITERIA: We considered for inclusion all randomised controlled trials that evaluated the role of remote ischaemic preconditioning in reducing mortality and systemic injury in patients undergoing open vascular or endovascular surgery. DATA COLLECTION AND ANALYSIS: We collected the data on characteristics of the trial, methodological quality, the remote ischaemic preconditioning stimulus used, mortality, morbidity, operating time and hospital stay from each trial. We analysed the data with both the fixed-effect and the random-effects models using RevMan analysis. For each outcome we calculated the risk ratio (RR) or mean difference with 95% confidence interval (CI) based on an intention-to-treat analysis. MAIN RESULTS: We included four studies with a total of 115 patients randomised to undergo a vascular procedure with remote ischaemic preconditioning and 117 patients randomised to have the procedure without remote ischaemic preconditioning. None of the trials were of low risk of bias. There was no significant difference in mortality between the two groups (RR 1.70, 95% CI 0.51 to 5.72). Similarly, there was no statistically significant difference between the two groups for all other outcomes except reduced risk of myocardial infarction in the remote ischaemic preconditioning group, which was significant by the fixed-effect model (RR 0.31, 95% CI 0.10 to 0.90) but not by the random-effects model (RR 0.34, 95% CI 0.11 to 1.08). This positive effect was from the results of only one trial and was not consistently observed. Furthermore, it was noted that there was an observed trend of high incidence of unplanned critical care admission in the remote ischaemic preconditioning group, although this was not statistically significant (RR 2.15, 95% CI 0.87 to 5.33). AUTHORS' CONCLUSIONS: Based on current evidence from small pilot trials, there are too few data to be able to say whether remote ischaemic preconditioning has any beneficial or harmful effects. The safety of this technique needs to be confirmed in adequately powered trials. Therefore, further randomised trials on this technique are required.

An aortic model for the physiological assessment of endovascular stent-grafts.

BACKGROUND: The aim of this study was to manufacture a new aortic model with physiological properties, which could be used for long-term durability testing of endovascular stent-grafts, as per the recommendations of the Food and Drug Administration. METHODS: Porcine abdominal aortas were acquired to establish values for compliance. The aortic model was manufactured using a nanocomposite polymer. Latex mock aorta was used for comparison. A pulsatile flow phantom perfused the aortas and synthetic tubes at physiological pulse pressure and flow. Diametrical compliance and stiffness index were calculated over mean pressures from 30 to 120 mm Hg. Data were analyzed using one-way analysis of variance and Bonferroni's test. RESULTS: Flow circuit hemodynamic values were similar for porcine aorta and synthetic tubes. Compliance of aorta ranged from 2.97 ± 0.72 (mean ± SD) to 1.42 ± 0.37%/mm Hg × 10⁻². The polymer model showed significantly better compliance (range, 3.66 ± 1.05-2.72 ± 0.28%/mm Hg × 10⁻²; p < 0.05), with no significant difference in elastic stiffness index (range, 101.6 ± 28.9-51.3 ± 10.7 for aorta and 39.8 ± 8.5-34.2 ± 3.8 for polymer model; p > 0.05). It also showed anisotropic behavior similar to the aorta. Latex tubes showed compliance that was lower than that in aorta (range, 0.87 ± 0.24-0.86 ± 0.2%/mm Hg × 10⁻²) and failed by a significant distension on increase in pressure from mean of 90 mm Hg. CONCLUSIONS: We have developed physiologically relevant aortic model showing compatible anatomy, compliance, and viscoelasticity, which could be used for long-term fatigue analysis of vascular stents and grafts. The latex mock aortas can fail at physiological pressures.

Role of prosthetic conduits in coronary artery bypass grafting.

Prosthetic grafts are required for coronary artery bypass grafting (CABG) when the availability of suitable autologous conduits is limited. The ideal cardiovascular bypass graft requires a broad range of characteristics including strength, viscoelasticity, biocompatibility, blood compatibility and biostability. Many alternative conduits have been developed and used in the past, but most of them have failed, except in rare instances. This review aims to analyse the current status of their use and prospects for the future. We performed a literature search on PubMed using the generic terms 'conduits for coronary artery bypass grafting'; 'reoperative coronary artery bypass grafting'; 'redo coronary artery bypass grafting'; 'PTFE'; 'Dacron or PET'; 'gastroepiploic artery'; 'inferior epigastric artery'; 'biological grafts'; 'tissue-engineered grafts'; 'synthetic grafts'; 'prosthetic grafts'; 'polyurethane grafts'; 'cephalic veins'; 'short saphenous vein;' and 'alternative conduits'. In addition, we searched through related citations and references from selected articles. A total of 1253 references and 110 full-text articles were reviewed, and they were further selected based on available information. This review concludes that, over the past three to four decades, achieving the goal of a prosthetic graft with equivalent function and durability to the internal mammary artery or long saphenous vein has proved to be elusive.

Isolated endarterectomy of femoral bifurcation in critical limb ischemia: is restoration of inline flow essential?

This retrospective study reviews clinical outcomes of isolated common femoral endarterectomy (CFE) for critical limb ischemia (CLI), in particular whether poor runoff and inability to restore inline flow has negative impact. In 30 patients, runoff was assessed on preoperative angiograms and categorized into groups based on Society of Vascular Surgery criteria. Data were evaluated using Cox Regression survival analysis. Freedom from secondary revascularization was not affected by runoff score (hazard ratio for compromised and poor groups being 1.8 (95% CI 0.16 to 20.8) and 1.47 (95% CI 0.09 to 24.3), respectively; P = .894). Distal inline flow was not achieved in 25 (83%) patients, but this was not associated with significantly worse outcome (P = .295, log-rank test). In conclusion, CFE can be performed in CLI with high technical success and there is no significant effect of runoff score on recurrence of symptoms. Limb salvage can be achieved even if options to restore inline flow are limited.

A review of Candida prophylaxis in the neonatal intensive care population.

OBJECTIVE: To review the efficacy and safety of antifungal prophylaxis in the neonatal intensive care setting. DATA SOURCES: English-language literature was accessed using MEDLINE (January 1988- December 2010). The following Medical Subject Heading (MeSH) search terms were used: "amphotericin B," "fluconazole," "nystatin," "itraconazole," "caspofungin," "voriconazole," "Candida," "prevention and control," and "critically ill." Literature was further limited to studies focusing on patient birth to 6 months of age. Abstracts and original research articles were included. Preference was given to published controlled trials. Articles providing descriptions of the safety and effectiveness of antifungal prophylaxis in neonatal intensive care patients were also used in this review. RESULTS: Twenty-two studies have evaluated the impact of antifungal prophylaxis on Candida colonization or invasive infections in the Neonatal Intensive Care Unit (NICU). The two antifungal agents most commonly studied were nystatin and fluconazole. All of the nystatin studies demonstrated that nystatin is effective at reducing fungal colonization and invasive fungal infections. All of the studies designed to evaluate the impact of fluconazole prophylaxis on fungal colonization demonstrated a reduction in the incidence of fungal colonization with fluconazole prophylaxis. A total of 12 of 16 studies that evaluated the impact of fluconazole prophylaxis on the incidence of invasive fungal infections demonstrated a reduction in invasive fungal infections with fluconazole prophylaxis. Two studies found no difference between fluconazole and nystatin when used for prophylaxis. CONCLUSION: Antifungal prophylaxis appears to be effective in reducing the incidence of Candida colonization and invasive Candida infections in the NICU. Antifungal prophylaxis also appears to be safe in the NICU population. The impact of antifungal prophylaxis on resistance patterns could be significant and needs to be evaluated long term before widespread prophylaxis can be recommended.

Inhibition of neointimal formation and hyperplasia in vein grafts by external stent/sheath.

Synthetic and to a lesser extent vein graft failure is still a major problem in the treatment of peripheral arterial disease, with neointimal hyperplasia being the main cause for graft occlusion in the medium and long term. This review aims to establish the current status of external stents or sheaths in the prevention of intimal hyperplasia in small diameter (< 6 mm) vein grafts.

AAA stent-grafts: past problems and future prospects.

Endovascular aneurysm repair (EVAR) has quickly gained popularity for infrarenal abdominal aortic aneurysm repair during the last two decades. The improvement of available EVAR devices is critical for the advancement of patient care in vascular surgery. Problems are still associated with the grafts, many of which can necessitate the conversion of the patient to open repair, or even result in rupture of the aneurysm. This review attempts to address these problems, by highlighting why they occur and what the failings of the currently available stent grafts are, respectively. In addition, the review gives critical appraisal as to the novel methods required for dealing with these problems and identifies the new generation of stent grafts that are being or need to be designed and constructed in order to overcome the issues that are associated with the existing first- and second-generation devices.