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Biomedical subjects

U Settmacher

Publications and source records attributed to U Settmacher.

At least 19 recordsLinked to original sources
PubMed2006

PEG-hirudin/iloprost coating of small diameter ePTFE grafts effectively prevents pseudointima and intimal hyperplasia development.

OBJECTIVES: Small diameter PTFE grafts are prone to thrombosis and intimal hyperplasia development. Heparin graft coating has beneficial effects but also potential drawbacks. The purpose of this study was to evaluate the experimental efficacy of PEG-hirudin/iloprost coated small caliber PTFE grafts. METHODS: Thirty-six femoro-popliteal ePTFE grafts (expanded polytetrafluoroethylene, diameter 4 mm) were inserted into 18 pigs. Grafts were randomised individually for each leg and grouped for 3 groups. Group I consisted of native ePTFE grafts, group II were grafts coated with a polylactide polymer (PLA) without drugs and group III grafts were coated with PLA containing a polyethylene glycol (PEG)-hirudin/iloprost combination. The follow-up period was 6 weeks. Patency rates were calculated and development of pseudointima inside the grafts was noted. Thickness of intimal hyperplasia at the distal anastomoses was measured using light microscopy. RESULTS: Patency rates for group I were 6/9 (67%), for group II 9/10 (90%) and 12/12 (100%) for group III. In groups I and II there was a significant reduction of blood flow proximal to the graft at graft harvest, to 29+/-12 and 28+/-20 ml/min respectively (both p<0.01 versus preoperative value), whilst in group III blood flow, 99+/-21 ml/min, remained at the preoperative level. Subtotal stenosis due to development of pseudointima was noted in each of the native and PLA coated grafts but not in group III grafts. Intimal hyperplasia at the distal anastomosis was lowest in group III. CONCLUSIONS: The PEG-hirudin/iloprost coating of ePTFE prostheses effectively reduced pseudointima and intimal hyperplasia development and led to superior graft patency.

Anastomosis, Surgical↗
PubMed2005

ECG recording of central venous catheter misplaced in inferior thyroid artery.

A 71-year-old male patient with liver metastases secondary to rectal carcinoma was scheduled for hemi-hepatectomy. Two months earlier he had undergone subtotal resection of the thyroid gland. Prior to surgery, a triple-lumen catheter and an introducer sheath were introduced into the right internal jugular vein using a landmark technique. No problems occurred during insertion of the triple-lumen catheter, but resistance was noticed during insertion of the 8.5 FG introducer sheath. After placement of the introducer sheath, intra-arterial misplacement was confirmed using a pressure transducer. The opportunity was taken to record and compare intravascular ECG by the arterial and venous catheters before removal. No difference was noticed in the P-wave patterns; both showed a marked increase. Surgical exploration of the neck, recommended by the vascular surgeon consulted, showed that the carotid artery was not injured. The introducer sheath had completely punctured the right internal jugular vein and entered the inferior thyroid artery. A thrill was felt. The management of this case is discussed, with suggestions for best practice. Intravascular ECG was unhelpful in differentiating between venous and arterial placement of the catheter.

Aged↗
PubMed2005

Primary immunosuppression with tacrolimus after liver transplantation: 12-years follow-up.

The early safety and efficacy of tacrolimus after liver transplantation has been shown in two multicenter trials. Herein, we report our single-center long-term follow-up of a randomized controlled trial. As part of a European multicenter trial, 121 patients entered the study at our institution and were randomly assigned to receive either tacrolimus and steroids (n=61) or a quadruple protocol (n=60) using ciclosporin A, steroids, azathioprine, and antithymocyte globulin (ATG). Twelve-year figures of patient survival were 74% in the tacrolimus group and 66% in the cyclosporine-based group. Graft survival after 12 years was 69% in the tacrolimus group compared to 56% in the cyclosporin-based group (not significant, p=0.15). The total rate of graft loss and retransplantation decreased significantly in the tacrolimus arm (p<0.05). De novo malignancies increased significantly in the ciclosporin-based group and dominated as single cause of death beyond 5 years posttransplant. The use of tacrolimus after liver transplantation resulted in a decreased rate of graft loss over the long-term. An increased number of de novo malignancies in the ciclosporin-based group may be attributable to the use of ATG as induction therapy.

Administration, Oral↗
PubMed2005

Changes in serum levels of growth factors in healthy individuals after living related liver donation.

INTRODUCTION: To obtain better insight into the kinetics of hepatic growth factors following partial hepatectomy for living related liver donation, we investigated the postoperative changes in serum levels of hepatocyte growth factor (HGF), epidermal growth factor (EGF), vascular epidermal growth factor (VEGF), and transforming growth factor-alpha (TGF-alpha). PATIENTS AND METHODS: Eighteen healthy donors undergoing right hepatectomy for living related donation were enrolled in this study. Serum levels of HGF, EGF, VEGF, and TGF-alpha were measured using enzyme-linked immunosorbent assay kits before surgery, at 2 hours after resection, and daily during 5 days postoperatively. RESULTS: Mean preoperative HGF serum levels in healthy adults were 778 +/- 64 pg/mL. Within 2 hours after operation, they significantly increased to 9608 +/- 3111 pg/mL afterward decreasing to 2726 +/- 241 at day 1 and 2283 +/- 250 pg/mL at day 2. Hereafter HGF serum levels stabilized at increased levels until day 5 (2109 +/- 138, 2047 +/- 219, 2283 +/- 336 pg/mL, respectively). At all time points, the differences between pre- and postoperative HGF levels were significant (P < .01). In contrast, VEGF and EGF serum levels showed no significant differences between pre- and postoperative levels at all time points. TGF-alpha was not detected using a commercially available test with a detection limit of 10 ng/mL, suggesting only low TGF-alpha serum levels following liver resection. CONCLUSION: Significantly increased HGF serum levels after hepatectomy demonstrate its crucial role among the other investigated growth factors in regeneration of the remnant liver tissue during the early period after the operation.

Epidermal Growth Factor↗
PubMed2005

[Resection and reconstruction of the retrohepatic vena cava in combination with liver resections].

Liver resection combined with the resection and reconstruction of the vena cava represents the only potential curative therapy for malignant hepatic tumors with invasion of the vena cava. We performed a liver resection with segmental replacement of the retrohepatic vena cava by synthetic grafts in 29 patients. In three cases, the additional presence of central involvement of all three hepatic veins required ex situ tumor resection. Four patients underwent a simultaneous exstirpation of the primary tumor (kidney or suprarenals). The remaining hepatic veins were reimplanted into the graft in three cases, and in two cases the renal veins were reimplanted. There was no perioperative mortality. A distal arteriovenous fistula was not applied. Five patients revealed postoperative transient liver insufficiency, requiring temporary dialysis in three cases. Two of these patients developed a transient multiorgan failure with the need of mechanical ventilation. 18 patients died during the course of follow-up, 17 of these cases due to recurrent metastases of the primary disease. Infection or thrombosis of the prosthetic vascular graft have not been observed. Beside tumor exstirpation, extended liver resection and concomitant vena cava replacement may prevent embolism as well as the obstruction of the vena cava with lower extremity swelling and the possibility of developing a Budd Chiari syndrome. We were able to achieve a long-term survival for surgically treated patients even in cases with advanced tumor stages.

Adult↗
PubMed2004

[The multidisciplinary approach to reconstructive surgery of the extremities-considerations for trauma and orthopedic surgery].

Interdisciplinary reconstructive surgery of the extremities involves a variety of indications ranging from IIIB/C open fractures with major segmental loss of bone and soft tissue, to arterial vessel injury necessitating vascular repair, and to biological, plastic reconstruction following resection of musculoskeletal tumors. The multidisciplinary approach involving trauma/orthopedic surgery combined with vascular, plastic, and neuro- resp. microsurgery has significantly increased the rate of limb-sparing operations and improved morbidity, function, quality of life, and long-term oncological outcome. The multidisciplinary treatment of both complex trauma and malignant bone/soft tissue sarcoma of the extremity is an integral task of surgical trauma and tumor centers. Close interactive communication between the individual surgical disciplines has decisively influenced prognosis and is the precondition for priority-adapted therapeutic strategies.

Amputation, Surgical↗
PubMed2004

[Reconstruction of visceral arteries with homografts in excision of the pancreas].

BACKGROUND: At present, surgical treatment with R(0) resection offers the only chance of cure for patients suffering from pancreatic cancer. Carcinomas of the pancreas are frequently diagnosed at an inoperable stage because of local tumor progression by vessel wall infiltration. In a small series of patients, efforts have been made to increase curative resection rates for advanced pancreatic cancer by excision and reconstruction of the involved visceral arteries. Whether this provides clinical benefit remains uncertain. METHODS: Since 2001 we have been employing "en bloc" tumor resection for advanced pancreatic carcinomas with extended infiltration of visceral vessels. Technical experience was gained previously by performing portal vein resection as well as arterial excision and reconstruction by direct anastomosis in the presence of malignant wall infiltration. A total of ten patients underwent vascular reconstruction by arterial homograft interposition. In six of ten cases, combined extended reconstructions of the hepatic and superior mesenteric arteries were performed. One patient died during the perioperative course due to fulminant bleeding. One patient developed severe diarrhea. During a 3- to 18-month follow-up, one case of liver metastasis and one case of local tumor recurrence were documented. CONCLUSIONS: In selective cases, operability and R(0) resection can be achieved in advanced pancreatic cancer by performing extended resection procedures with vascular reconstruction using arterial homografts. Vascular substitution of visceral arteries can be conducted without ischemic disturbances of the small bowel and liver. Only a few perioperative complications were observed.

Adenocarcinoma↗
PubMed2004

[Interdisciplinarity in reconstructive surgery of the extremities].

From the perspective of trauma and orthopedic surgery interdisciplinary reconstructive surgery of the extremities encompasses different indications ranging from IIIB/Copen fractures with major segmental loss of bone and soft tissue, to arterial vessel in-jury necessitating vascular repair and to biological, plastic reconstructions following resections of musculoskeletal tumors. The interdisciplinary treatment concept including trauma-orthopedic surgery combined with vascular, plastic and neuro- as well as microsurgery has significantly decreased amputation rates and functional deficits thereby improving quality of life and long-term oncological outcome The multisdisciplinary management of both complex trauma and malignant bone/ soft tissue sarcoma of the extremity is an integral task of the surgical trauma or tumor center. Close interdisciplinary communication and expierence are the precondition for performance of a priority-adapted therapeutic strategy, low complication rates and improvement of overall prognosis.

Extremities↗
PubMed2004

[Verrucous carcinoma of the esophagus - a rare entity].

Verrucous carcinoma of the esophagus is a very rare entity. It has a high mortality. Treatment is different. 14 cases are reported. With this 15th case we report on a 66-year-old female with a verrucous carcinoma of the esophagus and surgical treatment after 4 times of recurrence and unsuccessful endoscopic resection of the tumor. The patient received transthoracic removal of the distal esophagus and interposition of the stomach. The patient recovered completely and was discharged from hospital after 18 days. Considering this case therapeutic options will be discussed.

Aged↗
PubMed2004

[Surgical treatment of bile duct injuries following laparoscopic cholecystectomy. Does the concomitant hepatic arterial injury influence the long-term outcome?].

BACKGROUND: Bile duct injuries are the most dreaded complication associated with laparoscopic cholecystectomy. Recent collective reviews have outlined the management of bile duct injuries, but only few have reported on the significance of concomitant injuries of the right hepatic artery. This study was conducted to compare the outcome of patients with isolated bile duct injuries and patients with additional vascular injuries. PATIENTS AND METHODS: From January 1990 to February 2002, a total of 54 patients with bile duct injuries during laparoscopic cholecystectomy were surgically treated in our institution. In 46 patients a Roux-Y hepaticojejunostomy was performed. Eight patients underwent other surgical procedures and were not included in the statistical analysis. 11 patients had a concomitant vascular injury. Multivariate analysis was performed to evaluate the impact of vascular injuries. RESULTS: The rate of postoperative biliary complications was 21.7 % for all patients. Patients with combined bile duct and hepatic arterial injuries had a higher risk for the development of a biliary complication (6 of 11 patients (54.5 %) versus 4 of 35 patients (11.4 %); p = 0.006). After a median follow-up time of 61 months (range, 2-164 months) a successful overall outcome was achieved in 42 of 46 patients (91.3 %), which included the patients who required additional endoscopic or surgical treatment after primary reconstruction. The long-term outcome was successful in 9 of 11 patients (81.8 %) with combined bile duct and hepatic arterial injuries and in 33 of 35 patients (94.3 %) with solitary bile duct injury. CONCLUSION: The outcome of patients with combined bile duct and arterial injuries is worse than in patients with isolated bile duct injuries. We therefore recommend the evaluation of patients with major bile duct injuries for additional vascular injuries. Vascular reconstruction should be performed when ever possible in early recognised injuries to prevent late complications.

Anastomosis, Surgical↗
PubMed2003

[Innovations in liver surgery through transplantation from living donors].

Living-donor liver transplantation was introduced into clinical practice in the early 1990s. At first the results were unsatisfactory, but today's results after living donation are as good as those obtained after conventional liver transplantation with full-sized organs. With minimally invasive diagnostic methods, it is now possible to determine the quality of potential donor livers and exclude focal lesions and anatomical variants which influence the strategy of organ retrieval procedures. Donor liver resection is done without hilar occlusion after determining the anatomical variants of the bile system (especially for right lobes) and localizing of the course of the middle hepatic vein. Microsurgical techniques are used for reconstruction of the biliary system and hepatic vessels. Living-donor liver transplantation allows us to investigate the complex changes after liver resection. The surgical techniques and pathophysiological postoperative changes can be adapted unconventionally to complex oncological liver resections. Therapeutic optimization and better risk management are becoming possible for liver resections.

Bile Ducts↗
PubMed2003

Correlation of intimal hyperplasia development and shear stress distribution at the distal end-side-anastomosis, in vitro study using particle image velocimetry.

Low shear areas at the distal anastomosis of peripheral bypasses are thought to promote neointimal hyperplasia. In this study we evaluated the fluid dynamic environment at the distal anastomosis of peripheral bypasses by means of a new method for in vitro flow visualization and quantitative velocity field measurement. A silastic model of a distal end-side anastomosis was attached to a mock circulation loop driven by an artificial heart. High resolution velocity fields were measured by means of particle image velocimetry (PIV). The velocity vector data were used to calculate vorticity omega, strain rates ex, shear rates h and shear stresses tau. Two separations and a stagnation zone were identified by means of flow visualization. Measured velocities inside the three zones were significantly lower than in the high velocity mainstream. Calculated shear rates and shear stresses inside the zones were significantly lower than human wall shear rates. At the transition between the effective mainstream and the boundary layers high vorticity and compressive strain fields existed, indicating the presence of high shear forces. The locations of these areas corresponded to the well known zones of intimal hyperplasia. The high resolution shear stress analysis supports the low shear theory of intimal hyperplasia development. A wall diversion angle greater than 6 degrees leads to flow separation and presumed IH promotion until high shear transition areas are reached.

Anastomosis, Surgical↗
PubMed2003

Local haemodynamics and shear stress in cuffed and straight PTFE-venous anastomoses: an in-vitro comparison using particle image velocimetry.

OBJECTIVES: To use particle image velocimetry (PIV) to study the haemodynamics and shear stress associated with cuffed and straight PTFE-venous anastomoses. METHODS: Silastic models of a straight and cuffed (Venaflo) PTFE-venous anastomoses were attached to a pulsatile flow 'Berlin Heart' circuit filled with glycerine/water and hollow glass tracer spheres. Instantaneous velocity fields were obtained PIV and shear rates and patterns calculated from frame-by-frame analysis. RESULTS: A high velocity jet struck the anastomotic 'floor' and was deflected toward the venous outflow. Shear stresses near the floor were significantly higher, in the straight anastomosis. Sites of high shear stress correlated well with the known sites of intimal hyperplasia. CONCLUSIONS: A cuffed anastomosis type may be favourable in terms of local haemodynamics so enhancing the long-term patency of PTFE-venous grafts.

Anastomosis, Surgical↗
PubMed2003

Technique of bile duct reconstruction and management of biliary complications in right lobe living donor liver transplantation.

From December 1999 to January 2002, 50 right lobe living donor liver transplantations were performed. The donor operations included an intraoperative cholangiography to elicit variations in bile duct anatomy. The biliary reconstruction was done whenever possible as an end-to-end microanastomosis of the donor right hepatic duct with the recipient's bile duct. As a result of the early segmental branching of the donor biliary tree, two segment bile ducts had to be anastomosed in 20 patients and three segment bile ducts in three patients. In 12 patients, a Roux-en-Y hepaticojejunostomy was performed. All anastomoses were drained externally. We observed two leakages at the resection surface which could be treated successfully by an external drainage. Six leaks occurred at the site of end-to-end biliary anastomoses. Twice the problem could be conservatively solved placing a stent percutaneously. In two patients a hepaticojejunostomy was performed after a bile duct necrosis. In two patients with an anastomotic leak, occurring 3 d, respectively, 3 month after the original transplantation, the bile duct could be directly reconstructed over a T-tube. Two anastomotic stenoses were observed, one in combination with a leak treated by percutaneous stent implantation and the second, 3 month after transplantation which was treated surgically. Biliary reconstruction after living donor liver transplantation requires microsurgical techniques and can be performed as a direct end-to-end anastomosis in most cases. Biliary complications were treated by percutaneous drainage or surgical revision in all cases.

Adolescent↗
PubMed2003

[Accuracy of the CT-estimated weight of the right hepatic lobe prior to living related liver donation (LRLD) for predicting the intraoperatively measured weight of the graft].

PURPOSE: Due to the shortage of cadaver donors, living related liver donation (LRLD) has emerged as an alternative to cadaver donation. The expected graft weight is one of the main determinants for donor selection. This study investigates the accuracy of preoperatively performed CT-volumetry to predict the actual weight of the right liver lobe graft. MATERIALS AND METHODS: In a prospective study the weight of the right hepatic lobe was calculated by volumetric analysis based on CT in 33 patients (21 females, 12 males, mean age 42.1 years, median age 41 years) prior to living related liver donation. Graft weight was calculated as the product of CT-based graft volume and 1.00 g/ml (the approximated density of healthy liver parenchyma). The calculated weight was compared with the intraoperatively measured weight of the harvested right hepatic lobe. The difference was used to determine a correction factor for estimating the actual graft weight. RESULTS: Based on the assumption of a parenchymal density of 1.00 g/ml, the preoperatively estimated graft weight (mean 980 g +/- 168 g) deviated +33 % from the intraoperatively measured right hepatic lobe weight (mean 749 g +/- 170 g). By reducing the preoperatively predicted weight of the right hepatic lobe with a correction factor of 0.75, the actual graft weight can be calculated. CONCLUSION: Preoperative estimation of the weight of the right hepatic lobe based on CT of living related liver donors predicts the weight of the right lobe graft with sufficient accuracy by applying a single correction factor. Intraoperative fluid loss (i.e., blood, bile) from the harvested liver as well as variations in parenchymal density may contribute to the observed preoperative overestimation of the actual graft volume by CT-based volumetry.

Adult↗
PubMed2003

Noninvasive analysis of conjunctival microcirculation during carotid artery surgery reveals microvascular evidence of collateral compensation and stenosis-dependent adaptation.

OBJECTIVE: Hemodynamically relevant internal carotid artery (ICA) stenosis is a major cause of ischemic stroke. Despite its long-term benefit, carotid endarterectomy may also be associated with severe neurologic deficits. Intraoperative and early recognition of ischemia in the region of the ICA may reduce this risk. To date, direct imaging and quantitative analysis of microvascular structures and function in the human ICA region have not been possible. We purposed to visualize and quantify ischemia/reperfusion-induced microcirculatory changes in the terminal vascular bed of the ICA in patients undergoing unilateral ICA endarterectomy. METHODS: Sequential analysis of the ipsilateral and contralateral conjunctival microcirculation was performed with orthogonal polarized spectral imaging in 33 patients undergoing unilateral ICA endarterectomy because of moderate or severe ICA stenosis (North American Symptomatic Carotid Endarterectomy Trial score, 75% +/- 13%), before clamping the ICA (baseline), during clamping of the external carotid artery and ICA, during reperfusion of the ICA (intraluminal shunt), during the second clamping of the ICA (shunt removal), after declamping (reperfusion) of the external carotid artery and ICA, and 15 to 20 minutes after the second ICA reperfusion. RESULTS: During ICA clamping for shunt placement, ipsilateral and contralateral conjunctival capillary perfusion was significantly decreased, but it was completely restored after reperfusion with carotid shunting. Reclamping of the ICA for shunt removal caused microvascular dysfunction, which was significantly less pronounced than that observed during the first clamping. The individual degree of ICA stenosis was inversely correlated with the ipsilateral and contralateral decrease in conjunctival functional capillary density during the first ICA clamping. CONCLUSIONS: These results suggest adaptive mechanisms of capillary perfusion with increasing stenosis and development of collateral compensatory circulation in the vascular region of the human ICA. Conjunctival orthogonal polarized spectral imaging during unilateral ICA reconstruction enables continuous noninvasive analysis of bilateral conjunctival microcirculation in the terminal region of the ICA and enables monitoring for efficient carotid shunt perfusion during and after endarterectomy.

Adaptation, Physiological↗
PubMed2002

Short (1-10 cm) superficial femoral artery occlusions: results of treatment with excimer laser angioplasty.

PURPOSE: To evaluate the safety and long-term results after laser angioplasty of short occlusions of the superficial femoral artery (SFA). METHODS: In a prospective trial in 312 patients with short occlusions of the SFA excimer laser angioplasty for recanalization was applied. The average occlusion length of the SFA was 7.5 cm (range 1-10 cm). The recanalization attempt was done using either a cross-over technique from the contralateral femoral artery (278 patients), antegrade technique (16 patients) or transpopliteal technique (18 patients). RESULTS: Percutaneous transluminal laser angioplasty (PTLA) produced successful recanalization of the SFA in 286 of 312 patients (91.7%). In 26 patients (8.3%) recanalization was not possible. The reason for the unsuccessful PTLAs was obstructing calcified materialn = 8) which was resistant to laser application. In nine cases obstructing calcifications resulted in positioning of the laser catheter in subintimal tissue or perforation of the SFA. In another four patients there was an aberrant anatomy of the SFA which resulted in a direct vessel injury after advancing the laser catheter. In five patients subintimal recanalization failed. After a follow-up period of 36 months there was a primary, primary assisted and secondary patency rate of 49.2%, 76.5% and 86.3%. CONCLUSION: Excimer laser angioplasty of short occlusions of the SFA is a feasible procedure with a low failure rate. Long-term results are promising but additional interventions are required in most patients to achieve a patency rate of 86.3% after 3 years. Further studies are needed to compare the clinical outcome of PTLA and PTA in short occlusions of the SFA.

Angioplasty, Balloon, Laser-Assisted↗