A Hirner

University of Bonn, Bonn, North Rhine-Westphalia, Germany

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Publications (272)383.14 Total impact

  • Zeitschrift für Gastroenterologie 08/2015; 41(08). DOI:10.1055/s-0035-1555386 · 1.05 Impact Factor
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    ABSTRACT: Background: Active matrix metallopeptidase 9 (MMP-9) disruption of the extracellular matrix (ECM) plays an important role in inflammatory disorders. In this study, we investigated the inflammatory role of MMP-9 and the ECM breakdown product hyaluronan as a trigger for the postoperative intestinal inflammatory response of postoperative ileus. Methods: We performed a standardized intestinal surgical manipulation on rats to produce ileus assessed by the oral non-digestible fluorescein isothiocyanate-dextran transit assay. We studied isolated intestinal muscularis extracts for mRNA expressions of interleukin 6 (IL-6), MMP-9 and CD44. We quantified peritoneal MMP-9 activity using zymography, and quantified peritoneal fluid and serum for hyaluronan and tissue inhibitor of metalloproteinase 1 levels by enzyme-linked immunosorbent assay (ELISA). We cultured peritoneal macrophages and exposed them to peritoneal fluid or synthetic hyaluronan for ELISA analysis of IL-6 and macrophage inflammatory protein-1α. Results: Transit was significantly delayed after surgical manipulation, and extracts of the isolated jejunal and colonic muscularis demonstrated a significant induction of IL-6, MMP-9, and CD44 mRNAs compared with controls. Zymography confirmed significant MMP-9 activity in peritoneal fluid compared with controls. Enzyme-linked immunosorbent assay measurements showed a significant up-regulation in hyaluronan and tissue inhibitor of metalloproteinase 1 in the peritoneal fluid and serum. In addition, ELISA and reverse transcriptase-polymerase chain reaction measurements of peritoneal macrophages stimulated with postsurgical peritoneal fluid and synthetic hyaluronan resulted in higher expressions of IL-6 and macrophage inflammatory protein-1α in the macrophage supernatant. Conclusions: Our results confirm that MMP-9 disruption in the ECM with hyaluronan release and muscularis CD44 receptor induction has the potential to trigger muscularis proinflammatory cascades that cause postoperative ileus. Matrix metallopeptidase 9 inhibition may be a novel therapeutic approach to limit postoperative ileus.
    Journal of Surgical Research 06/2012; 178(2). DOI:10.1016/j.jss.2012.05.044 · 1.94 Impact Factor
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    ABSTRACT: Abstract Background: The aim of this study was to analyze the efficiency and safety of the bipolar tissue/vessel sealing and cutting device EnSeal(™) in comparison to the conventional clamp and ligation technique in visceral surgery. Material and methods: In an acute animal model, a part of the small bowel, a part of the colon and the kidneys were resected either with the conventional clamp and ligation technique or with EnSeal(™). Operation time, blood loss and blood parameters as well as the lateral thermal spread were evaluated. Results:Small bowel, colon and kidney resection time with the EnSeal(™) device was shorter compared to the conventional clamp and ligation technique (small bowel: EnSeal(™): 4.7 ± 1.0 min vs. con: 35.1 ± 2.3 min; colon: EnSeal(™): 7.0 ± 1.4 min vs. con: 16.3 ± 1.5 min, kidney: EnSeal(™): 5.7 ± 1.3 min vs. con: 16.7 ± 3.7 min, p < 0.05) and blood loss was significantly lower. Blood analysis demonstrated no differences in both groups. The lateral thermal spread was not more than 1 mm with EnSeal(™). Conclusion: The bipolar sealing in visceral surgery with EnSeal(™) can be performed more efficiently in a shorter time, with significantly less blood loss, minimal thermal damage and without changes of blood parameters, indicating biological safety and integrity.
    Minimally invasive therapy & allied technologies: MITAT: official journal of the Society for Minimally Invasive Therapy 01/2012; 21(6). DOI:10.3109/13645706.2011.651145 · 1.27 Impact Factor
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    ABSTRACT: Zusammenfassung Im Vergleich zur konventionellen Technik mittels offener Netzimplantation (Sublay-Technik) können mit der laparoskopischen intraperitonealen Onlay-Mesh (IPOM)-Technik Narbenhernien und Nabelhernien, insbesondere bei adipösen Patienten, mit einem geringeren Operationstrauma erfolgreich versorgt werden. Der kürzeren Operationsdauer und der schnelleren postoperativen Rekonvaleszenz der Patienten und dementsprechend kürzeren Krankenhausverweildauer stehen höhere (Material-)Kosten entgegen. Diese Studie soll anhand einer vergleichenden Analyse beider Operationstechniken unter Berücksichtigung des DRG-Systems die perioperativen Vor- und Nachteile beider Methoden aufzeigen.
    Der Chirurg 09/2011; DOI:10.1007/s00104-011-2076-x · 0.57 Impact Factor
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    ABSTRACT: In comparison to the conventional technique of incisional or umbilical hernia repair with sublay mesh augmentation, incisional hernias in obese patients can be surgically treated with minor surgical trauma by laparoscopic intraperitoneal onlay mesh (IPOM) repair. However, although shortened operation time, hospital stay and faster postoperative reconvalescence might be possible with IPOM repair, the economic calculation including mesh costs is significantly higher. In this study the two operation techniques were compared and the perioperative advantages and disadvantages of both methods were analyzed based on the German diagnosis-related groups (DRG) system.
    Der Chirurg 03/2011; 82(9):813-9. · 0.57 Impact Factor
  • N Fischer · C Fisang · A Hirner · S C Müller ·
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    ABSTRACT: Intrathoracic kidneys are rare and are often only diagnosed incidentally. The literature on intrathoracic kidneys in children and adults is reviewed and discussed, focusing on diagnostic procedures and surgical therapy. Additionally, the case of a 35-year-old woman with a relapse of a left-sided intrathoracic kidney after pregnancy is reported. Diagnostic procedures and the surgical management are discussed.
    Der Chirurg 02/2011; 82(2):160, 162-3. · 0.57 Impact Factor
  • N. Fischer · C. Fisang · A. Hirner · S.C. Müller ·
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    ABSTRACT: Intrathorakale Nieren sind seltene und meist zufällig erhobene Befunde. Eine Besprechung der Fachliteratur über intrathorakale Nieren bei Kindern und Erwachsenen soll die Schwerpunkte der diagnostischen Vorangehensweise und der Indikation zur operativen Versorgung beleuchten. Ergänzend wird der Fall einer 35-jährigen Frau mit dem Rezidiv einer linksseitigen intrathorakalen Niere nach Schwangerschaft diskutiert. Intrathoracic kidneys are rare and are often only diagnosed incidentally. The literature on intrathoracic kidneys in children and adults is reviewed and discussed, focusing on diagnostic procedures and surgical therapy. Additionally, the case of a 35-year-old woman with a relapse of a left-sided intrathoracic kidney after pregnancy is reported. Diagnostic procedures and the surgical management are discussed. SchlüsselwörterThoraxniere–Bochdalek-Hernie–Hernienverschluss–Flankenschmerzen–Ultrasonographie KeywordsIntrathoracic kidneys–Bochdalek hernia–Hernia closure–Lateral pain–Ultrasonography
    Der Chirurg 02/2011; 82(2):160-163. DOI:10.1007/s00104-010-1967-6 · 0.57 Impact Factor
  • A Koscielny · D Engel · J Maurer · A Hirner · C Kurts · J C Kalff ·
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    ABSTRACT: Standardized intestinal manipulation (IM) leads to local bowel wall inflammation subsequently spreading over the entire gastrointestinal tract. Previously, we demonstrated that this so-called gastrointestinal field effect (FE) is immune mediated. This study aimed to investigate the role of CCR7 in IM-induced FE. Since CCR7 is expressed on activated dendritic cells and T cells and is well known to control their migration, we hypothesized that lack of CCR7 reduces or abolishes FE. Small bowel muscularis and colonic muscularis from CCR7(-/-) and wild-type (WT) mice were obtained after IM of the jejunum or sham operation. FE was analyzed by measuring gastrointestinal transit time of orally given fluorescent dextran (geometric center), colonic transit time, infiltration of MPO-positive cells, and circular smooth muscle contractility. Furthermore, mRNA levels of the inflammatory cytokine IL-6 were determined by RT-PCR. The number of dendritic cells and CD3+CD25+ T cells separately isolated from jejunum and colon was determined in mice after IM and sham operation. There was no significant difference in IL-6 mRNA upregulation in colonic muscularis between sham-operated WT and CCR7(-/-) mice after IM. Contractility of circular muscularis strips of the colon was significantly improved in CCR7(-/-) animals following IM and did not vary significantly from sham-operated animals. Additionally, inflammation of the colon determined by the number of MPO-positive cells and colonic transit time was significantly reduced in CCR7(-/-) mice. In contrast, jejunal contractility and jejunal inflammation of transgenic mice did not differ significantly from WT mice after IM. These data are supported by a significant increase of CD3+CD25+ T cells in the colonic muscularis of WT mice after IM, which could not be observed in CCR7(-/-) mice. These data demonstrate that CCR7 is required for FE and postoperative ileus. CCR7 indirectly affects FE by inhibiting migration of activated dendritic cells and of T cells from the jejunum to the colon. These findings support the critical role of the adaptive immune system in FE.
    AJP Gastrointestinal and Liver Physiology 02/2011; 300(4):G665-75. DOI:10.1152/ajpgi.00224.2010 · 3.80 Impact Factor
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    ABSTRACT: Localized abdominal surgery can lead to disruption of motility in the entire gastrointestinal tract (postoperative ileus). Intestinal macrophages produce mediators that paralyze myocytes, but it is unclear how the macrophages are activated, especially those in unmanipulated intestinal areas. Here we show that intestinal surgery activates intestinal CD103(+)CD11b(+) dendritic cells (DCs) to produce interleukin-12 (IL-12). This promotes interferon-γ (IFN-γ) secretion by CCR9(+) memory T helper type 1 (T(H)1) cells which activates the macrophages. IL-12 also caused some T(H)1 cells to migrate from surgically manipulated sites through the bloodstream to unmanipulated intestinal areas where they induced ileus. Preventing T cell migration with the drug FTY720 or inhibition of IL-12, T-bet (T(H)1-specific T box transcription factor) or IFN-γ prevented postoperative ileus. CCR9(+) T(H)1 memory cells were detected in the venous blood of subjects 1 h after abdominal surgery. These findings indicate that postoperative ileus is a T(H)1 immune-mediated disease and identify potential targets for disease monitoring and therapy.
    Nature medicine 12/2010; 16(12):1407-13. DOI:10.1038/nm.2255 · 27.36 Impact Factor
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    ABSTRACT: As we have shown in the past, acute rejection-related TNF-α upregulation in resident macrophages in the tunica muscularis after small bowel transplantation (SBTx) results in local amplification of inflammation, decisively contributing to graft dysmotility. Therefore, the aim of this study is to investigate the effectiveness of the chimeric-monoclonal-anti-TNF-α antibody infliximab as perioperative single shot treatment addressing inflammatory processes during acute rejection early after transplantation. Orthotopic, isogenic and allogenic SBTx was performed in rats (BN-Lewis/BN-BN) with infliximab treatment. Vehicle and IV-immunoglobulin-treated animals served as controls. Animals were sacrificed after 24 and 168 h. Leukocyte infiltration was investigated in muscularis whole mounts by immunohistochemistry, mediator mRNA expression by Real-Time-RT-PCR, apoptosis by TUNEL and smooth muscle contractility in a standard organ bath. Both, infliximab and Sandoglobulin® revealed antiinflammatory effects. Infliximab resulted in significantly less leukocyte infiltration compared to allogenic controls and IV-immunoglobulin, which was accompanied by lower gene expression of MCP-1 (24 h), IFN-γ (168 h) and infiltration of CD8-positive cells. Smooth muscle contractility improved significantly after 24 h compared to all controls in infliximab treated animals accompanied by lower iNOS expression. Perioperative treatment with infliximab is a possible pharmaceutical approach to overcome graft dysmotility early after SBTx.
    American Journal of Transplantation 11/2010; 10(11):2431-41. DOI:10.1111/j.1600-6143.2010.03279.x · 5.68 Impact Factor
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    ABSTRACT: Mechanical trauma of the gut is an unavoidable event in abdominal surgery. Former studies demonstrated that intestinal manipulation induces a strong inflammation within the tunica muscularis. We hypothesized that mechanical strain initiates or aggravates proinflammatory responses in intestinal smooth muscle cells (iSMC) or macrophages. First, an appropriate isolation and culture method for neonatal rat iSMC was established. Purified iSMC and primary peritoneal macrophages (pMacs) were subjected to static or cyclic strain, and gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6, and IL-1β was analyzed by quantitative PCR. Supernatants from stretched iSMC were transferred to untreated pMacs or contrariwise, and medium transfer-triggered inflammatory gene expression was measured in unstretched cells. Finally, we investigated the synergistic effect of static strain on LPS-induced proinflammatory gene expression. Although cyclic strain failed, static strain significantly induced iNOS, COX-2, and IL-1β mRNA in iSMC. pMacs showed an increase in all inflammatory genes investigated as well as macrophage inflammatory protein (MIP)-1α and MIP-2 mRNA after static strain. Both cell entities liberated unknown mediators in response to stretch that mutually stimulated iNOS gene expression. Finally, mechanostimulation amplified LPS-induced iNOS and IL-1β gene expression in iSMC as well as COX-2 and IL-6 mRNA in pMacs. In conclusion, static strain initiates proinflammatory gene expression in iSMC and pMacs and triggers a bidirectional paracrine communication between both cultured cell entities via the liberation of unknown mediators. Furthermore, static strain synergistically operates with Toll-like receptor 4 ligation in a cell-specific manner. Hence, this study demonstrates that mechanical strain functions as an immunomodulatory stimulus in abdominal cells.
    AJP Gastrointestinal and Liver Physiology 11/2010; 299(5):G1187-97. DOI:10.1152/ajpgi.00452.2009 · 3.80 Impact Factor
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    ABSTRACT: Here we report on a patient with a primary hepatocellular carcinoma in a non-cirrhotic liver, in whom heterozygosity for an AAT-deficiency allele was found (PiMZ). Based on this observation and the current literature, the possible mechanisms for an eventual contribution of a heterozygosity of a heterozygous AAT-deficiency for a hepatocellular carcinoma are discussed. Alpha-1-antitrypsin (AAT)-deficiency (Laurell-Eriksson syndrome) is a genetic disorder, in which individuals who are homozygous for a deficiency allele are at an increased lifetime risk for pulmonary emphysema, liver cirrhosis, and primary hepatocellular carcinoma. It has been controversially discussed whether the heterozygous form (PiMZ) is also associated with an increased risk for liver diseases. Hepatocarcinogenesis for AAT-deficiency is probably based on a series of toxic events. Precipitation of AAT aggregates in hepatocytes is the initial step. These accumulate in the endoplasmic reticulum and cannot be eliminated from all hepatocytes by proteasomal and non-proteasomal mechanisms. AAT aggregates induce proinflammatory pathways and may be a stimulus for hepatocarcinogenesis. This hypothesis is based mostly on studies of individuals homozygous for a deficiency allele (PiZZ). The mechanism may also play a role in heterozygous patients. Since not all patients with precipitates of AAT-aggregates are develop a hepatocellular carcinoma related comorbidities such as chronic hepatitis B, C, chronic alcohol abuse, or so far unknown genetic and environmental factors may be crucial.
    Zeitschrift für Gastroenterologie 10/2010; 48(10):1211-4. DOI:10.1055/s-0029-1245204 · 1.05 Impact Factor
  • T R Glowka · J C Kalff · D Pantelis · A Hirner · J Standop ·
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    ABSTRACT: Early revision procedures after pancreatic head resection significantly increase mortality. Due to their complexity, secondary operations at a later stage rank amongst the most demanding surgical procedures. We sought to critically analyze indications and outcome from early revision and subsequent redo procedures following distal pancreatic resection (DPR). During a 5-year period 53 subsequent patients undergoing DPR were identified from a pancreatic resection database and analyzed regarding indication for and outcome of early revision and late redo procedures. Six patients (11%) underwent early revision procedures during the same hospital stay. Indications were peritonitis (n = 3), intraabdominal hemorrhage (n = 2) and oncologic re-resection (n = 1). Four patients (7.6%) were readmitted after 192 days (d) on average (range 53 - 538d) and underwent subsequent redo surgery due to occurrence of metastases in 2 cases, and insufficiency of an ascendo-rectostomy and adhesive ileus. Hospital stay and mortality were significantly increased after early revision surgery (40d vs. 18d; 33% vs. 0%). Splenectomy during DPR was carried out in all patients requiring early operative reintervention, compared to 63% in patients without secondary surgery (p < 0.07). Early revision surgery following DPR increases postoperative mortality and length of hospital stay. Risk factors were complex injuries (e.g. gun shot wound), concomitant portal hypertension with collateral circulation and splenectomy. Subsequent redo surgery following DPR was performed on average within 7 month following the index operation without mortality and with comparable morbidity. Indications were recurrent malignant disease and complications of the intestine.
    Hepato-gastroenterology 07/2010; 57(101):952-6. · 0.93 Impact Factor
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    ABSTRACT: In small bowel transplantation (SBTx), graft manipulation, ischemia/reperfusion injury and acute rejection initiate a severe cellular and molecular inflammatory response in the muscularis propria leading to impaired motility of the graft. This study examined and compared the effect of tacrolimus and sirolimus on inflammation in graft muscularis. After allogeneic orthotopic SBTx, recipient rats were treated with tacrolimus or sirolimus. Tacrolimus and sirolimus attenuated neutrophilic, macrophage and T-cell infiltration in graft muscularis, which was associated with reduced apoptotic cell death. Nonspecific inflammatory mediators (IL-6, MCP-1) and T-cell activation markers (IL-2, IFN-gamma) were highly upregulated in allogeneic control graft muscularis 24 h and 7 days after SBTx, and tacrolimus and sirolimus significantly suppressed upregulation of these mediators. In vitro organ bath method demonstrated a severe decrease in graft smooth muscle contractility in allogeneic control (22% of normal control). Correlating with attenuated upregulation of iNOS, tacrolimus and sirolimus treatment significantly improved contractility (64% and 72%, respectively). Although sirolimus reduced cellular and molecular inflammatory response more efficiently after 24 h, contrary tacrolimus prevented acute rejection more efficiently. In conclusion, tacrolimus and sirolimus attenuate cellular and molecular inflammatory response in graft muscularis and subsequent dysmotility of the graft after allogeneic SBTx.
    American Journal of Transplantation 07/2010; 10(7):1545-55. DOI:10.1111/j.1600-6143.2010.03117.x · 5.68 Impact Factor
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    ABSTRACT: Parkinson's disease (PD) is a progressive degenerative disease of the human central nervous system with a demographical increase in surgical patients. Comorbidities are known to increase the perioperative risk profile and therefore amplify treatment expenses. The aim of this study was to analyse whether the reimbursement of additional costs due to PD in surgical patients was sufficiently considered by diagnosis-related grouping (DRG). Over a period of 13 years, 50 patients suffering from MP treated in the Department of Surgery were retrospectively compared using matched-pair analysis with controls not affected by PD. Both groups of patients were assessed regarding hospital stay and mortality and morbidity with an emphasis on reimbursement by the National Ordinance on Hospital Rates (Bundespflegesatzverordung, BPflV) from 2004 (last year of employment) compared to DRG in 2007. Extra reimbursement for PD patients in comparison to controls diminished from 20 % according to BPflV (2004) to 2 % according to DRG (2007). Within the DRG System of 2007, total compensation for PD and control patients was significantly lower (47 vs. 35 %) compared to the BPflV of 2004. Compensation of surgical therapy in PD patients has significantly decreased within the DRG system, not considering the increased perioperative risk profile of these patients. In times of rising economic pressure, inadequate reimbursement of treatment costs bears the risk of rejection or restriction for patients with concomitant PD in spite of medical indications.
    Zentralblatt für Chirurgie 05/2010; 136(2):168-71. · 1.05 Impact Factor

  • Zentralblatt für Chirurgie 04/2010; 135(02). DOI:10.1055/s-0030-1247354 · 1.05 Impact Factor
  • T R Glowka · M Webler · A Hirner · J C Kalff · J Standop ·
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    ABSTRACT: Distal pancreatectomy is performed less frequently than pancreatic head resection. Secondary operations due to postoperative complications are surgically complex and demanding, hence often interdisciplinary approaches are pursued. We have analysed the indications and outcome of revision surgery and interventional procedures subsequent to pancreatic left resection. Between 2001 and 2009 we prospectively evaluated 61 patients regarding demographic factors, hospital stay, diagnosis, closure technique, redo operations and interventions, morbidity and mortality. Major complications without redo procedures were observed in 4 (9 %) of 44 patients. 8 (13 %) patients underwent early (7 +/- 8 days) postoperative revision procedures. A significant in-crease in hospital stay and mortality appeared in this group. Interventional procedures (7 x CT-guided abscess drains, 1 x haemorrhage with angio-graphic coiling, 1 x transgastral stenting of a pseudocyst) were performed significantly later (22 +/- 11 days p. o., p < 0,01) in 9 (15 %) patients. Pancreatic fistulas and related complications represent the most common indications for revisions, but can usually be controlled by interventional procedures. In contrast to secondary surgery, interventional revisions do not significantly increase the length of hospital stay or mortality. There was no benefit of any certain closure technique of the pancreatic remnant.
    Zentralblatt für Chirurgie 04/2010; 135(2):139-42. · 1.05 Impact Factor
  • T. Glowka · M. Webler · A. Hirner · J. Kalff · J. Standop ·

    Zentralblatt für Chirurgie 04/2010; 135(02):139-142. DOI:10.1055/s-0029-1224742 · 1.05 Impact Factor
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    ABSTRACT: Pancreaticoduodenectomy is a demanding procedure even in selected patients but becomes formidable when performed in cases of emergency. This study analyzed our experience with urgent pancreatoduodenectomies; special emphases were put on the evaluation of diagnostic means and the validation of existing indications for performance of this procedure. Three hundred one patients who underwent pancreatoduodenectomy between 1989 and 2008 were identified from a pancreatic resection database and reviewed for emergency indications. Six patients (2%) underwent emergency pancreatoduodenectomy. Indications included endoscopy-related perforation, postoperative complications, and uncontrollable intraduodenal tumor bleeding. Length of stay and occurrence of nonsurgical complications were increased in emergency compared with elective pancreatoduodenectomies. Although increased, no significant differences were found regarding mortality and surgery-related complications. Indications for emergency pancreatoduodenectomies were based on clinical decisions rather than on radiologic diagnostics. Urgent pancreatic head resections may be considered as an option in selected patients if handling of local complications by interventional measures or limited surgery seems unsafe.
    Pancreas 03/2010; 39(2):156-9. DOI:10.1097/MPA.0b013e3181bb98d2 · 2.96 Impact Factor
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    A Koscielny · U Pütz · W Willinek · A Hirner · G Mommertz ·
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    ABSTRACT: The aim of this study was to compare preoperative and postoperative findings, and clinical progress in patients with peripheral arterial occlusive disease undergoing femoropopliteal supragenicular bypass or profundaplasty in a case-control study. Between January 2001 and June 2004, 171 patients with occlusion of the superficial femoral artery underwent surgery. A retrospective analysis of 28 matched patient pairs was performed. Endpoints were bypass occlusion, surgical revision, amputation and death. Mean length of follow-up was 36 months. At 3 years after surgery there was no statistically significant difference in outcome between femoropopliteal bypass surgery and profundaplasty. There was a trend towards improved results in patients who had bypass surgery for critical leg ischaemia. Preoperative patency of the crural outflow arteries was an independent prognostic factor in multivariable analysis. There were no significant outcome differences between supragenicular bypass surgery or profundaplasty in patients who had surgery for intermittent claudication or ischaemic rest pain. Patients with a single patent tibial artery and gangrene or ulceration appeared to benefit more from bypass surgery.
    British Journal of Surgery 03/2010; 97(3):344-8. DOI:10.1002/bjs.6876 · 5.54 Impact Factor

Publication Stats

2k Citations
383.14 Total Impact Points


  • 1992-2012
    • University of Bonn
      • • Faculty of Medicine
      • • Klinik und Poliklinik für Herzchirurgie
      • • Klinik und Poliklinik für Nuklearmedizin
      Bonn, North Rhine-Westphalia, Germany
  • 1990-2011
    • University of Bonn - Medical Center
      Bonn, North Rhine-Westphalia, Germany
  • 1997-2001
    • University of Pittsburgh
      • • Division of Pediatric Gastroenterology
      • • Department of Plastic and Reconstructive Surgery
      Pittsburgh, Pennsylvania, United States
  • 1998
    • Clinic for Minimally Invasive Surgery
      Berlín, Berlin, Germany
  • 1995
    • Friedrich-Alexander Universität Erlangen-Nürnberg
      Erlangen, Bavaria, Germany
  • 1981-1985
    • Freie Universität Berlin
      Berlín, Berlin, Germany