Small-diameter Arteries Research Articles

Comparison of patients with occlusive or hemorrhagic access site complications requiring reintervention after percutaneous transfemoral transcatheter aortic valve implantation.

Background: Transcatheter aortic valve implantation (TAVI) via transfemoral (TF) access is increasingly integral to aortic valve disease treatment, expanding beyond high-risk patients. Despite technical advancements, access-related vascular complications, occurring in approximately 10% of TAVI procedures, remain a substantial challenge. Objective: This study investigated the clinical and morphological characteristics of percutaneous TF-TAVI patients experiencing occlusive (OC) and hemorrhagic (HC) complications managed with surgical or endovascular reintervention. Methods: The cohort included patients from a Dutch and a German tertiary referral hospital, managed with TF-TAVI procedures between 2017 and 2021 that required reintervention for OC or HC. Demographics, comorbidities, procedural details, and preoperative imaging data were collected and compared between groups. Results: Among 109 TF-TAVI patients, 32 with OC and 77 with HC required reintervention. The OC group presented significantly smaller access arterial diameters (common femoral artery: OC 6.7 mm vs. HC 8.9 mm, p<.001; external iliac artery: OC 7.2 mm vs. HC 8.3 mm, p<.001; common iliac artery: OC 9.4 mm vs. HC 10.5 mm, p=.012) while the HC group presented higher tortuosity index (TI) (OC 1.24 vs. HC 1.30; p=.017). No differences were observed regarding baseline characteristics, vessel calcification or vascular closure device use. Conclusions: In patients requiring reintervention following TF-TAVI, smaller arterial diameters were associated with OC, while higher TI was linked to HC. These findings emphasize the importance of preoperative imaging in developing individualized prevention strategies.

Feasibility and radial artery occlusion rate of sheathless distal transradial access using balloon guide catheters.

Distal transradial access (dTRA), performed through an anatomical snuffbox, minimizes post-procedural burdens of endovascular treatments. However, despite the benefits of balloon-guide catheters (BGCs), their use in dTRA is limited by their small radial artery diameter. Herein, we evaluated the feasibility and radial artery occlusion (RAO) rate of 8Fr BGCs used in sheathless dTRA. This retrospective study reviewed patients treated with sheathless dTRA using an 8Fr Optimo at a single center between July 2023 and May 2024. dTRA procedures were performed under general anesthesia in patients not requiring urgent treatment. The RAO was assessed using ultrasonography 24h after the procedure. The demographic and procedural characteristics were compared between the radial artery patency and occlusion groups. Of 170 patients, 50 underwent dTRA, and 43 (86%) completed the procedure. RAO occurred in 12/43 (28%) patients with dTRA. Univariate and receiver operating characteristic curve analyses demonstrated that the median radial artery diameter was significantly smaller in the RAO group (P < 0.001), with an optimal cut-off value of 2.4mm to predict RAO. Complications included minor cerebral ischemia in two patients, but no severe ischemia was observed. Sheathless dTRA using an 8Fr Optimo BGC is feasible, but the risk of RAO should be noted, particularly in patients with small radial artery diameters. This study suggests a radial artery diameter cutoff value of 2.4mm to predict RAO, aiding access decisions for large-bore BGC. Further multicenter prospective studies are warranted to confirm these findings and assess long-term outcomes.

Freezing and bioreactor in the low-concentration detergents: A novel approach in the decellularization of small-diameter arteries.

Using decellularized small-diameter vascular bypass substitutes (<6 mm) is an efficient method for bypass grafting. A solution containing 0.5% SDS (weight/volume) is commonly used for extended periods to generate acellular tissues. However, this solution causes damage to the microfibril structure and alters the mechanical forces. Hence, the objective of this study is to reduce the concentration of SDS to preserve the structure and achieve efficient decellularization. The study employs a diluted solution of 0.3% SDS (weight/volume) to treat fresh and frozen swine small-diameter arteries, utilizing physical methods such as freezing and thawing. The effectiveness of cell removal was evaluated using histological analysis and the remaining DNA content of the sample. Furthermore, the acellular circuit also assesses the cytotoxicity and proliferation of HUVECs to gauge their safety. Through the use of 0.3% SDS, a bioreactor system, and freezing-thawing, the pig arteries are successfully decellularized, resulting in residual DNA levels of less than 50 ng/mg dry weight. This process does not cause any major changes to the biomechanical or structural properties of the arteries. The acellular samples exhibit no toxicity on the L929 cell line and promote the growth of HUVECs at their highest rate on the fourth day. This allows for the placement of acellular vascular grafts to evaluate physiological processes within the animal body. This is an important requirement in clinical blood vessel transplantation.

Comparison of radial artery occlusion between traditional radial access and distal radial access for coronary angiography and intervention: A prospective cohort study

BackgroundThe radial approach is now recommended as the default strategy in diagnostic coronary angiography and percutaneous coronary intervention. Radial artery occlusion (RAO) is the most common complication that limits subsequent angiographic procedures through this access. Recently, distal radial access (DRA) has been recommended as an alternative access site. Despite lower RAO rates in DRA in some recent clinical trials, concerns remain regarding possible complications and limitations due to the small size of the distal radial artery. ObjectiveThe present study aimed to compare traditional radial access (TRA) and DRA concerning RAO in percutaneous coronary procedures. MethodsIn the present prospective cohort study, percutaneous coronary procedures were performed via DRA or TRA in 2 study groups. All consecutive participants underwent DRA from September 2021 to March 2022 and TRA from April 2022 to June 2022. Ultrasonography was performed preprocedurally in the DRA group, and patients with small distal artery diameters (<2 mm) were excluded. The same 6-Fr sheaths and standard air-filled compression devices were used in both groups. The primary endpoint was RAO in ultrasound sonography on the first postprocedural day, and the secondary endpoints were the success rate, access time, angiography time, radial artery spasms, and vascular access complications. ResultsA total of 298 patients were assigned to the DRA group and 278 to the TRA group. The RAO rate was significantly higher in the TRA group than in the DRA group (10.1 % vs 0.9 %; P = 0.0001; OR, 0.08, 95 % CI, 0.01–0.27). The success rate was significantly higher in the TRA group (96 % vs 90.2 %; P = 0.009). Access crossovers were done on 12 patients (4.0 %) in the TRA group and 24 patients (9.8 %) in the DRA group (P < 0.001). The mean access time was significantly lower in the TRA group than in the DRA group (1.9 min vs 2.9 min; P < 0.001). The mean angiography time did not significantly differ between the groups (10.2 min in the TRA group vs 9.9 min in the DRA group). The rate of radial artery spasms was not significantly different between the 2 groups (13.8 % in the TRA group vs 14.5 % in the DRA group). The rates of access site hematoma (12.4 % vs 2.3 %; P < 0.001) and bleeding (10.7 % vs 4.1; P = 0.005) were significantly higher in the TRA group. ConclusionsDRA was safe and feasible with lower rates of RAO and access site complications than TRA. Thus, it could be used as an alternative approach in percutaneous coronary procedures. However, the trade-off for these advantages of DRA is an increase in cross-over rate, and a decrease in puncture success rate.

A comparative study of Newtonian and non-Newtonian blood flow through Bi-Leaflet Mechanical Heart Valve

The present study examines flow through Bi-Leaflet Mechanical Heart Valves (BMHV) at physiological conditions considering both Newtonian and non-Newtonian fluid models for blood rheology. It is well known that the non-Newtonian effects of blood are pronounced in small diameter arteries. Most of the earlier works on Mechanical Heart Valves (MHV) have considered blood as a Newtonian fluid as the flow involves large-diameter artery such as the aorta. In this work, we have reported the predicted parameters, such as leaflet kinematics, vortex structures, wall shear stress, and blood damage index for both blood models. It is found that the leaflet attributes smaller asynchronous motion in the case of non-Newtonian Carreau fluid model with slightly reduced angular velocity compared to the Newtonian assumption. Predictions on the blood damage index suggest a 21% higher damage while using non-Newtonian model than Newtonian model, which may be attributed to higher levels of mechanical stress within the fluid. However, vortex structures, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) are found to be similar in predictions using both the fluid models. We have used an in-house sharp interface immersed boundary method with fluid–structure interaction to simulate the coupled action of moving valves and pulsatile blood flow. Our findings suggest that the general consensus of using Newtonian model in large arteries may not be appropriate for prediction of leaflet kinematics and blood damage index in Mechanical heart valves.

Comparative Analysis of Outcomes of Unibody Endoprosthesis and Aortobifemoral Bypass for Aortoiliac Occlusive Disease

Aortoiliac occlusive disease (AIOD) has traditionally been treated with aortobifemoral bypass (ABF). Unibody endograft (UBE) for AIOD, however, has been increasingly utilized in selected patients. We report outcomes of patients undergoing ABF or UBE for AIOD. Patients (2016-2021) undergoing elective ABF or UBE with a unibody device for AIOD were identified at an academic institution. Chi-square and Kaplan-Meier analysis were used to evaluate outcomes by group. One hundred thirty-one patients undergoing UBE or ABF were screened, with 82 included. Twenty-one patients underwent UBE (25.6%) and 61 (74.4%) underwent ABF. UBE patients were older (63.8 vs. 58.2years; P=0.01), with a higher prevalence of diabetes (52.4 vs. 19.7%; P=0.004). Significant differences were seen between UBE and ABF including a shorter surgery length (214 vs. 360min; P=0.0001), less blood loss (300 vs. 620mls; P=0.001), larger minimum aortic diameter (14.6 vs. 12.6; P=0.0006), larger common iliac artery (9.5 vs. 7.9; P=0.005) and lower postoperative ankle-brachial index (0.8 vs. 0.9; P=0.04). There were no differences in TASC C/D iliac lesions in the UBE than ABF group (66.6% vs. 63.9%; P<0.82) or Trans-Atlantic Inter-Society Consensus classification femoropopliteal lesions. Unadjusted analysis revealed no significant differences between UBE and ABF for 30-day mortality (0 vs. 1.6%; P=1), stroke (0 vs. 3.3%; P=1), or major adverse cardiac events (4.8 vs. 4.9%; P=1). There were no significant differences in mid-term surgical outcomes over a mean follow-up period of 23.7months between UBE and ABF groups; specifically endovascular (0 vs. 8.2%; P=0.3) or open/hybrid reintervention (9.5 vs. 14.8%; P=0.7) with similar limb occlusion (4.8 vs. 27.8; P=0.12). Kaplan-Meier estimated primary, primary-assisted, and secondary patency at 36months were similar with 94%, 100%, and 94% for UBE and 86%, 95%, and 86% for ABF, respectively. Estimated survival at 36months was 95% for UBE and 97% for ABF (P=0.8). Equivalent outcomes were seen between AIOD treated with UBE or ABF in similar patient populations. Mid-term outcomes such as reintervention and patency are similar for UBE and ABF. We still recommend ABF over UBE as a primary modality of treatment in surgically fit patients with greater complexity aortoiliac lesions and with smaller arterial diameters, especially women.

#2331 Distal arteriovenous fistulas for hemodialysis – too many interventions?

Abstract Background and Aims Distal arteriovenous fistula (dAVF) for haemodialysis (HD) is preferred due to lesser complications, despite greater risk of maturation failure. In HD patients, age and comorbid conditions increased the risk of access failure and number of procedures necessary for fistula patency. Preferred location for AVF poses a challenging decision. Advantages of dAVF must be taken into account although these may lead an unreasonably high number of interventions. Our aim was to determine time to functioning distal AFV in our centre and number of procedures necessary to achieve such status. Method Single centre retrospective analysis was performed on a cohort of patients submitted to distal AFV construction from 2015-2021. Success rate was defined as AFV patency in time for dialysis. Results Of 528 patients submitted to AVF construction from 2015 - 2021, 110 radiocephalic fistulas were seen, 59% male patients, mean age 68.5±12,0 yrs. Comorbidities were prevalent (80.9%, n=89), DM (54.6%) and HF (41.1%). Outcomes at 6 weeks were adequate maturation in 4.5% (n=59), 31.8% (n=35) late maturation (LM) and 14.5%(n=16) primary failure (PF). Causes of LM included inflow and outflow stenosis, 34.3% and 37.1%, respectively. LM (&amp;gt; 6 weeks) requiring no further intervention was seen in 28.6%. PF patients had smaller artery diameters on pre-operative US, with no statistical significance (0.23±0.07; 0.30 ± 0.2; p=0,375). Assisted patency rate was 78.2%. Number of procedures for access permeability was 1, 2 e 3 in 40%, 25.5% and 6.4%, respectively. Mean of 1,5±0,7 interventions per patient. Median time-to-adequate AFV was 2.0 (IQR 2,0 - 6,45) months. Success rate was 72,8%. Conclusion Outcomes at 6 weeks in our cohort were similar to those reported in literature. Timely referencing may increase access patency with resort to vascular intervention. Individualized management is essential, discussing risks and benefits taking into account the treatment burden associated with numerous procedures. Patency rates and outcomes after HD initiation and even cost analysis are essential to guide recommendations.

3D printed grafts with gradient structures for organized vascular regeneration

Synthetic vascular grafts suitable for small-diameter arteries (<6 mm) are in great need. However, there are still no commercially available small-diameter vascular grafts (SDVGs) in clinical practice due to thrombosis and stenosis after in vivo implantation. When designing SDVGs, many studies emphasized reendothelization but ignored the importance of reconstruction of the smooth muscle layer (SML). To facilitate rapid SML regeneration, a high-resolution 3D printing method was used to create a novel bilayer SDVG with structures and mechanical properties mimicking natural arteries. Bioinspired by the collagen alignment of SML, the inner layer of the grafts had larger pore sizes and high porosity to accelerate the infiltration of cells and their circumferential alignment, which could facilitate SML reconstruction for compliance restoration and spontaneous endothelialization. The outer layer was designed to induce fibroblast recruitment by low porosity and minor pore size and provide SDVG with sufficient mechanical strength. One month after implantation, the arteries regenerated by 3D-printed grafts exhibited better pulsatility than electrospun grafts, with a compliance (8.9%) approaching that of natural arteries (11.36%) and significantly higher than that of electrospun ones (1.9%). The 3D-printed vascular demonstrated a three-layer structure more closely resembling natural arteries while electrospun grafts showed incomplete endothelium and immature SML. Our study shows the importance of SML reconstruction during vascular graft regeneration and provides an effective strategy to reconstruct blood vessels through 3D-printed structures rapidly.

The effect of different taping techniques on transtibial amputation walking parameters: A case report.

Buerger disease is a nonatherosclerotic, segmental inflammatory disease of the occlusive tract, often involving medium-sized muscular and small-diameter arteries and veins of the extremities. If medical treatment is not successful, amputation is inevitable. The aim of this study was to investigate the effect of different kinesiological taping techniques on walking parameters of transtibial amputee with knee extension limitation. Two different kinesiological taping methods (Kinesio Tape and Dynamic Tape) were applied to the transtibial patient with knee extension limitation. Walking performance of patients was assessed with The Biodex Gait Trainer 2. Gait parameters without tape were as follows: average walking speed 0.38 m/s, average step cycle 0.48 cyl/s, average left step length 50 cm, average right step length 43 cm, coefficient of variation 9% at the left, and coefficient of variation 9% at the right. After applying Kinesio Tape and Dynamic Tape, these values were measured as follows: average walking speed 0.50.56 m/s, average step cycle 0.51.56 cyl/s, average left step length 61-60 cm, average right step length 53-54 cm, coefficient of variation 6%-5% at the left, and coefficient of variation 6%-4% at the right side. Dynamic Tape and Kinesio Tape both had positive effects on active joint motion and walking parameters. Regarding walking speed and step length, Dynamic Tape was found to be more effective than Kinesio Tape. Taping methods applied to amputees have positive effects on range of motion, which in return causes improvements on walking parameters.

Polyzwitterion-grafted decellularized bovine intercostal arteries as new substitutes of small-diameter arteries for vascular regeneration.

Coronary artery bypass grafting is acknowledged as a major clinical approach for treatment of severe coronary artery atherosclerotic heart disease. This procedure typically requires autologous small-diameter vascular grafts. However, the limited availability of the donor vessels and associated trauma during tissue harvest underscore the necessity for artificial arterial alternatives. Herein, decellularized bovine intercostal arteries were successfully fabricated with lengths ranging from 15 to 30 cm, which also closely match the inner diameters of human coronary arteries. These decellularized arterial grafts exhibited great promise following poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) grafting from the inner surface. Such surface modification endowed the decellularized arteries with superior mechanical strength, enhanced anticoagulant properties and improved biocompatibility, compared to the decellularized bovine intercostal arteries alone, or even those decellularized grafts modified with both heparin and vascular endothelial growth factor. After replacement of the carotid arteries in rabbits, all surface-modified vascular grafts have shown good patency within 30 days post-implantation. Notably, strong signal was observed after α-SMA immunofluorescence staining on the PMPC-grafted vessels, indicating significant potential for regenerating the vascular smooth muscle layer and thereby restoring full structures of the artery. Consequently, the decellularized bovine intercostal arteries surface modified by PMPC can emerge as a potent candidate for small-diameter artificial blood vessels, and have shown great promise to serve as viable substitutes of arterial autografts.

Vasodilators activate the anion channel TMEM16A in endothelial cells to reduce blood pressure.

Systemic blood pressure is acutely controlled by total peripheral resistance as determined by the diameter of small arteries and arterioles, the contractility of which is regulated by endothelial cells lining the lumen of blood vessels. We investigated the physiological functions of the chloride (Cl-) channel TMEM16A in endothelial cells. TMEM16A channels generated calcium (Ca2+)-activated Cl- currents in endothelial cells from control (TMEM16Afl/fl) mice that were absent in those from mice with tamoxifen-inducible, endothelial cell-specific knockout of TMEM16A (TMEM16A ecKO). TMEM16A currents in endothelial cells were activated by the muscarinic receptor agonist acetylcholine and an agonist of the Ca2+ channel TRPV4, which localized in nanoscale proximity with TMEM16A as assessed by single-molecule localization imaging of endothelial cells. Acetylcholine stimulated TMEM16A currents by activating Ca2+ influx through surface TRPV4 channels without altering the nanoscale properties of TMEM16A and TRPV4 surface clusters or their colocalization. In pressurized arteries, activation of TMEM16A channels in endothelial cells induced by acetylcholine; TRPV4 channel stimulation; or intraluminal ATP, another vasodilator, produced hyperpolarization and dilation. Furthermore, deficiency of TMEM16A channels in endothelial cells resulted in increased systemic blood pressure in conscious mice. These data indicate that vasodilators stimulate TRPV4 channels, leading to Ca2+-dependent activation of nearby TMEM16A channels in endothelial cells to produce arterial hyperpolarization, vasodilation, and reduced blood pressure. Thus, TMEM16A is an anion channel in endothelial cells that regulates arterial contractility and blood pressure.

Development of a Novel Hierarchically Biofabricated Blood Vessel Mimic Decorated with Three Vascular Cell Populations for the Reconstruction of Small-Diameter Arteries.

The availability of grafts to replace small-diameter arteries remains an unmet clinical need. Here, the validated methodology is reported for a novel hybrid tissue-engineered vascular graft that aims to match the natural structure of small-size arteries. The blood vessel mimic (BVM) comprises an internal conduit of co-electrospun gelatin and polycaprolactone (PCL) nanofibers (corresponding to the tunica intima of an artery), reinforced by an additional layer of PCL aligned fibers (the internal elastic membrane). Endothelial cells are deposited onto the luminal surface using a rotative bioreactor. A bioprinting system extrudes two concentric cell-laden hydrogel layers containing respectively vascular smooth muscle cells and pericytes to create the tunica media and adventitia. The semi-automated cellularization process reduces the production and maturation time to 6 days. After the evaluation of mechanical properties, cellular viability, hemocompatibility, and suturability, the BVM is successfully implanted in the left pulmonary artery of swine. Here, the BVM showed good hemostatic properties, capability to withstand blood pressure, and patency at 5 weeks post-implantation. These promising data open a new avenue to developing an artery-like product for reconstructing small-diameter blood vessels.

Abstract P3008: A Computational Model Predicts Sex-specific Responses To Calcium Channel Blockers In Mesenteric Vascular Smooth Muscle

The electrical activity of smooth muscle cells underlies the regulation of the diameter of small resistance arteries and arterioles to control blood flow and blood pressure. Historically, measurements of pressure in blood vessels and their responses to drug interventions have been based entirely on data from male animals. Recently, experiments have indicated sex-specific differences in smooth muscle. We hypothesize that the fundamental differences in ion channel expression measured in male and female cells may underlie variable responses to antihypertensive drugs between males and females. To determine if this hypothesis is plausible, we developed a computational model to investigate the effects of measured sex-specific differences in the electrophysiology and Ca 2+ signaling of vascular smooth muscle cells. Contrary to established models suggesting that K V 1.5 channels are the most prominent K V channels regulating membrane potential, our model predicts that K V 2.1 channels play an unexpectedly primary role in the control of membrane potential in female but not in male cells. In addition, we found that sex-specific differences in the amplitude and voltage dependencies of L-type Ca V 1.2 currents between males and females cause higher Ca 2+ influx and higher [Ca 2+ ] i , in female than in male mesenteric smooth muscle cells. To simulate sex differences in the regulation of resistance arteries and arterioles, we developed an idealized vessel model by connecting smooth muscle cells through simulated resistances to represent gap junctional coupling. The model predictions suggest that female arterial smooth muscle is more sensitive to clinically used Ca 2+ channel blockers than male smooth muscle. Our computational framework initiates the first steps toward the investigation of the potential sex-specific impact of antihypertensive drugs, which may lead to more effective treatment for hypertension.

Piezo1 channels mediate vasorelaxation of uterine arteries from pseudopregnant rats.

Introduction: There is a great increase in uterine arterial blood flow during normal pregnancy, which is a result of the cardiovascular changes that occur in pregnancy to adapt the maternal vascular system to meet the increased metabolic needs of both the mother and the fetus. The cardiovascular changes include an increase in cardiac output and more importantly, dilation of the maternal uterine arteries. However, the exact mechanism for the vasodilation is not fully known. Piezo1 mechanosensitive channels are highly expressed in endothelial and vascular smooth muscle cells of small-diameter arteries and play a role in structural remodeling. In this study, we hypothesize that the mechanosensitive Piezo1 channel plays a role in the dilation of the uterine artery (UA) during pregnancy. Methods: For this, 14-week-old pseudopregnant and virgin Sprague Dawley rats were used. In isolated segments of UA and mesenteric resistance arteries (MRA) mounted in a wire myograph, we investigated the effects of chemical activation of Piezo1, using Yoda 1. The mechanism of Yoda 1 induced relaxation was assessed by incubating the vessels with either vehicle or some inhibitors or in the presence of a potassium-free physiological salt solution (K+-free PSS). Results: Our results show that concentration-dependent relaxation responses to Yoda 1 are greater in the UA of the pseudo-pregnant rats than in those from the virgin rats while no differences between groups were observed in the MRAs. In both vascular beds, either in virgin or in pseudopregnant, relaxation to Yoda 1 was at least in part nitric oxide dependent. Discussion: Piezo1 channel mediates nitric oxide dependent relaxation, and this channel seems to contribute to the greater dilation that occurs in the uterine arteries of pseudo-pregnant rats.

Features of remodeling of newly formed vascular tissue based on biodegradable vascular prostheses implanted in the carotid artery of sheep: morphogenetic analysis

Tissue-engineered vascular prostheses developed for prosthesis of small-diameter arteries have high biocompatibility and coverage of their patency after implantation into the vascular bed, and should also show a high probability of forming on their basis a newly formed tissue that is largely susceptible to native vascular tissue.Aim: To evaluate the expected patency of biodegradable vascular prostheses with athrombogenic drug coating in large laboratory animal models.Material and Methods. Vascular prostheses Ø 4 mm were fabricated by electrospinning from a polymer composition of 5% polyhydrosibutyrate/valeriate (PHBV) and 10% polycaprolactone (PCL) and a complex of proangiogenic tissues (GFmix): vascular endothelial growth (VEGF), rare fibroblast growth (bFGF) and chemoattractant molecule (SDF-1α). To induce thromboresistant properties of grafts, an athrombogenic modification of the surface of parts of the fabricated prostheses with heparin and iloprost was carried out. Modified prostheses were implanted in the carotid artery for a period of 12 months. The group with autoarterial implantation acted as a control.Results. In 12 months after implantation, the patency of auto-arterial grafts was 87.5%. The patency of PHBV/PCL/GFmix with heparin and iloprost reached 50% at the time of implantation. The biodegradable frame made of reinforced prostheses was almost completely resorbed with the formation of aneurysms throughout. In the modified prostheses, the main elements of the newly formed vascular tissue are present. There is no formation in the walls of the prostheses.Conclusion. The results showed that biodegradable vascular prostheses PHBV/PCL/GFmixHep/Ilo have a high final patency, which allows us to consider them suitable for the formation of newly formed vascular tissue on their basis. However, due to the aneurysm formation, a long-term execution of the bone tissue of the prosthesis and the thrombogenic properties of the inner surface are required.

Bioreactors for engineering patient-specific tissue grafts

Bioreactors have the potential to advance the clinical application of cell-based therapies. Cell expansion bioreactors have been used commercially for therapeutic applications; however, bioreactor-based engineering of 3D tissue grafts remains challenging owing to the complexity of tissue architectures, cellular heterogeneity and the lack of non-invasive, tissue-specific biomarkers with which to assess graft viability and maturation. Consequently, only a few bioreactor-based start-up companies that engineer patient-specific tissue grafts have emerged. In this Review, we discuss patient-specific bioreactors that can be used to engineer skin, small-diameter arteries and musculoskeletal tissues. We evaluate the impact of precision manufacturing, including 3D bioprinting, automation and non-invasive sensing, on optimizing the biological, chemical and physical parameters of the bioreactors that are required for specific tissue regeneration. We discuss the commercially available tissue-engineering bioreactors and the potential of digital twins and automation, and we outline the scientific and regulatory pathways that must be followed to enable the translation of tissue-specificbioreactors to the clinic. Bioreactors enable the cultivation of mammalian cells in a closely monitored and controlled microenvironment. This Review discusses bioreactor technologies and closed-loop set-ups for producing patient-specific engineered-tissue grafts, including skin, small-diameter arteries and musculoskeletal tissues, with a particular focus on commercialization and regulatory considerations.

Characteristics and Distribution of Intracranial Aneurysms in Patients with Autosomal Dominant Polycystic Kidney Disease Compared with the General Population: A Meta-Analysis.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic condition associated with intracranial aneurysms (IAs). The associated pathophysiology remains unknown but an association with wall shear stress (WSS) is suspected. Cerebral arterial location is the principal factor influencing IA natural history. This study aims to compare IA location specific distribution between ADPKD- and non-ADPKD-patients. The ADPKD-group was composed of data from a systematic review of the literature (2016-2020, N=7), and three cohorts: @neurIST, Novosibirsk and UCAS. The non-ADPKD-group was formed from the @neurIST, UCAS, ISGC and the Finnish cohort from the literature. Patients and IAs characteristics were compared between ADPKD- and non-ADPKD-groups, and a meta-analysis for IA locations was performed. 1184 IAs from ADPKD-patients were compared to 21040 IAs from non-ADPKD-patients. 78.6% of ADPKD-patients had hypertension versus 39.2% of non-ADPKD-patients. 32.4% of ADPKD-patients were smokers versus 31.5% of non-ADPKD-patients. 30.1% of ADPKD-patients had a positive family history for IA versus 15.8% of the non-ADPKD-patients. ADPKD-patients showed a higher rate of IA multiplicity (33.2% versus 23.1%). IAs from ADPKD-patients showed a significant predominance across the internal carotid (ICA) and middle cerebral (MCA) arteries. Posterior communicating (Pcom) IAs were more frequently found in the non-ADPKD-group. The meta-analysis confirmed a predominance of IAs in the ADPKD-patients across large caliber arteries (OR (95% CI): ICA: 1.90 (1.10-3.29); MCA: 1.18 (1.02-1.36)). Small diameter arteries such as the Pcom were observed more in non-ADPKD-patients (0.21 (0.11-0.88)). This analysis shows that IAs diagnosed in ADPKD-patients are more often localized in large caliber arteries from the anterior circulation in comparison to IAs in non-ADPKD-patients. It shows that primary cilia driven wall shear stress vessel remodeling to be more critical in cerebral anterior circulation large caliber arteries.

Dynamic Changes in Retinal Vessel Diameters and Arteriovenous Ratio within 10 Days of Birth

Purpose This study monitored the dynamic changes in retinal vascular width and the AVR in full-term neonates within 1–10 days of birth. Methods It was conducted at hospitals in the Anhui province from October 2020 to March 2022. A total of 700 full-term, healthy infants were chosen randomly within 10 days of birth, and the Star Pupil Medical Cloud Data System (XBDS) was used to collect fundus images. Infants within 6 days of birth were grouped into groups one to six, while those within the 7th to 10th days were grouped into group seven. The fundus photographs were imported into Image-Pro-Plus (IPP) software. The optic disc diameter was measured. The retinal artery and vein’s diameter was measured at a distance between 0.5- and 1.0-disc diameter from the optic disc’s margin. The AVR was also calculated. Finally, each group’s retinal vessel diameters and AVR were compared separately to show their dynamic changes. Results There were differences in the retinal artery diameter between groups one and two, three and four, four and five, and five and six. For retinal vein diameter, there were differences between groups one and two and groups six and seven. There were also differences in the AVR between all groups. In addition, there was a significant positive correlation between the small retinal artery and vein diameters. Conclusion The retinal artery and vein diameters and AVR in neonates change dynamically during the first 10 days of life. The AVR undergoes the most dramatic change daily and is considerably smaller than the AVR in adults. Hence, this study found that the external environment undergoes significant changes following birth that affect the microcirculation. Then, the retinal central vascular system undergoes similar emergency and adaptive alterations.

Risk factor analysis and treatment outcome of patients with spontaneous isolated celiac axis or superior mesenteric artery dissection.

Spontaneous isolated mesenteric artery (celiac axis or superior mesenteric artery [SMA]) dissection (IMAD) is a rare clinical entity. The aim of the present study was to examine the patient demographics, comorbidities, clinical and radiologic features, management, and prognosis and to identify the risk factors predictive of symptoms. We performed a single-center, retrospective review from November 2005 to November 2021 of prospectively collected data from patients with a diagnosis of IMAD. The clinical data and radiologic images were reviewed, and statistical analysis was performed to compare the symptomatic and asymptomatic groups. A total of 78 patients were identified. Of the 78 patients, 24 (31%) had had celiac dissections, 51 (65%) had had SMA dissections, and 3 (4%) had had both celiac and SMA dissections. The mean age was 57.7years (range, 36-84years), with a male predominance (86%). More than one half (55%) of the patients had had hypertension. In addition, 29 patients (37%) were symptomatic, and 24 (31%) had been admitted to the hospital. The symptomatic patients with celiac axis dissections were more likely to have thrombosis (P= .02), significant stenosis (P= .01) or branch extension (P= .02). The symptomatic patients with SMA dissections were more likely to have a smaller artery diameter (P= .07), a longer dissection length (P= .05), thrombosis (P< .001), significant stenosis (P< .001), or branch extension (P= .003). The symptomatic patients were more likely to have been treated with antiplatelet or anticoagulant therapy (P< .001). Only three patients had undergone an intervention. Seven patients (9%) had died of unrelated causes. The Kaplan-Meier survival analysis showed a 5-year survival rate of 96% and 10-year survival rate of 91%. IMAD is an uncommon disease entity with a risk of visceral ischemia. Nonetheless, most of these patients can be treated conservatively with medication, with only a small minority requiring emergency surgery.

Prospective Randomized Controlled Trial Comparing Laparoscopic Palomo Surgery versus Scrotal Antegrade Sclerotherapy in Adolescent Varicocele.

Varicocele is a common condition in adolescence and the most common correctable cause of infertility. This study aimed to analyze and compare the outcomes of scrotal antegrade sclerotherapy (SAS) and laparoscopic Palomo surgery (LPS) in a tertiary referral centre. Patients with left grade 3 varicocele indicated for surgery were prospectively enrolled and randomly allocated to the SAS and LPS groups, with their respective contralateral normal testes taken as controls. The primary outcome measures were clinical varicocele recurrence, testicular catch-up growth, and post-operative hydrocele. All patients were evaluated clinically and using Doppler ultrasound by radiologists. From 2015 to 2020, 113 patients completed the study and were statistically analyzed (SAS, n = 57; LPS, n = 56). All patients had significantly smaller testes pre-operatively that the testicular volume differences with control testes were -23% in SAS and -19% in LPS. At 12-month follow-up, there were no statistical significant difference in clinical recurrences between the 2 groups (SAS = 5.3% vs LPS = 5.4%, P>.05, non-inferiority test). Testicular catch-up growths were observed in both groups, the mean testicular volume difference between the treatment and control testes reduced from -23% to -8.1% in SAS (P<.001) and -19% to -9.3% in LPS (P<.001) at 12-month follow-up. There was no post-operative hydrocele in SAS compared to 7 in LPS (0% vs 13%, P = .006). Both SAS and LPS are safe and effective procedures for treatment of adolescent varicocele with significant positive effect on testicular catch-up growth. SAS is not inferior to LPS in terms of clinical recurrence rate and with significantly less post-operative hydrocele.