Use of EndoAnchors during index endovascular aortic aneurysm repair in patients with hostile proximal aortic neck anatomy.

PURPOSE: Standard endovascular aortic aneurysm repair (EVAR) is sometimes the only treatment option for patients with hostile aortic neck anatomy, but it carries an increased risk of both early and late procedure-related complications. The aim of this study was to report on single-center experience with the Heli-FX EndoAnchors (Medtronic, Santa Rosa, CA) as an adjunctive procedure to endovascular aneurysm repair (EVAR) for prevention and perioperative treatment of proximal neck complications in patients with hostile neck anatomy.  MATERIALS AND METHODS: A single-centre, retrospective study evaluating 24 consecutive patients treated with EndoAnchors during the index EVAR procedure between November 2018 and August 2021. EndoAnchor implantation was indicated for cases with hostile proximal aortic neck anatomy characterised by the presence of at least one of the following parameters: length of 28 mm, angle of >60°, circumferential thrombus/calcification involving ≥50%, and reverse taper. RESULTS:  Median follow-up period was 22.5 months (IQR 2-31.5 months) with no aneurysm-related death, rupture, or conversion to open surgical repair during the follow-up. The procedural success rate was 100%, with no type Ia endoleak at the completion angiography. A mean of 7 EndoAnchors was used per patient (range 4-12). There were no EndoAnchor fractures and dislocations or stent graft fabric damage due to anchor implants. Twenty-three patients (95.8%) remained free of type Ia endoleak and migration on follow-up imaging. Aneurysm sac regression was observed in 13 patients (54.1%), while in 8 patients (33.3%) the sac remained stable. Sac enlargement was present in 1 patient (4.2%) due to late type Ia endoleak. Two patients were lost to the follow-up immediately after the procedure. Between two groups of patients (sac regression versus failure to regress), the larger initial diameter of the proximal neck was the only significant independent factor associated with a lower possibility of sac regression (p= 0,021). CONCLUSIONS:  The use of EndoAnchors during the index EVAR procedure in cases with challenging aortic neck anatomy with or without perioperative type Ia endoleak was associated with good midterm results and led to sac regression in most of the patients (Tab. 4, Fig. 3, Ref. 31).

Aortic remodelling based on false lumen communications in patients undergoing acute type I dissection repair with AMDS hybrid prosthesis: a substudy of the DARTS trial.

OBJECTIVES: The Dissected Aorta Repair Through Stent (DARTS) Implantation trial demonstrated positive proximal aortic remodelling following aortic dissection repair with the AMDS hybrid prosthesis. In this study, we look to identify predictors of aortic remodelling following aortic dissection repair with AMDS including whether communications between branch vessels and the false lumen (FL) predict aortic growth. METHODS: The DARTS implantation trial included patients who underwent acute DeBakey type I aortic dissection (ATAD I) repair with the AMDS from March 2017 to January 2019. Anatomic measurements were collected from original computerized tomography scans. Measurements were taken at zones 2, 3, 6 and 9. Patients were grouped based on the number of FL communications with the supra-aortic branch vessels or visceral branch vessels. RESULTS: Forty-seven patients were included in the original DARTS implantation trial. Patients with FL communications with the supra-aortic branch vessels tended to have significant growth at zone 3 (P = 0.02-0.0018), while greater numbers of visceral FL communications tended to predict aortic growth at zones 3 (P = 0.003), 6 (P = 0.017-0.0087) and 9 (P = 0.0016-0.0003). CONCLUSIONS: Aortic remodelling following ATAD I repair using the AMDS may be predicted by local FL communications with branch vessels. Patients undergoing ATAD I repair were more likely to experience significant aortic growth in zone 3 with more head vessel communications and in zones 3, 6 and 9 with more visceral FL communications. Predictors of aortic remodelling may help to guide initial surgical management for aortic dissection patients.

Transplantation of cryopreserved cardiovascular homografts.

Due to degeneration, homografts were since the 1950s only used strictly for replacement of complex arterial segments and lesions incl. the aortic valve, replacement of infected arterial prostheses, and vascular access for patients on haemodialysis. During the 1990s, rate-differentiated freezing methods and anti-crystallization agents proved to prevent crystallisation, and more widespread use with expanded indications incl. coronary and lower limb bypasses began justified by promising midterm results. In 2021, the first Scandinavian homograft biobank was founded in Odense in Denmark. This review summarises the history and the experiences from this biobank.

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.

Multicentre experience of antegrade thoracic endovascular aortic repair for the treatment of thoracic aortic diseases.

OBJECTIVES: The goal of this multicentre retrospective cohort study was to evaluate technical success and early and late outcomes of thoracic endovascular repair (TEVAR) with grafts deployed upside down through antegrade access, to treat thoracic aortic diseases. METHODS: Antegrade TEVAR operations performed between January 2010 and December 2021 were collected and analysed. Both elective and urgent procedures were included. Exclusion criteria were endografts deployed in previous or concomitant surgical or endovascular repairs. RESULTS: Fourteen patients were enrolled; 13 were males (94%) with a mean age of 71 years (interquartile range 62; 78). Five patients underwent urgent procedures (2 ruptured aortas and 3 symptomatic patients). Indications for treatment were 8 (57%) aneurysms/pseudoaneurysms, 3 (21%) dissections and 3 (21%) penetrating aortic ulcers. Technical success was achieved in all procedures. Early mortality occurred in 4 (28%) cases, all urgent procedures. Median follow-up was 13 months (interquartile range 1; 44). Late deaths occurred in 2 (20%) patients, both operated on in elective settings. The first died at 19 months of aortic-related reintervention; the second died at 34 months of a non-aortic-related cause. Two patients (14%) underwent aortic-related reinterventions for late type I endoleak. The survival rate of those having the elective procedures was 100%, 84% and 67% at 12, 24 and 36 months, respectively. Freedom from reintervention was 92%, 56% and 56% at 12, 24 and 36 months, respectively. CONCLUSIONS: Antegrade TEVAR can seldom be considered an alternative when traditional retrograde approach is not feasible. Despite good technical success and few access-site complications, this study demonstrates high rates of late type I endoleak and aortic-related reinterventions.

Analysis of morphological properties of fibrous electrospun polyurethane grafts using image segmentation.

The concentration of the polymer in the electrospinning solution greatly influences the mechanical behaviour of electrospun vascular grafts due to the influence on scaffold morphology. The scaffold morphology (fiber diameter, fiber orientation and inter-fiber voids) of the grafts plays an important role in their behaviour during use. Even though manual methods and complex algorithms have been used so far for characterisation of the morphology of electrospun architecture, they still have several drawbacks that limit their reliability. This study therefore uses conventional, statistical region merging and a hybrid image segmentation algorithm, to characterise the morphology of the electrospun vascular grafts. Consequently, vascular grafts were fabricated using an in-house electrospinning equipment using three polymer material concentration levels (14%, 16% and 18%) of medical-grade thermoplastic polyurethane (Pellethane®). The image thresholding and segementation algorithms were then used for segmentation of SEM images extracted from the polymer grafts and then morphological parameters were investigated in terms of fiber diameter, fiber orientation, and interfiber spaces (pore area and porosity). The results indicate that electrospun image segmentation was "best" when the hybrid algorithm and the conventional algorithm was used, which implied that fiber property values computed from the hybrid algorithm were closed to the manually measurements especially for the 14% PU with fiber diameter 2.2%, fiber orientation 7.6% and porosity at 1.9%. However there was higher disperity between the manual and hybrid algorithm. This suggests more fiber uniformity in the 14%PU potentially affected the accuracy of the hybrid algorithm.

Improving hemocompatibility of decellularized vascular tissue by structural modification of collagen fiber.

Decellularized vascular tissue has high potential as a tissue-engineered vascular graft because of its similarity to native vessels in terms of mechanical strength. However, exposed collagen on the tissue induces blood coagulation, and low hemocompatibility is a major obstacle to its vascular application. Here we report that freeze-drying and ethanol treatment effectively modify collagen fiber structure and drastically reduce blood coagulation on the graft surface without exogenous chemical modification. Decellularized carotid artery of ostrich was treated with freeze-drying and ethanol solution at concentrations ranging between 5 and 99.5 %. Collagen fiber distance in the graft was narrowed by freeze-drying, and the non-helical region increased by ethanol treatment. Although in vitro blood coagulation pattern was similar on the grafts, platelet adhesion on the grafts was largely suppressed by freeze-drying and ethanol treatments. Ex vivo blood circulation tests also indicated that the adsorption of platelets and Von Willebrand Factor was largely reduced to approximately 80 % by ethanol treatment. These results indicate that structural modification of collagen fibers in decellularized tissue reduces blood coagulation on the surface by inhibiting platelet adhesion.

Bioengineered vascular grafts with a pathogenic TGFBR1 variant model aneurysm formation in vivo and reveal underlying collagen defects.

Thoracic aortic aneurysm (TAA) is a life-threatening vascular disease frequently associated with underlying genetic causes. An inadequate understanding of human TAA pathogenesis highlights the need for better disease models. Here, we established a functional human TAA model in an animal host by combining human induced pluripotent stem cells (hiPSCs), bioengineered vascular grafts (BVGs), and gene editing. We generated BVGs from isogenic control hiPSC-derived vascular smooth muscle cells (SMCs) and mutant SMCs gene-edited to carry a Loeys-Dietz syndrome (LDS)-associated pathogenic variant (TGFBR1A230T). We also generated hiPSC-derived BVGs using cells from a patient with LDS (PatientA230T/+) and using genetically corrected cells (Patient+/+). Control and experimental BVGs were then implanted into the common carotid arteries of nude rats. The TGFBR1A230T variant led to impaired mechanical properties of BVGs, resulting in lower burst pressure and suture retention strength. BVGs carrying the variant dilated over time in vivo, resembling human TAA formation. Spatial transcriptomics profiling revealed defective expression of extracellular matrix (ECM) formation genes in PatientA230T/+ BVGs compared with Patient+/+ BVGs. Histological analysis and protein assays validated quantitative and qualitative ECM defects in PatientA230T/+ BVGs and patient tissue, including decreased collagen hydroxylation. SMC organization was also impaired in PatientA230T/+ BVGs as confirmed by vascular contraction testing. Silencing of collagen-modifying enzymes with small interfering RNAs reduced collagen proline hydroxylation in SMC-derived tissue constructs. These studies demonstrated the utility of BVGs to model human TAA formation in an animal host and highlighted the role of reduced collagen modifying enzyme activity in human TAA formation.

In situ densification and heparin immobilization of bacterial cellulose vascular patch for potential vascular applications.

Nowadays, developing vascular grafts (e.g., vascular patches and tubular grafts) is challenging. Bacterial cellulose (BC) with 3D fibrous network has been widely investigated for vascular applications. In this work, different from BC vascular patch cultured with the routine culture medium, dopamine (DA)-containing culture medium is employed to in situ synthesize dense BC fibrous structure with significantly increased fiber diameter and density. Simultaneously, BC fibers are modified by DA during in situ synthesis process. Then DA on BC fibers can self-polymerize into polydopamine (PDA) accompanied with the removal of bacteria in NaOH solution, obtaining PDA-modified dense BC (PDBC) vascular patch. Heparin (Hep) is subsequently covalently immobilized on PDBC fibers to form Hep-immobilized PDBC (Hep@PDBC) vascular patch. The obtained results indicate that Hep@PDBC vascular patch exhibits remarkable tensile and burst strength due to its dense fibrous structure. More importantly, compared with BC and PDBC vascular patches, Hep@PDBC vascular patch not only displays reduced platelet adhesion and improved anticoagulation activity, but also promotes the proliferation, adhesion, spreading, and protein expression of human umbilical vein endothelial cells, contributing to the endothelialization process. The combined strategy of in situ densification and Hep immobilization provides a feasible guidance for the construction of BC-based vascular patches.

Dynamically Cross-Linked Double-Network Hydrogels with Matched Mechanical Properties and Ideal Biocompatibility for Artificial Blood Vessels.

Vessel transplantation is currently considered the "gold standard" treatment for cardiovascular disease. However, ideal artificial vascular grafts should possess good biocompatibility and mechanical strength that match those of native autologous vascular tissue to promote in vivo tissue regeneration. In this study, a series of dynamic cross-linking double-network hydrogels and the resultant hydrogel tubes were prepared. The hydrogels (named PCO), composed of rigid poly(vinyl alcohol) (PVA), flexible carboxymethyl chitosan (CMCS), and a cross-linker of aldehyde-based ß-cyclodextrin (OCD), were formed in a double-network structure with multiple dynamical cross-linking including dynamic imine bonds, hydrogen bonds, and microcrystalline regions. The PCO hydrogels exhibited superior mechanical strength, good network stability, and fatigue resistance. Additionally, it demonstrated excellent cell and blood compatibility. The results showed that the introduction of CMCS/OCD led to a significant increase in the proliferation rate of endothelial cells seeded on the surface of the hydrogel. The hemolysis rate in the test was lower than 0.3%, and both protein adsorption and platelet adhesion were reduced, indicating an excellent anticoagulant function. The plasma recalcification time test results showed that endogenous coagulation was alleviated to some extent. When formed into blood vessels and incubated with blood, no thrombus formation was observed, and there was minimal red blood cell aggregation. Therefore, this novel hydrogel tube, with excellent mechanical properties, exhibits antiadhesive characteristics toward blood cells and proteins, as well as antithrombotic properties, making it hold tremendous potential for applications in the biomedical and engineering fields.

Safety and efficacy of the novel Alpha stent for the treatment of intracranial wide-necked aneurysm.

The Alpha stent is an intracranial closed-cell stent with a unique mesh design to enhance wall apposition. It recently underwent structural modifications to facilitate easier stent deployment. This study aimed to evaluate the safety and efficacy of stent-assisted coil embolization for unruptured intracranial aneurysms using the Alpha stent. Between January 2021 and November 2021, 35 adult patients with 35 unruptured intracranial aneurysms in the distal internal carotid artery were prospectively enrolled. For efficacy outcomes, magnetic resonance angiography at the 6-month follow-up was evaluated using the Raymond-Roy occlusion classification (RROC). The safety outcome evaluated the occurrence of symptomatic procedure-related neurological complications up to 6 months postoperatively. Technical success was achieved in 34/35 (97.1%). Six months postoperatively, aneurysm occlusion showed RROC I in 32/35 (91.4%) and RROC II in 3/35 (8.6%) patients. Procedure-related neurologic complications occurred in one patient (2.9%) who experienced hemiparesis due to acute lacunar infarction, which resulted in a 6-month mRS score of 1. The Alpha stent demonstrated excellent efficacy and safety outcomes in stent-assisted coil embolization of unruptured distal ICA aneurysms. The recent structural modifications allowed for easier stent delivery and deployment.Clinical trial registration number: KCT0005841; registration date: 28/01/2021.

A challenging case of emergency redo surgery for acute type A aortic dissecting aneurysm of ascending and aortic arch with frozen elephant trunk following aortic root replacement.

Redo ascending and aortic arch surgeries following previous cardiac or aortic surgery are associated with high risk of morbidity and mortality due to multiple factors included sternal re-entry injury, extensive aortic arch surgery, emergency aortic surgery, prolonged cardiopulmonary bypass duration, poor heart function, and patients with older age. Therefore, appropriate surgical strategies are important. We report a case of a 72-year-old gentleman with previous surgery of aortic root replacement who presented with acute Type A aortic dissecting aneurysm of ascending and aortic arch complicated with left hemothorax, which was successfully treated by emergency redo aortic surgery with frozen elephant trunk (FET) technique.

Inflammation in aortic surgery: postoperative evolution of biomarkers according pathologies and segments of the aorta.

OBJECTIVES: Aortic pathologies often present with elevated inflammatory biomarkers due to the nature of the disease. Open aortic surgery causes significant trauma to the body due to often mandatory ischemic periods, long cardiopulmonary bypass times and polytransfusion. We aim to determine postoperative trends on inflammation biomarkers for different aortic pathologies and type of surgery in different segments of the aorta. METHODS: Retrospective review of prospectively collected data of 193 consecutive patients who underwent aortic surgery in our centre between 2017 and 2021, grouped according to the type of aortic intervention: (1) Type A aortic dissection (AD) repair with ascending aorta/hemiarch replacement, (2) Aortic root replacement (ARR), (3) Aortic arch + Frozen elephant trunk (FET), (4) Descending thoracic aorta (DTA)/Thoraco-Abdominal aortic repair (TAA). Primary outcomes were daily values of white blood cells (WBC) and C-Reactive Protein (CRP) during the first 15 postoperative days. RESULTS: All groups had a similar inflammatory peak in the first 2-4 days (WBC 12-15 × 109 c/L). AD and FET groups show similar trends with WBC and CRP peaks on days 2 and 10. The ARR group didn't experience the 2nd peak as most patients were already discharged. DTA/TAA patients experienced a more prolonged inflammatory response, reaching a plateau by day 5-10. AD group shows the highest WBC levels and the DTA/TAAA group the highest CRP levels. CRP levels remain elevated (100-200 mg/L) in all groups after 15 postoperative days. CONCLUSIONS: Inflammatory biomarkers show different postoperative trends depending on the clinical presentation and complexity of the aortic procedure performed. Further understanding of the inflammatory response to different aortic pathologies and surgical procedures will permit reduction on the liberal use of antibiotics that this cohort of patients are usually exposed to. An earlier version of the data included in this manuscript was presented as Oral Abstract in the UK Society of Cardiothoracic Surgery Annual meeting in 2021.

Transcatheter aortic valve implantation for pure aortic insufficiency in a patient following David-type aortic valve-sparing root replacement after aortic dissection-A successful off-label procedure.

Transcatheter aortic valve implantation (TAVI) has traditionally been indicated for the treatment of aortic stenosis. However, in this case report, we describe a successful TAVI procedure in a 46-year-old male patient who had previously undergone David aortic valve-sparing aortic root replacement for type 1 aortic dissection. The patient presented with aortic valve insufficiency 4 years after the initial surgery and was subsequently treated with a 34 mm Medtronic CoreValve Evolut R prosthesis via TAVI. This case highlights the feasibility of TAVI as a viable treatment option for postoperative aortic valve insufficiency in patients with prior ascending aortic or aortic arch surgery.

Exploiting light-based 3D-printing for the fabrication of mechanically enhanced, patient-specific aortic grafts.

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ± 0.05 MPa and 1.61 ± 0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts.

Hemodynamics and Wall Mechanics of Vascular Graft Failure.

Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.

Surgeon-modified fenestrated endovascular grafts and thoracoscope-assisted fixation for treatment of thoraco-abdominal aortic aneurysms.

BACKGROUND: Total endovascular technique with fenestrated endovascular graft might be hampered for the late dilatation of proximal landing zone, which may cause endografts migration. We describe a successful urgent hybrid procedure for extent III thoracoabdominal aortic aneurysm with aortic intramural hematoma. CASE PRESENTATION: A 55-year-old female with thoracoabdominal aortic aneurysm was considered at high surgical risk and unfit for open repair due to multiple comorbidities. Therefore, a hybrid procedure of surgeon-modified fenestrated endovascular graft combined with thoracoscope-assisted Transaortic epicardial fixation of endograft was finally chosen and performed in the endovascular operating room. A 3-port technique was performed through a left video-assisted thoracoscopic approach. After the first tampering stent-graft was deployed, a double-needle suture was penetrated both the aortic wall and stent-graft to fixate it in the proximal descending aorta. Then the second endograft, which had been fenestrated on table, was introduced and oriented extracorporeally by rotating superior mesenteric artery and left renal artery fenestration radiopaque markers and deployed with perfect apposition between the fenestrations and target visceral artery. Each vessel was sequentially stented using Viabahn self-expandable stent to finish target vessel stenting. An Ankura cuff stent was deployed in the distal abdominal aortic artery. CONCLUSION: Surgeon-modified fenestrated endovascular graft combined with thoracoscope-assisted fixation may be an innovative and viable alternative for selected high-risk patients with extent III thoracoabdominal aortic aneurysm. A longer follow-up is needed to ascertain the success of this approach.

High-precision 3D printing of multi-branch vascular scaffold with plasticized PLCL thermoplastic elastomer.

Three-dimensional (3D) printing has emerged as a transformative technology for tissue engineering, enabling the production of structures that closely emulate the intricate architecture and mechanical properties of native biological tissues. However, the fabrication of complex microstructures with high accuracy using biocompatible, degradable thermoplastic elastomers poses significant technical obstacles. This is primarily due to the inherent soft-matter nature of such materials, which complicates real-time control of micro-squeezing, resulting in low fidelity or even failure. In this study, we employ Poly (L-lactide-co-ϵ-caprolactone) (PLCL) as a model material and introduce a novel framework for high-precision 3D printing based on the material plasticization process. This approach significantly enhances the dynamic responsiveness of the start-stop transition during printing, thereby reducing harmful errors by up to 93%. Leveraging this enhanced material, we have efficiently fabricated arrays of multi-branched vascular scaffolds that exhibit exceptional morphological fidelity and possess elastic moduli that faithfully approximate the physiological modulus spectrum of native blood vessels, ranging from 2.5 to 45 MPa. The methodology we propose for the compatibilization and modification of elastomeric materials addresses the challenge of real-time precision control, representing a significant advancement in the domain of melt polymer 3D printing. This innovation holds considerable promise for the creation of detailed multi-branch vascular scaffolds and other sophisticated organotypic structures critical to advancing tissue engineering and regenerative medicine.

Latest evidence on chimney endovascular repair of abdominal aortic aneurysms and the renal artery angulation pitfall.

This article summarizes the key findings in literature up to date on the endovascular treatment of complex abdominal aortic aneurysms (AAAs) employing the chimney technique. Additionally, an unexplored pitfall is described regarding the target vessel angulation. Although balloon-expandable covered stents present more favorable configuration in downward-oriented target vessels, transverse and upward-oriented target vessels may benefit from other endovascular techniques imploring careful case planning and further investigation on the topic.