Latex-Infused Porcine Abdominal Model: A Novel Microsurgery Simulator for Deep Inferior Epigastric Perforator Dissection.

BACKGROUND: Perforator dissection and flap elevation are routinely performed for microsurgical reconstruction; however, there is a steep learning curve to mastering these technical skills. Though live porcine models have been utilized as a microsurgical training model, there are significant drawbacks that limit their use, including cost, limited ability for repetition, and obstacles associated with animal care. Here we describe the creation of a novel perforator dissection model using latex augmented non-living porcine abdominal walls. We provide anatomic measurements that demonstrate valuable similarities and differences to human anatomy to maximize microsurgical trainee practice. METHODS: Six latex-infused porcine abdomens were dissected based on the deep cranial epigastric artery (DCEA). Dissection was centered over the abdominal wall mid-segment between the second and fourth nipple line. Dissection steps included exposure of lateral and medial row perforators, incision of anterior rectus sheath with perforator dissection, and dissection of DCEA pedicle. DCEA pedicle and perforator measurements were compared with deep inferior epigastric artery (DIEA) data in the literature. RESULTS: An average of seven perforators were consistently identified within each flap. Assembly of the model was performed quickly and allowed for two training sessions per specimen. Porcine abdominal walls demonstrate similar DCEA pedicle (2.6 ± 0.21 mm) and perforator (1.0 ± 0.18 mm) size compared with a human's DIEA (2.7 ± 0.27 mm, 1.1 ± 0.85 mm). CONCLUSION: The latex-infused porcine abdominal model is a novel, realistic simulation for perforator dissection practice for microsurgical trainees. Impact on resident comfort and confidence within a microsurgical training course is forthcoming.

Activity of Gas Transmitters in Vessels of the Anterior Abdominal Wall after Implantation of a Polypropylene Mesh.

The distribution of NO and H2S in the arterial vessels of the anterior abdominal wall after implantation of a polypropylene mesh was studied by immunohistochemical methods at different stages of healing of the surgical wound in mature male Wistar rats. The presence of enzymes of NO and H2S synthesis in the wall of arterial vessels of the soft tissues of the anterior abdominal wall has been established. It has been shown that endothelial NO synthase is localized exclusively in the endothelium of both large and small vessels. Cystathionine γ lyase in small vessels is located only in the endothelial lining, whereas in large arteries and vessels of medium caliber, it is located in the endothelium and in myocytes. Inducible NO synthase appears in the artery wall only in animals with implanted polypropylene mesh by day 5 of the postoperative period, reaching the maximum by day 10. The content and localization of cystathionine γ lyase in the vascular wall of sham-operated and experimental rats did not much differ from the control values.

Comparison of Polypropylene and Bioabsorbable Mesh for Abdominal Wall Reinforcement following Microsurgical Breast Reconstruction.

BACKGROUND: Abdominal wall morbidity following microvascular breast reconstruction continues to be an area of interest due to both functional and aesthetic concerns. Donor-site closure technique has been shown to affect bulge and hernia rates and ranges from primary closure to various uses of mesh. Few studies to date have compared types of mesh. The present study compares BARD polypropylene to bioabsorbable GORE Bio-A (polyglycolic acid/trimethylene carbonate) mesh used as a fascial underlay with primary fascial closure. METHODS: A retrospective review of all consecutive deep inferior epigastric artery-based microvascular breast reconstructions, including perforator and muscle-sparing flaps, performed between September 2014 and February 2017 was performed. All patients underwent primary fascial closure with mesh underlay. Risk factors for the formation of an abdominal bulge or hernia were identified by multivariate logistic regression. RESULTS: Eighty-seven patients, with 123 abdominal donor sites, were included. Heavy-weight polypropylene mesh was used for 58 donor sites, while polyglycolic acid/trimethylene carbonate mesh was used in 65 donor sites. The overall incidence of bulge or hernia was 11.4%. The bioabsorbable cohort experienced significantly more bulges/hernias than the polypropylene mesh cohort (20% vs. 1.7% by donor site). Time to diagnosis of bulge was longer for the bioabsorbable group (219 ± 107 vs. 69 days). Flap type and perforator row were not associated with bulge/hernia. The polyglycolic acid/trimethylene carbonate mesh was associated with a 13.3-fold risk of bulge/hernia (p = 0.016). CONCLUSION: Polyglycolic acid/trimethylene carbonate mesh is not appropriate for anterior rectus fascia reinforcement following abdominal tissue transfer.

Phacomatosis pigmentovascularis type 2b (phacomatosis cesioflammea) with double superior vena cava, abdominal varicosities, and natal tooth: Novel associations.

Phacomatosis pigmentovascularis is characterized by coexistent extensive cutaneous vascular (capillary) and pigmentary anomalies. We describe a 2-month-old infant presenting with classic features of phacomatosis pigmentovascularis 2b (phacomatosis cesioflammea). He was also found to have hitherto unreported associations in the form of extensive venous anomalies presenting as striking abdominal wall varicosities and persistent left superior vena cava and natal tooth.

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.

[DELAYED AND PRIMARY RECONSTRUCTION OF MAMMARY GLAND IN PATIENTS WITH THE BREAST CANCER].

Immediate and late follow­up results of oncoplastic operations, performed in 75 patients, suffering mammary gland cancer (MGC), including in 22­a delayed, and in 53­primary reconstruction of the breast, were analyzed. In 66 patients musculo­ cutaneous flaps on nutrient pedicle, taken up from the back and abdominal wall tissues, with underlying mammary gland endoprosthesis,were applied as a transplant. Ductal invasive MGC was diagnosed in 70 patients, invasive lobular one ­ in 5. After delayed reconstruction of the breast 81.8% patients have survived five years, and after primary reconstruction ­ 73.6%. Performance of oncoplastic operations in patients, suffering MGC, have permitted to achieve satisfactory immediate and late follow­up results of treatment, it constitutes essential element in complex of rehabilitation measures after performance of radical mastectomy.

Foreign-body response to sterile catheters is variable over 20 weeks.

We hypothesized that placement of sterile catheter material into the peritoneal cavity results in a foreign-body response that varies with exposure duration. Sterile medical Silastic catheter material was aseptically implanted into the abdomens of 42 anesthetized Sprague-Dawley rats. Controls (n = 18) underwent sham operations without catheter implantation. After 4, 8, or 20 weeks, the animals were anesthetized, the abdomen was opened, and the catheter material was recovered and processed to separate the cells adhering to the catheters. The cells, abdomen, and catheter material were all cultured to demonstrate sterility, and transport experiments were carried out. After euthanasia of the animals, abdominal wall tissue was examined for submesothelial thickness and vascular density, and immunohistochemistry (IHC) for cytokines was performed. Cells from the catheter material were processed for immunocytochemistry (ICC). The catheter, adherent cells, and abdomen were free of bacteria. Inflammatory changes in peritoneal thickness and angiogenesis were highest at 4 weeks and declined thereafter to 20 weeks. Transport of mannitol was higher at 4 weeks in treated animals than in controls, and albumin transport was higher at 8 weeks in treated animals than in controls. The IHC for cytokines demonstrated changes paralleling the structural alterations (p < 10(-5)). The ICC of the catheter cell layer demonstrated mesothelial cells, macrophages, fibroblasts, and T cells. Over 20 weeks, the foreign-body response to polymer catheters placed intraperitoneally in rats without injection of solution depends on exposure time, with an initial immune response evident at 4 weeks and decreasing thereafter.

Intraoperative near-infrared fluorescence imaging in perforator flap reconstruction: current research and early clinical experience.

Despite recent advances in perforator flap reconstruction, there can be significant variability in vessel size and location. Although preoperative evaluation may provide valuable information, real-time intraoperative methods have the potential to provide the greatest benefit. Our laboratory has developed the Fluorescence-Assisted Resection and Exploration (FLARE) near-infrared (NIR) fluorescence imaging system for intraoperative visualization of details of the underlying vasculature. The FLARE system uses indocyanine green, a safe and reliable NIR fluorophore already FDA-approved for other indications. The system has been optimized in large-animal models for the identification of perforator size, location, and perfusion and has also been translated to the clinic for use during breast reconstruction after mastectomy. In this article, we review our preclinical and clinical data, as well as literature describing the use of similar NIR fluorescence imaging systems in plastic and reconstructive surgery.

Transarterial embolization with n-butyl cyanoacrylate for the treatment of abdominal wall hemorrhage.

PURPOSE: We aimed to evaluate the effectiveness and safety of n-butyl cyanoacrylate (n-BCA) in the context of the transarterial embolization (TAE) of abdominal wall hemorrhage in an urgent scenario. METHODS: A retrospective study of cases admitted from January 2008 to December 2017 in the emergency unit of our institution revealed 11 patients with abdominal wall hemorrhage who underwent digital subtraction angiography and TAE with n-BCA. We analyzed the sex, age, hemorrhagic risk factors, etiology, embolized vessel, technical success (no rebleeding in the embolized area), clinical success (hemoglobin level control and hemodynamic stability after the procedure), complications inherent to the procedure, and clinical outcome (mortality in 30 days). RESULTS: The mean age was 63.4 years (52-83 years), with a predominance of the female sex (64%). The majority (91%) of patients presented hemorrhagic risk factors (chronic hepatopathy and anticoagulation drug usage). Spontaneous hemorrhage was present in 18% of patients, and the other 82% had an iatrogenic etiology. Technical success was achieved in 100% of the patients, which required the embolization of inferior epigastric artery in 10 patients (91%), circumflex iliac artery in 2 (18%), and superior epigastric artery in 1 (9%). Five patients were hemodynamically unstable, and despite achieving technical success, 4 (36%) died in less than 30 days due to decompensation of their clinical comorbidities caused by the acute phase. There were no complications inherent to the procedures. CONCLUSION: The present study concludes that TAE with n-BCA is a safe and effective treatment for abdominal wall hemorrhage in an urgent scenario, with high rates of technical and clinical success.

The in vivo anatomy of the deep circumflex iliac artery perforators: defining the role for the DCIA perforator flap.

The deep circumflex iliac artery (DCIA) provides a dependable option for use as an osteo-musculo-cutaneous flap, particularly in mandibular reconstruction. Modifications to flaps based on DCIA perforators have been sought to prevent donor site morbidity as a consequence of muscle cuff harvest. Previous studies have been inconsistent in their descriptions of perforator anatomy, and means of assessing these preoperatively have not been widely described. A clinical anatomical study was undertaken, with a cohort of 44 hemiabdominal walls in 22 consecutive patients undergoing preoperative computed tomographic angiography (CTA) before free flap surgery. The feasibility of CTA and the regional vascular anatomy were both assessed. The use of CTA was shown to demonstrate DCIA perforators with high resolution and to be able to assess vessel size and location. In 44 hemiabdominal walls, there were 44 perforators of >0.8 mm diameter. There were no suitable perforators in 40% of sides, with 32% of sides having one perforator >0.8 mm diameter, 16% having two perforators, <10% had three perforators, and only one side had over four perforators. Perforators emerged from the deep fascia on an average of 5.1 cm cranial and 3.9 cm posterior to the anterior superior iliac spine (ASIS). Of the 44 perforators identified, 82% of perforators were located within a 4 cm by 4 cm area, 3 cm superior, and 2 cm posterior to the ASIS. The current study has demonstrated the utility of preoperative CTA for identifying DCIA perforators, and for selecting patients who may be suitable for a DCIA perforator flap given the variable perforator anatomy.

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.

[Protective silicone prosthesis prior to radiotherapy of recurrent colonic cancer]. / Skjermende silikonprotese ved bestråling for residiv av coloncancer.

Radiation therapy for abdominal recurrence of colon cancer is rarely an option due to subsequent bowel injury. Our case is a woman who underwent resection for a large retroperitoneal recurrence of caecal cancer. Tumour deposits encasing the iliac vessels had to be left behind. A silicone breast prosthesis for displacement of the abdominal content was implanted, allowing postoperative irradiation with 50 Gy. The prosthesis was removed once radiotherapy was accomplished; tumour regression was then complete. Complications are described, so are indications for surgical management of local recurrences of colonic origin as well as technical aspects of abdominal implantation of displacing prostheses. At follow-up after eighteen months the patient has no signs of enteropathy, she enjoys a good quality of life, and she is free of disease. Still, her prognosis is considered uncertain.

Carbon nanotubes as VEGF carriers to improve the early vascularization of porcine small intestinal submucosa in abdominal wall defect repair.

Insufficient early vascularization in biological meshes, resulting in limited host tissue incorporation, is thought to be the primary cause for the failure of abdominal wall defect repair after implantation. The sustained release of exogenous angiogenic factors from a biocompatible nanomaterial might be a way to overcome this limitation. In the study reported here, multiwalled carbon nanotubes (MWNT) were functionalized by plasma polymerization to deliver vascular endothelial growth factor165 (VEGF165). The novel VEGF165-controlled released system was incorporated into porcine small intestinal submucosa (PSIS) to construct a composite scaffold. Scaffolds incorporating varying amounts of VEGF165-loaded functionalized MWNT were characterized in vitro. At 5 weight percent MWNT, the scaffolds exhibited optimal properties and were implanted in rats to repair abdominal wall defects. PSIS scaffolds incorporating VEGF165-loaded MWNT (VEGF-MWNT-PSIS) contributed to early vascularization from 2-12 weeks postimplantation and obtained more effective collagen deposition and exhibited improved tensile strength at 24 weeks postimplantation compared to PSIS or PSIS scaffolds, incorporating MWNT without VEGF165 loading (MWNT-PSIS).

Successful treatment of mesenteric varices by retrograde transvenous obliteration by the delivery of N-butyl-2-cyanoacrylate via an abdominal wall vein.

Bleeding from mesenteric varices associated with portal hypertension is occasionally life-threatening. A 53-year-old man who had undergone esophageal transection for esophageal varices and balloon-occluded retrograde transvenous obliteration for gastric varices presented with melena due to ruptured mesenteric varices. He was treated by injecting N-butyl-2-cyanoacrylate via an abdominal wall vein to obtain retrograde transvenous obliteration.

Impregnation of implantable polypropylene mesh with S-nitrosoglutathione-loaded poly(vinyl alcohol).

Clinical complications of implantable polypropylene (PP) meshes used to repair urinary incontinence and vaginal prolapse may be associated with their low surface energy and consequent poor tissue integration. For improving tissue integration, we impregnated monofilament PP meshes with physically crosslinked poly(vinyl alcohol) (PVA), resulting in PVA deposits tightly attached inside the knot spaces of the PP knit. While preserving the mesh porosity, the PVA deposits acted as an array of hydrophilic regions leading to a great increase in the overall mesh wettability, reflected by a contact angle decrease from 111 to ca. 66°. The PVA deposits were also used as reservoirs for the local release of S-nitrosoglutathione (GSNO), a nitric oxide (NO) donor. Plain and impregnated PP meshes (1.0cm×1.0cm) were implanted in the subcutaneous tissue of 21 adult female Wistar rats. Histological analysis of the abdominal wall 21 days after the surgeries revealed lower edema and greater angiogenesis while a marked decrement of NOx concentration in the tissue surrounding the impregnated meshes was observed after 2 days. These results indicate that PVA and PVA/GSNO impregnation might be a new strategy for decreasing the frequency of mesh extrusion after PP mesh implants.

Transcatheter arterial embolization of intramuscular active hemorrhage with N-butyl cyanoacrylate.

PURPOSE: This study was designed to evaluate the clinical efficacy and safety of transcatheter arterial embolization (TAE) with n-butyl cyanoacrylate (NBCA) for intramuscular active hemorrhage of varied etiologies and anatomic sites. METHODS: Eighteen patients who demonstrated hematoma with pseudoaneurysm and/or active extravasation of contrast media underwent TAE with NBCA. Etiologies of hematoma included trauma, postoperative complication, and coagulopathy (due to underlying disease or anticoagulation therapy). Sites of embolization included chest wall, abdomen wall, retroperitoneum, and extremity. TAE was performed by using 1:3 to 1:5 mixtures of NBCA and iodized oil, either solely (n = 15) or in combination with microcoil (n = 3). The technical and clinical success rate, procedure-related complications, and clinical outcomes were evaluated. RESULTS: The technical and clinical success rates were 100% and 83% (15/18), respectively. Two patients expired while admitted due to other comorbidities. One patient expired due to recurrent bleeding at another site. There were no serious complications relating to the embolization procedure. CONCLUSIONS: TAE with NBCA is effective and safe treatment modality for intramuscular active hemorrhage.

Comparison of Permacol™ and Strattice™ for the repair of abdominal wall defects.

BACKGROUND: Incisional hernias repaired with mesh can be expected have a lower recurrence rate than with primary repair. Biologic implants have replaced synthetic meshes in certain complex settings. We compared two porcine-dermis derived implants--cross-linked Permacol™ biologic implant and non-cross linked Strattice-firm™ tissue matrix--in a ventral hernia animal model. Our hypothesis is that cross-linked biologic implants are remodeled differently and thus behave differently than non-cross-linked biologic implants. METHODS: Eighty-nine, female Sprague-Dawley rats had a 3 × 3 cm full-thickness segment of the abdominal wall excised. A 3 × 3 cm biologic mesh, either Permacol™ or Strattice™, was secured and the skin was closed. At 1-, 3-, 6- and 12-month time intervals, rats in each group were sacrificed and the mesh was excised. The number of adhesions, surface area, mesh thickness and tensile strength were determined, and immunohistochemical analysis performed. RESULTS: Permacol™ biologic implant maintained thickness while Strattice™ thickness decreased significantly starting at 3 months. Adhesion area and tenacity were not significantly different between Permacol™ and Strattice™ at all time points. The tensile strength of the Permacol™ biologic implant was greater than that of Strattice™ at 3, 6 and 12 months. Migration of host cells and neo-vascularization was observed in both implant groups. CONCLUSIONS: Cross-linked materials may prove more durable in the remodeling process as suggested by the increased thinning and weakening observed in non-cross-linked biomesh.

In-vivo and in-vitro histological evaluation of two commercially available acellular dermal matrices.

PURPOSE: Post-herniation abdominal wall repair can be performed with synthetic or biologic meshes. Synthetics have been associated with complications, so biologics are promising alternatives. The methods used to decellularize biological matrices may affect the extracellular components. This study evaluated the post-implantation biological response of two allogenic acellular dermal matrices (ADMs) in a hernia model. METHODS: Testing was conducted with two ADMs from different manufacturers: RTI Biologics (ADM-R) and LifeCell (ADM-L). Samples were evaluated for collagen IV, glycosaminoglycans (GAGs), and elastin before implantation. Samples were also used to repair bilateral full-thickness defects in rat abdominal walls. Pathologist evaluations included explant dimensions, inflammation, neovascularization, mature implant tissue, fibrosis, encapsulation, necrosis, mineralization, adhesions, granulomas, and hemorrhages at four and eight weeks post-implantation. RESULTS: GAG distribution in ADM-R samples was more consistent with native dermis than that in ADM-L samples. Collagen IV was visible in ADM-R, but not in ADM-L. The four-week ADM-R explants showed primarily lymphocytic infiltrates, and less inflammation at eight weeks. The four-week ADM-L explants showed primarily lymphocytic infiltrates, and sustained inflammation at eight weeks. Fibroplasia at four and eight weeks was higher in ADM-L than in ADM-R. Encapsulation, mature connective tissue, and vascular profile scores were comparable between groups. Picrosirius red image analysis showed no significant differences between groups. CONCLUSIONS: The post-processing matrix characterization and in-vivo response showed notable differences in these ADMs, despite similar allogenic origin. Future investigations into the different matrix composition with regard to fibrosis and inflammation are warranted.