Transcatheter aortic valve implantation in patients with high-risk symptomatic native aortic regurgitation (ALIGN-AR): a prospective, multicentre, single-arm study.

BACKGROUND: Surgery remains the only recommended intervention for patients with native aortic regurgitation. A transcatheter therapy to treat patients at high risk for mortality and complications with surgical aortic valve replacement represents an unmet need. Commercial transcatheter heart valves in pure aortic regurgitation are hampered by unacceptable rates of embolisation and paravalvular regurgitation. The Trilogy transcatheter heart valve (JenaValve Technology, Irvine, CA, USA) provides a treatment option for these patients. We report outcomes with transfemoral transcatheter aortic valve implantation (TAVI) in patients with pure aortic regurgitation using this dedicated transcatheter heart valve. METHODS: The ALIGN-AR trial is a prospective, multicentre, single-arm study. We recruited symptomatic patients (aged ≥18 years) with moderate-to-severe or severe aortic regurgitation at high risk for mortality and complications after surgical aortic valve replacement at 20 US sites for treatment with the Trilogy transcatheter heart valve. The 30-day composite primary safety endpoint was compared for non-inferiority with a prespecified performance goal of 40·5%. The primary efficacy endpoint was 1-year all-cause mortality compared for non-inferiority with a performance goal of 25%. This trial is registered with ClinicalTrials.gov, NCT04415047, and is ongoing. FINDINGS: Between June 8, 2018, and Aug 29, 2022, we screened 346 patients. We excluded 166 (48%) patients and enrolled 180 (52%) patients with symptomatic aortic regurgitation deemed high risk by the heart team and independent screening committee assessments. The mean age of the study population was 75·5 years (SD 10·8), and 85 (47%) were female, 95 (53%) were male, and 131 (73%) were White. Technical success was achieved in 171 (95%) patients. At 30 days, four (2%) deaths, two (1%) disabling strokes, and two (1%) non-disabling strokes occurred. Using standard Valve Academic Research Consortium-2 definitions, the primary safety endpoint was achieved, with events occurring in 48 (27% [97·5% CI 19·2-34·0]) patients (pnon-inferiority<0·0001), with new pacemaker implantation in 36 (24%) patients. The primary efficacy endpoint was achieved, with mortality in 14 (7·8% [3·3-12·3]) patients at 1 year (pnon-inferiority<0·0001). INTERPRETATION: This study shows the safety and effectiveness of treating native aortic regurgitation using a dedicated transcatheter heart valve to treat patients with symptomatic moderate-to-severe or severe aortic regurgitation who are at high risk for mortality or complications after surgical aortic valve replacement. The observed short-term clinical and haemodynamic outcomes are promising as are signs of left ventricular remodelling, but long-term follow-up is necessary. FUNDING: JenaValve Technology.

Clinical journey for patients with aortic regurgitation: A retrospective observational study from a multicenter database.

BACKGROUND: Data using real-world assessments of aortic regurgitation (AR) severity to identify rates of Heart Valve Team evaluation and aortic valve replacement (AVR), as well as mortality among untreated patients, are lacking. The present study assessed these trends in care and outcomes for real-world patients with documented AR. METHODS: Using a deidentified data set (January 2018-March 2023) representing 1,002,853 patients >18 years of age from 25 US institutions participating in the egnite Database (egnite, Inc.) with appropriate permissions, patients were classified by AR severity in echocardiographic reports. Rates of evaluation by the Heart Valve Team, AVR, and all-cause mortality without AVR were examined using Kaplan-Meier estimates and compared using the log-rank test. RESULTS: Within the data set, 845,113 patients had AR severity documented. For moderate-to-severe or severe AR, respectively, 2-year rates (95% confidence interval) of evaluation by the Heart Valve Team (43.5% [41.7%-45.3%] and 65.4% [63.3%-67.4%]) and AVR (19.4% [17.6%-21.1%] and 46.5% [44.2%-48.8%]) were low. Mortality at 2 years without AVR increased with greater AR severity, up to 20.7% for severe AR (p < 0.001). In exploratory analyses, 2-year mortality for untreated patients with left ventricular end-systolic dimension index > 25 mm/m2 was similar for moderate (34.3% [29.2%-39.1%]) and severe (37.2% [24.9%-47.5%]) AR. CONCLUSIONS: Moderate or greater AR is associated with poor clinical outcomes among untreated patients at 2 years. Rates of Heart Valve Team evaluation and AVR were low for those with moderate or greater AR, suggesting that earlier referral to the Heart Valve Team could be beneficial.

CT in Transcatheter-delivered Treatment of Valvular Heart Disease.

Minimally invasive strategies to treat valvular heart disease have emerged over the past 2 decades. The use of transcatheter aortic valve replacement in the treatment of severe aortic stenosis, for example, has recently expanded from high- to low-risk patients and became an alternative treatment for those with prohibitive surgical risk. With the increase in transcatheter strategies, multimodality imaging, including echocardiography, CT, fluoroscopy, and cardiac MRI, are used. Strategies for preprocedural imaging strategies vary depending on the targeted valve. Herein, an overview of preprocedural imaging strategies and their postprocessing approaches is provided, with a focus on CT. Transcatheter aortic valve replacement is reviewed, as well as less established minimally invasive treatments of the mitral and tricuspid valves. In addition, device-specific details and the goals of CT imaging are discussed. Future imaging developments, such as peri-procedural fusion imaging, machine learning for image processing, and mixed reality applications, are presented.

Coronary CT Fractional Flow Reserve before Transcatheter Aortic Valve Replacement: Clinical Outcomes.

Background The role of CT angiography-derived fractional flow reserve (CT-FFR) in pre-transcatheter aortic valve replacement (TAVR) assessment is uncertain. Purpose To evaluate the predictive value of on-site machine learning-based CT-FFR for adverse clinical outcomes in candidates for TAVR. Materials and Methods This observational retrospective study included patients with severe aortic stenosis referred to TAVR after coronary CT angiography (CCTA) between September 2014 and December 2019. Clinical end points comprised major adverse cardiac events (MACE) (nonfatal myocardial infarction, unstable angina, cardiac death, or heart failure admission) and all-cause mortality. CT-FFR was obtained semiautomatically using an on-site machine learning algorithm. The ability of CT-FFR (abnormal if ≤0.75) to predict outcomes and improve the predictive value of the current noninvasive work-up was assessed. Survival analysis was performed, and the C-index was used to assess the performance of each predictive model. To compare nested models, the likelihood ratio χ2 test was performed. Results A total of 196 patients (mean age ± standard deviation, 75 years ± 11; 110 women [56%]) were included; the median time of follow-up was 18 months. MACE occurred in 16% (31 of 196 patients) and all-cause mortality in 19% (38 of 196 patients). Univariable analysis revealed CT-FFR was predictive of MACE (hazard ratio [HR], 4.1; 95% CI: 1.6, 10.8; P = .01) but not all-cause mortality (HR, 1.2; 95% CI: 0.6, 2.2; P = .63). CT-FFR was independently associated with MACE (HR, 4.0; 95% CI: 1.5, 10.5; P = .01) when adjusting for potential confounders. Adding CT-FFR as a predictor to models that include CCTA and clinical data improved their predictive value for MACE (P = .002) but not all-cause mortality (P = .67), and it showed good discriminative ability for MACE (C-index, 0.71). Conclusion CT angiography-derived fractional flow reserve was associated with major adverse cardiac events in candidates for transcatheter aortic valve replacement and improved the predictive value of coronary CT angiography assessment. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Choe in this issue.

Native Coronary Artery Pseudoaneurysm after Coronary Artery Bypass Grafting.

Coronary artery pseudoaneurysms are extremely rare and most often occur after trauma or endovascular procedures [Aoki 2008; Kar 2017]. Delay in diagnosis or treatment may lead to coronary thrombosis with resultant ischemia or hemorrhage subsequent tamponade. Here, we present the case of a 66-year-old female who developed a coronary artery pseudoaneurysm of a non-grafted vessel three weeks after coronary artery bypass grafting. To avoid re-sternotomy, the pseudoaneurysm was successfully managed with a covered coronary stent and mini-left anterior thoracotomy to evacuate the hemopericardium and relieve tamponade.

Use of a pedicled omental flap to reduce inflammation and vascularize an abdominal wall patch.

BACKGROUND: Although a variety of synthetic materials have been used to reconstruct tissue defects, these materials are associated with complications such as seromas, fistulas, chronic patient discomfort, and surgical site infection. While alternative, degradable materials that facilitate tissue growth have been examined. These materials can still trigger a foreign body inflammatory response that can lead to complications and discomfort. MATERIALS AND METHODS: In this report, our objective was to determine the effect of placing a pedicled omental flap under a biodegradable, microfibrous polyurethane scaffold serving as a full-wall thickness replacement of the rat abdominal wall. It was hypothesized that the presence of the omental tissue would stimulate greater vascularization of the scaffold and act to reduce markers of elevated inflammation in the patch vicinity. For control purposes, a polydimethylsiloxane sheet was placed as a barrier between the omental tissue and the overlying microfibrous scaffold. Both groups were sacrificed 8 wk after the implantation, and immunohistological and reverse transcription polymerase chain reaction (RT-PCR) assessments were performed. RESULTS: The data showed omental tissue placement to be associated with increased vascularization, a greater local M2/M1 macrophage phenotype response, and mRNA levels reduced for inflammatory markers but increased for angiogenic and antiinflammatory factors. CONCLUSIONS: From a clinical perspective, the familiarity with utilizing omental flaps for an improved healing response and infection resistance should naturally be considered as new tissue engineering approaches that are translated to tissue beds where omental flap application is practical. This report provides data in support of this concept in a small animal model.

Left atrial to coronary sinus shunting for treatment of heart failure with mildly reduced or preserved ejection fraction: The ALT FLOW Early Feasibility Study 1-year results.

AIMS: Patients with heart failure and mildly reduced or preserved ejection fraction have limited therapeutic options. The ALT-FLOW Early Feasibility Study evaluated safety, haemodynamics and outcomes for the APTURE transcatheter shunt system, a novel left atrium to coronary sinus shunt in these patients. METHODS AND RESULTS: Safety and shunt implantation success was evaluated for all 116 enrolled patients. An analysis population of implanted patients with a left ventricular ejection fraction (LVEF) >40% (n = 95) was chosen to assess efficacy via paired comparison between baseline and follow-up haemodynamic (3 and 6 months), and echocardiographic, clinical and functional outcomes (6 months and 1 year). Health status and quality of life outcomes were assessed using the Kansas City Cardiomyopathy Questionnaire overall summary score (KCCQ-OSS). The primary safety endpoint, major adverse cardiac, cerebral, and renal events, and reintervention through 30 days, occurred in 3/116 patients (2.6%). All implanted shunts were patent at 1 year. In patients with LVEF >40%, the mean (95% confidence interval) reduction in exercise pulmonary capillary wedge pressure (PCWP) at 20 W was -5.7 (-8.6, -2.9) mmHg at 6 months (p < 0.001). At baseline, 8% had New York Heart Association class I-II status and improved to 68% at 1 year (p < 0.001). KCCQ-OSS at baseline was 39 (35, 43) and improved at 6 months and 1 year by 25 (20-30) and 27 (22-32) points, respectively (both p < 0.0001). No adverse changes in haemodynamic and echocardiographic indices of right heart function were observed at 1 year. Overall, the reduction in PCWP at 20 W and improvement in KCCQ-OSS in multiple subgroups were consistent with those observed for the entire population. CONCLUSIONS: In patients with heart failure and LVEF >40%, the APTURE shunt demonstrated an acceptable safety profile with significant sustained improvements in haemodynamic and patient-centred outcomes, underscoring the need for further evaluation of the APTURE shunt in a randomized trial.

Short- and long-term outcomes with drug-eluting and bare-metal coronary stents: a mixed-treatment comparison analysis of 117 762 patient-years of follow-up from randomized trials.

BACKGROUND: Drug-eluting stents (DES) have been in clinical use for nearly a decade; however, the relative short- and long-term efficacy and safety of DES compared with bare-metal stents (BMS) and among the DES types are less well defined. METHODS AND RESULTS: PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for randomized clinical trials, until March 2012, that compared any of the Food and Drug Administration-approved durable stent and polymer DES (sirolimus-eluting stent [SES], paclitaxel-eluting stent [PES], everolimus-eluting stent [EES], zotarolimus-eluting stent [ZES], and ZES-Resolute [ZES-R]) with each other or against BMS for de novo coronary lesions, enrolling at least 100 patients and with follow-up of at least 6 months. Short-term (≤ 1 year) and long-term efficacy (target-vessel revascularization, target-lesion revascularization) and safety (death, myocardial infarction, stent thrombosis) outcomes were evaluated and trial-level data pooled by both mixed-treatment comparison and direct comparison analyses. From 76 randomized clinical trials with 117 762 patient-years of follow-up, compared with BMS, each DES reduced long-term target-vessel revascularization (39%-61%), but the magnitude varied by DES type (EES~SES~ZES-R>PES~ZES>BMS), with a >42% probability that EES had the lowest target-vessel revascularization rate. There was no increase in the risk of any long-term safety outcomes, including stent thrombosis, with any DES (versus BMS). In addition, there was reduction in myocardial infarction (all DES except PES versus BMS) and stent thrombosis (with EES versus BMS: Rate ratio, 0.51; 95% credibility interval, 0.35-0.73). The safest DES appeared to be EES (>86% probability), with reduction in myocardial infarction and stent thrombosis compared with BMS. Short-term outcomes were similar to long-term outcomes, with SES, ZES-R, and everolimus-eluting stent being the most efficacious and EES being the safest stent. CONCLUSIONS: DES are highly efficacious at reducing the risk of target-vessel revascularization without an increase in any safety outcomes, including stent thrombosis. However, among the DES types, there were considerable differences, such that EES, SES, and ZES-R were the most efficacious and EES was the safest stent.

Outcomes After Transcatheter Mitral Valve Repair in Patients With Renal Disease.

BACKGROUND: Renal disease is associated with poor prognosis despite guideline-directed cardiovascular therapy, and outcomes by sex in this population remain uncertain. METHODS AND RESULTS: Patients (n=5213) who underwent a MitraClip procedure in the National Cardiovascular Data Registry Transcatheter Valve Therapy registry were evaluated for the primary composite outcome of all-cause mortality, stroke, and new requirement for dialysis by creatinine clearance (CrCl). Centers for Medicare and Medicaid Services-linked data were available in 63% of patients (n=3300). CrCl was <60 mL/min in 77% (n=4010) and <30 mL/min in 23% (n=1183) of the cohort. Rates of primary outcome were higher with lower CrCl (>60 mL/min, 1.4%; 30-<60 mL/min, 2.7%; <30 mL/min, 5.2%; dialysis, 7.8%; P<0.001), and all low CrCl groups were independently associated with the primary outcome (30-<60 mL/min: adjusted odds ratio, 2.32; 95% CI, 1.38-3.91; <30 mL/min: adjusted odds ratio, 4.44; 95% CI, 2.63-7.49; dialysis: adjusted hazards ratio, 4.52; 95% CI, 2.08-9.82) when compared with CrCl >60 mL/min. Rates of 1-year mortality were higher with lower CrCl (>60 mL/min, 13.2%; 30-<60 mL/min, 18.8%; <30 mL/min, 29.9%; dialysis, 32.3%; P<0.001), and all low CrCl groups were independently associated with 1-year mortality (30-<60 mL/min: adjusted hazards ratio, 1.50; 95% CI, 1.13-1.99; <30 mL/min: adjusted hazards ratio, 2.38; 95% CI, 1.78-3.20; adjusted hazards ratio: dialysis, 2.44; 95% CI, 1.66-3.57) when compared with CrCl >60 mL/min. CONCLUSIONS: The majority of patients who undergo MitraClip have renal disease. Preprocedural renal disease is associated with poor outcomes, particularly in stage 4 or 5 renal disease where 1-year mortality is observed in nearly one-third. Studies to determine how to further optimize outcomes in this population are warranted.

Evaluation of Poly (Carbonate-Urethane) Urea (PCUU) Scaffolds for Urinary Bladder Tissue Engineering.

Although the previous success of bladder tissue engineering demonstrated the feasibility of this technology, most polyester based scaffolds used in previous studies possess inadequate mechanical properties for organs that exhibit large deformation. The present study explored the use of various biodegradable elastomers as scaffolds for bladder tissue engineering and poly (carbonate-urethane) urea (PCUU) scaffolds mimicked urinary bladder mechanics more closely than polyglycerol sebacate-polycaprolactone (PGS-PCL) and poly (ether-urethane) urea (PEUU). The PCUU scaffolds also showed cyto-compatibility as well as increased porosity with increasing stretch indicating its ability to aid in infiltration of smooth muscle cells. Moreover, a bladder outlet obstruction (BOO) rat model was used to test the safety and efficacy of the PCUU scaffolds in treating a voiding dysfunction. Bladder augmentation with PCUU scaffolds led to enhanced survival of the rats and an increase in the bladder capacity and voiding volume over a 3 week period, indicating that the high-pressure bladder symptom common to BOO was alleviated. The histological analysis of the explanted scaffold demonstrated smooth muscle cell and connective tissue infiltration. The knowledge gained in the present study should contribute towards future improvement of bladder tissue engineering technology to ultimately aide in the treatment of bladder disorders.

Impact of Aortic Root Anatomy and Geometry on Paravalvular Leak in Transcatheter Aortic Valve Replacement With Extremely Large Annuli Using the Edwards SAPIEN 3 Valve.

OBJECTIVES: The aim of this study was to determine factors affecting paravalvular leak (PVL) in transcatheter aortic valve replacement (TAVR) with the Edwards SAPIEN 3 (S3) valve in extremely large annuli. BACKGROUND: The largest recommended annular area for the 29-mm S3 is 683 mm2. However, experience with S3 TAVR in annuli >683 mm2 has not been widely reported. METHODS: From December 2013 to July 2017, 74 patients across 16 centers with mean area 721 ± 38 mm2 (range: 684 to 852 mm2) underwent S3 TAVR. The transfemoral approach was used in 95%, and 39% were under conscious sedation. Patient, anatomic, and procedural characteristics were retrospectively analyzed. Valve Academic Research Consortium-2 outcomes were reported. RESULTS: Procedural success was 100%, with 2 deaths, 1 stroke, and 2 major vascular complications at 30 days. Post-dilatation occurred in 32%, with final balloon overfilling (1 to 5 ml extra) in 70% of patients. Implantation depth averaged 22.3 ± 12.4% at the noncoronary cusp and 20.7 ± 9.9% at the left coronary cusp. New left bundle branch block occurred in 17%, and 6.3% required new permanent pacemakers. Thirty-day echocardiography showed mild PVL in 22.3%, 6.9% moderate, and none severe. There was no annular rupture or coronary obstruction. Mild or greater PVL was associated with larger maximum annular and left ventricular outflow tract (LVOT) diameters, larger LVOT area and perimeter, LVOT area greater than annular area, and higher annular eccentricity. CONCLUSIONS: TAVR with the 29-mm S3 valve beyond the recommended range by overexpansion is safe, with acceptable PVL and pacemaker rates. Larger LVOTs and more eccentric annuli were associated with more PVL. Longer term follow-up will be needed to determine durability of S3 TAVR in this population.

Skeletal muscle derived stem cells microintegrated into a biodegradable elastomer for reconstruction of the abdominal wall.

A variety of techniques have been applied to generate tissue engineered constructs, where cells are combined with degradable scaffolds followed by a period of in vitro culture or direct implantation. In the current study, a cellularized scaffold was generated by concurrent deposition of electrospun biodegradable elastomer (poly(ester urethane)urea, PEUU) and electrosprayed culture medium + skeletal muscle-derived stem cells (MDSCs) or electrosprayed culture medium alone as a control. MDSCs were obtained from green fluorescent protein (GFP) transgenic rats. The created scaffolds were implanted into allogenic strain-matched rats to replace a full thickness abdominal wall defect. Both control and MDSC-integrated scaffolds showed extensive cellular infiltration at 4 and 8 wk. The number of blood vessels was higher, the area of residual scaffold was lower, number of multinucleated giant cells was lower and area of connective tissue was lower in MDSC-integrated scaffolds (p < 0.05). GFP + cells co-stained positive for VEGF. Bi-axial mechanical properties of the MDSC-microintegrated constructs better approximated the anisotropic behavior of the native abdominal wall. GFP + cells were observed throughout the scaffold at ∼5% of the cell population at 4 and 8 wk. RNA expression at 4 wk showed higher expression of early myogenic marker Pax7, and b-FGF in the MDSC group. Also, higher expression of myogenin and VEGF were seen in the MDSC group at both 4 and 8 wk time points. The paracrine effect of donor cells on host cells likely contributed to the differences found in vivo between the groups. This approach for the rapid creation of highly-cellularized constructs with soft tissue like mechanics offers an attractive methodology to impart cell-derived bioactivity into scaffolds providing mechanical support during the healing process and might find application in a variety of settings.

Early Outcomes of Percutaneous Transvenous Transseptal Transcatheter Valve Implantation in Failed Bioprosthetic Mitral Valves, Ring Annuloplasty, and Severe Mitral Annular Calcification.

OBJECTIVES: The aim of this study was to examine 1-year outcomes of transseptal balloon-expandable transcatheter heart valve implantation in failed mitral bioprosthesis, ring annuloplasty, and mitral annular calcification (MAC). BACKGROUND: Immediate outcomes following transseptal mitral valve implantation in failed bioprostheses are favorable, but data on subsequent outcomes are lacking. METHODS: Percutaneous transseptal implantation of balloon-expandable transcatheter heart valves was performed in 87 patients with degenerated mitral bioprostheses (valve in valve [VIV]) (n = 60), previous ring annuloplasty (valve in ring) (n = 15), and severe MAC (valve in MAC) (n = 12). RESULTS: The mean Society of Thoracic Surgeons risk score was 13 ± 8%, and the mean age was 75 ± 11 years. Acute procedural success was achieved in 78 of 87 patients (90%) in the overall group and 58 of 60 (97%) in the VIV group, with a success rate of 20 of 27 (74%) in the valve in ring/valve in MAC group. Thirty-day survival free of death and cardiovascular surgery was 95% (95% confidence interval [CI]: 92% to 97%) in the VIV subgroup and 78% (95% CI: 70% to 86%) in the valve in ring/valve in MAC group (p = 0.008). One-year survival free of death and cardiovascular surgery was 86% (95% CI: 81% to 91%) in the VIV group compared with 68% (95% CI: 58% to 78%) (p = 0.008). At 1 year, 36 of 40 patients (90%) had New York Heart Association functional class I or II symptoms, no patients had more than mild residual mitral prosthetic or periprosthetic regurgitation, and the mean transvalvular gradient was 7 ± 3 mm Hg. CONCLUSIONS: One-year outcomes following successful transseptal balloon-expandable transcatheter heart valve implantation in high-risk patients with degenerated mitral bioprostheses are excellent, characterized by durable symptom relief and prosthesis function. Although mitral valve in ring and valve in MAC have higher operative morbidity and mortality, 1-year outcomes after an initially successful procedure are favorable in carefully selected patients.

Nanometer-sized extracellular matrix coating on polymer-based scaffold for tissue engineering applications.

Surface modification can play a crucial role in enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering applications. Here, we report a novel approach for layer-by-layer (LbL) fabrication of nanometer-size fibronectin and gelatin (FN-G) layers on electrospun fibrous poly(carbonate urethane)urea (PCUU) scaffolds. Alternate immersions into the solutions of fibronectin and gelatin provided thickness-controlled FN-G nano-layers (PCUU(FN-G) ) which maintained the scaffold's 3D structure and width of fibrous bundle of PCUU as evidenced by scanning electron miscroscopy. The PCUU(FN-G) scaffold improved cell adhesion and proliferation of bladder smooth muscles (BSMCs) when compared to uncoated PCUU. The high affinity of PCUU(FN-G) for cells was further demonstrated by migration of adherent BSMCs from culture plates to the scaffold. Moreover, the culture of UROtsa cells, human urothelium-derived cell line, on PCUU(FN-G) resulted in an 11-15 µm thick multilayered cell structure with cell-to-cell contacts although many UROtsa cells died without forming cell connections on PCUU. Together these results indicate that this approach will aid in advancing the technology for engineering bladder tissues in vitro. Because FN-G nano-layers formation is based on nonspecific physical adsorption of fibronectin onto polymer and its subsequent interactions with gelatin, this technique may be applicable to other polymer-based scaffold systems for various tissue engineering/regenerative medicine applications.

Abdominal wall reconstruction by a regionally distinct biocomposite of extracellular matrix digest and a biodegradable elastomer.

Current extracellular matrix (ECM) derived scaffolds offer promising regenerative responses in many settings, however in some applications there may be a desire for more robust and long lasting mechanical properties. A biohybrid composite material that offers both strength and bioactivity for optimal healing towards native tissue behavior may offer a solution to this problem. A regionally distinct biocomposite scaffold composed of a biodegradable elastomer (poly(ester urethane)urea) and porcine dermal ECM gel was generated to meet this need by a concurrent polymer electrospinning/ECM gel electrospraying technique where the electrosprayed component was varied temporally during the processing. A sandwich structure was achieved with polymer fiber rich upper and lower layers for structural support and an ECM-rich inner layer to encourage cell ingrowth. Increasing the upper and lower layer fiber content predictably increased tensile strength. In a rat full thickness abdominal wall defect model, the sandwich scaffold design maintained its thickness whereas control biohybrid scaffolds lacking the upper and lower fiber-rich regions failed at 8 weeks. Sandwich scaffold implants also showed higher collagen content 4 and 8 weeks after implantation, exhibited an increased M2 macrophage phenotype response at later times and developed biaxial mechanical properties better approximating native tissue. By employing a processing approach that creates a sheet-form scaffold with regionally distinct zones, it was possible to improve biological outcomes in body wall repair and provide the means for further tuning scaffold mechanical parameters when targeting other applications. Copyright © 2013 John Wiley & Sons, Ltd.

Large strain stimulation promotes extracellular matrix production and stiffness in an elastomeric scaffold model.

Mechanical conditioning of engineered tissue constructs is widely recognized as one of the most relevant methods to enhance tissue accretion and microstructure, leading to improved mechanical behaviors. The understanding of the underlying mechanisms remains rather limited, restricting the development of in silico models of these phenomena, and the translation of engineered tissues into clinical application. In the present study, we examined the role of large strip-biaxial strains (up to 50%) on ECM synthesis by vascular smooth muscle cells (VSMCs) micro-integrated into electrospun polyester urethane urea (PEUU) constructs over the course of 3 weeks. Experimental results indicated that VSMC biosynthetic behavior was quite sensitive to tissue strain maximum level, and that collagen was the primary ECM component synthesized. Moreover, we found that while a 30% peak strain level achieved maximum ECM synthesis rate, further increases in strain level lead to a reduction in ECM biosynthesis. Subsequent mechanical analysis of the formed collagen fiber network was performed by removing the scaffold mechanical responses using a strain-energy based approach, showing that the denovo collagen also demonstrated mechanical behaviors substantially better than previously obtained with small strain training and comparable to mature collagenous tissues. We conclude that the application of large deformations can play a critical role not only in the quantity of ECM synthesis (i.e. the rate of mass production), but also on the modulation of the stiffness of the newly formed ECM constituents. The improved understanding of the process of growth and development of ECM in these mechano-sensitive cell-scaffold systems will lead to more rational design and manufacturing of engineered tissues operating under highly demanding mechanical environments.

Superficial Femoral Artery Intervention by Single Transpedal Arterial Access.

BACKGROUND: Atherosclerotic disease of the superficial femoral artery (SFA) is frequently seen and can be treated with percutaneous interventions, traditionally via femoral artery access. There are limited reports of transpedal artery access for peripheral artery interventions, but none to date describing routine primary transpedal artery approach for SFA stenting. METHODS: In this preliminary study, we report 4 patients who underwent successful endovascular SFA stenting using a single transpedal artery access via a new ultra-low profile 6 Fr sheath (Glidesheath Slender; Terumo Corporation). RESULTS: All patients underwent successful SFA stenting without complication. Procedure time varied from 51 to 72 minutes. The mean contrast amount used was 56 mL; mean fluoroscopy time was 21 minutes; mean radiation dose was 91 mGy. At 1-month follow-up, duplex ultrasonography showed that all pedal arteries had remained patent. CONCLUSIONS: Transpedal artery approach as a primary approach to SFA stenting appears feasible and safe. Comparative trials with standard percutaneous femoral approach are warranted.

Feasibility and Safety of Routine Transpedal Arterial Access for Treatment of Peripheral Artery Disease.

OBJECTIVE: To demonstrate the feasibility and safety of transpedal arterial access for lower-extremity angiography and intervention. BACKGROUND: Traditionally, the femoral artery is chosen for the initial access site in symptomatic peripheral artery disease (PAD), but this approach carries a substantial portion of the entire procedural complication risk. METHODS: 80 patients were prospectively evaluated for the treatment of PAD between May and July 2014. All patients underwent peripheral angiography, and intervention if necessary. A pedal artery was the initial access site for all patients. Under ultrasound guidance, one of the pedal arteries was visualized and accessed, and a 4 Fr Glidesheath was inserted. Retrograde orbital atherectomy and balloon angioplasty were performed with a 4 Fr sheath or upsizing to a 6 Fr Glidesheath Slender (Terumo) for stenting as needed. Clinical and ultrasound assessment of the pedal arteries were performed before the procedure and at 1-month follow-up. RESULTS: Diagnostic transpedal peripheral angiography was performed in all 80 patients. 43 out of 51 patients (84%) who required intervention were successful using a pedal artery as the sole access site. No immediate or delayed access-site complications were detected. Clinical follow-up was achieved in 77 patients (96%) and access artery patency was demonstrated by ultrasound at 1 month in 100% of patients. CONCLUSION: The routine use of a transpedal approach for the treatment of PAD may be feasible and safe. Pedal artery access may also avoid many of the complications associated with the traditional femoral approach, but further study is needed.

Fabrication of elastomeric scaffolds with curvilinear fibrous structures for heart valve leaflet engineering.

Native semi-lunar heart valves are composed of a dense fibrous network that generally follows a curvilinear path along the width of the leaflet. Recent models of engineered valve leaflets have predicted that such curvilinear fiber orientations would homogenize the strain field and reduce stress concentrations at the commissure. In the present work, a method was developed to reproduce this curvilinear fiber alignment in electrospun scaffolds by varying the geometry of the collecting mandrel. Elastomeric poly(ester urethane)urea was electrospun onto rotating conical mandrels of varying angles to produce fibrous scaffolds where the angle of fiber alignment varied linearly over scaffold length. By matching the radius of the conical mandrel to the radius of curvature for the native pulmonary valve, the electrospun constructs exhibited a curvilinear fiber structure similar to the native leaflet. Moreover, the constructs had local mechanical properties comparable to conventional scaffolds and native heart valves. In agreement with prior modeling results, it was found under quasi-static loading that curvilinear fiber microstructures reduced strain concentrations compared to scaffolds generated on a conventional cylindrical mandrels. Thus, this simple technique offers an attractive means for fabricating scaffolds where key microstructural features of the native leaflet are imitated for heart valve tissue engineering.