Marweh Schmitz

PHDs inhibitor DMOG promotes the vascularization process in the AV loop by HIF-1a up-regulation and the preliminary discussion on its kinetics in rat

BackgroundThe Arterovenous Loop (AV Loop) model is a vascularization model in tissue engineering research, which is capable of generating a three dimensional in vivo unit with cells as well as the supporting vessels within an isolation chmaber. In our previous studies the AV loop in the isolation chamber was discovered to undergo hypoxia, characterized by Hypoxia Inducible Factor (HIF) up-regulation. The vascularization followed the increase of HIF-α temporally, while it was spatially positively correlated with the HIF-α level, as well. This study aims to prove that HIF-1a up-regulation is the stimulus for vascularization in the AV loop model.MethodThe AV loop model in rats was created by interposing a femoral vein graft into the distal ends of the contralateral femoral artery and vein, and the loop was embeded in fibrin matrix and fixed in isolation chamber. PHD (prolyl hydroxylases) inhibitor DMOG (Dimethyloxallyl Glycine) was applied systemically in the rats in 40 mg/KG at day 0 and day 3 (DMOG-1), or in 15 mg/KG at day 8, day10 and day12 (DMOG-2). Two weeks later the specimens were explanted and underwent morphological and molecular evaluations.ResultsCompared to the control group, in the DMOG-2 group the HIF-1α positive rate was siginicantly raised as shown in immunohistochemistry staining, accompanied with a smaller cross section area and greater vessel density, and a HIF-1α accumulation in the kidney. The mRNA of HIF-1α and its angiogenic target gene all increased in different extends. Ki67 IHC demostrate more positive cells. There were no significant change in the DMOG-1 group.ConclusionBy applying DMOG systemically, HIF-1α was up-regulated at the protein level and at the mRNA level, acompanied with angiogenic target gene up-regulateion, and the vascularization was promoted correspondingly. DMOG given at lower dosage constantly after one week tends to have better effect than the group given at larger dosage in the early stage in this model, and promotes cell proliferation, as evidenced by Ki67 IHC. Thus, this study proves that HIF-1a up-regulation is the stimulus for vascularization in the AV loop model and that the process of the vessel outgrowth can be controlled in the AV Loop model utilizing this mechanism.

Experimental total wrapping of breast implants with acellular dermal matrix: A preventive tool against capsular contracture in breast surgery?

BACKGROUND Capsular contracture remains a hitherto unsolved complication after implantation of silicone gel-filled breast prostheses. Based on clinical and experimental data, the use of an acellular dermal matrix as a sheath around implants may lead to lesser capsular contracture acting as a proposed biological environment mimicking wound bed tissue. The aim of our study was to analyse the tissue reaction after implantation of silicone prosthesis with and without an envelope of acellular dermal matrix. METHODS Implantation of 60 silicone prostheses in the back of Lewis rats were carried out, randomly paired taking one rat from group A and one from group B. Group A included implants completely enveloped with xenogenic acellular dermis and group B undraped silicone implants. At 3, 6 and 12 weeks postoperatively, the samples were explanted and subjected to histological and immunohistochemical evaluation. RESULTS A new myofibroblast tissue layer was identified in proximity to the implant in both groups. The thickness of the layer in group A was continuously thinner than in group B regarding the different explantation time points. Implants completely wrapped with acellular dermal matrix showed significantly lesser inflammatory signs at 3 and 12 weeks after implantation compared to controls. Cell proliferation after 12 weeks was significantly decreased in group A. CONCLUSION The slight myofibroblast layer and reduced rate of inflammation and proliferation in the treatment group show a positive effect of total acellular dermal matrix envelope and hypothesise the decrease of capsular contracture in long-term periods.

Combined free flaps with arteriovenous loops for reconstruction of extensive thoracic defects after sternal osteomyelitis

Various local flaps have been described for patients suffering from sternal osteomyelitis and are regarded as a standard procedure for defect reconstruction. In contrast, the use of microsurgical free flaps has been reported anecdotally only. We present our experiences with the combination of an arteriovenous loop and a free flap transfer in defects larger than half of the sternum.

Zonal perfusion patterns in pedicled free-style perforator flaps.

INTRODUCTION Local perforator flaps have become a standard procedure in reconstructive surgery. They allow the transfer of large tissue units with minimal donor-site morbidity. However, clinical studies on flap perfusion changes over time are lacking. The aim of this study was to investigate the perfusion of free-style single perforator flaps with an eccentrically located main perforator by combined laser Doppler spectrophotometry. PATIENTS AND METHODS Ten patients (six male, four female, 29-71 years) were included in this prospective clinical study. All flaps were based on one perforator. Flaps were harvested from the trunk (n = 6) or the proximal upper or lower extremity (n = 4). Flap perfusion was assessed using a combined laser Doppler spectrophotometry (CLDS) device (O2C, Oxygen to See, LEA Medizintechnik, Giessen, Germany) at days 0, 1, 7 and 14 in different zones. RESULTS Flap dimensions were 18.6 ± 4.7 × 7.2 ± 1.6 cm. Two flaps developed minor tip necroses (<10%), eight flaps survived completely. CLDS proved to be very sensitive for the detection of regional perfusion problems. A considerable perfusion gradient was observed at days 0 and 1. Here, reduced blood flow and post-capillary oxygen saturations were found at the tip when compared to the region above main perforator (RAMP). Blood flow remained stable proximally while it improved significantly from day 1 to 14 at the tip region. CONCLUSION CLDS is an effective method for objective evaluation of flap perfusion. Although distal flap perfusion is diminished initially, the majority of perforator flaps with eccentrically located perforators survive completely. Obviously, flap perfusion improved between days 1 and 14. This clinical finding might be explained by reorganisation of the vascular system with opening of so-called connecting or choke vessels. This knowledge might influence decision making in perforator flap surgery.

Cracking the perfusion code?: Laser-assisted Indocyanine Green angiography and combined laser Doppler spectrophotometry for intraoperative evaluation of tissue perfusion in autologous breast reconstruction with DIEP or ms-TRAM flaps

The aim of this prospective study was to assess the correlation of flap perfusion analysis based on laser-assisted Indocyanine Green (ICG) angiography with combined laser Doppler spectrophotometry in autologous breast reconstruction using free DIEP/ms-TRAM flaps. Between February 2014 and July 2015, 35 free DIEP/ms-TRAM flaps were included in this study. Besides the clinical evaluation of flaps, intraoperative perfusion dynamics were assessed by means of laser-assisted ICG angiography and post-capillary oxygen saturation and relative haemoglobin content (rHb) using combined laser Doppler spectrophotometry. Correlation of the aforementioned parameters was analysed, as well as the impact on flap design and postoperative complications. Flap survival rate was 100%. There were no partial flap losses. In three cases, flap design was based on the angiography, contrary to clinical evaluation and spectrophotometry. The final decision on the inclusion of flap areas was based on the angiographic perfusion pattern. Angiography and spectrophotometry showed a correlation in most of the cases regarding tissue perfusion, post-capillary oxygen saturation and relative haemoglobin content. Laser-assisted ICG angiography is a useful tool for intraoperative evaluation of flap perfusion in autologous breast reconstruction with DIEP/ms-TRAM flaps, especially in decision making in cases where flap perfusion is not clearly assessable by clinical signs and exact determination of well-perfused flap margins is difficult to obtain. It provides an objective real-time analysis of flap perfusion, with high sensitivity for the detection of poorly perfused flap areas. Concerning the topographical mapping of well-perfused flap areas, laser-assisted angiography is superior to combined laser Doppler spectrophotometry.

Is there a Rationale for Autologous Breast Reconstruction in Older Patients? A Retrospective Single Center Analysis of Quality of life, Complications and Comorbidities after DIEP or ms‐TRAM Flap Using the BREAST‐Q

Autologous breast reconstruction with the deep inferior epigastric perforator (DIEP) or muscle‐sparing transverse rectus abdominis myocutaneous (ms‐TRAM) flap is a common method in the majority of patients after mastectomy. Because of an increased perioperative risk profile the benefit in older patients is questionable. To assess the postoperative quality of life and peri‐ and post‐operative complications of older compared to younger patients is the aim of this retrospective study. In a retrospective analysis 39 older (i.e. >60 years) and 140 younger patients (i.e. <60 years) with autologous breast reconstruction in the Department of Plastic Surgery at the University Hospital of Erlangen‐Nuernberg were surveyed at least 6 month postoperative using the BREAST‐Q questionnaire. Correlations were generated between comorbidities and complications. Significant differences were observed regarding hospitalization, pre‐existing diseases and the choice of DIEP versus ms‐TRAM flaps. Parameters such as major and minor complications, bulging or hernia and risk factors (e.g. smoking or obesity) showed no significant differences. The results of the questionnaire parameters showed no significant difference between both groups, revealing high satisfaction with the aesthetic result and an improvement in quality of life independent of age. Autologous breast reconstruction after mastectomy generates a gain in quality of life and shows a good to excellent overall satisfaction in older as well as younger patients. Despite a longer hospitalization and a different risk profile there were no significant differences regarding minor and major complications in the postoperative course. Hence autologous breast reconstruction for older patients is justified and should be taken into consideration.

Penile reconstruction with dermal template and vacuum therapy in severe skin and soft tissue defects caused by Fournier's gangrene and hidradenitis suppurativa

The aim of this article is to improve the treatment of patients with complete skin loss of the penile shaft after Fourniers gangrene or hidradenitis suppurativa using modern biomatrices and topical negative pressure therapy.

[Avoidance of complications in oncological surgery of the pelvic region : combined oncosurgical and plastic reconstruction measures].

Prevention of perioperative and postoperative complications resulting from surgical oncology in the pelvic region remains a major interdisciplinary challenge. With modern interdisciplinary concepts joining forces of various surgical specialties, tumor resection can be sufficiently carried out with wide margins and the patients benefit from reduced morbidity even in complex situations. As an example chronic fistulation and secretion from the presacral cavity and sinus may result as potential sequelae from intra-abdominal and intrapelvic tumor resection, especially when neoadjuvant multimodal therapies have been applied. This can be prevented by simultaneous transplantation of for example transpelvic vertical rectus abdominis myocutaneous (VRAM) flap transfer, while extensive perineal skin and soft tissue defects may also be simultaneously reconstructed. In cases of malignant soft tissue tumors in the pelvic region a staged surgical procedure can be performed with a period of time between tumor resection and reconstruction. Thus, a histological R0 status can be secured prior to plastic reconstruction surgery in order to increase oncological safety. In cases of postresectional exposition of e. g. pelvic or femoral vessels or intrapelvic and intra-abdominal organs simultaneous flap procedure is mandatory.The reconstructive armamentarium of the plastic surgeon should contain not only pedicled but also free microsurgical flaps so that no compromise in terms of the extent of the oncological resection has to be accepted. At the same time perioperative and postoperative complications may be avoided and the patient quality of life can be preserved even in more complex cases.

Komplikationsvermeidung in der onkologischen Chirurgie der Becken-/Leistenregion

Prevention of perioperative and postoperative complications resulting from surgical oncology in the pelvic region remains a major interdisciplinary challenge. With modern interdisciplinary concepts joining forces of various surgical specialties, tumor resection can be sufficiently carried out with wide margins and the patients benefit from reduced morbidity even in complex situations. As an example chronic fistulation and secretion from the presacral cavity and sinus may result as potential sequelae from intra-abdominal and intrapelvic tumor resection, especially when neoadjuvant multimodal therapies have been applied. This can be prevented by simultaneous transplantation of for example transpelvic vertical rectus abdominis myocutaneous (VRAM) flap transfer, while extensive perineal skin and soft tissue defects may also be simultaneously reconstructed. In cases of malignant soft tissue tumors in the pelvic region a staged surgical procedure can be performed with a period of time between tumor resection and reconstruction. Thus, a histological R0 status can be secured prior to plastic reconstruction surgery in order to increase oncological safety. In cases of postresectional exposition of e. g. pelvic or femoral vessels or intrapelvic and intra-abdominal organs simultaneous flap procedure is mandatory.The reconstructive armamentarium of the plastic surgeon should contain not only pedicled but also free microsurgical flaps so that no compromise in terms of the extent of the oncological resection has to be accepted. At the same time perioperative and postoperative complications may be avoided and the patient quality of life can be preserved even in more complex cases.

Salvage of a free radial forearm flap by creation of an arteriovenous fistula at the distal arterial pedicle.

Interdisciplinary approaches with infrainguinal bypass grafts and free flaps between the plastic and vascular surgery may well offer an opportunity for diabetic patients with peripheral vascular disease to salvage their critically affected limbs. A free flap transfer combined with an autologous vein graft can cover large tissue defects and simultaneously improve distal perfusion even in patients with arterial occlusive disease. We are presenting a case of bypass‐free radial forearm flap used to cover a foot defect in an old diabetic patient with peripheral arterial disease. The flap perfusion deteriorated significantly during the early postoperative period. The patient was brought back to the operating room with acute thrombosis of the popliteal‐radial venous graft and the arterial pedicle of the flap. The flap was salvaged by thrombectomy and creation of an additional arteriovenous fistula at the distal arterial pedicle. The procedure improved the flap perfusion and decreased the high internal resistance that was noticed in the flap when trying to flush the radial artery during the revision surgery and was evident by continuous wave ‐Doppler sonography. The successful salvage of the flap in the presented case and the convenient long‐term follow up suggest that this technique may be safe and helpful as a last effort to salvage a bypass‐free flap with a suspected high internal resistance.