Impact of Focused Abdominal Ultrasound Utilization on Outcomes for Children With Midgut Volvulus.

BACKGROUND: Ultrasound (US) is gaining acceptance for the evaluation of midgut volvulus in children. However, its impact on clinical outcomes is unknown. We aim to determine whether using US as a first-line modality changes imaging mobilization, time to surgery and re-feeding, length of stay, and frequency of bowel necrosis, short bowel syndrome, and death. METHODS: An IRB-approved retrospective cohort study was performed at a tertiary pediatric institution. Eighty children with surgically confirmed midgut volvulus from 2014 to 2021 were compared before and after implementation of US as first-line imaging and based on the modality used to diagnose midgut volvulus. RESULTS: Outcomes were not statistically different pre- versus post-implementation. Compared with patients who had UGI only, those who had US only or both had significantly quicker imaging mobilization (median: -33 min; 95% CI: -61.2, -4.8; p = 0.023 and median: -31 min; 95% CI: -58.5, -3.6; p = 0.028 respectively). Patients with US only were less likely to have bowel necrosis compared with those who had UGI only (9.1% versus 43.8%, p = 0.042). Patients who had US only or both were less likely to develop short bowel syndrome compared to UGI only (4.8% US only, 0% both, 40% UGI only; p = 0.027 for US only, p = 0.005 for both). CONCLUSIONS: No statistically significant change in outcomes was found after implementation of US as first-line imaging for midgut volvulus. However, patients diagnosed with US only or US in combination with UGI had quicker imaging mobilization and decreased frequency of bowel necrosis and short bowel syndrome. Findings suggest that US has potential to improve patient outcomes. LEVEL OF EVIDENCE: III.

Case report: Spindle cell neoplasm presenting as a spontaneous intestinal perforation in a term infant.

Spontaneous intestinal perforations in the neonatal population are mostly associated with low birth weight, prematurity, and necrotizing enterocolitis. Spontaneous intestinal perforation in the absence of these risk factors is extremely rare and should raise clinical concern for an underlying bowel pathology. Here we present a unique case of a normal-weight, full-term girl with spontaneous intestinal perforation due to a spindle cell neoplasm with a novel BRAF mutation and infantile fibrosarcoma-like morphology. Though rare, malignancy should be considered in the differential diagnosis for bowel perforation in an otherwise healthy, term infant as complete surgical excision can be curative.

Spontaneous reversal of stenosis in tissue-engineered vascular grafts.

We developed a tissue-engineered vascular graft (TEVG) for use in children and present results of a U.S. Food and Drug Administration (FDA)-approved clinical trial evaluating this graft in patients with single-ventricle cardiac anomalies. The TEVG was used as a Fontan conduit to connect the inferior vena cava and pulmonary artery, but a high incidence of graft narrowing manifested within the first 6 months, which was treated successfully with angioplasty. To elucidate mechanisms underlying this early stenosis, we used a data-informed, computational model to perform in silico parametric studies of TEVG development. The simulations predicted early stenosis as observed in our clinical trial but suggested further that such narrowing could reverse spontaneously through an inflammation-driven, mechano-mediated mechanism. We tested this unexpected, model-generated hypothesis by implanting TEVGs in an ovine inferior vena cava interposition graft model, which confirmed the prediction that TEVG stenosis resolved spontaneously and was typically well tolerated. These findings have important implications for our translational research because they suggest that angioplasty may be safely avoided in patients with asymptomatic early stenosis, although there will remain a need for appropriate medical monitoring. The simulations further predicted that the degree of reversible narrowing can be mitigated by altering the scaffold design to attenuate early inflammation and increase mechano-sensing by the synthetic cells, thus suggesting a new paradigm for optimizing next-generation TEVGs. We submit that there is considerable translational advantage to combined computational-experimental studies when designing cutting-edge technologies and their clinical management.

Acute histologic inflammatory activity and postoperative outcomes in pediatric patients with ulcerative colitis.

BACKGROUND: The aim of this study was to determine whether acute histologic inflammatory activity at the rectal margin predicts postoperative complications in children with ulcerative colitis following ileal pouch-anal anastomoses (IPAA). METHODS: Patients who underwent IPAA following previous total abdominal colectomy for ulcerative colitis between 2006 and 2014 were included. Data collected included demographics, operative and postoperative data, histologic grading of the rectal margin at time of IPAA, and stooling outcomes at one, six and 12 months following ileostomy closure. RESULTS: Twenty-seven patients were included. Acute inflammation scores ranged between 2 and 13. Unadjusted and adjusted models showed no statistically significant relationship between inflammation and presence of any postoperative complications, number of daily stools, nighttime stooling, soiling, or stool-altering medication usage. CONCLUSION: Acute histologic inflammatory activity at the rectal margin is not associated with increased rates of postoperative complications following IPAA creation in children, nor with poorer continence outcomes following ileostomy closure.

Degradation and in vivo evaluation of polycaprolactone, poly(ε-caprolactone-co-L-lactide), and poly-L-lactic acid as scaffold sealant polymers for murine tissue-engineered vascular grafts.

Aim: This study evaluates scaffold degradation and neotissue formation as a function of sealant polymer composition in tissue-engineered vascular grafts (TEVGs). Materials & methods: Scaffolds fabricated from polyglycolic acid core and sealant composed of polycaprolactone (PCL), poly-L-lactic-acid (PLLA) or 50:50 copolymer poly(ε-caprolactone-co-L-lactide) (PCLA) were analyzed in vitro using accelerated degradation and scanning electron microscopy, and in vivo following implantation in a murine inferior vena cava interposition model. Results:In vitro and in vivo characterization revealed statistically greater degradation of PCLA compared with both PCL and PLLA scaffolds, with similar neotissue formation across all groups. The wall thickness of PLLA TEVGs was statistically greater than PCL TEVGs at 2 weeks postimplant. Conclusion: Results of this study can be used to inform the rational design of future TEVGs.

Factors Influencing Poor Outcomes in Synthetic Tissue-Engineered Tracheal Replacement.

OBJECTIVES: Humans receiving tissue-engineered tracheal grafts have experienced poor outcomes ultimately resulting in death or the need for graft explantation. We assessed the performance of the synthetic scaffolds used in humans with an ovine model of orthotopic tracheal replacement, applying standard postsurgical surveillance and interventions to define the factors that contributed to the complications seen at the bedside. STUDY DESIGN: Large animal model. SETTING: Pediatric academic research institute. SUBJECTS AND METHODS: Human scaffolds were manufactured with an electrospun blend of polyethylene terephthalate and polyurethane reinforced with polycarbonate rings. They were seeded with autologous bone marrow-derived mononuclear cells and implanted in sheep. Animals were evaluated with routine bronchoscopy and fluoroscopy. Endoscopic dilation and stenting were performed to manage graft stenosis for up to a 4-month time point. Grafts and adjacent native airway were sectioned and evaluated with histology and immunohistochemistry. RESULTS: All animals had signs of graft stenosis. Three of 5 animals (60%) designated for long-term surveillance survived until the 4-month time point. Graft dilation and stent placement resolved respiratory symptoms and prolonged survival. Necropsy demonstrated evidence of infection and graft encapsulation. Granulation tissue with signs of neovascularization was seen at the anastomoses, but epithelialization was never observed. Acute and chronic inflammation of the native airway epithelium was observed at all time points. Architectural changes of the scaffold included posterior wall infolding and scaffold delamination. CONCLUSIONS: In our ovine model, clinically applied synthetic tissue-engineered tracheas demonstrated infectious, inflammatory, and mechanical failures with a lack of epithelialization and neovascularization.

The relationships of surgeon volume and specialty with outcomes following pediatric thyroidectomy.

BACKGROUND: Previous studies of pediatric thyroidectomies suggest a volume-outcome relationship, but none have focused exclusively on pediatric surgical specialists. Our objective was to examine the effects of pediatric surgeon volume and specialty on post-thyroidectomy outcomes. METHODS: The Pediatric Health Information System was queried for patients ≤21 years who underwent partial or total thyroidectomy between 2005 and 2016. Multivariable logistic regression with propensity score weighting was used to assess the relationships between surgeon volume or specialty and 90-day thyroidectomy-specific complications. High-volume surgeons/hospitals were defined as those in the top tertile of annual thyroidectomies. RESULTS: The inclusion criteria were met by 3149 patients. Patients treated by higher-volume surgeons had significantly fewer complications than those treated by lower-volume surgeons (15.0% vs. 19.2%, p = 0.01). Patients with thyroid cancer also had less morbidity when treated by higher-volume surgeons compared to lower-volume surgeons (25.0% vs. 35.1%, p = 0.03), as did children with Graves' disease (19.8% vs. 29.3%, p = 0.007). Patients managed by pediatric surgeons had fewer complications than those managed by pediatric otolaryngologists across all patients (14.0% vs. 22.5%, p < 0.001) and among cancer (25.3% vs. 42.1%, p < 0.001) and Graves' patients (20.1% vs. 37.3%, p < 0.001) specifically. CONCLUSIONS: Morbidity following pediatric thyroidectomy is associated with surgeon volume. TYPE OF STUDY: Prognostic Study. LEVEL OF EVIDENCE: Level II.

Complications after proctocolectomy and ileal pouch-anal anastomosis in pediatric patients: A systematic review.

BACKGROUND/PURPOSE: Colectomy with ileal pouch-anal anastomosis (IPAA) is the standard of care for patients with familial adenomatous polyposis (FAP) and refractory ulcerative colitis (UC). The rates of postoperative complications are not well established in children. The objective of this systematic review is to establish benchmark data for morbidity after pediatric IPAA. METHODS: PubMed, Embase, and The Cochrane Library were searched for studies of colectomy with IPAA in patients ≤21 years old. UC studies were limited to the anti-tumor necrosis factor-α agents era (1998-present). All postoperative complications were extracted. RESULTS: Thirteen studies met the inclusion criteria (763 patients). Compared to patients with FAP, UC patients had a higher prevalence of pouch loss (10.6% vs. 1.5%). Other major complications such as anastomotic leak, abscess, and fistula were uncommon (mean prevalence 4.9%, 4.2%, and 5.0%, respectively, for patients with UC; 8.7%, 4.2%, and 4.3% for FAP). The most frequent complication was pouchitis (36.4% of UC patients). CONCLUSIONS: Devastating complications from colectomy and IPAA are rare, but patients with UC have poorer outcomes than those with FAP. Much of the morbidity may therefore stem from patient or disease factors. Multicenter, prospective studies are needed to identify modifiable risks in patients with UC undergoing IPAA. LEVEL OF EVIDENCE: Prognostic, level II.

Value of Global Surgical Activities for US Academic Health Centers: A Position Paper by the Association for Academic Surgery Global Affairs Committee, Society of University Surgeons Committee on Global Academic Surgery, and American College of Surgeons' Operation Giving Back.

BACKGROUND: Academic global surgery value to low- and middle-income countries (LMICs) is increasingly understood, yet value to academic health centers (AHCs) remains unclear. STUDY DESIGN: A task force from the Association for Academic Surgery Global Affairs Committee and the Society for University Surgeons Committee on Global Academic Surgery designed and disseminated a survey to active US academic global surgeons. Questions included participant characteristics, global surgeon qualifications, trainee interactions, academic output, productivity challenges, and career models. The task force used the survey results to create a position paper outlining the value of academic global surgeons to AHCs. RESULTS: The survey had a 58% (n = 36) response rate. An academic global surgeon has a US medical school appointment, spends dedicated time in an LMIC, spends vacation time doing mission work, or works primarily in an LMIC. Most spend 1 to 3 months abroad annually, dedicating <25% effort to global surgery, including systems building, teaching, research, and clinical care. Most are university-employed and 65% report compensation is equivalent or greater than colleagues. Academic support includes administrative, protected time, funding. Most institutions do not use specific global surgery metrics to measure productivity. Barriers include funding, clinical responsibilities, and salary support. CONCLUSIONS: Academic global surgeons spend a modest amount of time abroad, require minimal financial support, and represent a low-cost investment in an under-recognized scholarship area. This position paper suggests measures of global surgery that could provide opportunities for AHCs and surgical departments to expand missions of service, education, and research and enhance institutional reputation while achieving societal impact.

Quantification of tissue-engineered trachea performance with computational fluid dynamics.

OBJECTIVES/HYPOTHESIS: Current techniques for airway characterization include endoscopic or radiographic measurements that produce static, two-dimensional descriptions. As pathology can be multilevel, irregularly shaped, and dynamic, minimal luminal area (MLA) may not provide the most comprehensive description or diagnostic metric. Our aim was to examine the utilization of computational fluid dynamics (CFD) for the purpose of defining airway stenosis using an ovine model of tissue-engineered tracheal graft (TETG) implantation. STUDY DESIGN: Animal research model. METHODS: TETGs were implanted into sheep, and MLA was quantified with imaging and endoscopic measurements. Graft stenosis was managed with endoscopic dilation and stenting when indicated. Geometries of the TETG were reconstructed from three-dimensional fluoroscopic images. CFD simulations were used to calculate peak flow velocity (PFV) and peak wall shear stress (PWSS). These metrics were compared to values derived from a quantitative respiratory symptom score. RESULTS: Elevated PFV and PWSS derived from CFD modeling correlated with increased respiratory symptoms. Immediate pre- and postimplantation CFD metrics were similar, and implanted sheep were asymptomatic. Respiratory symptoms improved with stenting, which maintained graft architecture similar to dilation procedures. With stenting, baseline PFV (0.33 m/s) and PWSS (0.006 Pa) were sustained for the remainder of the study. MLA measurements collected via bronchoscopy were also correlated with respiratory symptoms. PFV and PWSS found via CFD were correlated (R2 = 0.92 and 0.99, respectively) with respiratory symptoms compared to MLA (R2 = 0.61). CONCLUSIONS: CFD is valid for informed interventions based on multilevel, complex airflow and airway characteristics. Furthermore, CFD may be used to evaluate TETG functionality. LEVEL OF EVIDENCE: NA. Laryngoscope, E272-E279, 2018.

The Heart and Great Vessels.

Cardiovascular disease is the leading cause of mortality worldwide. We have made large strides over the past few decades in management, but definitive therapeutic options to address this health-care burden are still limited. Given the ever-increasing need, much effort has been spent creating engineered tissue to replaced diseased tissue. This article gives a general overview of this work as it pertains to the development of great vessels, myocardium, and heart valves. In each area, we focus on currently studied methods, limitations, and areas for future study.

Designing a tissue-engineered tracheal scaffold for preclinical evaluation.

OBJECTIVE: Recent efforts to tissue engineer long-segment tracheal grafts have been complicated by stenosis and malacia. It has been proposed that both the mechanical characteristics and cell seeding capacity of TETG scaffolds are integral to graft performance. Our aim was to design a tracheal construct that approximates the biomechanical properties of native sheep trachea and optimizes seeding with bone marrow derived mononuclear cells prior to preclinical evaluation in an ovine model. METHODS: A solution of 8% polyethylene terephthalate (PET) and 3% polyurethane (PU) was prepared at a ratio of either 8:2 or 2:8 and electrospun onto a custom stainless steel mandrel designed to match the dimensional measurements of the juvenile sheep trachea. 3D-printed porous or solid polycarbonate C-shaped rings were embedded within the scaffolds during electrospinning. The scaffolds underwent compression testing in the anterior-posterior and lateral-medial axes and the biomechanical profiles compared to that of a juvenile ovine trachea. The most biomimetic constructs then underwent vacuum seeding with ovine bone marrow derived mononuclear cells. Fluorometric DNA assay was used to quantify scaffold seeding. RESULTS: Both porous and solid rings approximated the biomechanics of the native ovine trachea, but the porous rings were most biomimetic. The load-displacement curve of scaffolds fabricated from a ratio of 2:8 PET:PU most closely mimicked that of native trachea in the anterior-posterior and medial-lateral axes. Solid C-ringed scaffolds had a greater cell seeding efficiency when compared to porous ringed scaffolds (Solid: 19 × 104 vs. Porous: 9.6 × 104 cells/mm3, p = 0.0098). CONCLUSION: A long segment tracheal graft composed of 2:8 PET:PU with solid C-rings approximates the biomechanics of the native ovine trachea and demonstrates superior cell seeding capacity of the two prototypes tested. Further preclinical studies using this graft design in vivo would inform the rational design of an optimal TETG scaffold.

The role of myeloid cell-derived PDGF-B in neotissue formation in a tissue-engineered vascular graft.

AIM: Inflammatory myeloid lineage cells mediate neotissue formation in tissue-engineered vascular grafts, but the molecular mechanism is not completely understood. We examined the role of vasculogenic PDGF-B in tissue-engineered vascular graft neotissue development. MATERIALS & METHODS: Myeloid cell-specific PDGF-B knockout mice (PDGF-KO) were generated using bone marrow transplantation, and scaffolds were implanted as inferior vena cava interposition grafts in either PDGF-KO or wild-type mice. RESULTS: After 2 weeks, grafts from PDGF-KO mice had more remaining scaffold polymer and less intimal neotissue development. Increased macrophage apoptosis, decreased smooth muscle cell proliferation and decreased collagen content was also observed. CONCLUSION: Myeloid cell-derived PDGF contributes to vascular neotissue formation by regulating macrophage apoptosis, smooth muscle cell proliferation and extracellular matrix deposition.

Endoscopic management of tissue-engineered tracheal graft stenosis in an ovine model.

OBJECTIVE: To evaluate the safety and efficacy of bronchoscopic interventions in the management of tissue-engineered tracheal graft (TETG) stenosis. STUDY DESIGN: Animal research study. METHODS: TETGs were constructed with seeded autologous bone marrow-derived mononuclear cells on a bioartificial graft. Eight sheep underwent tracheal resection and orthotopic implantation of this construct. Animals were monitored by bronchoscopy and fluoroscopy at 3 weeks, 6 weeks, 3 months, and 4 months. Bronchoscopic interventions, including dilation and stenting, were performed to manage graft stenosis. Postdilation measurements were obtained endoscopically and fluoroscopically. RESULTS: Seven dilations were performed in six animals. At the point of maximal stenosis, the lumen measured 44.6 ± 8.4 mm2 predilation and 50.7 ± 14.1 postdilation by bronchoscopy (P = 0.3517). By fluoroscopic imaging, the airway was 55.9 ± 12.9 mm2 predilation and 65.9 ± 22.4 mm2 postdilation (P = 0.1303). Stents were placed 17 times in six animals. Pre- and poststenting lumen sizes were 62.8 ± 38.8 mm2 and 80.1 ± 54.5 mm2 by bronchoscopy (P = 0.6169) and 77.1 ± 38.9 mm2 and 104 ± 60.7 mm2 by fluoroscopy (P = 0.0825). Mortality after intervention was 67% with dilation and 0% with stenting (P = 0.0004). The average days between bronchoscopy were 8 ± 2 for the dilation group and 26 ± 17 in the stenting group (P = 0.05). One hundred percent of dilations and 29% of stent placements required urgent follow-up bronchoscopy (P = 0.05). CONCLUSION: Dilation has limited efficacy for managing TETG stenosis, whereas stenting has a more lasting clinical effect. LEVEL OF EVIDENCE: NA. Laryngoscope, 127:2219-2224, 2017.

Intravascular Ultrasound Characterization of a Tissue-Engineered Vascular Graft in an Ovine Model.

Patients who undergo implantation of a tissue-engineered vascular graft (TEVG) for congenital cardiac anomalies are monitored with echocardiography, followed by magnetic resonance imaging or angiography when indicated. While these methods provide data regarding the lumen, minimal information regarding neotissue formation is obtained. Intravascular ultrasound (IVUS) has previously been used in a variety of conditions to evaluate the vessel wall. The purpose of this study was to evaluate the utility of IVUS for evaluation of TEVGs in our ovine model. Eight sheep underwent implantation of TEVGs either unseeded or seeded with bone marrow-derived mononuclear cells. Angiography, IVUS, and histology were directly compared. Endothelium, tunica media, and graft were identifiable on IVUS and histology at multiple time points. There was strong agreement between IVUS and angiography for evaluation of luminal diameter. IVUS offers a valuable tool to evaluate the changes within TEVGs, and clinical translation of this application is warranted.

Objective characterization of airway dimensions using image processing.

OBJECTIVES: With the evolution of medical and surgical management for pediatric airway disorders, the development of easily translated techniques of measuring airway dimensions can improve the quantification of outcomes of these interventions. We have developed a technique that improves the ability to characterize endoscopic airway dimensions using common bronchoscopic equipment and an open-source image-processing platform. METHODS: We validated our technique of Endoscopic Airway Measurement (EAM) using optical instruments in simulation tracheas. We then evaluated EAM in a large animal model (Ovis aries, n = 5), comparing tracheal dimensions obtained with EAM to measurements obtained via 3-D fluoroscopic reconstruction. The animal then underwent resection of the measured segment, and direct measurement of this segment was performed and compared to radiographic measurements and those obtained using EAM. RESULTS: The simulation tracheas had a direct measurement of 13.6, 18.5, and 24.2 mm in diameter. The mean difference of diameter in simulation tracheas between direct measurements and measurements obtained using EAM was 0.70 ± 0.57 mm. The excised ovine tracheas had an average diameter of 18.54 ± 0.68 mm. The percent difference in diameter obtained from EAM and from 3-D fluoroscopic reconstruction when compared to measurement of the excised tracheal segment was 4.98 ± 2.43% and 10.74 ± 4.07% respectively. Comparison of these three measurements (EAM, measurement of resected trachea, 3-D fluoroscopic reconstruction) with repeated measures ANOVA demonstrated no statistical significance. CONCLUSIONS: Endoscopic airway measurement (EAM) provides equivalent measurements of the airway with the improved versatility of measuring non-circular and multi-level dimensions. Using optical bronchoscopic instruments and open-source image-processing software, our data supports preclinical and clinical translation of an accessible technique to provide objective quantification of airway diameter.

Nonoperative management of esophageal perforations in the newborn.

BACKGROUND: Esophageal perforation in neonates occurs most often in cases of extreme prematurity and is commonly due to iatrogenic causes. Treatment over recent decades has become more conservative. The purpose of this study was to review cases of esophageal perforation in neonates and to describe the presentation, management, and outcomes. MATERIALS AND METHODS: A retrospective chart review was performed for patients with International Classification of Diseases, Ninth Revision code for esophageal perforation treated at our institution between the years 2009 and 2015. Data collected included demographic information, etiology of perforation (specifically focusing on cases secondary to orogastric tube placement), treatment course, time to resumption of enteral feeds, length of antibiotic use, time to subsequent radiographic resolution, and mortality. RESULTS: Twenty-five patients met study criteria. The average post-conceptual age at time of diagnosis was 26.5 ± 2.3 wk. All 25 patients were managed nonoperatively with bowel rest, parenteral nutrition, and broad-spectrum antibiotics. Enteral feeds were resumed after a median of 8 d (interquartile range [IQR]: 7-11), the median antibiotic duration was 7 d (IQR: 7-10), and the median time to follow-up esophagram was 7 d (IQR: 7-10). Overall, 24 of 25 patients (96%) demonstrated radiological resolution of perforation on initial follow-up esophagram. Four patients died during the study period, but no deaths were related to the diagnosis of esophageal perforation. CONCLUSIONS: In this largest reported sample of neonates treated for esophageal perforation, nonoperative management with bowel rest, parenteral nutrition, and antibiotics was successful.

Clinical Translation of Tissue Engineered Trachea Grafts.

OBJECTIVE: To provide a state-of-the-art review discussing recent achievements in tissue engineered tracheal reconstruction. DATA SOURCES AND REVIEW METHODS: A structured PubMed search of the current literature up to and including October 2015. Representative articles that discuss the translation of tissue engineered tracheal grafts (TETG) were reviewed. CONCLUSIONS: The integration of a biologically compatible support with autologous cells has resulted in successful regeneration of respiratory epithelium, cartilage, and vascularization with graft patency, although the optimal construct composition has yet to be defined. Segmental TETG constructs are more commonly complicated by stenosis and delayed epithelialization when compared to patch tracheoplasty. IMPLICATIONS FOR PRACTICE: The recent history of human TETG recipients represents revolutionary proof of principle studies in regenerative medicine. Application of TETG remains limited to a compassionate use basis; however, defining the mechanisms of cartilage formation, epithelialization, and refinement of in vivo regeneration will advance the translation of TETG from the bench to the bedside.

Long-Term Functional Efficacy of a Novel Electrospun Poly(Glycerol Sebacate)-Based Arterial Graft in Mice.

Many surgical interventions for cardiovascular disease are limited by the availability of autologous vessels or suboptimal performance of prosthetic materials. Tissue engineered vascular grafts show significant promise, but have yet to achieve clinical efficacy in small caliber (<5 mm) arterial applications. We previously designed cell-free elastomeric grafts containing solvent casted, particulate leached poly(glycerol sebacate) (PGS) that degraded rapidly and promoted neoartery development in a rat model over 3 months. Building on this success but motivated by the need to improve fabrication scale-up potential, we developed a novel method for electrospinning smaller grafts composed of a PGS microfibrous core enveloped by a thin poly(ε-caprolactone) (PCL) outer sheath. Electrospun PGS-PCL composites were implanted as infrarenal aortic interposition grafts in mice and remained patent up to the 12 month endpoint without thrombosis or stenosis. Many grafts experienced a progressive luminal enlargement up to 6 months, however, due largely to degradation of PGS without interstitial replacement by neotissue. Lack of rupture over 12 months confirmed sufficient long-term strength, due primarily to the persistent PCL sheath. Immunohistochemistry further revealed organized contractile smooth muscle cells and neotissue in the inner region of the graft, but a macrophage-driven inflammatory response to the residual polymer in the outer region of the graft that persisted up to 12 months. Overall, the improved surgical handling, long-term functional efficacy, and strength of this new graft strategy are promising, and straightforward modifications of the PGS core should hasten cellular infiltration and associated neotissue development and thereby lead to improved small vessel replacements.