Small-diameter Vessels Research Articles

Usage patterns and outcomes of drug coated ballons at a tertiary care center - a cohort analysis in 462 patients

Abstract Background The usage of drug coated ballons (DCB) in percutaneous coronary interventions (PCI) is rising. Initially applied in in-stent restenosis (ISR), wider clinical applications especially in de novo lesions (DNL) are discussed. Here we aim to assess the pattern of usage as well as the clinical and angiographic outcomes associated with DCB. Methods For this analysis we included all patients treated with DCB during PCI, at a tertiary care centre between 01/2015 and 12/2021. Cath lab results of all patients were screened to assess the DCB indication. Patients were followed up until 09/2022 to assess clinical as well as angiographic complications. Results A total of 7608 interventions were carried out between 2015 and 2021, in 462 (6.1%) a DCB was used. The median follow-up time were 3.1 years (IQR 1.6 to 4.4 years), the median age of our patient population was 66 (IQR 58-75) and 24.7% (n=114) were female. There were 92 of 462 (19.9%) cases including a DNL preparation, 335 (72.5%) cases treating an ISR, in 6 (1.3%) cases both, DNL and ISR were treated, and in 29 (6.3%) cases DCB were used for other reasons (e.g. pre-/ postdilatation in coronary stenting). The mean DCB inflation diameter was significantly higher in ISR with 3.50mm (IQR 3.0-3.5mm) compared to DNL with 2.50mm (2.00-2.50mm, p-value <0.001 ) While the number of DCBs used is rising over time (179 cases [38.7%] in 2015-2018, 283 cases [61.3%] in 2019-2021), the proportion of de novo lesions showed no significant difference (37/179 [20.7%] in 2015-2018, 61/282 [21.6%] in 2019-2021, p-value 0.806, Figure 1). Patients with DCB for ISR had significantly higher rates of arterial hypertension (ISR: 255 [76.1%], DNL: 57 [62.0%], both: 3 [50.0%], other: 20 [69.0%] p value 0.029), hyperlipidaemia (ISR: 228 [68.1%], DNL: 56 [60.9%], both: 2 [33.3%], other: 14 [48.3%], p value 0.041) and previous myocardial infarction (ISR: 231 [69.0%], DNL: 33 [35.9%], both: 2 [33.3%], other: 8 [27.6%], p-value <0.001). When analysing the outcomes, patients with DNL showed lower rates of acute myocardial infarction (8 [8.2%] vs 51 [15.0%]) as well as target lesion (6 [6.1%] vs 56 [16.5%]) and any revascularization (27 [27.6%] vs 122 [35.9%])%]), yet a higher rate of cardiovascular mortality (19 [5.6] vs 9 [9.2%]) during the follow up period compared to patients treated for ISR (Figure 2). Both groups showed a very low rate of target lesion thrombosis within 30 days after PCI (1 [1.0%] vs 1 [0.3%], p-value 0.745). Conclusions The use of DCB in PCIs is increasing, yet as we were able to emphasize with our data, they are primarily used in ISR as well as lesions with a small vessel diameter with favourable outcomes indicated by low event rates. Research should expand beyond small-vessel disease and ISR to assess safety and outcomes of DCB in DNL, larger vessels and bifurcation interventions with one stent to further assess its potential benefits in a wider field of indications.

Impact of the lower extremity arterial calcification score on clinical outcomes after drug-coated balloon angioplasty for de novo femoropopliteal artery disease

Abstract Background Severe calcification, assessed using the peripheral artery calcification scoring system (PACCS), is associated with poor clinical outcomes after endovascular treatment (EVT) for de novo femoropopliteal lesions. However, the PACCS classification is a qualitative assessment performed in the angiographic room, and there are no established indicators for the quantitative assessment of calcification prior to treatment. Purpose We aimed to investigate the impact of the lower extremity arterial calcification score (LEACS) calculated using non-contrast lower limb computed tomography on clinical outcomes after drug-coated balloon angioplasty for de novo femoropopliteal artery disease. Methods We retrospectively analyzed the clinical outcomes of 141 consecutive patients treated at our center for de novo femoropopliteal artery disease using a drug-coated balloon between April 2018 and December 2022. Patients who did not undergo lower limb computed tomography before EVT were excluded from the analyses. LEACS was determined based on the method used to calculate the Agatston score for the coronary arteries. Each patient’s score consisted of a sum of calcification scores from ostium of superficial artery to the popliteal artery at the knee joint of treated limb. The primary and secondary outcomes measured were primary patency and clinically-driven target vessel revascularization (CD-TVR) at 1 year. Cox proportional hazards analysis was used to explore independent predictors of clinical outcomes. The study population was divided into higher and lower LEACS groups based on the cut-off value (1750), which best discriminated patency, and the outcomes were compared between the two groups. Results In the higher and lower LEACS groups, the mean age was 75.1 ± 9.1 years and 75.5 ± 11.0 years (p = 0.87) and the mean lesion length was 170.3±102.8 mm and 157.7±112.1 mm (p = 0.64), respectively. The higher LEACS group showed significantly lower 1-year patency than the lower LEACS group (53.5% vs. 84.3%, log-rank, p = 0.041). In addition, freedom from 1-year CD-TVR was significantly lower in the higher LEACS group than in the lower LEACS group (66.8% vs. 93.7%, p = 0.047). The Cox proportional hazard analysis showed that the higher LEACS group was an independent predictor of 1-year restenosis (odds ratio: 2.80, 95% confidence interval: 1.24–8.84, p=0.037), along with a small (< 5 mm) reference vessel diameter (odds ratio: 3.55, 95% confidence interval: 1.44–9.53, p=0.028). Conclusion Higher LEACS scores were independently associated with clinical outcomes after drug-coated balloon angioplasty for de novo femoropopliteal artery disease. Non-contrast lower limb computed tomography is an acceptable and feasible option for predicting the outcomes in patients with de novo femoropopliteal artery disease prior to treatment.

Frictional forces in stent retriever procedures: The impact of vessel diameter, angulation, and deployment position

Background: Mechanical thrombectomy has improved the outcome of patients with acute ischemic stroke, but complications such as subarachnoid hemorrhage (SAH) can worsen the prognosis. This study investigates the frictional forces exerted by stent retrievers (SRs) on vessel walls, hypothesizing that these forces contribute to vascular stress and a risk of hemorrhage. We aimed to understand how vessel diameter, curvature, and stent deployment position influence these forces. Methods: Using a silicone vascular model simulating the middle cerebral artery, we created virtual vessels with diameters of 2.0 mm and 2.5 mm, each with branching angles of 60° and 120°. A Trevo NXT (4 × 28 mm) SR was deployed and retracted through these models, measuring the maximum static frictional force at the moment the SR began to move. The stent deployment position relative to the curvature (straight, distal 1/4, center, and proximal 1/4) was also varied to assess its impact on frictional forces. Each condition was tested 15 times, and the results were statistically analyzed. Results: The highest frictional force was observed in the 2.0 mm/120° model, followed by the 2.0 mm/60°, 2.5 mm/120°, and 2.5 mm/60° models. Narrower and more sharply curved vessels exhibited significantly higher frictional forces. Friction also increased with more distal stent deployment, particularly in the narrower vessels. Conclusion: Smaller vessel diameters, greater curvature, and more distal stent deployment positions increase frictional forces during thrombectomy, potentially leading to SAH. These findings highlight the importance of selecting appropriately sized SRs and considering stent deployment positions to minimize vascular stress.

Depth-Dependent Contributions of Various Vascular Zones to Cerebral Autoregulation and Functional Hyperemia: An In-Silico Analysis.

Autoregulation and neurogliavascular coupling are key mechanisms that modulate myogenic tone (MT) in vessels to regulate cerebral blood flow (CBF) during resting state and periods of increased neural activity, respectively. To determine relative contributions of distinct vascular zones across different cortical depths in CBF regulation, we developed a simplified yet detailed and computationally efficient model of the mouse cerebrovasculature. The model integrates multiple simplifications and generalizations regarding vascular morphology, the hierarchical organization of mural cells, and potentiation/inhibition of MT in vessels. Our analysis showed that autoregulation is the result of the synergy between these factors, but achieving an optimal balance across all cortical depths and throughout the autoregulation range is a complex task. This complexity explains the non-uniformity observed experimentally in capillary blood flow at different cortical depths. In silico simulations of cerebral autoregulation support the idea that the cerebral vasculature does not maintain a plateau of blood flow throughout the autoregulatory range and consists of both flat and sloped phases. We learned that small-diameter vessels with large contractility, such as penetrating arterioles and precapillary arterioles, have major control over intravascular pressure at the entry points of capillaries and play a significant role in CBF regulation. However, temporal alterations in capillary diameter contribute moderately to cerebral autoregulation and minimally to functional hyperemia. In addition, hemodynamic analysis shows that while hemodynamics within capillaries remain relatively stable across all cortical depths throughout the entire autoregulation range, significant variability in hemodynamics can be observed within the first few branch orders of precapillary arterioles or transitional zone vessels. The computationally efficient cerebrovasculature model, proposed in this study, provides a novel framework for analyzing dynamics of the CBF regulation where hemodynamic and vasodynamic interactions are the foundation on which more sophisticated models can be developed.

Biomimetic bilayer scaffold from Bombyx mori silk materials for small diameter vascular applications in tissue engineering.

Enhancing the biocompatibility and mechanical stability of small diameter vascular scaffolds remain significant challenges. To address this challenge, small-diameter tubular structures were electrospun from silk fibroin (SF) from silk textile industry discarded materials to generate bilayer scaffolds that mimic native blood vessels, but derived from a sustainable natural material resource. The inner layer was obtained by directly dissolving SF in formic acid, while the middle layer (SF-M) was achieved through aqueous concentration of the protein. Structural and biological properties of each layer as well as the bilayer were evaluated. The inner layer exhibited nano-scale fiber diameters and 57.9% crystallinity, and degradation rates comparable with the SF-M layer. The middle layer displayed micrometer-scale fibers diameters with an ultimate extension of about 274%. Both layers presented contact angles suitable for cell growth and cytocompatibility, while the bilayer material displayed an intermediate mechanical response and a reduced enzymatic degradation rate when compared to each individual layer. The bilayer material emulates many of the characteristics of native small-diameter vessels, thereby suggesting further studies towards in vivo opportunities.

Perfusion Bioreactor Conditioning of Small-diameter Plant-based Vascular Grafts.

Vascular grafts are mainly composed of synthetic materials, but are prone to thrombosis and intimal hyperplasia at small diameters. Decellularized plant scaffolds have emerged that provide promising alternatives for tissue engineering. We previously developed robust, endothelialized small-diameter vessels from decellularized leatherleaf viburnum. This is the first study to precondition and analyze plant-based vessels under physiological fluid flow and pressure waveforms. Using decellularized leatherleaf viburnum as tissue-engineered grafts for implantation can have profound impacts on healthcare due to their biocompatibility and cost-effective production. A novel perfusion bioreactor was designed, capable of accurately controlling fluid flow rate and pressure waveforms for preconditioning of small-diameter vascular grafts. A closed-loop system controlled pressure waveforms, mimicking physiological values of 50-120mmHg at a frequency of 8.75Hz for fluid flow reaching 5mL/min. Plant-based vascular grafts were recellularized with endothelial and vascular smooth muscle cells and cultured for up to 3weeks in this bioreactor. Cell density, scaffold structure and mechanics, thrombogenicity, and immunogenicity of grafts were evaluated. Bioreactor treatment with fluid flow significantly increased luminal endothelial cell density, while pressure waveforms reduced thrombus formation and maintained viable vascular smooth muscle cells within inner layers of grafts compared to static controls. Suture retention of grafts met transplantation standards and white cell viability was suitable for vascular remodeling. Low thrombogenicity of endothelialized leatherleaf viburnum holds great potential for vascular repair. This study provides insight into benefits of conditioning plant-based materials with hemodynamic forces at higher frequencies that have not previously been investigated.

Optimizing Femoral Access in Emergency EVAR with a Decision-Making Algorithm.

Endovascular aneurysm repair (EVAR) has become the preferred approach over open repair for abdominal aortic aneurysms (AAAs) due to its minimally invasive nature. The common femoral artery (CFA) is the main access vessel for EVAR, with both surgical exposure and percutaneous access being utilized. However, in emergent cases, percutaneous access can be challenging and may result in complications such as bleeding or dissection thrombosis, leading to the need for surgical conversion. This study aimed to share experiences in implementing a decision-making algorithm to reduce surgical conversions due to percutaneous access failures. A total of 74 aortic patients treated with EVAR in emergency settings were included in this retrospective study. This study focused on various outcomes such as perioperative mortality, morbidity, procedure time, surgical exposure time, and surgical conversion rate. After the implementation of the decision-making algorithm, decreases in surgical conversions and operating time were observed. Percutaneous access was found to be more challenging in cases with specific anatomical characteristics of the CFA, such as severe atherosclerosis or smaller vessel diameter. This study highlighted the importance of carefully assessing patient anatomical features and utilizing a decision-making algorithm to optimize outcomes in EVAR procedures. Further research is needed to continue improving practices for managing aortic aneurysms and reducing complications in femoral artery access approaches.

Modified Ex Vivo Renal Reconstruction to Facilitate Fenestrated-Branched Endovascular Repair of a Thoracoabdominal Aortic Aneurysm.

To report the use of modified ex vivo renal artery (RA) reconstruction in a patient with 2 small right RAs (RRAs) in anticipation of planned fenestrated-branched endovascular aortic repair (FB-EVAR) of thoracoabdominal aortic aneurysm (TAAA). A staged hybrid repair was utilized in a patient with Extent II TAAA involving celiac axis (CA), superior mesenteric artery (SMA), single left RA (LRA), and 2 small (<3 mm) RRAs. The first-stage operation consisted of hepato-renal bypass using modified ex vivo renal reconstruction with single end-to-end anastomosis to both RAs using a saphenous vein graft. A second stage FB-EVAR was performed using patient-specific manufactured stent-graft with 3 fenestrations for the CA, SMA, and LRA 6 weeks later. The patient recovered with no complications. At 4 years, the patient had widely patent hepato-renal bypass and target vessels with normal renal function. The use of adjunctive hybrid procedures may optimize or facilitate FB-EVAR. In this patient, salvage of 2 small RAs was not ideally suited for branch stenting but was possible using modified ex vivo RA reconstruction with preservation of kidney parenchyma and function. This case report illustrates a hybrid approach to overcome one of the most frequent limitations to total endovascular incorporation of renal arteries, eg small diameter, early bifurcation and multiple vessels. The modified ex vivo technique allows meticulous renal artery reconstruction without the deleterious effect of warm ischemia and without the cumbersome reconstruction of ureter and vein that is needed with traditional on table ex vivo auto transplantation. The technique is used in a minority of cases and adds the morbidity of open approach. Case selection is of paramount importance.

Wood Quality of Pendulate Oak on Post-Agricultural Land: A Case Study Based on Physico-Mechanical and Anatomical Properties

Oak is one of the most economically important hardwood tree species in Europe, and its prevalence will increase due to progressing global climate change, according to predictive models. With the increasing demand for timber and with the need for a balance between carbon emissions and sequestration, it is essential to address the afforestation of agricultural land. Therefore, this research aimed to investigate the physico-mechanical properties and anatomical structure of pendulate oak (Quercus robur L.) wood—specifically focusing on the trunk’s cross-section—in post-agricultural areas compared with the forest land in the western part of Poland. Wood density, bending strength, modulus of elasticity, and other parameters were analyzed from 1626 wood samples. The analysis of physico-mechanical properties reveals that, historically, agricultural land use has an almost negligible impact on wood quality. Despite significant differences in small vessel diameter and fiber length favoring trees from post-agricultural land, the physico-mechanical properties remain consistent. Large vessel measurements show comparable diameter and length in both land types. These findings suggest that post-agricultural land can serve as an effective alternative for high-quality pendulate oak wood production for industrial purposes. However, wood from post-agricultural land may exhibit a decrease in modulus of rupture by over 30% and potentially lower density above the trunk’s halfway point. This observation hints at the fact that oak trees in post-agricultural areas could be cultivated in shorter rotation periods compared to forest land.

Exploring Optimal Strategies for Surgical Access in Transcatheter Aortic Valve Implantation.

Transcatheter aortic valve implantation (TAVI) has revolutionised the management of severe aortic stenosis, particularly for patients deemed high risk or inoperable for traditional surgical aortic valve replacement. The transfemoral approach is the preferred route whenever feasible, attributed to its minimally invasive nature, reduced procedural morbidity, and shorter recovery times. In total, 80-90% of TAVI procedures are performed via the transfemoral route. However, anatomical constraints such as severe peripheral arterial disease, small vessel diameter, or significant vessel tortuosity can preclude the use of this access site. In such cases, alternative access strategies must be considered to ensure the successful implantation of the valve. This review aims to provide a comprehensive summary of the various surgical techniques available for TAVI access, exploring the rationale, technical aspects, and challenges associated with each method. We will explore alternative routes, including the transapical, transaortic, transaxillary, and transcarotid approaches, highlighting their respective benefits and limitations.

Rupture risk of intracranial aneurysms: Comparison between small ruptured intracranial aneurysms and large unruptured intracranial aneurysms.

To compare the differences in clinical and morphological features between small ruptured intracranial aneurysms and large unruptured intracranial aneurysms to evaluate the risk factors for the rupture of IAs. The clinical data of 189 consecutive patients with 193 IAs were reviewed. The patients and IAs were divided into ruptured (<5 mm) and unruptured groups (>10 mm). The characteristics of the patients and the intracranial aneurysms (IAs) were compared between the 2 groups, and the risk factors for rupture of IAs were assessed using multiple logistic regression. Patient age (odds ratio [OR], 0.955), IA located at the internal carotid artery (ICA, OR, 0.202), irregular shape (OR, 0.083) and parent vessel diameter (OR, 0.426) were negatively correlated with the risk of IA rupture. IAs located at bifurcations (OR, 6.766) were positively correlated with the risk of IA rupture. In addition to the size of the IAs, regardless of IAs shape, other factors, such as younger age (<63.5 years), location at a bifurcation, IAs located at the ICA and a small parent vessel diameter (<3.25 mm), can influence the risk of IA rupture.

Quantitative assessment of colour fundus photography in hyperopia children based on artificial intelligence

ObjectivesThis study aimed to quantitatively evaluate optic nerve head and retinal vascular parameters in children with hyperopia in relation to age and spherical equivalent refraction (SER) using artificial intelligence (AI)-based...

Peripheral intravascular lithotripsy to facilitate transfemoral transcatheter aortic valve replacement – Defining optimal treatable peripheral arterial disease burden

BackgroundTransfemoral transcatheter aortic valve replacement (TF-TAVR) has proven superior to alternative access. However, some patients evaluated for TF-TAVR are unfit secondary to peripheral arterial disease (PAD). Peripheral intravascular lithotripsy (IVL) can facilitate femoral access. This study aimed to characterize optimal lesions that can be treated with IVL. MethodsSingle-center, retrospective analysis of an institutional database, queried from 1/2018 through 7/2023 for all patients who underwent TAVR. Patients who received IVL-facilitated transfemoral access were analyzed. ResultsOf 2862 TAVR cases identified, 92 (3.2 %) underwent lithotripsy. The IVL-facilitated cohort had a mean age of 78 ± 9.2 years and 45 % were female. The right common iliac artery was most treated (47). Most IVL was performed with 7-mm balloons (73.9 %). All cases were successful. 30-day mortality was 1.1 % (1/92). ConclusionsIn our cohort, complications after IVL-facilitated TF-TAVR were more common with small vessel diameter (≤4.7 mm), significant luminal loss (>50 % stenosis), and heavy calcium burden (arc calcification >180°). The findings support the use of IVL to expand the population of patients who can undergo TF-TAVR without the increased risks associated with the various forms of alternative access. Summary for annotated table of contentsIVL-facilitated TF-TAVR is safe and feasible. Despite its introduction to TAVR clinical practice in 2018, IVL-facilitated TF-TAVR is not regularly performed and could increase the population of patients eligible for TF-TAVR.

Influence of Substrate Structure and Associated Properties on Endothelial Cell Behavior in the Context of Behaviors Associated with Laminar Flow Conditions.

In order to treat most vascular diseases, arterial grafts are commonly employed for replacing small-diameter vessels, yet they often cause thrombosis. The growth of endothelial cells along the interior surfaces of these grafts (substrates) is critical to mitigate thrombosis. Typically, endothelial cells are cultured inside these grafts under laminar flow conditions to emulate the native environment of blood vessels and produce an endothelium. Alternatively, the substrate structure could have a similar influence on endothelial cell behavior as laminar flow conditions. In this study, we investigated whether substrates with aligned fiber structures could induce responses in human umbilical vein endothelial cells (HUVECs) akin to those elicited by laminar flow. Our observations revealed that HUVECs on aligned substrates displayed significant morphological changes, aligning parallel to the fibers, similar to effects reported under laminar flow conditions. Conversely, HUVECs on random substrates maintained their characteristic cobblestone appearance. Notably, cell migration was more significant on aligned substrates. Also, we observed that while vWF expression was similar between both substrates, the HUVECs on aligned substrates showed more expression of platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31), laminin, and collagen IV. Additionally, these cells exhibited increased gene expression related to critical functions such as proliferation, extracellular matrix production, cytoskeletal reorganization, autophagy, and antithrombotic activity. These findings indicated that aligned substrates enhanced endothelial growth and behavior compared to random substrates. These improvements are similar to the beneficial effects of laminar flow on endothelial cells, which are well-documented compared to static or turbulent flow conditions.

The journey of decellularized vessel: from laboratory to operating room.

Over the past few decades, there has been a remarkable advancement in the field of transplantation. But the shortage of donors is still an urgent problem that requires immediate attention. As with xenotransplantation, bioengineered organs are promising solutions to the current shortage situation. And decellularization is a unique technology in organ-bioengineering. However, at present, there is no unified decellularization method for different tissues, and there is no gold-standard for evaluating decellularization efficiency. Meanwhile, recellularization, re-endothelialization and modification are needed to form transplantable organs. With this mind, we can start with decellularization and re-endothelialization or modification of small blood vessels, which would serve to address the shortage of small-diameter vessels while simultaneously gathering the requisite data and inspiration for further recellularization of the whole organ-scale vascular network. In this review, we collect the related experiments of decellularization and post-decellularization approaches of small vessels in recent years. Subsequently, we summarize the experience in relation to the decellularization and post-decellularization combinations, and put forward obstacle we face and possible solutions.

Comparison of Small Blood Vessel Diameter with Intravascular Ultrasound and Coronary Angiography for Guidance of Percutaneous Coronary Intervention.

Major cardiovascular events (MACEs) are a cause of major mortality worldwide. The narrowing and blockage of coronary arteries with atherosclerotic plaques are diagnosed and treated with percutaneous coronary intervention (PCI). During this procedure, coronary angiography (CAG) remains the most widely used guidance modality for the evaluation of the affected blood vessel. The measurement of the blood vessel diameter is an important factor to consider in order to decide if stent colocation is suitable for the intervention. In this regard, a small blood vessel (<2.75 mm) is majorly left without stent colocation; however, small vessel coronary artery disease (SvCAD) is a significant risk factor for the recurrence of MACEs, maybe due to the lack of a standardized treatment related to the diameter of the affected blood vessel; therefore, a more precise measurement is needed. The use of CAG for the measurement of the blood vessel diameter has some important limitations that can be improved with the use of newer techniques such as intravascular ultrasound (IVUS), although at higher costs, which might explain its underuse. To address differences in blood vessel diameter measurements and identify specific cases where IVUS might be of additional benefit for the patient, we conducted a retrospective study in patients who underwent PCI for MACEs with affection for at least one small blood vessel. We compared the measurements of the affected small blood vessels' diameter obtained by CAG and IVUS to identify cases of reclassification of the affected blood vessel; additionally, we underwent a multivariate analysis to identify risk factors associated with blood vessel reclassification. We included information from 48 patients with a mean ± SD age of 69.1 ± 11.9 years; 70.8% were men and 29.2% were women. The mean diameter with CAG and IVUS was 2.1 mm (95% CI 1.9-2.2), and 2.8 (2.8-3.0), respectively. The estimated difference was of 0.8 mm (95% CI 0.7-0.9). We found a significant positive low correlation in diameter measurements of small blood vessels obtained with CAG and IVUS (r = 0.1242 p = 0.014). In total, 37 (77%) patients had a reclassification of the affected blood vessel with IVUS. In 21 cases, the affected blood vessel changed from a small to a medium size (2.75-3.00 mm), and in 15 cases, the affected vessel changed from a small to a large size (<3.00 mm). The Bland-Altman plot was used to evaluate agreement in measurements with CAG and IVUS. The change in blood vessel classification with IVUs was important for the decision of intervention and stent collocation. The only variable associated with reclassification of blood vessels after adjustment in a multivariate analysis was T2D (type 2 diabetes) (p = 0 0.035). Our findings corroborate that blood vessels might appear smaller with CAG, especially in patients with T2D; therefore, at least in these cases, the use of IVUS is recommended over CAG.

The promotion of vascular reconstruction by hierarchical structures in biodegradable small-diameter vascular scaffolds

Tissue engineering of small-diameter vessels remains challenging due to the inadequate ability to promote endothelialization and infiltration of smooth muscle cells (SMCs). Ideal vascular graft is expected to provide the ability to support endothelial monolayer formation and SMCs infiltration. To achieve this, vascular scaffolds with both orientation and dimension hierarchies were prepared, including hierarchically random vascular scaffold (RVS) and aligned vascular scaffold (AVS), by utilizing degradable poly(ε-caprolactone)-co-poly(ethylene glycol) (PCE) and the blend of PCE/gelatin (PCEG) as raw materials. In addition to the orientation hierarchy, dimension hierarchy with small pores in the inner layer and large pores in the outer layer was also constructed in both RVS and AVS to further investigate the promotion of vascular reconstruction by hierarchical structures in vascular scaffolds. The results show that the AVS with an orientation hierarchy that consists with the natural vascular structure had better mechanical properties and promotion effect on the proliferation of vascular cells than RVS, and also exhibited excellent contact guidance effects on cells. While the dimension hierarchy in both RVS and AVS was favorable to the rapid infiltration of SMCs in a short culture time in vitro. Besides, the results of subcutaneous implantation further demonstrate that AVS achieved a fully infiltrated outer layer with wavy elastic fibers-mimic strips formation by day 14, ascribing to hierarchies of aligned orientation and porous dimension. The results further indicate that the scaffolds with both orientation and dimension hierarchical structures have great potential in the application of promoting the vascular reconstruction.

Transformation of metallo-elastomer grafts in a carotid artery interposition model over a year

Current vascular grafts, primarily Gore-Tex® and Dacron®, don't integrate with the host and have low patency in small-diameter vessels (<6 mm). Biomaterials that possess appropriate viscoelasticity, compliance, and high biocompatibility are essential for their application in small blood vessels. We have developed metal ion crosslinked poly(propanediol-co-(hydroxyphenyl methylene)amino-propanediol sebacate) (M-PAS), a biodegradable elastomer with a wide range of mechanical properties. We call these materials metallo-elastomers. An initial test on Zn-, Fe-, and Cu-PAS grafts reveals that Cu-PAS is the most suitable because of its excellent elastic recoil and well-balanced polymer degradation/tissue regeneration rate. Here we report host remodeling of Cu-PAS vascular grafts in rats over one year. 76 % of the grafts remain patent and >90 % of the synthetic polymer is degraded by 12 months. Extensive cell infiltration leads to a positive host remodeling. The remodeled grafts feature a fully endothelialized lumen. Circumferentially organized smooth muscle cells, elastin fibers, and widespread mature collagen give the neoarteries mechanical properties similar to native arteries. Proteomic analysis further reveals the presence of important vascular proteins in the neoarteries. Evidence suggests that Cu-PAS is a promising material for engineering small blood vessels.

Development and performance evaluation of a novel elastic bacterial nanocellulose/polyurethane small caliber artificial blood vessels

There is an increasing demand for small-diameter blood vessels. Currently, there is no clinically available small-diameter artificial vessel. Bacterial nanocellulose (BNC) has vast potential for applications in artificial blood vessels due to its good biocompatibility. At the same time, medical polyurethane (PU) is a highly elastic polymer material widely used in artificial blood vessels. This study reports a composite small-diameter BNC/PU conduit using a non-solvent-induced phase separation method with the highly hydrophilic BNC tube as the skeleton and the hydrophobic polycarbonate PU as the filling material. The results revealed that the compliance and mechanical matching of BNC/PU tubes were higher than BNC tubes; the axial/radial mechanical strength, burst pressure, and suture strength were significantly improved; the blood compatibility and cell compatibility were also excellent. The molecular and subcutaneous embedding tests showed that the composite tubes had lighter inflammatory reactions. The results of the animal substitution experiments showed that the BNC/PU tubes kept blood flow unobstructed without tissue proliferation after implantation in rats for 9 months. Thus, the BNC/PU small-diameter vascular prosthesis had the potential for long-term patency and acted as an ideal material for small-diameter vessels.

Starting from Scratch: Experiences from Developing the First Vascular Anastomotic Training Program in North Macedonia Using the Porcine Thigh as a Simulation Model

AbstractMicrosurgical reconstruction constitutes a fundamental part of plastic and reconstructive surgery. It demands high dexterity and intricate technical skills. Its steep learning curve benefits from thorough training throughout residency, where using realistic simulation models in the appropriate sequence of complexity progression is essential in ensuring patient safety prior to progressing to a clinical setting. Commencing training on microvascular-like small diameter vessels could prove unsuitable and ineffective for inexperienced surgeons, however, the larger diameter neurovascular structures in the porcine thigh can provide excellent anastomotic training without compromising the animal tissue training sought after by residents. We present the results from implementing the first vascular anastomotic course in our country, where reconstructive theory was combined with simulated anastomotic training on the porcine thigh. Junior plastic surgery residents described acquiring comprehensive knowledge of reconstructive techniques and could successfully complete anastomoses, despite none to minimal previous experience. Using the porcine thigh should be encouraged as a start-up vascular anastomotic training tool as it provides realistic conditions and tissue handling training, and could improve quality of further training on microvascular structures.