Application of Novosorb biodegradable temporising matrix in wounds of different aetiologies: a case series

DECLARATION OF INTEREST

The authors have no conflicts of interest to declare.

Microindentation of fresh soft biological tissue: A rapid tissue sectioning and mounting protocol

Microindentation of fresh biological tissues is necessary for the creation of 3D biomimetic models that accurately represent the native extracellular matrix microenvironment. However, tissue must first be precisely sectioned into slices. Challenges exist in the preparation of fresh tissue slices, as they can tear easily and must be processed rapidly in order to mitigate tissue degradation. In this study, we propose an optimised mounting condition for microindentation and demonstrate that embedding tissue in a mixture of 2.5% agarose and 1.5% gelatin is the most favourable method of tissue slice mounting for microindentation. This protocol allows for rapid processing of fresh biological tissue and is applicable to a variety of tissue types.

Systematic Review and Meta-analysis of Fenestrated and Chimney/Snorkel Techniques for Endovascular Repair of Juxtarenal Aortic Aneurysms

OBJECTIVES

Comparative effectiveness of fenestrated endovascular aneurysm repair (FEVAR) and chimney graft endovascular aneurysm repair (ChEVAR) for juxtarenal aortic aneurysms (JAAs) remains unclear. Our objective was to identify and analyze the current body of evidence comparing the effectiveness of both techniques for JAA.

METHODS

We performed a systematic review and meta-analysis comparing the effectiveness of FEVAR and ChEVAR for JAA repair. We searched MEDLINE, EMBASE, and Cochrane Register for Controlled Trials from January 1, 1990, for randomized and non-randomized studies assessing outcomes of FEVAR and ChEVAR for JAA repair. Screening, data extraction, risk of bias assessment, and GRADE (Grading of Recommendations, Assessments, Development, and Evaluations) certainty of evidence were performed in duplicate. Data were pooled statistically where possible.

RESULTS

Nine retrospective cohort studies comparing the use of FEVAR and ChEVAR for juxtarenal aneurysm were included for meta-analysis. The FEVAR and ChEVAR arms of the meta-analysis consisted of 726 participants and 518 participants, respectively. There were 598 (86.8%) and 332 (81.6%) men in each arm. The mean diameter was larger in the ChEVAR arm (59 mm vs 52.5 mm). Both techniques had similar rates of postoperative 30-day mortality, 3.38% (8/237) versus 3.52% (8/227), acute kidney injury, 16.76% (31/185) versus 17.31% (18/104), and major adverse cardiac events, 7.30% (46/630) versus 6.60% (22/333). The meta-analysis supported the use of FEVAR for most outcomes, with significant advantage for technical success (odds ratio [OR]: 3.24, 95% CI: 1.24-8.42) and avoidance of type 1 endoleak (OR: 5.76, 95% CI: 1.94-17.08), but a disadvantage for spinal cord ischemia (OR: 10.21, 95% CI: 1.21-86.11), which had a very low number of events. The quality of evidence was "moderate" for most outcomes.

CONCLUSION

Both endovascular techniques had good safety profiles. The evidence does not support superiority of either FEVAR or ChEVAR for JAA.

CLINICAL IMPACT

While lack of equipoise has hampered the design of randomised trials of open versus endovascular repair of juxtarenal aortic aneurysms, concern about the durability of endovascular repair highlights the need for stronger evidence of the comparative efficacy of endovascular techniques. This review performed meta-analysis and evidence appraisal of recent data from large observational studies comparing fenestrated and chimney techniques, using a comprehensive outcome set. Superiority of either intervention could not be established due to differences in participants' baseline risk in each study arm. However, data suggests that both techniques are safe and suitable for use when indicated.

Effect of Pseudomonas colonisation on lower limb venous ulcer healing: a systematic review

OBJECTIVE

Pseudomonas aeruginosa is a Gram-negative bacillus that commonly colonises lower limb venous ulcers. Its effects on venous ulcer healing are widely debated. It produces exotoxins and elastase, as well as forming biofilms in hard-to-heal wounds. It is postulated that these virulence factors lead to slower healing times in patients with lower limb venous ulcers colonised with Pseudomonas. This review aimed to summarise the available evidence pertaining to this topic.

METHOD

A systematic review was performed in August 2019, where the Pubmed, Cochrane and Embase databases were searched for relevant literature according to PRISMA guidelines. Retrospective and prospective studies examining the effect of Pseudomonas colonisation on any measure of ulcer healing were included.

RESULTS

Some 282 articles were screened, of which seven studies including 491 patients were ultimately included for analysis. Of these, no study demonstrated a significant association between Pseudomonas colonisation and delayed healing of venous ulcers. In five of the seven studies, the effect of Pseudomonas aeruginosa on initial ulcer size at presentation was recorded.

CONCLUSION

All the studies demonstrated an association between ulcer size and the presence of Pseudomonas aeruginosa. While Pseudomonas aeruginosa may colonise larger ulcers or those with a worse prognosis, no evidence was found to support the hypothesis that this colonisation had a negative impact on lower limb venous ulcer healing.

Outcomes of Acute Limb Ischaemia in Patients with Underlying Malignancy: A Systematic Review

Objective

Previous studies have demonstrated amputation and mortality rates to be 14.3% – 30% and 11.4% – 28.9%, respectively, for all patients presenting with acute limb ischaemia (ALI). Rates of ALI are higher in patients with malignancy than in those without. Despite this, there remains uncertainty with regards to the most appropriate management for patients with cancer presenting with ALI. This is because of previously published high rates of associated morbidity and mortality in this population. The aim of this review was to summarise the available evidence reporting on outcomes of ALI in patients with underlying malignancy.

Method

A systematic review was performed in August 2020 in accordance with the PRISMA guidelines. The Medline, Scopus, Cochrane, and Embase databases were searched with the following search string ((acute limb ischaemia) OR (acute limb ischemia)) AND ((cancer) OR (malignancy)). A total of 849 papers were identified and reviewed; six studies were included. Studies were assessed for bias using the National Institute of Health/National Heart, Lung and Blood Institute Quality Assessment Tool. Data including demographics, Rutherford classification, baseline performance scores, method of revascularisation, and peri-procedural outcomes were extracted and analysed. Data were pooled based on outcomes of interest and pooled prevalence was reported with 95% confidence intervals (CI).

Results

Six studies with 284 patients with cancer were included for analysis. The pooled overall risk of amputation was 15% (95% CI 5.9 – 26.9). The pooled 30 day mortality rate was 24% (95% CI 14.7 – 34.6).

Conclusion

Despite limitations of interstudy selection bias and some clinical heterogeneity, the included studies demonstrated acceptable short and medium term outcomes for patients with cancer undergoing revascularisation for acute limb ischaemia. This is in line with current recommendations that patients with underlying malignancy should be considered strongly for revascularisation.

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Review of data on acute limb ischaemia in the presence of underlying malignancy.

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Demonstrates acceptable short and medium term survival rates.

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Such patients should be considered for revascularisation.

Open repair of a type II endoleak facilitated by temporary disconnection of graft components

Endoleaks are a frequent indication for reintervention after endovascular repair of an abdominal aortic aneurysm. Here we present a method of open repair of a persistent type II endoleak involving graft component separation and reconstruction, in a patient with symptomatic interval aneurysmal sac enlargement despite endovascular coiling and embolization. This case report demonstrates an alternative open technique of endograft component separation and reconstruction that may be required in cases where open repair with sac exploration and vessel oversewing is hindered by the graft position.

Hybrid covered endovascular reconstruction of the aortic bifurcation (CERAB) procedure is preferable to aortobifemoral bypass for limb-threatening aortoiliac occlusive disease during the COVID-19 crisis

The COVID-19 pandemic is disrupting the provision of acute vascular surgery across the globe. Limited evidence of the impact of nosocomial infection on patient outcomes as well as concerns about critical care capacity will likely have an impact on surgical decision-making. Endovascular therapy offers a way by which perioperative risk can be reduced for vascular patients while also reducing the impact of acute surgery on intensive care unit capacity. This case report describes the management of a patient with complex aortoiliac occlusive disease by a hybrid endovascular approach in light of these constraints, with a successful outcome.

Correlating Ex Vivo Carotid Calcification Measurements With Cerebrovascular Symptoms: A Proof-of-Concept Study

BACKGROUND AND PURPOSE

The purpose of this study is to examine the ability of ex vivo derived Agatston, Volume, and Density-Volume calcium scores or calcium density measurements to differentiate between carotid plaques based on preoperative cerebrovascular symptomatology.

METHODS

Thirty-eight carotid plaques were acquired from standard endarterectomy. Micro-computed tomography was performed on the ex vivo samples. Image series were downsampled to represent the resolution of clinical multidetector computed tomography. Agatston, Volume, and Density-Volume carotid calcium scores were then calculated using coronary methodologies. The fractions of low- and high-density calcification were also determined.

RESULTS

The coronary calcium scores could not differentiate between carotid plaques from asymptomatic versus symptomatic patients. However, plaques from asymptomatic patients contained significantly lower fractions of low-density calcification and higher fractions of high-density calcification.

CONCLUSIONS

Screening for carotid calcium density in noncontrast computed tomography could reflect plaque stability.

An international experience of electronic communication and implementation of eHealth solutions in a vascular surgery clinic

INTRODUCTION

Communication is key to any successful relationship with the patient-physician partnership being no different. Recent advances in technology have provided us with an array of new communication tools such as the mobile phone, computer, internet, and email. This new technology has revolutionized communications; however, limitations to their widespread use include access, literacy, and willingness for both the physician and patient to change.

METHODS

To gather international data, questionnaires were completed by patients attending vascular surgery outpatient clinics in hospitals in Ireland and Canada.

RESULTS

Five hundred ninety-seven patients participated in the study. Of the participants, 83.2% were over 50 years old. The mean age was 63.1 years, with a range of 18-95 years. Overall, home phone call was the most preferred method of communication with 41.0% of patients selecting this option. Of the patients, 82.4% had a mobile phone but just 48.5% use text message. In those over the age of 70, 72.1% use a mobile phone and just 25.3% use text message. Of the participants, 64.1% had access to a computer, and 67.2% had access to the internet with a decline in the usage of both with increasing age.

DISCUSSION

Within this patient population, the use of technologies decreases with increasing age of the patients. This demonstrates a large population of service users who are contented with conventional methods of communication. Change within healthcare ICT is inevitable, and therefore, these patients need to be guided and educated to allow a smooth transition from the old to the new.

The Presence of a High Peak Feature Within Low-Average Shear Stimuli Induces Quiescence in Venous Endothelial Cells

Wall shear stress (WSS) is an important stimulus in vascular remodelling and vascular lesion development. The current methods to assess and predict the risk associated with specific unsteady WSS consider the WSS mean values or the presence of reverse phases described by the oscillatory shear index. Recent evidence has shown that the accuracy of these methods is limited, especially with respect to the venous environment. Unsteady WSS are characterised by several features that may individually affect endothelial cells. Consequently, we assessed the effects of averaged WSS (TAWSS), temporal WSS gradient (TWSSG), maximum WSS (WSS peak) and reverse phase (OSI) by applying different WSS profiles to venous EC in-vitro, using a real-time controlled cone-and-plate cell-shearing device for 24 h. We found that TWSSG and WSS peak affect cell elongation and alignment respectively. We also found that the WSS waveforms with a peak of 1.5 Pa or higher significantly correlate with the induction of a protective phenotype. Cell phenotype induced by these high peak waveforms does not correlate to what is predicted by the hemodynamic indices currently used. The definition of reliable hemodynamic indices can be used to inform the computational models aimed at estimating the hemodynamic effects on vascular remodelling.

Comparative analysis of calcification parameters with Agatston Score approximations for ex vivo atherosclerotic lesions

BACKGROUND

The Agatston Calcium Score is a predictor of major adverse cardiovascular events but it is unable to identify high-risk lesions. Recent research suggests that examining calcification phenotype could be more indicative of plaque stability.

OBJECTIVE

To examine the Agatston score's ability to determine atherosclerotic calcification phenotype.

METHODS

Micro-Computed Tomography was performed on 20 carotid and 20 peripheral lower limb lesions. ImageJ pixel histogram analysis quantified the non-calcified (≥30HU, <130HU) and calcified (≥130HU) tissue volumes. ImageJ '3D Objects Counter' plugin determined the calcified particle count, volumes and maximum attenuation density of each particle. Image stacks were subsequently downsampled to a resolution of 0.7 × 0.7 × 3 mm and an approximation for the Extra-Coronary Calcium Scores (ECCS) were calculated. Spearman's correlation examined the relationships between ECCS approximations and calcification parameters.

RESULTS

ECCS has a strong positive correlation with the Calcified Volume Fraction (CVF) (r_s = 0.865, p < 0.0005), weak positive correlations with Calcified Particle Fraction (CPF) (r_s = 0.422, p = 0.007) and Microcalcification Fraction (micro-CF) (r_s = 0.361, p = 0.022). There is no correlation evident between ECCS and Calcified Particle Index (CPI) (r_s = -0.162, p = 0.318). It is apparent that there is a high prevalence of microcalcifications in both carotid and peripheral lower limb lesions. Additionally, an inverse relationship exists between calcified particle volume and maximum-recorded attenuation density.

CONCLUSION

The density-weighted Agatston calcium scoring methodology needs to be reviewed. Calcium scoring which differentiates between critical calcification morphologies, rather than presenting a density-weighted score, is required to direct high-risk plaques towards tailored treatment.

Relating the mechanical properties of atherosclerotic calcification to radiographic density: A nanoindentation approach

Calcification morphology can determine atherosclerotic plaque stability and is associated with increased failures rates for endovascular interventions. Computational efforts have sought to elucidate the relationship between calcification and plaque rupture in addition to predicting tissue response during aggressive revascularisation techniques. However, calcified material properties are currently estimated and may not reflect real tissue conditions. The objective of this study is to correlate calcification mechanical properties with three radiographic density groups obtained from corresponding Computed Tomography (CT) images. Seventeen human plaques extracted from carotid (n = 10) and peripheral lower limb (n = 7) arteries were examined using micro-computed tomography (µCT), simultaneously locating the calcified deposits within their internal structure and quantifying their densities. Three radiographic density groups were defined based on the sample density distribution: (A) 130-299.99 Hounsfield Units (HU), (B) 300-449.99 HU and (C) >450 HU. Nanoindentation was employed to determine the Elastic Modulus (E) and Hardness (H) values within the three density groups. Results reveal a clear distinction between mechanical properties with respect to radiographic density groups (p < 0.0005). No significant differences exist in the density-specific behaviours observed between carotid and peripheral samples. Previously defined calcification classifications indicate an association with specific radiographic density patterns. Scanning Electron Microscopy (SEM) examination revealed that density group A regions consist of both calcified and non-calcified tissues. Further research is required to define the radiographic thresholds which identify varying degrees of tissue calcification. This study demonstrates that the mechanical properties of fully mineralised atherosclerotic calcification emulate that of bone tissues (17-25 GPa), affording computational models with accurate material parameters. STATEMENT OF SIGNIFICANCE: Global mechanical characterisation techniques disregard the heterogeneous nature of atherosclerotic lesions. Previous nanoindentation results for carotid calcifications have displayed a wide range. This study evaluates calcification properties with respect to radiographic density obtained from Micro-CT images. This is the first work to characterise calcifications from peripheral lower limb arteries using nanoindentation. Results demonstrate a strong positive correlation between radiographic density and calcification mechanical properties. Characterising calcifications using their density values provides clarity on the variation in published properties for calcified tissues. Furthermore, this study confirms the hypothesis that fully calcified plaque tissue behaviour similar to that of bone. Appropriate material parameters for calcified tissues can now be employed in computational simulations.

On the effect of computed tomography resolution to distinguish between abdominal aortic aneurysm wall tissue and calcification: A proof of concept

PURPOSE

The purpose of this study is to determine the optimal target CT spatial resolution for accurately imaging abdominal aortic aneurysm (AAA) wall characteristics, distinguishing between tissue and calcification components, for an accurate assessment of rupture risk.

MATERIALS AND METHODS

Ruptured and non-ruptured AAA-wall samples were acquired from eight patients undergoing open surgical aneurysm repair upon institutional review board approval and informed consent was obtained from all patients. Physical measurements of AAA-wall cross-section were made using scanning electron microscopy. Samples were scanned using high resolution micro-CT scanning. A resolution range of 15.5-155μm was used to quantify the influence of decreasing resolution on wall area measurements, in terms of tissue and calcification. A statistical comparison between the reference resolution (15.5μm) and multi-detector CT resolution (744μm) was also made.

RESULTS

Electron microscopy examination of ruptured AAAs revealed extremely thin outer tissue structure <200μm in radial distribution which is supporting the aneurysm wall along with large areas of adjacent medial calcifications far greater in area than the tissue layer. The spatial resolution of 155μm is a significant predictor of the reference AAA-wall tissue and calcification area measurements (r=0.850; p<0.001; r=0.999; p<0.001 respectively). The tissue and calcification area at 155μm is correct within 8.8%±1.86 and 26.13%±9.40 respectively with sensitivity of 87.17% when compared to the reference.

CONCLUSION

The inclusion of AAA-wall measurements, through the use of high resolution-CT will elucidate the variations in AAA-wall tissue and calcification distributions across the wall which may help to leverage an improved assessment of AAA rupture risk.

Patient knowledge of peripheral vascular disease in an outpatient setting: an Achilles heel?

Peripheral vascular disease (PVD) has numerous modifiable risk factors. This study aimed to establish patients' awareness of risk factors and causes of PVD and their understanding of mechanisms of secondary prevention. A prospective survey of awareness of PVD among patients attending a tertiary vascular clinic for management of peripheral vascular disease was undertaken. Institutional review board approval was granted. Statistical analysis was performed using SPSS version 18.0 software. There was a 100% response rate, with 97 participants (53 male). Seventeen patients (19%) reported an interval of greater than six months from the onset of symptoms to first seeking medical attention with their General Practitioner. Only 19 (20%) could correctly identify 3 or more risk factors for peripheral vascular disease. Patients have limited awareness of PVD and its consequences. Educational initiatives are needed to encourage patients to seek early medical attention and raise awareness of modifiable risk factors in the community.

Two weeks taurine supplementation reverses endothelial dysfunction in young male type 1 diabetics

Type 1 diabetics have a well-recognised risk of accelerated cardiovascular disease. Even in the absence of clinical signs there are detectable abnormalities of conduit vessel function. Our group has previously reported reversal of endothelial dysfunction in diabetics with pravastatin. In young asymptomatic smokers, taurine supplementation has a beneficial impact on macrovascular function, assessed by FMD, and shows an up-regulation of nitric oxide from monocyte-endothelial cell interactions. We hypothesise that taurine supplementation reverses early endothelial abnormalities in young male type 1 diabetics, as assessed by applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry. Asymptomatic, male diabetics (n=9) were scanned prior to treatment and then randomised in a double-blind cross-over fashion to receive either 2 weeks placebo or taurine. Control patients (n=10) underwent a baseline scan. Assessed diabetics had detectable, statistically significant abnormalities when compared with controls, in both arterial stiffness (augmentation index) and brachial artery reactivity (FMD). Both of these parameters were returned to control levels with 2 weeks taurine supplementation. In conclusion, 2 weeks taurine supplementation reverses early, detectable conduit vessel abnormalities in young male diabetics. This may have important implications in the long-term treatment of diabetic patients and their subsequent progression towards atherosclerotic disease.

Acute aortic occlusion in a patient with heparin-induced thrombocytopenia treated by thrombectomy

INTRODUCTION

Heparin-induced thrombocytopenia syndrome (HITS) is an infrequent complication of heparin anticoagulation.

CASE REPORT

We present the case of a 44-year-old male who was admitted with acute ischaemia of his right lower limb. He was initially treated with unfractionated heparin and thrombolysis, but subsequently developed acute aortic thrombosis 8 days following initiation of heparin therapy. This was treated with bilateral per-femoral thrombectomy with curative result.

CONCLUSION

This case report draws the attention of surgeons to the difficulties in diagnosing HITS and highlights the multidisciplinary management of a complicated case of acute ischaemia.

Iodinated contrast media alter immune responses in pro-inflammatory states

BACKGROUND

Hypertonic saline causes a transient elevation of blood osmolality and has been shown to alter cellular inflammatory responses in pro-inflammatory states. Intravascular administration of iodine contrast media also causes a transient elevation of blood osmolarity.

PURPOSE

To investigate the effect of iodine contrast media on leukocyte-endothelial interaction in vivo using intravital microscopy.

MATERIAL AND METHODS

Male Sprague-Dawley rats (n=36) were randomized into six groups and were treated with: saline, high osmolar contrast medium, low osmolar contrast medium, and endotoxin alone and in combination with the high and low osmolar contrast media. The effect on leukocyte-endothelial interaction in the post-mesenteric venules was observed using the technique of intravital microscopy. The sequence of leukocyte rolling velocity, leukocyte-endothelial cell adherence, and transmigration was recorded and analyzed at 10 min intervals to a maximum of 120 min.

RESULTS

Endotoxin significantly decreased the rolling velocity and increased the adherence and transmigration of leukocytes in a time-dependent manner. Both types of iodine contrast media attenuated this pro-inflammatory response to endotoxin. This effect began between 60 and 70 min after the onset of the experiment.

CONCLUSION

Hyperosmolar and lower osmolar iodine contrast media attenuate the pro-inflammatory leukocyte-endothelial response to endotoxin in vivo.

Femoral shaft perforation at arthroplasty: to treat or not to treat

Femoral shaft perforation at total hip arthroplasty is a complication that is being noted more frequently, and it is often associated with femoral shaft fracture below the prosthesis. This study examines the anatomic and biomechanical effects of femoral shaft perforation at arthroplasty, and the effects of supporting the perforated bone with Partridge plates and bands. Two models, pig femora and Pedilen cylinders, were employed. Testing the bone models to failure in tensile mode showed that the perforations weakened the bone and that the Partridge plates and bands decreased the weakening effects of the perforation. The strengthening effect of the Partridge plates and bands on the bone with a perforation, allied with the presence of an internal splint in the event of a fracture through the perforation, suggests the benefit of using Partridge plates and bands if a cortical perforation is found at arthroplasty and revision is not feasible.

The mechanical effects of femoral shaft perforation at total hip replacement

Perforation of the femoral shaft at total hip arthroplasty is a complication which is being reported more frequently. It has been suggested that the presence of bone cement in the perforation decreases the weakening effect of the perforation, but the mechanical basis for this belief is dubious. The anatomy of perforation was studied by cadaver dissection and its mechanical consequences were assessed in two models using Pedilen, a polyurethane foam, and pig femora. It was found that cement in a hole in bone decreased the weakening effect of the hole to tensile stress.