Alexander Meyer

Current practice of first-line treatment strategies in patients with critical limb ischemia.

OBJECTIVE Critical limb ischemia (CLI) is growing in global prevalence and is associated with high rates of limb loss and mortality. However, a relevant gap of evidence about the most optimal treatment strategy still exists. The aim of this study of the prospective, multicenter First-Line Treatments in Patients With Critical Limb Ischemia (CRITISCH) registry was to assess the current practice of all first-line treatments strategies in CLI patients in German vascular centers. METHODS Between January 2013 and September 2014, five first-line treatment strategies-endovascular revascularization (ER), bypass surgery (BS), femoral/profundal artery patchplasty (FAP), conservative treatment, and primary amputation-were determined among CLI patients in 27 vascular tertiary centers. The main composite end point was major amputation or death, or both, during the hospital stay. Secondary outcomes were hemodynamic failure, major adverse cardiovascular and cerebral events, and reintervention. Univariate logistic models were additionally built to preselect possible risk factors for either event, which were then used as candidates for a multivariate logistic model. RESULTS The study included 1200 consecutive patients. First-line treatment of choice was ER in 642 patients (53.4%), BS in 284 (23.7%), FAP in 126 (10.5%), conservative treatment in 118 (9.8%), and primary amputation in 30 (2.5%). The composite end point was met in 24 patients (4%) after ER, in 17 (6%) after BS, in 8 (6%) after FAP, and in 9 (8%) after conservative treatment (P = .172). The highest rate of in-hospital death was observed after primary amputation (10%) and of hemodynamic failure after conservative treatment (91%). Major adverse cardiovascular and cerebral events developed in 4% of patients after ER, in 5% after BS, in 6% after FAP, in 5% after conservative treatment, and in 13% after primary amputation. The reintervention rate was 8%, 14%, 6%, 5%, and 3% in each group, respectively. In the multivariate regression model, coronary artery disease (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.42-6.17) and previous myocardial infarction (PMI) <6 months (OR, 3.67, 95% CI, 1.51-8.88) were identified as risk factors for the composite end point. Risk factors for amputation were dialysis (OR, 3.31, 95% CI, 1.44-7.58) and PMI (OR, 3.26, 95% CI, 1.23-8.36) and for death, BS compared with ER (OR, 3.32; 95% CI, 1.10-10.0), renal insufficiency without dialysis (OR, 6.34; 95% CI, 1.71-23.5), and PMI (OR, 7.41; 95% CI, 2.11-26.0). CONCLUSIONS The CRITISCH registry revealed ER as the most common first-line approach in CLI patients. Coronary artery disease and PMI <6 months were independent risk factors for the composite end point. Special attention should be also paid to CLI patients with renal insufficiency, with or without dialysis, and those undergoing BS.

Results of combined vascular reconstruction and free flap transfer for limb salvage in patients with critical limb ischemia

OBJECTIVE Combined vascular reconstruction and free flap transfer has been established in centers as a feasible therapeutic option in cases with critical limb ischemia (CLI) and large tissue defects otherwise destined for major amputation. However, the number of patients treated with this combined approach is limited, and data regarding long-term follow-up and functional outcome are scarce. We therefore report our 10-year experience in free flap transplantation after vascular reconstruction as a last attempt for limb salvage, with special emphasis of complication rate, limb salvage, and postoperative mobility. METHODS CLI patients undergoing combined vascular reconstruction and consequent free flap transfer from 2003 to 2013 were retrospectively observed. Of 80 cases in total, patients with traumatic and oncologic indications were excluded; 33 (mean age, 66 years; range, 51-82 years) of these cases were performed for limb salvage and were included in this study. Long-term follow-up was possible in 32 of 33 patients (mean, 58 months; range, 2-126 months). RESULTS Thirty-three patients were analyzed. We performed arterial revascularization with 9 arteriovenous loops, 23 bypass grafts (10 popliteal-pedal, 9 femoral-crural, and 4 femoral-popliteal), and 1 venous interposition graft. For defect coverage, tissue transfer was comprised of six different flap entities (10 latissimus dorsi, 2 gracilis, 1 anterior lateral thigh, 7 rectus abdominis, 11 radialis, and 2 greater omentum flaps). Complications occurred in 16 of 33 patients (49%). Early complications included eight acute occlusions of arterial reconstructions; major bleedings were seen in eight patients as well. There were two flap losses and one major amputation in the early postoperative period. No in-hospital deaths were observed. Late results revealed a limb salvage rate of 87% after 1 year and 83% after 5 years. Amputation-free survival was 87% after 1 year and 75% after 5 years. Overall survival was 100% and 87% after 1 year and 5 years, respectively. Follow-up showed 42% of patients with no limitations in ambulation, 54% with maintained preoperative ambulatory status, and one bedridden patient. CONCLUSIONS The combined approach for limb salvage in CLI patients is associated with excellent results in limb salvage and functional outcome in patients who would otherwise be candidates for major amputation, despite an initially elevated complication rate. The option of combined revascularization with free tissue transfer should be evaluated in all mobile patients with CLI, large tissue defects, and exposed tendon or bone structures before major amputation. However, further studies are required to support these results.

The Angiosome Concept Evaluated on the Basis of Microperfusion in Critical Limb Ischemia Patients-an Oxygen to See Guided Study.

Aim of this clinical study was to evaluate the angiosome concept with regard to the microcirculation of the foot in patients with CLI and to evaluate its relevance by means of combined laser Doppler flowmetrie and white‐light tissue spectrophotometry.

Immediate changes of angiosome perfusion during tibial angioplasty.

Objective: In recent years, a controversial discussion about the clinical relevance of the angiosome concept during tibial angioplasty has developed. Therefore, we conducted a prospective study to evaluate the angiosome concept on the level of microcirculation during tibial vascular interventions. Methods: Thirty patients with isolated tibial angioplasty were examined prospectively. Macrocirculation was evaluated by measurement of the ankle‐brachial index (ABI). For the assessment of microcirculation, a combined method of laser Doppler flowmetry and tissue spectrometry (O2C; LEA Medizintechnik GmbH, Giessen, Germany) was applied. Microcirculatory parameters were measured continuously during the procedures. Measuring points were located over different angiosomes of the index foot; a control probe was placed on the contralateral leg. Results: Cumulated microcirculation parameters (sO2, flow) as well as the ABI showed a significant improvement postinterventionally (ABI, P < .001; sO2, P < .001; flow, P < .001). Assessment of the separate angiosomes of the index leg and the comparison of the directly revascularized (DR) and indirectly revascularized (IR) angiosomes showed no significant difference concerning the microperfusion postinterventionally (DR − IR: sO2, P = .399; flow, P = .909) as well as during angioplasty. Even a further subdivision of the collective into patients with diabetes (sO2, P = .445; flow, P =.758) and renal insufficiency (sO2, P = .246; flow, P = .691) could not demonstrate a superiority of the direct revascularization at the level of microcirculation in these patients (comparison DR − IR). Conclusions: There is a significant overall improvement in tissue perfusion of the foot immediately after tibial angioplasty. The effect shown in this study, however, was found to be global and was not restricted to certain borders, such as defined by angiosomes.

Automated magnet assembly for large PM synchronous machines with integrated permanent magnets

The manufacturing of large synchronous motors and generators with integrated permanent magnets currently contains a large amount of manual processes as well for handling as assembly. Magnets have to be separated and prepared for insertion manually, bearing a high risk for injuries. Due to increasing batch sizes in industrial as well as in traction drive applications, the efficiency of these processes has to be examined and developed towards an automated assembly. The paper presents an approach for partially automated manufacturing of a wide portfolio of rotors for drives on a single assembly machine.

Distal pedal bypasses combined with free microsurgical flaps in chronic limb ischaemia for problematic wounds

Dear Editors, We want to congratulate De Caridi and coauthors for their description of the value of what they called an extreme distal bypass to improve wound healing in Buerger’s disease (1). They describe the successful management of a 53-year-old patient with thromboangiitis obliterans (TAO/Buerger’s disease), which is a rare non-atherosclerotic inflammatory disease and they highlight the value of distal peripheral bypass surgery in such occasions. Although this is only a single case report, it has been shown that beyond the successful treatment of an infected wound in a poorly vascularised extremity, such surgical approaches with limb salvage after successful pedal bypass grafting are associated with improved long-term survival (2). Studies concerning the long-term morbidity and mortality after reconstruction for critical limb ischaemia following pedal bypasses with often multiple operative or interventional steps show high rates of primary and secondary patency. But when amputation becomes necessary this is associated with significantly worse long-term survival (2). We want to add our experiences with distal pedal branch bypasses over the last 20 years for limb salvage, where we found a number of technical factors that may be associated with graft patency and limb salvage (3) (Figures 1, 2). The indication for distal pedal bypass grafts has become an accepted treatment form for all patients who suffer from peripheral arterial occlusive disease, limb-threatening peripheral ischaemia and wounds with or without major infections. We found that the preoperative assessment and the accuracy of imaging diagnostics is a prerequisite for proper planning of how to proceed, and we could not identify a typical systemic contraindication, because the results were unaltered regardless of age or diabetic status. However, there are a number of problematic wounds with exposed vital structures where neither vascular surgery alone nor plastic surgery with free flap transplantation is sufficient when applied solely. When distal pedal revascularisation however is combined with simultaneous or staged free microvascular tissue transplantations, new horizons may be opened for patients with such severe wounds as described by De Caridi et al. (4). In cachectic patients in whom no sufficient muscle tissues could be harvested, we have demonstrated the value of the greater omentum as a source of well-vascularised autologous tissue that can be combined with revascularisation processes (5). Surgical principles of radical wound debridement – regardless of underlying vital structures are exposed – and if necessary a second-look operation with intermittent negative pressure wound treatment, simultaneous or Figure 1 Typical angiographic picture of chronic limb ischaemia in a patient following distal pedal bypass to dorsalis pedis artery. Inset: Intraoperative aspect of distal pedal bypass anastomotis to recipient vessel.

Results of combined vascular reconstruction by means of AV loops and free flap transfer in patients with soft tissue defects

PURPOSE Free flap transplantation to vascular reconstructions as arteriovenous (AV) loops has been established in centers as a feasible therapeutic option for defect reconstruction in the absence of proper recipient vessels, caused by oncologic resections, radiation, or trauma. We report our 10-year experience in free flap transplantation after vascular reconstruction with special emphasis on complication rate and postoperative mobility. PATIENTS AND METHODS Forty-seven patients (mean age: 60 years, range: 19-86) were included. Defect etiology was posttraumatic in 19 patients; 14 defects were due to oncological resections and seven sternal osteomyelitis; three patients presented with radiation ulcers, two with aseptic femoral head necrosis, and one with defects caused by acne inversa and hip joint prosthesis infection. Long-term follow-up was 45 months (range: 0-126). We performed arterial revascularization with 36 AV loops, eight bypass grafts, and three venous interposition grafts. Subsequent tissue transfer comprised 24 latissimus dorsi, two vastus lateralis, one gracilis, one anterior lateral thigh (ALT), 16 rectus abdominis, one radialis forearm, and two osteocutaneous vascularized fibula flaps. RESULTS Complications occurred in 25/47 patients (53%). Early complications included five acute occlusions of arterial reconstructions and six major bleedings. There were six flap losses and three major amputations. Two in-hospital deaths were observed (4%). Overall survival accounted for 89.0 and 74.7% after 1 and 5 years, respectively. CONCLUSION The 5-year survival rate in long-term follow-up is favorable, despite an initially elevated complication rate. Successful defect coverage can be achieved by this method in a high percentage of patients.

Energy Efficient Strategies for Processing Rare Earth Permanent Magnets

Due to high magnetic fields causing strong interactions between permanent magnets and other ferromagnetic material, transport and handling of magnetized magnet bodies is challenging. To avoid undesired effects, such as influences on sensitive devices or difficult separation of the single magnets from stack, spacing and shielding of the magnet bodies is required leading to larger package sizes and thus in some cases higher energy demand during transport referred to the transported magnet mass. An optimization of the transport chain can be reached using the software tool presented in this paper. Further magnetizing high coercive rare earth magnets needs strong magnetic fields. To create the necessary field strength, copper coils are used requiring current strengths of several kA. Since the electrical resistance of copper differs from zero, this also means enormous thermal losses. Hence to reduce the losses and to avoid thermal damage of the coil, only short current pulses are applied generated by a pulse magnetizer. However, the efficiency of the process is very poor and lies in the lower per mil range. The presented paper explains the magnetization process in detail with focus on the losses within the magnetization device. Further different material parameters influencing the saturation field strength, such as conductivity, size and diameter to length ratio are presented and possibilities to improve the energy efficiency are shown.

Time‐extended local rtPA infiltration for acutely thrombosed hemodialysis fistulas

Introduction: This study describes results of a modified local thrombolysis technique for acutely thrombosed hemodialysis (HD) arteriovenous fistulas (AVF), which is characterized by prolonged recombinant tissue plasminogen activator (rtPA) local exposure times. Contrary to the standard lyse‐ and‐ wait (L&W) technique with local reaction times of 20–40 minutes, the modified protocol allows timing of challenging angioplasty maneuvers to the next regular working day.

Association between statin therapy and amputation-free survival in patients with critical limb ischemia in the CRITISCH registry

Objective Secondary prevention in patients with critical limb ischemia (CLI) is crucial for the reduction of cardiovascular morbidity and mortality. Nonetheless, current recommendations are extrapolated from other high‐risk populations because of the lack of CLI‐dedicated trials. The aim of this explorative study was to evaluate the association of statin therapy with the outcomes of CLI patients. Methods The First‐Line Treatments in Patients With Critical Limb Ischemia (CRITISCH) registry is a prospective multicenter registry analyzing the effectiveness of all available treatment strategies in 1200 CLI patients. For the purposes of this analysis, patients were divided into two groups based on statin administration. Treatment crossovers and nonadherent patients were excluded from analysis. The primary composite end point of this study was the amputation‐free survival (AFS). Major adverse cardiovascular and cerebral events (MACCEs), time to death, and time to major amputation were also analyzed. Results Statin therapy was applied in 445 individuals (37%), 371 (31%) patients received no statins, and 384 subjects were excluded from analysis (treatment crossovers). Patients receiving statins were more likely to be younger (P < .001) and to have a history of coronary heart disease (P < .001) or previous intervention at index limb (P < .001). Patients receiving statin therapy had a lower hazard regarding AFS (hazard ratio [HR], 0.45; 95% confidence interval [CI], 0.34‐0.63; P < .001) and death (HR, 0.40; 95% CI, 0.24‐0.66; P < .001) as well as lower odds of MACCE (odds ratio, 0.41; 95% CI, 0.23‐0.69; P = .001). However, statin therapy was not associated with reduced amputation rates (HR, 1.02; 95% CI, 0.67‐1.56; P = .922). Statin effect on AFS was consistent among diabetics (HR, 0.47; 95% CI, 0.31‐0.70; P < .001), patients with chronic kidney disease (HR, 0.53; 95% CI, 0.32‐0.87; P = .012), and patients older than 75 years (HR, 0.40; 95% CI, 0.26‐0.60; P < .001). Statin administration was also associated with an improved AFS in patients with antiplatelet medication (HR, 0.64; 95% CI, 0.41‐0.99; P = .049) and without antiplatelet medication (HR, 0.26; 95% CI, 0.12‐0.57; P = .001) and after both endovascular therapy (HR, 0.51; 95% CI, 0.34‐0.76; P = .001) and bypass revascularization (HR, 0.38; 95% CI, 0.21‐0.68; P = .001). Conclusions Statin therapy in CLI patients is associated with an increased AFS and lower rates of mortality and MACCEs without improving, however, the salvage rates of the affected limb.