Graft type for femoro-popliteal bypass surgery

Ex Vivo and In Vivo Analysis of a Novel Porcine Aortic Patch for Vascular Reconstruction

(1) Background: The aim of the present study was the biocompatibility analysis of a novel xenogeneic vascular graft material (PAP) based on native collagen won from porcine aorta using the subcutaneous implantation model up to 120 days post implantationem. As a control, an already commercially available collagen-based vessel graft (XenoSure®) based on bovine pericardium was used. Another focus was to analyze the (ultra-) structure and the purification effort. (2) Methods: Established methodologies such as the histological material analysis and the conduct of the subcutaneous implantation model in Wistar rats were applied. Moreover, established methods combining histological, immunohistochemical, and histomorphometrical procedures were applied to analyze the tissue reactions to the vessel graft materials, including the induction of pro- and anti-inflammatory macrophages to test the immune response. (3) Results: The results showed that the PAP implants induced a special cellular infiltration and host tissue integration based on its three different parts based on the different layers of the donor tissue. Thereby, these material parts induced a vascularization pattern that branches to all parts of the graft and altogether a balanced immune tissue reaction in contrast to the control material. (4) Conclusions: PAP implants seemed to be advantageous in many aspects: (i) cellular infiltration and host tissue integration, (ii) vascularization pattern that branches to all parts of the graft, and (iii) balanced immune tissue reaction that can result in less scar tissue and enhanced integrative healing patterns. Moreover, the unique trans-implant vascularization can provide unprecedented anti-infection properties that can avoid material-related bacterial infections.

Pathological Change and Whole Transcriptome Alternation Caused by ePTFE Implantation in Myocardium

Expanded polytetrafluoroethylene (ePTFE) is commonly used in cardiovascular surgery, but usually causes postoperation complications. Although great efforts have been done to relieve these complications or to understand their mechanism, there are no applicable strategies available and no understanding mechanisms, especially in the myocardium. Here, ePTFE membranes are implanted into the right ventricular outflow tract of rabbits, and the implant-related myocardium is dissected and analyzed by histology and transcriptome sequencing. ePTFE implantation causes myocardium inflammation and fibrosis. There are 1867 differently expressed mRNAs (DEmRNAs, 1107 upregulated and 760 downregulated) and 246 differently expressed lncRNAs (DElncRNAs, 110 upregulated and 136 downregulated) identified. Bioinformatic analysis indicates that the upregulated DEmRNAs and DElncRNAs are mainly involved in inflammatory, immune responses, and extracellular matrix remodeling, while the downregulated DEmRNAs and DElncRNAs are predominantly functioned in the metabolism and cardiac remodeling. Analysis of coexpression and regulatory relationship of DEmRNAs and DElncRNAs reveals that most DElncRNAs are trans-regulated on the relevant DEmRNAs. In conclusion, ePTFE implantation causes severe myocardial tissue damages and alters the transcriptome profiles of the myocardium. Such novel data may provide a landscape of mechanisms underlying the adverse reactions caused by ePTFE implantation and uncover new therapeutic targets for inhibiting the ePTFE-related complications.

Dynamic Luminal Topography: A Potential Strategy to Prevent Vascular Graft Thrombosis

Aim

Biologic interfaces play important roles in tissue function. The vascular lumen-blood interface represents a surface where dynamic interactions between the endothelium and circulating blood cells are critical in preventing thrombosis. The arterial lumen possesses a uniform wrinkled surface determined by the underlying internal elastic lamina. The function of this structure is not known, but computational analyses of artificial surfaces with dynamic topography, oscillating between smooth and wrinkled configurations, support the ability of this surface structure to shed adherent material (Genzer and Groenewold, 2006; Bixler and Bhushan, 2012; Li et al., 2014). We hypothesized that incorporating a luminal surface capable of cyclical wrinkling/flattening during the cardiac cycle into vascular graft technology may represent a novel mechanism of resisting platelet adhesion and thrombosis.

Methods and Results

Bilayer silicone grafts possessing luminal corrugations that cyclically wrinkle and flatten during pulsatile flow were fabricated based on material strain mismatch. When placed into a pulsatile flow circuit with activated platelets, these grafts exhibited significantly reduced platelet deposition compared to grafts with smooth luminal surfaces. Constrained wrinkled grafts with static topography during pulsatile flow were more susceptible to platelet accumulation than dynamic wrinkled grafts and behaved similar to the smooth grafts under pulsatile flow. Wrinkled grafts under continuous flow conditions also exhibited marked increases in platelet accumulation.

Conclusion

These findings provide evidence that grafts with dynamic luminal topography resist platelet accumulation and support the application of this structure in vascular graft technology to improve the performance of prosthetic grafts. They also suggest that this corrugated structure in arteries may represent an inherent, self-cleaning mechanism in the vasculature.

Successful long-term limb salvage using cephalic and small saphenous vein grafts: A case report

In this case report, we present a patient scheduled for operation due to critical leg ischemia in whom a bilateral great saphenous vein (GSV) had already been used during previous cardiac and peripheral vascular surgeries. The patient underwent femorofemoral crossover bypass from left to right with a small saphenous vein and right femoropopliteal bypass with cephalic vein (CV) during the same session. Distal pulses became palpable, and symptoms regressed dramatically following the operation. A control computed tomographic angiography scan revealed no signs of graft stenosis 32 months after the surgery. Despite the recent advances in synthetic graft materials, small saphenous and CVs should be remembered as alternative long-standing conduits in the absence of the GSV.

Asia-Pacific Consensus Statement on the Management of Peripheral Artery Disease: A Report from the Asian Pacific Society of Atherosclerosis and Vascular Disease Asia-Pacific Peripheral Artery Disease Consensus Statement Project Committee

BACKGROUND

Peripheral artery disease (PAD) is the most underdiagnosed, underestimated and undertreated of the atherosclerotic vascular diseases despite its poor prognosis. There may be racial or contextual differences in the Asia-Pacific region as to epidemiology, availability of diagnostic and therapeutic modalities, and even patient treatment response. The Asian Pacific Society of Atherosclerosis and Vascular Diseases (APSAVD) thus coordinated the development of an Asia-Pacific Consensus Statement (APCS) on the Management of PAD.

OBJECTIVES

The APSAVD aimed to accomplish the following: 1) determine the applicability of the 2016 AHA/ACC guidelines on the Management of Patients with Lower Extremity Peripheral Artery Disease to the Asia-Pacific region; 2) review Asia-Pacific literature; and 3) increase the awareness of PAD.

METHODOLOGY

A Steering Committee was organized to oversee development of the APCS, appoint a Technical Working Group (TWG) and Consensus Panel (CP). The TWG appraised the relevance of the 2016 AHA/ACC PAD Guideline and proposed recommendations which were reviewed by the CP using a modified Delphi technique.

RESULTS

A total of 91 recommendations were generated covering history and physical examination, diagnosis, and treatment of PAD-3 new recommendations, 31 adaptations and 57 adopted statements. This Asia-Pacific Consensus Statement on the Management of PAD constitutes the first for the Asia-Pacific Region. It is intended for use by health practitioners involved in preventing, diagnosing and treating patients with PAD and ultimately the patients and their families themselves.

[Reconstruction of lower limbs in old age-an interdisciplinary approach : Strategies for trauma surgery, vascular surgery and plastic surgery]

The treatment of complex injuries of the lower extremities in geriatric and/or multimorbid patients requires optimized preoperative and perioperative management as well as differentiated and interdisciplinary surgical approaches. Timely and definitive treatment should be strived for to avoid longer periods of immobilization. Temporary external stabilization of complex fractures, when necessary, should be followed by permanent loading stable internal osteosynthesis as soon as possible. Accompanying soft tissue defects are reconstructed after wound débridement using the full armamentarium of plastic and reconstructive surgical procedures, including microvascular free flap. In the context of perfusion compromised soft tissue situations, negative pressure wound therapy can provide sterile temporary defect coverage and aid in preconditioning poorly vascularized tissue before definitive reconstruction. A clarification of the vascular status in geriatric patients is paramount and relevant perfusion disorders should be treated either by intervention or open surgery before complex reconstructive interventions. Close interdisciplinary coordination of the various surgical procedures is imperative in order to guarantee an optimized stable reconstructive outcome with acceptable patient risk. Taking these principles into account, the reconstruction of complex trauma to the extremities can be carried out even in geriatric or multimorbid patients in specialized interdisciplinary surgical centers with excellent functional results.

Thrombosis of a Long-Segment Aneurysm from the Iliac to Popliteal Artery Associated with Arteriovenous Malformation and Varicose Veins

A 58-year-old male patient with severe claudication due to thrombosis of the left ilio-femoro-popliteal artery aneurysm. He also had a venous stasis ulcer with a history of multiple embolotherapy of arteriovenous malformation. Duplex sonography revealed reflux and varicose veins of the left great saphenous vein (GSV). A sequential bypass surgery was performed that consisted of excision of the left external iliac and common femoral artery aneurysm, external iliac to deep femoral interposition with an expanded polytetrafluoroethylene graft, and femoro-posterior tibial artery bypass with the reversed left GSV. Symptoms of claudication were alleviated and the chronic ulcer was healed in time. To our knowledge, this is the first report of successful bypass in a patient with arterial aneurysm, arteriovenous malformation, and venous insufficiency that can be diagnosed as an atypical case of Parkes Weber syndrome. Long-term follow-up is needed to define the fate of aneurysms and varicose vein graft.

Successful repair of a popliteal aneurysm with saphenous vein graft in a patient with Marfan syndrome

Marfan syndrome is an autosomal dominant disorder caused by mutations in the fibrillin 1 gene (FBN1). This leads to defective elasticity of connective tissue in the arterial wall. Aortic aneurysms and dissections are the most common vascular anomalies; the incidence of peripheral artery aneurysms is not well understood. Treatment options for infrainguinal disease are limited as endovascular interventions are generally contraindicated. The best conduit for arterial reconstruction is also unknown because there is concern that saphenous vein may become aneurysmal. Currently, there are few case reports regarding outcomes of infrainguinal arterial reconstructions, and follow-up has been very short term. We report a rare case of successful repair of a popliteal aneurysm using a saphenous vein graft in a patient with Marfan syndrome.

CHIVA to treat saphenous vein insufficiency in chronic venous disease: characteristics and results

There is considerable debate in the literature with relation to the best method to treat patients with chronic venous disease (CVD). CHIVA is an office-based treatment for varicose veins performed under local anesthesia. The aim of the technique is to lower transmural pressure in the superficial venous system and avoid destruction of veins. Recurrence of varicosities, nerve damage, bruising and suboptimal aesthetic results are common to all treatments for the disease. This paper evaluates and discusses the characteristics and results of the CHIVA technique. We conclude that CHIVA is a viable alternative to common procedures that is associated with less bruising, nerve damage, and recurrence than stripping saphenectomy. The main advantages are preservation of the saphenous vein, local anesthesia, low recurrence rates, low cost, low pain, and no nerve damage. The major disadvantages are the learning curve and the need to train the team in venous hemodynamics.

Case of lower limb revascularisation using composite sequential bypass graft with a 'diamond' intermediate anastomosis

In patients with critical infracrural disease, autologous saphenous vein grafting offers the best reported conduit patency and limb salvage rates but is only feasible in approximately 30% of patients due to the lack of available or suitable vein. In the absence of a suitable length of available vein, various composite grafting techniques have been explored with the aim to improve graft longevity, maximise native vein use and improve overall clinical outcomes, including limb salvage rates. We report a case of a 66-year-old man with critical limb ischaemia and a history of venous disease, where a complex composite sequential bypass graft combining both native vein and synthetic graft, incorporated into a novel intermediate anastomotic technique in a 'diamond' configuration, offered promising results in limb salvage. This case highlights the key steps and advantages in this novel technique.

Region-Specific Microstructure in the Neonatal Ventricles of a Porcine Model

The neonate transitions from placenta-derived oxygen, to supply from the pulmonary system, moments after birth. This requires a series of structural developments to divert more blood through the right heart and onto the lungs, with the tissue quickly remodelling to the changing ventricular workload. In some cases, however, the heart structure does not fully develop causing poor circulation and inefficient oxygenation, which is associated with an increase in mortality and morbidity. This study focuses on developing an enhanced knowledge of the 1-day old heart, quantifying the region-specific microstructural parameters of the tissue. This will enable more accurate mathematical and computational simulations of the young heart. Hearts were dissected from 12, 1-day-old deceased Yorkshire piglets (mass: 2.1–2.4 kg, length: 0.38–0.51 m), acquired from a breeding farm. Evans blue dye was used to label the heart equator and to demarcate the left and right ventricle free walls. Two hearts were used for three-dimensional diffusion-tensor magnetic resonance imaging, to quantify the fractional anisotropy (FA). The remaining hearts were used for two-photon excited fluorescence and second-harmonic generation microscopy, to quantify the cardiomyocyte and collagen fibril structures within the anterior and posterior aspects of the right and left ventricles. FA varied significantly across both ventricles, with the greatest in the equatorial region, followed by the base and apex. The FA in each right ventricular region was statistically greater than that in the left. Cardiomyocyte and collagen fibre rotation was greatest in the anterior wall of both ventricles, with less dispersion when compared to the posterior walls. In defining these key parameters, this study provides a valuable insight into the 1-day-old heart that will provide a valuable platform for further investigation the normal and abnormal heart using mathematical and computational models.

Graft type for femoro-popliteal bypass surgery

BACKGROUND

Femoro-popliteal bypass is implemented to save limbs that might otherwise require amputation, in patients with ischaemic rest pain or tissue loss; and to improve walking distance in patients with severe life-limiting claudication. Contemporary practice involves grafts using autologous vein, polytetrafluoroethylene (PTFE) or Dacron as a bypass conduit. This is the second update of a Cochrane review first published in 1999 and last updated in 2010.

OBJECTIVES

To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro-popliteal arterial segment, for above- and below-knee femoro-popliteal bypass grafts.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Vascular Specialised Register (13 March 2017) and CENTRAL (2017, Issue 2). Trial registries were also searched.

SELECTION CRITERIA

We included randomised trials comparing at least two different types of femoro-popliteal grafts for arterial reconstruction in patients with femoro-popliteal ischaemia. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included.

DATA COLLECTION AND ANALYSIS

Both review authors (GKA and CPT) independently screened studies, extracted data, assessed trials for risk of bias and graded the quality of the evidence using GRADE criteria.

MAIN RESULTS

We included nineteen randomised controlled trials, with a total of 3123 patients (2547 above-knee, 576 below-knee bypass surgery). In total, nine graft types were compared (autologous vein, polytetrafluoroethylene (PTFE) with and without vein cuff, human umbilical vein (HUV), polyurethane (PUR), Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support). Studies differed in which graft types they compared and follow-up ranged from six months to 10 years.Above-knee bypassFor above-knee bypass, there was moderate-quality evidence that autologous vein grafts improve primary patency compared to prosthetic grafts by 60 months (Peto odds ratio (OR) 0.47, 95% confidence interval (CI) 0.28 to 0.80; 3 studies, 269 limbs; P = 0.005). We found low-quality evidence to suggest that this benefit translated to improved secondary patency by 60 months (Peto OR 0.41, 95% CI 0.22 to 0.74; 2 studies, 176 limbs; P = 0.003).We found no clear difference between Dacron and PTFE graft types for primary patency by 60 months (Peto OR 1.67, 95% CI 0.96 to 2.90; 2 studies, 247 limbs; low-quality evidence). We found low-quality evidence that Dacron grafts improved secondary patency over PTFE by 24 months (Peto OR 1.54, 95% CI 1.04 to 2.28; 2 studies, 528 limbs; P = 0.03), an effect which continued to 60 months in the single trial reporting this timepoint (Peto OR 2.43, 95% CI 1.31 to 4.53; 167 limbs; P = 0.005).Externally supported prosthetic grafts had inferior primary patency at 24 months when compared to unsupported prosthetic grafts (Peto OR 2.08, 95% CI 1.29 to 3.35; 2 studies, 270 limbs; P = 0.003). Secondary patency was similarly affected in the single trial reporting this outcome (Peto OR 2.25, 95% CI 1.24 to 4.07; 236 limbs; P = 0.008). No data were available for 60 months follow-up.HUV showed benefits in primary patency over PTFE at 24 months (Peto OR 4.80, 95% CI 1.76 to 13.06; 82 limbs; P = 0.002). This benefit was still seen at 60 months (Peto OR 3.75, 95% CI 1.46 to 9.62; 69 limbs; P = 0.006), but this was only compared in one trial. Results were similar for secondary patency at 24 months (Peto OR 4.01, 95% CI 1.44 to 11.17; 93 limbs) and at 60 months (Peto OR 3.87, 95% CI 1.65 to 9.05; 93 limbs).We found HBD to be superior to PTFE for primary patency at 60 months for above-knee bypass, but these results were based on a single trial (Peto OR 0.38, 95% CI 0.20 to 0.72; 146 limbs; very low-quality evidence). There was no difference in primary patency between HBD and HUV for above-knee bypass in the one small study which reported this outcome.We found only one small trial studying PUR and it showed very poor primary and secondary patency rates which were inferior to Dacron at all time points.Below-knee bypassFor bypass below the knee, we found no graft type to be superior to any other in terms of primary patency, though one trial showed improved secondary patency of HUV over PTFE at all time points to 24 months (Peto OR 3.40, 95% CI 1.45 to 7.97; 88 limbs; P = 0.005).One study compared PTFE alone to PTFE with vein cuff; very low-quality evidence indicates no effect to either primary or secondary patency at 24 months (Peto OR 1.08, 95% CI 0.58 to 2.01; 182 limbs; 2 studies; P = 0.80 and Peto OR 1.22, 95% CI 0.67 to 2.23; 181 limbs; 2 studies; P = 0.51 respectively)Limited data were available for limb survival, and those studies reporting on this outcome showed no clear difference between graft types for this outcome. Antiplatelet and anticoagulant protocols varied extensively between trials, and in some cases within trials.The overall quality of the evidence ranged from very low to moderate. Issues which affected the quality of the evidence included differences in the design of the trials, and differences in the types of grafts they compared. These differences meant we were often only able to combine and analyse small numbers of participants and this resulted in uncertainty over the true effects of the graft type used.

AUTHORS' CONCLUSIONS

There was moderate-quality evidence of improved long-term (60 months) primary patency for autologous vein grafts when compared to prosthetic materials for above-knee bypasses. In the long term (two to five years) there was low-quality evidence that Dacron confers a small secondary patency benefit over PTFE for above-knee bypass. Only very low-quality data exist on below-knee bypasses, so we are uncertain which graft type is best. Further randomised data are needed to ascertain whether this information translates into an improvement in limb survival.

2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines

Since 1980, the American College of Cardiology (ACC) and American Heart Association (AHA) have translated scientific evidence into clinical practice guidelines with recommendations to improve cardiovascular health. These guidelines, based on systematic methods to evaluate and classify evidence, provide a cornerstone of quality cardiovascular care.

In response to reports from the Institute of Medicine1 ,2 and a mandate to evaluate new knowledge and maintain relevance at the point of care, the ACC/AHA Task Force on Clinical Practice Guidelines (Task Force) modified its methodology.3 –5 The relationships among guidelines, data standards, appropriate use criteria, and performance measures are addressed elsewhere.5

2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines

Since 1980, the American College of Cardiology (ACC) and American Heart Association (AHA) have translated scientific evidence into clinical practice guidelines with recommendations to improve cardiovascular health. These guidelines, based on systematic methods to evaluate and classify evidence, provide a cornerstone of quality cardiovascular care.

In response to reports from the Institute of Medicine1 ,2 and a mandate to evaluate new knowledge and maintain relevance at the point of care, the ACC/AHA Task Force on Clinical Practice Guidelines (Task Force) modified its methodology.3 –5 The relationships among guidelines, data standards, appropriate use criteria, and performance measures are addressed elsewhere.5

Femoropopliteal Bypass with Varicose Greater Saphenous Vein

Surgical bypass for peripheral arterial occlusive disease can be performed using different graft materials. Autogenous greater saphenous vein (GSV) is the treatment of choice because of its superior long-term patency. We report a case of femoropopliteal bypass with varicose GSV in a 77-year-old man who was presented with limb ischemia and both varicose veins. We successfully performed bypass with varicose vein. He has been doing well for 15 months after the operation, and a computed tomography angiography of the lower leg, performed on the 15th postoperative month, demonstrated widely patent femoropopliteal bypass graft and no structural change.

In Vivo Remodeling of Fibroblast-Derived Vascular Scaffolds Implanted for 6 Months in Rats

There is a clinical need for tissue-engineered small-diameter (<6 mm) vascular grafts since clinical applications are halted by the limited suitability of autologous or synthetic grafts. This study uses the self-assembly approach to produce a fibroblast-derived decellularized vascular scaffold (FDVS) that can be available off-the-shelf. Briefly, extracellular matrix scaffolds were produced using human dermal fibroblasts sheets rolled around a mandrel, maintained in culture to allow for the formation of cohesive and three-dimensional tubular constructs, and decellularized by immersion in deionized water. The FDVSs were implanted as an aortic interpositional graft in six Sprague-Dawley rats for 6 months. Five out of the six implants were still patent 6 months after the surgery. Histological analysis showed the infiltration of cells on both abluminal and luminal sides, and immunofluorescence analysis suggested the formation of neomedia comprised of smooth muscle cells and lined underneath with an endothelium. Furthermore, to verify the feasibility of producing tissue-engineered blood vessels of clinically relevant length and diameter, scaffolds with a 4.6 mm inner diameter and 17 cm in length were fabricated with success and stored for an extended period of time, while maintaining suitable properties following the storage period. This novel demonstration of the potential of the FDVS could accelerate the clinical availability of tissue-engineered blood vessels and warrants further preclinical studies.

Management of Critical Limb Ischemia

Critical limb ischemia (CLI) is a clinical syndrome of ischemic pain at rest or tissue loss, such as nonhealing ulcers or gangrene, related to peripheral artery disease. CLI has a high short-term risk of limb loss and cardiovascular events. Noninvasive or invasive angiography help determine the feasibility and approach to arterial revascularization. An endovascular-first approach is often advocated based on a lower procedural risk; however, specific patterns of disease may be best treated by open surgical revascularization. Balloon angioplasty and stenting form the backbone of endovascular techniques, with drug-eluting stents and drug-coated balloons offering low rates of repeat revascularization. Combined antegrade and retrograde approaches can increase success in long total occlusions. Below the knee, angiosome-directed angioplasty may lead to greater wound healing, but failing this, any straight-line flow into the foot is pursued. Hybrid surgical techniques such as iliac stenting and common femoral endarterectomy are commonly used to reduce operative risk. Lower extremity bypass grafting is most successful with a good quality, long, single-segment autogenous vein of at least 3.5-mm diameter. Minor amputations are often required for tissue loss as a part of the treatment strategy. Major amputations (at or above the ankle) limit functional independence, and their prevention is a key goal of CLI therapy. Medical therapy after revascularization targets risk factors for atherosclerosis and assesses wound healing and new or recurrent flow-limiting disease. The ongoing National Institutes of Health-sponsored Best Endovascular Versus Best Surgical Therapy in Patients With Critical Limb Ischemia (BEST-CLI) study is a randomized trial of the contemporary endovascular versus open surgical techniques in patients with CLI.

The Diagnosis and Treatment of Peripheral Arterial Vascular Disease

BACKGROUND

In peripheral arterial occlusive disease (PAOD), arterial stenosis or occlusion impairs perfusion in the territory of the distal portion of the aorta and the iliac and leg arteries. In Germany, the prevalence of PAOD rises with age, reaching 20% among persons over age 70.

METHODS

This guideline was prepared by a collaboration of 22 medical specialty societies and two patient self-help organizations on the basis of pertinent publications that were retrieved by a systematic search in PubMed for articles that appeared from 2008 to April 2014, with a subsequent update to May 2015.

RESULTS

294 articles were assessed, including 34 systematic reviews and 98 randomized controlled trials (RCTs). The diagnostic assessment of PAOD is based on physical examination, blood pressure at the ankles, and color-coded duplex ultrasonography (grade A recommendation). Other tomographic imaging methods can be used for suitable indications. The main elements of the treatment of PAOD are the control of cardiovascular risk factors and structured vascular exercise (grade A recommendation). Acetylsalicylic acid and statins are the main drugs for symptomatic PAOD (grade A recommendation). Patients with claudication and correlated structural findings can undergo an endo - vascular or open surgical procedure. Critical ischemia is an indication for arterial revascularization as soon as possible (grade A recommendation); this may be performed either by open surgery or by an endovascular procedure of one of the types that are now undergoing rapid development, or one of the crural treatment options. There is inadequate evidence concerning the optimal drug regimen after revascularization procedures.

CONCLUSION

The diagnostic assessment of PAOD is based on physical examination, measurement of the ankle-brachial index (ABI), and duplex ultrasonography. Acetylsalicylic acid and statins are indicated for patients with symptomatic PAOD. Endovascular procedures should be used if indicated. Randomized studies are needed to provide better evidence on many open questions in the treatment of PAOD.

An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries: A Supplement to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II): The TASC Steering Comittee(.)

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines were last updated in 2007 (TASC II) and represented the collaboration of international vascular specialties involved in the management of patients with peripheral arterial disease (PAD). Since the publication of TASC II, there have been innovations in endovascular revascularization strategies for patients with PAD. The intent of this publication is to provide a complete anatomic lower limb TASC lesion classification, including the infrapopliteal segment, and an updated literature review of new endovascular techniques and practice patterns employed by vascular specialists today.

Macrophage Notch Ligand Delta-Like 4 Promotes Vein Graft Lesion Development: Implications for the Treatment of Vein Graft Failure

OBJECTIVE

Despite its large clinical impact, the underlying mechanisms for vein graft failure remain obscure and no effective therapeutic solutions are available. We tested the hypothesis that Notch signaling promotes vein graft disease.

APPROACH AND RESULTS

We used 2 biotherapeutics for Delta-like ligand 4 (Dll4), a Notch ligand: (1) blocking antibody and (2) macrophage- or endothelial cell (EC)-targeted small-interfering RNA. Dll4 antibody administration for 28 days inhibited vein graft lesion development in low-density lipoprotein (LDL) receptor-deficient (Ldlr(-/-)) mice, and suppressed macrophage accumulation and macrophage expression of proinflammatory M1 genes. Dll4 antibody treatment for 7 days after grafting also reduced macrophage burden at day 28. Dll4 silencing via macrophage-targeted lipid nanoparticles reduced lesion development and macrophage accumulation, whereas EC-targeted Dll4 small-interfering RNA produced no effects. Gain-of-function and loss-of-function studies suggested in vitro that Dll4 induces proinflammatory molecules in macrophages. Macrophage Dll4 also stimulated smooth muscle cell proliferation and migration and suppressed their differentiation.

CONCLUSIONS

These results suggest that macrophage Dll4 promotes lesion development in vein grafts via macrophage activation and crosstalk between macrophages and smooth muscle cells, supporting the Dll4-Notch axis as a novel therapeutic target.

An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries: A Supplement to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II)

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines were last updated in 2007 (TASC II) and represented the collaboration of international vascular specialties involved in the management of patients with peripheral arterial disease (PAD). Since the publication of TASC II, there have been innovations in endovascular revascularization strategies for patients with PAD. The intent of this publication is to provide a complete anatomic lower limb TASC lesion classification, including the infrapopliteal segment, and an updated literature review of new endovascular techniques and practice patterns employed by vascular specialists today.

A novel approach of arteriovenous fistula formation in cultivation of an arm vein for use in infrainguinal surgical bypass grafting

Autologous vein is preferable for use in lower limb arterial bypass rather than synthetic graft material. Suitable vein for grafting is often limited, particularly in patients who have had previous cardiac bypass grafting or varicose veins surgery. This case report describes the use of arteriovenous fistula formation to cultivate an arm vein of a suitable diameter for use in femorotibial bypassing.

Mapping of autogenous saphenous veins as an imaging adjunct to peripheral MR angiography in patients with peripheral arterial occlusive disease and peripheral bypass grafting: prospective comparison with ultrasound and intraoperative findings

BACKGROUND

Mapping of the great saphenous vein is very important for planning of peripheral and coronary bypass surgery. This study investigated mapping of the great saphenous vein as an adjunct to peripheral MR angiography using a blood pool contrast agent in patients who were referred for evaluation of peripheral arterial occlusive disease and bypass surgery.

METHODS

38 patients with peripheral arterial occlusive disease (21 men; mean age: 71 years, range, 44-88 years) underwent peripheral MR angiography using the blood pool contrast agent Gadofosveset trisodium. Apart from primary arterial assessment images were evaluated in order to determine great saphenous vein diameters at three levels: below the saphenofemoral junction, mid thigh and 10 cm above the knee joint (usability: diameter range: >3 and <10 mm at one level and >3.5 and <10 mm at a neighboring level). Duplex ultrasound was performed by an independent examiner providing diameter measurements at the same levels. Additionally, vessel usability was determined intraoperatively by the vascular surgeon during subsequent bypass surgery.

RESULTS

Mean venous diameters for MR angiography/duplex ultrasound were 5.4±2.6/5.5±2.8 mm (level 1), 4.7±2.7/4.6±2.9 mm (level 2) and 4.4±2.2/4.5±2.3 mm (level 3), respectively, without significant differences between the modalities (P = 0.207/0.806/0.518). Subsequent surgery was performed in 27/38 patients. A suitable saphenous vein was diagnosed in 25 and non-usability was diagnosed in 2 of the 27 patients based on MR angiography/duplex ultrasound, respectively. Usability was confirmed by intraoperative assessment in all of the 24 patients that received a venous bypass graft in subsequent bypass surgery. In 1 case, in which the great saphenous vein was assessed as useable by both MR angiography and duplex ultrasound, it was not used during subsequent bypass surgery due to the patients clinical condition and comorbidities.

CONCLUSION

Simultaneous mapping of the great saphenous vein as an imaging adjunct to peripheral MR angiography with a blood pool contrast agent is an alternative to additive duplex ultrasound in patients undergoing subsequent peripheral bypass grafting.

Comparisons between prosthetic vascular graft and saphenous vein graft in femoro-popliteal bypass

PURPOSE

Infrainguinalfemoropopliteal bypass (IFPB) is recommended to peripheral arterial disease (PAD) with a long occlusion of the superficial femoral artery (SFA). The aims of our study were to determine the patency of graft materials, and identify the risk factors of graft failure.

METHODS

From January 1995 to April 2011, we had performed 380 IFPBs in 351 patients, including 302 femoro-above the knee (AK) bypasses and 78 femoro-below the knee (BK) bypasses. We compare age, sex, severity of ischemia between polytetra-uoroethylene (PTFE) graft and saphenous vein (SV) graft, and evaluate patency rate rates of the two groups.

RESULTS

The primary patency rates at 5 years for SV (n = 76 limbs) and PTFE grafts (n = 226 limbs) in AK were 85.2% and 64.5% (log rank = 0.03), and the secondary patency rates at 5 years for SV and PTFE grafts in AK were 88.2% and 79.0% (log rank = 0.13). The primary patency rates at 5 years for SV (n = 50 limbs) and PTFE grafts (n = 28 limbs) in BK were 63.2% and 40.0% (log rank = 0.08), and the secondary patency rates at 5 years for SV and PTFE grafts in BK were 71.6% and 55.5% (log rank = 0.18).

CONCLUSION

There was no statistical significant difference in secondary patency rates between SV and PTFE in IFPB. PTFE grafts as SV grafts can be a good alternative bypass material in IFPB instead of SV grafts.

Healthcare quality indicators of peripheral artery disease based on systematic reviews

OBJECTIVES

Peripheral artery disease (PAD) is a major health problem whose clinical management includes multiple options regarding risk factor control, diagnosis, and medical and surgical treatment. The aim was to generate indicators based on systematic reviews to evaluate the quality of healthcare provided in PAD.

METHODS

Electronic searches were run for systematic reviews in The Cochrane Library (Issue 6, 2011), MEDLINE, EMBASE, and other databases (up to June 2011). Conclusive systematic reviews of high methodological quality were selected to formulate clinical recommendations. Indicators were derived from clinical recommendations with moderate to very high strength of evidence as assessed by the GRADE system.

RESULTS

From 1,804 reviews initially identified, 29 conclusive and high-quality systematic reviews were selected and nine clinical recommendations were formulated with a moderate to very high strength of recommendation. Six indicators were finally generated: four on pharmacological interventions, antiplatelet agents, naftidrofuryl, cilostazol, and statins; and two lifestyle interventions, exercise and tobacco cessation. No indicators were derived for diagnostic tests or surgical techniques. Most indicators targeted patients with intermittent claudication.

CONCLUSIONS

These quality indicators will help clinicians to assess the appropriateness of healthcare provided in PAD. The development of evidence-based indicators in PAD is limited by the lack of methodological quality of the research in this disease, the inconclusiveness of the evidence on diagnostic and surgical techniques, and the dynamic nature of the vascular diseases field.

[Management of peripheral vascular disease based on current guidelines. Peripheral artery occlusive disease of the iliac and femoral arteries and carotid artery stenosis]

The article summarizes the recommendations of current European and American guidelines concerning the diagnosis and treatment of peripheral arterial occlusive disease and carotid artery stenosis. In comparison to older recommendations, current guidelines concerning endovascular treatment and concomitant medical therapy have been changed in recent years. With the exception of very complex and long lesions, endovascular methods are seen as the therapy of choice for revascularization of the iliac and femoral arteries. For cardiovascular risk reduction, patients with symptomatic peripheral arterial disease and stenosis of the carotid arteries should receive antiplatelet as well as statin therapy and should not be treated different from patients with coronary artery disease.

Interposition vein cuff for infragenicular prosthetic bypass graft

BACKGROUND

The use of prosthetic grafts such as polytetrafluorethylene (PTFE) or Dacron to bypass occluded arteries in the lower leg is an accepted practice in the absence of suitable autologous vein. The aim is limb salvage or functional improvement in critical limb ischaemia, but patency rates for below knee prosthetic bypasses are low. Creating a vein cuff at the distal anastomosis is thought to improve outcomes. Other techniques including the use of pre-cuffed synthetic grafts, spliced segments of vein and the creation of an arterio-venous fistula (AVF) are also used to improve patency.

OBJECTIVES

To compare the beneficial effects of using vein cuffed prosthetic grafts for below knee bypass in critical limb ischaemia with other types of reconstruction.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2012) and CENTRAL (2012, Issue 5) for publications comparing prosthetic infragenicular bypass using vein cuffs with other bypass techniques.

SELECTION CRITERIA

Randomised controlled trials comparing interposition vein cuff prosthetic graft with autologous vein graft and non-cuffed prosthetic graft for infragenicular bypass in patients with critical limb ischaemia were included. Trials comparing vein cuff prosthetic grafts with or without AVF and vein cuff prosthetic grafts with pre-cuffed prosthetic grafts were also included.

DATA COLLECTION AND ANALYSIS

The trials were selected and assessed independently by two review authors.

MAIN RESULTS

Six trials with a combined total of 885 patients were included in this review. Only studies using prosthetic PTFE grafts were identified.Two trials compared PTFE graft with or without a vein cuff. In one underpowered trial for below knee bypass the cumulative primary patency rate was statistically significantly higher in the vein cuff group (80.3% versus 65.3% at 12 months and 51.8% versus 29.1% at 24 months, P = 0.03). There was no statistically significant difference in secondary patency (82.9% versus 72.5% and 58.6% versus 34.9%, P = 0.14) and limb salvage rates (86.3% versus 71.8% and 82.6% versus 62.2%, P = 0.08) at 12 and 24 months respectively. The other trial showed no statistically significant difference between the groups at three years in the below knee femoro-popliteal bypasses (primary patency rate 26% (95% confidence interval (CI) 18 to 38) and 43% (95% CI 33 to 58), secondary patency rate 32% (95% CI 23 to 44) and 42% (95% CI 31 to 56) and limb salvage rate 64% (95% CI 54 to 75) and 61% (95% CI 50 to 74) in the collar and no collar groups respectively). In the femoro-distal bypass group, the differences in primary patency, secondary patency and limb salvage rates were also not statistically significant at three years (primary patency rate 20% (95% CI 11 to 38) and 17% (95% CI 9 to 33), secondary patency rate 22% (95% CI 12 to 39) and 20% (95% CI 11 to 35) and limb salvage rate 59% (95% CI 46 to 76) and 44% (95% CI 32 to 61) in the collar and no collar groups respectively).One trial compared pre-cuffed PTFE grafts with vein cuffed grafts. There was no statistically significant difference in primary patency rate (62% pre-cuffed PTFE versus 52% vein cuff PTFE and 49% versus 44%, P = 0.53), secondary patency rate (66% pre-cuffed PTFE versus 53% vein cuff PTFE and 55% versus 50%, P = 0.30) or limb salvage rate (75% pre-cuffed PTFE versus 72% vein cuff PTFE and 62% versus 65%, P = 0.88) at 12 and 24 months respectively.One trial compared spliced vein grafts with vein cuffed PTFE grafts. At 24 months, the secondary patency rate was statistically significantly higher in the spliced vein group (86% in the spliced vein and 52% in the vein cuff group, P < 0.05). There was no statistical significant difference in primary patency rate (44% versus 50%, P > 0.05) and limb salvage rate (94% versus 85%, P > 0.05).Two trials compared vein cuff PTFE grafts with and without AVF. There was no statistical significant difference at 24 months in primary patency rate (29% versus 36%, P = 0.77; 32% versus 28%, P = 0.2), secondary patency rate (40% versus 40%, P = 0.89; 28% versus 24%, P = 0.2) and limb salvage rate (65% versus 70%, P = 0.97; 62% versus 71%, P = 0.3).

AUTHORS' CONCLUSIONS

There is evidence that a vein cuff at the distal anastomosis site improves primary graft patency rates for below knee PTFE graft, but this does not reduce the risk of limb loss. Pre-cuffed PTFE grafts have comparable patency and limb salvage rates to vein cuff PTFE grafts. The use of spliced veins improved secondary patency but this did not translate into improved limb salvage. The use of an AVF alone showed no added benefits. Evidence for a beneficial effect of vein cuffed PTFE grafts is weak and based on underpowered trials. A large study with a specific focus on below knee vein cuff prosthetic grafts, including PTFE, is required.

Preimplantation processing of ex vivo-derived vascular biomaterials: effects on peripheral cell adhesion

The use of ex vivo-derived scaffolds as vascular conduits has shown to be a clinically valid approach to repair or bypass occluded vessels. Implantation of allogeneic tissue grafts requires careful processing to lower immunogenicity and prevent bacterial infection. However, the mechanical/chemical treatments used to prepare biological scaffolds can result in significant alterations to the native structure and surface chemistry, which can affect in vivo performance. Of particular importance for vascular grafts are binding interactions between the implanted biomaterial and host cells from the circulation and adjacent vasculature. Here we present a comparison of four strategies used to decellularize allogeneic human umbilical vein (HUV) scaffolds: ethanol/acetone, sodium chloride, sodium dodecyl sulfate (SDS), or Triton X-100. Scanning electron microscopy revealed that all four techniques achieved removal of native cells from both the lumenal and ablumenal surfaces of HUV grafts. Platelets and promyelocytic HL-60 cells showed preferential binding on the more loosely structured ablumenal surface, although low surface coverage was observed overall by peripheral blood cells. Vascular endothelial cell adhesion was highest on HUV decellularized using ethanol/acetone, and significantly higher than on SDS-processed grafts (p = 0.016). Primary cells showed high viability on the lumenal surface regardless of decellularization technique (over 95% in all cases). These results demonstrate the critical effects of various chemical processing strategies on the adhesive properties of ex vivo-derived vascular grafts. Careful application-specific consideration is warranted when selecting a processing strategy that minimizes innate responses (e.g. thrombosis, inflammation) that are often deleterious to graft survival.

Novel fatty acid gentamicin salts as slow-release drug carrier systems for anti-infective protection of vascular biomaterials

Infections of vascular prostheses are still a major risk in surgery. The current work presents an in vitro evaluation of novel slow release antibiotic coatings based on new gentamicin fatty acid salts for polytetrafluoroethylene grafts. These grafts were coated with gentamicin sodium dodecyl sulfate, gentamicin laurate and gentamicin palmitate. Drug release kinetics, anti-infective characteristics, biocompatibility and haemocompatibility of developed coatings were compared to commercially available gelatin sealed PTFE grafts (SEALPTFE™) and knitted silver coated Dacron(®) grafts (InterGard(®)). Each gentamicin fatty acid coating showed a continuous drug release in the first eight hours followed by a low continuous release. Grafts coated with gentamicin fatty acids reduced bacterial growth even beyond pathologically relevant high concentrations. Cytotoxicity levels depending on drug formulation bringing up gentamicin palmitate as the most promising biocompatible coating. Thrombelastography studies, ELISA assays and an amidolytic substrate assay confirmed haemocompatibility of developed gentamicin fatty acid coatings comparable to commercially available grafts.

Concise review: tissue-engineered vascular grafts for cardiac surgery: past, present, and future

In surgical repair for heart or vascular disease, it is often necessary to implant conduits or correct tissue defects. The most commonly used graft materials to date are (a) artificial grafts; (b) autologous tissues, such as pericardium and saphenous vein; (c) allografts; and (d) xenografts. However, none of these four options offer growth potential, and all are associated with varying levels of thrombogenicity and susceptibility to infection. The lack of growth potential of these four options is particularly important in pediatric cardiac surgery, where patients will often outgrow their vascular grafts and require additional operations. Thus, developing a material with sufficient durability and growth potential that will function as the child grows older will eliminate the need for reoperation and significantly reduce morbidity and mortality of some types of congenital heart defects. Vascular tissue engineering is a relatively new field that has undergone enormous growth over the last decade. The goal of vascular tissue engineering is to produce neovessels and neo-organ tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of tissue-engineered implants is that these tissues can grow, remodel, rebuild, and respond to injury. Once the seeded autologous cells have deposited an extracellular matrix and the original scaffold is biodegraded, the tissue resembles and behaves as native tissue. When tissue-engineered vascular grafts are eventually put to use in the clinical arena, the quality of life in patients after surgery will be drastically improved.

Optimal conduit choice in the absence of single-segment great saphenous vein for below-knee popliteal bypass

BACKGROUND

Single-segment great saphenous vein (SSGSV) remains the conduit of choice for femoral to below-knee popliteal (F-BK) surgical revascularization. The purpose of this study was to determine the optimal conduit in patients with inadequate SSGSV.

METHODS

This was a retrospective review of a prospectively maintained vascular registry. Patients underwent F-BK bypass with alternative vein (AV; arm vein, spliced GSV, or composite vein) or prosthetic conduit (PC).

RESULTS

From January 1995 to June 2010, 83 patients had unusable SSGSV for F-BK popliteal reconstruction. Thirty-three patients had an AV conduit and 50 had PC. The AV group was a lower median age than the PC group (69 vs 75 years). The two groups were otherwise similar in comorbid conditions of diabetes mellitus (57.6% vs 58.0%; P > .99), smoking (15.2% vs 32.0%; P = .12), and hemodialysis (3% vs 12%; P = .23). The groups were similar in baseline characteristics such as limb salvage as indication (93.9% vs 86.0%; P = .31), mean runoff score (5.2 vs 4.6; P = .39), and prior ipsilateral bypass attempts (18.2% vs 18.0%; P > .99). The AV and PC groups were also similar in 30-day mortality (6.1% vs 4.0%; P > .99) and wound infection rates (6.1% vs 6.0%; P > .99). PC patients were more likely to be discharged on Coumadin (Bristol-Myers Squibb, Princeton, NJ) than AV patients (62.0% vs 27.3%; P = .002). Seventeen of the 50 PC patients (34%) had a distal anastomotic vein cuff. A log-rank test comparison of 5-year outcomes for the AV and PC groups found no significant difference in primary patency (55.3% ± 9.9% vs 51.9% ± 10.8%; P = .82), assisted primary patency (68.8% ± 9.6% vs 54.0% ± 11.0%; P = .45), secondary patency (68.4% ± 9.6% vs 63.7% ± 10.4% for PC; P = .82), or limb salvage rates (96.2% ± 3.8% vs 81.1% ± 8.1%; P = .19). Multivariable analysis demonstrated no association between conduit type and loss of patency or limb. The factors most predictive of primary patency loss were limb salvage as the indication for surgery (hazard ratio [HR], 4.23; 95% confidence interval [CI], 1.65-10.9; P = .003) and current hemodialysis (HR, 3.51; 95% CI, 1.08-11.4; P = .037). The most predictive factor of limb loss was current hemodialysis (HR, 7.02; 95% CI, 1.13-43.4; P = .036).

CONCLUSIONS

For patients with inadequate SSGSV, PCs, with varying degrees of medical and surgical adjuncts, appear comparable to AV sources in graft patency for below-knee popliteal bypass targets. This observation is tempered by the small cohort sample size of this single-institutional analysis. Critical limb ischemia as the operative indication and current hemodialysis predict impaired patency, and hemodialysis is associated with limb loss.

Antithrombotic agents for preventing thrombosis after infrainguinal arterial bypass surgery

BACKGROUND

Peripheral arterial disease (PAD) is frequently treated by either an infrainguinal autologous (using the patient's own veins) or synthetic graft bypass. The rate of occlusion of the graft after one year is between 12% and 60%. To prevent occlusion, patients are treated with an antiplatelet or antithrombotic drug, or a combination of both. Little is known about which drug is optimal to prevent infrainguinal graft occlusion. This is an update of a Cochrane review first published in 2003.

OBJECTIVES

To evaluate whether antithrombotic treatment improves graft patency, limb salvage and survival in patients with chronic PAD undergoing infrainguinal bypass surgery.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched August 2010) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 3).

SELECTION CRITERIA

Randomised, controlled trials; two review authors independently assessed the methodological quality of each trial using a standardised checklist.

DATA COLLECTION AND ANALYSIS

Data collected included patient details, inclusion and exclusion criteria, type of graft, antithrombotic therapy, outcomes, and side effects.

MAIN RESULTS

A total of 14 trials were included in this review; 4970 patient results were analysed. Four trials evaluating vitamin K antagonists (VKA) versus no VKA suggested that oral anticoagulation may favour autologous venous, but not artificial, graft patency as well as limb salvage and survival. Two other studies comparing VKA with aspirin (ASA) or aspirin and dipyridamole provided evidence to support a positive effect of VKA on the patency of venous but not artificial grafts. Three trials comparing low molecular weight heparin (LMWH) to unfractionated heparin (UFH) failed to demonstrate a significant difference on patency. One trial comparing LMWH with placebo found no significant improvement in graft patency over the first postoperative year in a population receiving aspirin. One trial showed an advantage for LMWH versus aspirin and dipyridamol at one year for patients undergoing limb salvage procedures. Perioperative administration of ancrod showed no greater benefit when compared to unfractionated heparin. Dextran 70 showed similar graft patency rates to LMWH but a significantly higher proportion of patients developed heart failure with dextran.

AUTHORS' CONCLUSIONS

Patients undergoing infrainguinal venous graft are more likely to benefit from treatment with VKA than platelet inhibitors. Patients receiving an artificial graft benefit from platelet inhibitors (aspirin). However, the evidence is not conclusive. Randomised controlled trials with larger patient numbers are needed in the future to compare antithrombotic therapies with either placebo or antiplatelet therapies.

[Role of duplex ultrasound for lower limb artery, abdominal aorta, and carotid artery surgery follow-up]

Long-term post-surgery follow-up is an essential part of the surgical and medical care for vascular surgery patients with peripheral arterial disease. Close collaboration with the patient's primary care physician is essential. In addition to close surveillance of the outcome after vascular surgery, follow-up includes an assessment and appropriate treatment of cardiovascular risk factors. Duplex ultrasound is a safe and noninvasive surveillance method, which should be performed by an experimented physician. We summarize the specific features of duplex ultrasound examinations after arterial surgery of the carotid arteries, the abdominal aorta and the lower limbs, and propose a surveillance schedule.