A Radiation-Crosslinked Gelatin Hydrogel That Promotes Tissue Incorporation of an Expanded Polytetrafluoroethylene Vascular Graft in Rats.

A prosthetic vascular graft that induces perigraft tissue incorporation may effectively prevent serious sequelae such as seroma formation and infection. Radiation-crosslinked gelatin hydrogel (RXgel) mimics the chemical and physical properties of the in vivo extracellular matrix and may facilitate wound healing by promoting tissue organization. Fibroblasts cultured on RXgel actively migrated into the gel for up to 7 days. RXgels of three different degrees of hardness (Rx[10], soft; Rx[15], middle; Rx[20], hard) were prepared, and small disc-like samples of RXgels were implanted into rats. In vitro and in vivo results indicated that Rx[10] was too soft to coat vascular grafts. Thus, expanded polytetrafluoroethylene (ePTFE) vascular grafts coated with RXgel were developed using Rx[15] and Rx[20] gels, and ring-shaped slices of the graft were implanted into rats. Alpha-smooth muscle actin (αSMA) and type III collagen (Col-III) levels were detected by immunohistochemistry. Immunohistochemical staining for αSMA and Col-III demonstrated that RXgel-coated vascular grafts induced more granulation tissue than non-coated grafts on days 14 and 28 after implantation. RXgel-coated ePTFE vascular grafts may provide a solution for patients by reducing poor perigraft tissue incorporation.

European registry of type A aortic dissection (ERTAAD) - rationale, design and definition criteria.

BACKGROUND: Acute Stanford type A aortic dissection (TAAD) is a life-threatening condition. Surgery is usually performed as a salvage procedure and is associated with significant postoperative early mortality and morbidity. Understanding the patient's conditions and treatment strategies which are associated with these adverse events is essential for an appropriate management of acute TAAD. METHODS: Nineteen centers of cardiac surgery from seven European countries have collaborated to create a multicentre observational registry (ERTAAD), which will enroll consecutive patients who underwent surgery for acute TAAD from January 2005 to March 2021. Analysis of the impact of patient's comorbidities, conditions at referral, surgical strategies and perioperative treatment on the early and late adverse events will be performed. The investigators have developed a classification of the urgency of the procedure based on the severity of preoperative hemodynamic conditions and malperfusion secondary to acute TAAD. The primary clinical outcomes will be in-hospital mortality, late mortality and reoperations on the aorta. Secondary outcomes will be stroke, acute kidney injury, surgical site infection, reoperation for bleeding, blood transfusion and length of stay in the intensive care unit. DISCUSSION: The analysis of this multicentre registry will allow conclusive results on the prognostic importance of critical preoperative conditions and the value of different treatment strategies to reduce the risk of early adverse events after surgery for acute TAAD. This registry is expected to provide insights into the long-term durability of different strategies of surgical repair for TAAD. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04831073 .

Patient characteristics predict patency of early-cannulation arteriovenous grafts.

There is a new emphasis on tailoring appropriate vascular access for hemodialysis to patients and their life-plans, but there is little known about the optimal use of newer devices such as early-cannulation arteriovenous grafts (ecAVG), with studies utilising them in a wide variety of situations. The aim of this study was to determine if the outcome of ecAVG can be predicted by patient characteristics known pre-operatively. This retrospective analysis of 278 consecutive ecAVG with minimum one-year follow-up correlated functional patency with demographic data, renal history, renal replacement and vascular access history. On univariate analysis, aetiology of renal disease, indication for an ecAVG, the number of previous tunnelled central venous catheters (TCVC) prior to insertion of an ecAVG, peripheral vascular disease, and BMI were significant associates with functional patency. On multivariate analysis the number of previous TCVC, the presence of peripheral vascular disease and indication were independently associated with outcome after allowing for age, sex and BMI. When selecting for vascular access, understanding the clinical circumstances such as indication and previous vascular access can identify patients with differing outcomes. Importantly, strategies that result in TCVC exposure have an independent and cumulative association with decreasing long-term patency for subsequent ecAVG. As such, TCVC exposure is best avoided or minimised particularly when ecAVG can be considered.

Atrial Fibrillation is Associated with Femoropopliteal Totally Occlusive In-Stent Restenosis: A Single-Center, Retrospective, Observational Study.

INTRODUCTION: The proportion of patients with comorbid atrial fibrillation (AF) and peripheral artery disease (PAD) has increased in this era. This study aimed to assess the relationship between AF and totally occlusive in-stent restenosis (ISR) in femoropopliteal (FP) lesions. METHODS: In this study, 363 patients (461 stents) who underwent endovascular therapy with de novo stent implantation in our hospital between April 2007 and December 2016 were retrospectively evaluated. The patients were divided into two groups according to the AF status (AF group, 61 patients; sinus group, 302 patients). The primary endpoint was the incidence of totally occlusive ISR within 3 years. The secondary endpoint was the incidence of acute limb ischemia (ALI) due to FP stent occlusion. RESULTS: Baseline characteristics were similar, except for higher age and a lower prevalence of dyslipidemia in the AF group. The incidence of a totally occlusive ISR was higher in the AF group than in the sinus group (29.5% vs. 14.6%, p=0.004). A multiple Cox regression model suggested that presence of AF (hazard ratio, 2.10) and CTO lesion (hazard ratio, 1.97) which were the independent predictors of a totally occlusive ISR within 3 years. The incidence of ALI was significantly higher in the AF group than in the sinus group (3.9% vs. 0%, p=0.0001). In the AF group, the introduction of an anticoagulant did not prevent the occurrence of totally occlusive ISR (p=0.71) for ALI (p=0.79). CONCLUSIONS: AF is independently associated with totally occlusive ISR of FP stents; however, anticoagulant use does not prevent stent occlusion.

Preemptive Femoral-Femoral Crossover Grafting of Artery and Vein Before Pelvic Exenterative Surgery for Locally Advanced and Recurrent Pelvic Malignancy Involving the Aortoiliac Axis.

INTRODUCTION: Achieving a negative resection through a pelvic exenteration for a recurrent or an advanced pelvic malignancy offers the potential for cure. Exenterative surgical units have expanded the boundaries and redefined what constitutes resectable disease through improved surgical technique. In selected cases, contiguous tumor involvement of the aortoiliac axis requires en bloc resection and subsequent vessel reconstruction. However, vascular reconstruction can be challenging in a contaminated field during an extended radical resection. TECHNIQUE: The aim of this Technical Note is to describe a novel method in the management of patients with recurrent or advanced pelvic malignancy involving the aortoiliac axis by performing preemptive femoral-femoral arterial and venous crossover grafts, with adjunctive arteriovenous loop fistula formation before undergoing an extended radical pelvic resection 4 weeks later. RESULTS: Four patients have undergone preemptive femoral-femoral arterial and venous crossover grafts at our institution (median age = 60 y (range, 47-66 y); 2 women). There were no early complications, and all of the patients subsequently underwent extended radical pelvic resections for a pelvic malignancy. CONCLUSIONS: Preemptive vascular reconstruction before major pelvic surgery reduces the risk of graft infection because this method avoids the wounds being contaminated by GI or genitourinary organisms. Other advantages to this technique include a reduction in the overall operating time for the pelvic exenteration, a significant reduction in the ischemia time to the lower limbs, and ensuring that the grafts are patent before embarking on major intra-abdominal surgery.

Endovascular Repair of Aortic Dissection Involving the Left Subclavian Artery by Castor Stent Graft: A Multicentre Prospective Trial.

OBJECTIVE: The left subclavian artery (LSA) origin can be intentionally covered by stent grafts, to provide adequate proximal landing zones during thoracic endovascular repair for Stanford type B aortic dissections (TBADs). To preserve the LSA, a novel single branched stent graft, named "Castor" was designed and a clinical trial conducted to investigate its suitability. METHODS: From April 2013 to March 2015, 73 patients with TBAD were treated by Castor stent grafts at 11 Chinese tertiary hospitals as part of a single arm prospective clinical trial. There were 50 acute (<2 weeks [68.5%]) and 23 chronic aortic dissections (>2 weeks [31.5%]). RESULTS: The technical success rate was 97% (n = 71/73). The two failures were caused by occlusion of the branch section of the stent graft. There were four intra-operative endoleaks (two type Ia, two type B from the LSA). The endoleak rate was 5% (n = 4/73). There was one in hospital death and no major complications. The median follow up time was 61 months (range 48-72 months). The mortality was 5% (n = 4/73) within one year and 7% within six years (n = 5/73). Two deaths were of unknown cause and three were not related to the aorta. Two new entry tears were found on the proximal or distal edge of the stent graft and were retreated endovascularly. Six occlusions of the branch section of the Castor stent graft were found, and the follow up patency rate of the branch section was 93% (n = 63/68). Two intra-operative endoleaks were left during follow up and eventually disappeared according to the latest computed tomography angiograms. CONCLUSION: For patients with TBADs needing anchoring proximal to the origin of LSA, the Castor single branched stent graft may provide an easily manipulated, safe, and effective endovascular treatment.

Long-Term Results After Drug-Eluting Versus Bare-Metal Stent Implantation in Saphenous Vein Grafts: Randomized Controlled Trial.

Background Efficacy data on drug-eluting stents (DES) versus bare-metal stents (BMS) in saphenous vein grafts are controversial. We aimed to compare DES with BMS among patients undergoing saphenous vein grafts intervention regarding long-term outcome. Methods and Results In this multinational trial, patients were randomized to paclitaxel-eluting or BMS. The primary end point was major adverse cardiac events (cardiac death, nonfatal myocardial infarction, and target-vessel revascularization at 1 year. Secondary end points included major adverse cardiac events and its individual components at 5-year follow-up. One hundred seventy-three patients were included in the trial (89 DES versus 84 BMS). One-year major adverse cardiac event rates were lower in DES compared with BMS (2.2% versus 16.0%, hazard ratio, 0.14; 95% CI, 0.03-0.64, P=0.01), which was mainly driven by a reduction of subsequent myocardial infarctions and need for target-vessel revascularization. Five-year major adverse cardiac event rates remained lower in the DES compared with the BMS arm (35.5% versus 56.1%, hazard ratio, 0.40; 95% CI, 0.23-0.68, P<0.001). A landmark-analysis from 1 to 5 years revealed a persistent benefit of DES over BMS (hazard ratio, 0.33; 95% CI, 0.13-0.74, P=0.007) in terms of target-vessel revascularization. More patients in the BMS group underwent multiple target-vessel revascularization procedures throughout the study period compared with the DES group (DES 1.1% [n=1] versus BMS 9.5% [n=8], P=0.013). Enrollment was stopped before the target sample size of 240 patients was reached. Conclusions In this randomized controlled trial with prospective long-term follow-up of up to 5 years, DES showed a better efficacy than BMS with sustained benefits over time. DES may be the preferred strategy in this patient population. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00595647.

Anatomic Suitability for Branched Thoracic Endovascular Repair in Patients with Aortic Arch Pathological Features.

Background Endovascular repair has become a viable alternative for aortic pathological features, including those located within the aortic arch. We investigated the anatomic suitability for branched thoracic endovascular repair in patients previously treated with conventional open surgery for aortic arch pathological features. Methods and Results Patients who underwent open surgery for aortic arch pathological features at our institution between 2000 and 2018 were included. Anatomic suitability was determined by strict compliance with the anatomic criteria within manufacturers' instructions for use for each of the following branched thoracic stent grafts: Relay Plus Double-Branched (Terumo-Aortic), TAG Thoracic Branch Endoprosthesis (W.L. Gore & Associates), Zenith Arch Branched Device (Cook-Medical), and Nexus Stent Graft System (Endospan Ltd/Jotec GmbH). Computed tomography angiography images were analyzed with outer luminal line measurements. A total of 377 patients (mean age, 64±14 years; 64% men) were identified, 153 of whom had suitable computed tomography angiography images for measurements. In total, 59 patients (15.6% of the total cohort and 38.6% of the measured cohort) were eligible for endovascular repair using at least one of the devices. Device suitability was 30.9% for thoracic aneurysms, 4.6% for type A dissections, 62.5% for type B dissections, and 28.6% for other pathological features. Conclusions The anatomic suitability for endovascular repair of all aortic arch pathological features was modest. The highest suitability rates were observed for thoracic aneurysms and for type B dissections, of which repair included part of the aortic arch. We suggest endovascular repair of arch pathological features should be reserved for high-volume centers with experience in endovascular arch repair.

Right subclavian artery cannulation for aortic dissection surgery, without infraclavicular incision.

The choice of arterial cannulation strategy for acute type A dissection surgery remains a controversial  issue and a subject of great debate because of its impact on clinical outcomes. A review of retrospective studies shows that surgeons are tending to switch from a retrograde to an antegrade perfusion strategy. Innominate artery cannulation has a number of advantages when compared to other cannulation techniques; however when the vessel is dissected, the proximal right subclavian artery can be used for arterial return. Also, because cannulation of the right subclavian artery does not require a second surgical incision in addition to median sternotomy, this decreases the number of incision sites and further simplifies the procedure.

Compliance of Textile Vascular Prostheses Is a Fleeting Reality.

OBJECTIVE: Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false aneurysm and intimal hyperplasia stenosis onset. Over the last decades, manufacturers have tried to develop substitutes that mechanically mimic arterial properties and avoid a compliance mismatch at the anastomoses in particular. However, data are missing about how initial compliance properties could change with time. The goal of this study was to evaluate how the compliance of vascular grafts evolves under cyclic loading conditions in vitro. METHODS: The compliance of three different models of commercially available textile polyethylene terephthalate (PET) grafts was evaluated. Tests were performed with and without their original coating. Compliance was assessed with a specific device dedicated to measure the deformations undergone by a graft under cyclic pressure loading conditions, using image analysis software. In each experiment, image analysis was performed under 60 and 140 mmHg pressure loading conditions at loading start (H0) and after three, six, and 24 h (H3, H6, H24) loading time. Average radial, longitudinal, and volumetric compliance was calculated from the obtained images. RESULTS: Twenty-four samples were tested. Results demonstrate that all values decreased significantly within only a few hours. On average, the loss of compliance after 3 h of cyclic loading ranged on average from 35% for longitudinal compliance to 39% for radial compliance and 37% (p < .050) for volume compliance. After 24 h, the loss of radial, longitudinal and volume compliance was respectively 63 ± 3%, 60.5 ± 2% and 61 ± 7%. CONCLUSION: In this in vitro model, PET graft compliance has already decreased significantly within 3 h. The rapid loss of compliance identified in this experimental study helps explain the mismatch mentioned in clinical observations.

Artificial vascular graft migration into hollow viscus organs in patients who underwent right lobe living donor liver transplantation.

BACKGROUND: To share our experience with hollow viscus migration of artificial vascular grafts (AVG) used for venous reconstruction of the right anterior sector in living donor liver transplantations (LDLT). METHODS: Clinical, radiological, and endoscopic data of 13 right lobe LDLT patients (range: 26-67 years) with a diagnosis of postoperative AVG migration into adjacent hollow viscus were analyzed. RESULTS: Biliary complications were detected in 12 patients. A median of four times endoscopic retrograde cholangiopancreatography (ERCP) procedures were performed in 11 patients prior to AVG migration diagnosis. A median of 2.5 times various percutaneous radiological interventional procedures were performed in eight patients prior to AVG migration diagnosis. The site of migration was the duodenum in eight patients, gastric antrum in four, and Roux limb in the remaining one patient. The migrated AVS were made of polytetrafluoroethylene (PTFE) in 10 patients and polyethylene terephthalate (Dacron) in three. The migrated AVGs were endoscopically removed in seven patients and surgically removed in six. Only one patient died due to sepsis unrelated to AVG migration. CONCLUSION: AVG migration into the adjacent hollow viscus following right lobe LDLT is a rare and serious complication. Repetitive ERCP, interventional radiological procedures, infection related to biliary leakage, and thrombosis of AVGs are among the possible risk factors.

Everolimus-Eluting Biodegradable Abluminal Coating Stent versus Durable Conformal Coating Stent: Termination of the Inflammatory Response Associated with Neointimal Healing in a Porcine Coronary Model.

OBJECTIVES: We evaluated the effect of the different carrier systems on early vascular response through histological analysis and scanning electron microscopy using a porcine model. BACKGROUND: Although Synergy™ and Promus PREMIER™ share an identical stent material and drug elution (everolimus), they use different drug carrier systems: biodegradable abluminal coating polymer or durable conformal coating polymer, respectively. However, data regarding the impact of the different coating systems on vessel healing are currently limited. METHODS: Twelve Synergy™ and Promus PREMIER™ were implanted in 12 swine. Histopathological analysis of the stented segments was performed on the 2nd and 14th days after implantation. Morphometric analysis of the inflammation and intimal fibrin content was also performed. RESULTS: On the 2nd day, neointimal thickness, percentage of neointimal area, and inflammatory and intimal fibrin content scores were not significantly different between the two groups. On the 14th day, the inflammatory and intimal fibrin content scores were significantly lower in Synergy™ versus those observed in Promus PREMIER™. In Synergy™, smooth muscle cells were found and the neointimal layers were smooth. In contrast, inflammatory cells were observed surrounding the struts of Promus PREMIER™. CONCLUSIONS: These results demonstrate that termination of reactive inflammation is accelerated after abluminal coating stent versus implantation of conformal coating stent.

Application of a clampless hemostatic device (HeartString®) for outflow graft anastomosis.

Performing an aortic anastomosis with a prosthetic graft (e.g. for left ventricular assist device implantation or veno-arterial extracorporeal membrane oxygenation) requires side-clamping of the aorta. Clamping of aorta is particularly challenging in redo cases and/or in patients with a short ascending aorta and open coronary artery bypass grafts, or atherosclerotic disease of the aorta. In this video tutorial, we provide a thorough description of the surgical technique for applying the HeartString® Proximal Seal System (MAQUET Holding B.V. & Co. KG, Rastatt, Germany) for the anastomosis of the aorta with a prosthesis graft. The feasibility of using the HeartString® device has been demonstrated and no procedure-related complications were experienced.

Evaluation of a hybrid small caliber vascular graft in a rabbit model.

OBJECTIVE: A hybrid small-caliber artificial vascular graft based on bilayer porcine small intestinal submucosa (SIS) with curdlan and dipyridamole mixture film serving as the so-called sandwich filler was developed for biological performance evaluation. We evaluated the performance of the graft and filler. METHODS: SIS was coated with heparin by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. Curdlan acted as the carrier of dipyridamole. Three types of graft tubes (2 mm internal diameter and 20 mm in length) were manufactured: bilayer SIS with 10% curdlan + 10% dipyridamole mixture film (SCD), bilayer SIS with 10% curdlan film (SC), and monolayer SIS (S). The remodeling characteristics of the grafts were evaluated by implanting them as bypass in rabbit carotid arteries for 2 and 3 months. Each group contained 16 rabbits, and 16 nonsurgical rabbits served as the control group. RESULTS: Eight rabbits of each group, including the graft occluded group, were killed at 2 months and the others were killed at 3 months. Follow-up showed that all 8 grafts in SCD group were patent at 2 months. Six of 16 grafts in the SC group and 5 of 16 grafts in the S group were occluded at 2 months. One of 8 SCD grafts were occluded at 3 months and the patent showed a confluent endothelium without intimal hyperplasia. The neointima layer was composed of circumferentially aligned vascular smooth muscle cells. At 3 months, SC and S group grafts showed incomplete endothelialization and varying degrees of mural thrombus, accompanied by occlusion in the SC group (3 of 8) and S group (2 of 8). CONCLUSIONS: The novel hybrid small caliber artificial vascular graft exhibited an improvement in revascularization resulting in high patency rate.

Fabrication Techniques for Vascular and Vascularized Tissue Engineering.

Impaired or damaged blood vessels can occur at all levels in the hierarchy of vascular systems from large vasculatures such as arteries and veins to meso- and microvasculatures such as arterioles, venules, and capillary networks. Vascular tissue engineering has become a promising approach for fabricating small-diameter vascular grafts for occlusive arteries. Vascularized tissue engineering aims to fabricate meso- and microvasculatures for the prevascularization of engineered tissues and organs. The ideal small-diameter vascular graft is biocompatible, bridgeable, and mechanically robust to maintain patency while promoting tissue remodeling. The desirable fabricated meso- and microvasculatures should rapidly integrate with the host blood vessels and allow nutrient and waste exchange throughout the construct after implantation. A number of techniques used, including engineering-based and cell-based approaches, to fabricate these synthetic vasculatures are herein explored, as well as the techniques developed to fabricate hierarchical structures that comprise multiple levels of vasculature.

Application of Baseline Clinical and Morphological Parameters for Prediction of Late Stent Graft Related Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysm.

OBJECTIVES: To evaluate the influence of baseline clinical and morphological parameters on the occurrence of a late stent graft related endoleak (srEL; types 1 and 3) after endovascular aneurysm repair (EVAR). METHODS: This is a retrospective case control study of patients who were routinely followed up after EVAR of abdominal aortic aneurysms. Pre-interventional, pre-discharge, and last available multislice computed tomography angiogram (MSCTA) of 279 patients were analysed. Stent graft related endoleaks detected by follow up MSCTA at least six months after EVAR were specified as late srEL. Baseline demographic characteristics and morphological variables were derived from the pre-interventional and pre-discharge MSCTA. Univariable and multivariable analysis with a Cox proportional hazards model were used to determine baseline factors associated with the occurrence of a late srEL. RESULTS: Twenty-four (8.6%) of 279 patients suffered a late srEL, during a mean MSCTA follow up of 30.9 ± 25.8 (23.5, IQR 10.6-42.8) months. In the univariable analysis, age (hazard ratio [HR] 1.09; p = .001), female sex (HR 3.25; p = .014), right iliac sealing diameter (HR 10.04; p = .03), left iliac sealing diameter (HR 8.65; p = .001), infrarenal aortic neck angulation (HR 1.02; p = .011), and suprarenal fixation level (HR 3.47; p = .014) were significantly associated with an increased incidence of late srEL. Age (HR 1.08; p = .012), female sex (HR 2.72; p = .049), and left iliac sealing diameter (HR 4.48; p = .033) proved to be risk factors significantly associated with a higher incidence of late srEL in multivariable analysis. CONCLUSIONS: Older patients, those with female gender, and those with larger left iliac sealing diameters seem to experience higher rates of late srEL. Independent confirmation of these must be addressed in larger studies.

Functional remodeling of an electrospun polydimethylsiloxane-based polyether urethane external vein graft support device in an ovine model.

Saphenous vein graft (SVG) failure rates are unacceptably high, and external mechanical support may improve patency. We studied the histologic remodeling of a conformal, electrospun, polydimethylsiloxane-based polyether urethane external support device for SVGs and evaluated graft structural evolution in adult sheep to 2 years. All sheep (N = 19) survived to their intended timepoints, and angiography showed device-treated SVG geometric stability over time (30, 90, 180, 365, or 730 days), with an aggregated graft patency rate of 92%. There was minimal inflammation associated with the device material at all timepoints. By 180 days, treated SVG remodeling was characterized by minimal/nonprogressive intimal hyperplasia; polymer fragmentation and integration; as well as the development of a neointima, and a confluent endothelium. By 1-year, the graft developed a media-like layer by remodeling the neointima, and elastic fibers formed well-defined structures that subtended the neo-medial layer of the remodeled SVG. Immunohistochemistry showed that this neo-media was populated with smooth muscle cells, and the intima was lined with endothelial cells. These data suggest that treated SVGs were structurally remodeled by 180 days, and developed arterial-like features by 1 year, which continued to mature to 2 years. Device-treated SVGs remodeled into arterial-like conduits with stable long-term performance as arterial grafts in adult sheep.