[Placement of a native arteriovenous access]. / Anlage nativer arteriovenöser Zugänge.

The epidemically increasing number of diabetics is resulting in an increasing number of patients with end-stage renal failure who, furthermore, show a high degree of co-morbidity. An increasingly longer survival time with dialysis also means that the group of patients requiring functional dialysis access is continuously growing. The autologous arteriovenous fistula with its high function and low complication rate is the best access form, and should be provided to as many of those patients requiring dialysis as possible. This article discusses the timing of dialysis access, the importance of the medical history and the physical examination, preoperative investigation of the prospective fistula vein, the possibilities of anastomosis, maturation of the fistula and long-term results.

Multidisciplinary management of vascular access for haemodialysis: from the preparation of the initial access to the treatment of stenosis and thrombosis.

In February 2008 a multidisciplinary study group was established in Germany to improve the treatment of patients with potential vascular access problems. As one of the first results of their work interdisciplinary recommendations for the management of vascular access were provided, from the creation of the initial access to the treatment of complications. As a rule the wrist arteriovenous fistula (AVF) is the access of choice due to its lower complication rate when compared to other types of access. The AVF should be created 3 months prior to the expected start of haemodialysis to allow for sufficient maturation. Second and third choice accesses are arteriovenous grafts (AVG) and central venous catheters (CVC). Ultrasound is a reliable tool for vessel selection before access creation, and also for the diagnosis of complications in AVF and grafts. Access stenosis and thrombosis can be treated surgically and interventionally. The comparison of both methods reveals advantages and disadvantages for each. The therapeutic decision should be based on the individual patients' constitution, and also on the availability and experience of the involved specialists.

Insufficient arteriovenous fistulae in hemodialysis patients.

BACKGROUND: For an accurate assessment of structural changes in arteriovenous fistulae (AVF) a microscopic analysis is mandatory. METHODS: 25 insufficient AVF were analyzed with the light microscope using standard histological and immunohistochemical techniques. RESULTS: In 7 patients (28%) atherosclerotic lesions as causes of AVF insufficiency were found. The other 18 patients (72%) had an inhomogeneous spectrum of nonatherosclerotic lesions, for instance intimal hyperplasia. CONCLUSIONS: Histopathologic analysis of insufficient AVF helps clarify the underlying changes in the structure of the vessel wall.

Central vein obstruction in vascular access.

Central venous obstruction has become a major problem because of the frequent need for central venous catheters in haemodialysis patients. This article discusses the epidemiology and clinical features of central venous obstruction and the different surgical and interventional alternatives for its treatment.

Fibromuscular dysplasia of the renal artery responsible for renovascular hypertension: a histological presentation based on a series of 102 patients.

BACKGROUND: Fibromuscular dysplasia (FMD) is a rare non-atherosclerotic and non-inflammatory disease in the arterial system. The purpose of the study was a retrospective analysis of FMD in the renal artery. PATIENTS AND METHODS: A total number of 102 patients (mean age: 36.9 years) who suffered from renovascular hypertension underwent a surgical therapy. The operative specimens of the renal arteries were analysed with the lightmicroscop using histological and immunohistochemical methods. RESULTS: 101 patients (99.02%) presented a medial FMD (extensive-medial subtype in 56 patients, 54.9%, subadventitial subtype in 29 patients, 28.4% and combined subtype in 16 patients, 15.7%). In 1 patient (0.98%) an adventitial FMD was found. We observed the following complications: true and dissecting aneurysms (75 patients, 74.5%), arterio-venous fistulae (2 patients, 1.96%) and chronic thrombosis (10 patients, 9.8%). CONCLUSIONS: With the progress in angioplasty, not all patients suffering from FMD undergo a primary surgical therapy and therefore this lesion is less seen in the daily work of the histopathologist.

[The stenosed Brescia-Cimino fistula: operation or intervention?]. / Die stenosierte Brescia-Cimino-Fistel: Operation oder Intervention?

INTRODUCTION: Stenosis of the vein close to the arteriovenous anastomosis is the most frequent cause for late failure of Brescia-Cimino fistulae (BCF). Although since decades proximal re-anastomosis has been regarded as the surgical standard treatment, success rates can hardly be deducted from the literature. Considering the increasing activities of interventional radiologists surgical position finding seems necessary. METHODS: Over three years 30 anastomotic BCF stenoses were treated in 28 patients. In 15 patients the stenosis had caused fistula thrombosis. In all cases the fistula vein was re-anastomosed to the proximal radial artery. All patients could be followed up (average 12 months). Each fistula functioning after 24 hours was classified as procedural success. For calculation of patency rates (life table analysis), however, usability of the needling segment of the access was assessed. RESULTS: Procedural success rate was 100%. One fistula thrombosed on the second postoperative day after a successful dialysis session due to an overlooked proximal stenosis of its feeding radial artery. In five fistulae stenoses developed after 4 to 13 months. In only one fistula this was a true re-stenosis of the newly created anastomosis (0.03 per patient-year). Two of the stenoses occurred in the needling segment of the access vein and within its central venous outflow, respectively. Overall re-intervention rate was 0.3 per patient-year, and primary (secondary) patency was 80% (95%) at one year and 67% (87%) at two years. CONCLUSION: In BCF proximal re-anastomosis is a simple and effective therapeutic option for anastomotic venous stenosis. Re-intervention rates are low and procedural success rates as well as primary and secondary patency rates at least equal those of interventional radiology.

Does a postimplantation syndrome following endovascular treatment of aortic aneurysms exist?

The postimplantation syndrome (PIS) is a weakly defined condition that has been observed following endovascular treatment of aortic aneurysms; the postulated criteria include significant leukocytosis, fever, and/or coagulation disturbances. Among the factors that are supposed to contribute to this syndrome are contact activation by the stent covering with consecutive endothelial activation. Associated clinical parameters of a PIS were perioperatively monitored in the postoperative phase in a total of 69 patients with infrarenal aortic aneurysms treated with Y-stent grafts. C-reactive protein (CRP)-levels, leukocyte concentrations, and body temperature curves were directly compared to those of 50 patients undergoing conventional transperitoneal aneurysm resection. A subgroup of 10 patients of the endovascular group was compared with 13 operated-on patients with regard to an ischemia-reperfusion syndrome of the lower extremities. The mediator determinations were performed on venous (femoral vein) as well as in systemic (arterial) blood samples. The incidence of temperature values above 38 degrees C was higher in patients following endovascular treatment (72%) compared to conventionally operated-on patients (28%). CRP levels were not significantly different within the first 8 post-operative days. During open surgery, significantly higher values for lactate and lower pH levels were observed (p<0.01), as well as higher 6 keto prostaglandin F1alpha (PGF1alpha) levels. There was a short peak of PGF1alpha during eventeration of the intestine during the operative procedure that could not be detected during endovascular manipulations. The clinical and biochemical parameters do not prove the presence of a PIS following endovascular treatment of aortic aneurysms. In contrast, during open surgery the unspecific inflammatory reaction is higher, but not long-lasting. In the future, the suggested phenomenon of a decreased antiinflammatory cytokine response during endovascular surgery needs to be further examined.

[Stent or bypass? Treatment results in benign central venous obstruction]. / Stent oder Bypass? Behandlungsergebnisse bei benignen zentralvenösen Obstruktionen.

PURPOSE: Surgical treatment of central venous obstruction is difficult and sometimes hazardous, but not always successful. Sufficient palliation of malign stenoses can often be achieved by stent implantation. Thus it seems necessary to define the relative value of stenting in comparison to surgical reconstruction for the treatment of benign obstructions, with special respect to the long-term results. METHODS: Between 1990 and 1999, 64 central venous stents were implanted. Mediastinal vein obstructions in 23 hemodialysis patients were treated with a total of 35 stents. 29 iliofemoral stents were implanted following operative or conservative treatment of 21 venous thromboses. During the same time period, only 6 surgical bypasses were performed (all in hemodialysis patients). All patients were followed-up prospectively. Patency rates were calculated according to the life table-method. RESULTS: Following stent implantation one asymptomatic pulmonary stent embolism (2.3%) and three stent misplacements (6.8%) were documented. Two of the latter were successfully treated with another stent. In the surgical group, one patient died at eight weeks due to late complications of a cephalosporine-associated Lyell syndrome. One to five year patency rates were not significantly different among the three groups. CONCLUSION: For benign central venous stenoses in hemodialysis patients and following iliofemoral venous thrombosis, stent implantation can be recommended as a simple, safe, and durable means to restore patency. Still there is a role for surgery in severely symptomatic central venous occlusions when stent implantation is impossible or has failed.

[Effects of carotid artery thrombendarterectomy on pulsatile ocular blood flow]. / Die Auswirkung einer Arteria-carotis-Thrombendarteriektomie auf den pulsatilen okulären Blutfluss.

UNLABELLED: Successful operations of clinically significant carotid artery stenosis by carotid endarterectomy (CEA) are leading to a better perfusion in the region of this artery. It still creates problems to make a statement about cerebral and ocular perfusion during the operation. METHODS: In 10 patients who underwent a CEA the pulse amplitude (PA) of the intraocular pressure (IOP) was measured intraoperatively by a pneumotomography (OBF-Systems, U.K.) and the so called pulsatile ocular blood flow (pOBF) was determined. The middle arterial blood pressure (MAP) was taken invasively during the operation. RESULTS: During the clamping phases no PA could be recorded. PA (p = 0.04) and pOBF (p = 0.028) increased on the side which had been operated on. No correlations of PA and pOBF to MAP were found. CONCLUSION: This method can prove an increased pulsatile ocular blood flow after successful CEA.

[Stent implantation after thrombectomy of pelvic veins. Indications, results]. / Stentimplantation nach Thrombektomie der Beckenvene. Indikation, Ergebnisse.

PURPOSE: Retrospective study on frequency of iliac venous stenoses that are cause (venous spur) or consequence (postoperative or postthrombotic) of iliofemoral thrombosis, and on the results of interventional treatment. METHODS: From 1990 through 1996, 76 patients were operated on for acute iliac vein thromboses. All patients had transfemoral venous thrombectomy with creation of an inguinal av-fistula. Immediate results of thrombectomy were documented by intraoperative completion venogram. Since 1995 venous spurs eventually detected during thrombectomy were immediately treated by stent implantation. Before scheduled closure of the av-fistula at three months, cross-over arteriovenography was performed. Additional significant iliofemoral venous stenoses were also treated interventionally at this time. RESULTS: 42 hemodynamically significant iliofemoral venous stenoses were found in 38 (50%) patients. Intraoperative phlebography revealed left common iliac vein obstructions suggestive of venous spurs in 30 patients (49% of left-sided thromboses). At three months, five patients (7%) had postthrombotic iliac vein stenoses, and seven patients (9%) had postoperative common femoral vein stenoses. A total of 26 stents were implanted into 20 stenoses (eight spurs, all postthrombotic and postoperative stenoses). There was an acute re-occlusion due to a technical error during stent implantation. In all other patients, the venous lumen could be completely restored. Three of four re-stenoses (at 3, 4, 7, and 12 months) were successfully treated by another intervention. We observed one late failure at 60 months. Cumulative primary (secondary) five-year patency rate (Kaplan-Meier) is 72% (88%). CONCLUSION: For venous spurs as well as for postthrombotic or postoperative venous stenoses, stent implantation can be recommended as a simple, safe, and durable means to prevent rethrombosis.

Left iliac venous thrombosis caused by venous spur: treatment with thrombectomy and stent implantation.

PURPOSE: To determine the frequency of iliac venous spurs in left iliofemoral venous thrombosis and to report the results of interventional management of venous spurs after transfemoral venous thrombectomy. METHODS: From 1990 through 1996, 77 patients with acute iliac venous thrombosis (61 left and 16 right) underwent surgical treatment. Patients with malignant disease were excluded from this series. All patients had transfemoral venous thrombectomy with construction of an inguinal arteriovenous fistula and perioperative anticoagulation with heparin with a switch to warfarin sodium for at least 12 postoperative months. Immediate results of thrombectomy were documented by means of intraoperative completion venography. Arteriovenous fistulas were ligated 3 months after control arteriovenography. Since 1995 venous spurs eventually detected during thrombectomy were treated immediately by means of stent implantation. RESULTS: Among 61 patients with left-sided thrombosis, intraoperative phlebography revealed common iliac venous obstruction suggestive of venous spurs in 30 patients (49%). In 16 of 22 patients (73%) with untreated spurs, postoperative rethrombosis of the iliac vein was documented despite adequate anticoagulation. Only one of eight patients (13%) with stented spurs had reocclusion (chi2 test P < .01). CONCLUSION: Venous spurs are found among about half of patients with left-sided iliac venous thrombosis. As long as the underlying venous pathologic process is left untreated, thrombectomy will not restore patency. Stent implantation is a simple and safe means to correct central venous strictures and provides excellent long-term results.

Coarctations of descending and abdominal aorta: long-term results of surgical therapy.

PURPOSE: Nonarteriosclerotic and nonarteritic descending and abdominal aortic coarctation (DAAC) is a rare disease with a great variety of morphologic findings. The additional affliction of renal and other splanchnic arteries often affords complex corrective procedures. We report on our single-center long-term experiences with operative treatment of this malformation. METHODS: Over a period of 21 years, 15 patients (10 female and 5 male patients; age range, 8 to 57 years) were operated on for DAAC. Six patients had additional stenoses of eight renal arteries, and three had splanchnic arterial obstructions. At 4 to 25 years after the operation, all surviving patients underwent a clinical and a spiral computed tomography examination. RESULTS: There was one intraoperative death due to exsanguination after the rupture of a poststenotic aneurysm of the infrarenal aorta. Fourteen patients were discharged free of symptoms. During follow-up, four repeated operations were necessary for renal arterial bypass stenoses or aneurysms. One late death occurred as the result of an unrelated disease. CONCLUSIONS: Complete operative correction of DAAC usually can be accomplished as a single-stage procedure with low morbidity and mortality rates. The reconstruction of all renal arteries is essential to cure hypertension. Consequent follow-up is recommended for detection of late postoperative complications.

Diagnostic value of spiral-CT angiography in comparison with digital subtraction angiography before and after peripheral vascular intervention.

To evaluate spiral-computed tomography (CT) angiography in primary diagnosis and/or in noninvasive follow-up after vascular intervention, we compared spiral-CT angiography and conventional angiography before and after vascular intervention. Helical-CT examinations before and after percutaneous transluminal angioplasty (PTA) or stent implantation were performed in 10 patients (mean age 63 years) with symptomatic peripheral arteriosclerotic disease. Stenoses were located in the iliac, femoral, or popliteal artery. CT examinations were done with a spiral-CT in double detector technique (CT Twin, Elscint). The parameters were as follows: slice thickness: 5.5 mm, increment: 2.7 mm, pitch: 1.5, contrast medium: 150 mL, flow rate: 2.5 mL/second, delay: 30 seconds. For evaluation, transverse planes as well as maximum intensity projections and 3-D reconstructions were used. The possible scan length reached from the aortic bifurcation down to about 10 cm below the ankle trifurcation. Preinterventional digital subtraction angiography (DSA) was superior to CT angiography (CTA: 94%, maximum intensity projection [MIP] alone: 65%), although high-grade stenoses were detected by both methods. After intervention, a resolved stenosis and improved peripheral flow could be detected by helical-CT as well as by intraarterial angiography in every patient (100%). In the primary diagnosis of vascular changes, intraarterial DSA remains the method of choice. Nevertheless, spiral-CT angiography shows comparable results after percutaneous intervention and becomes a noninvasive alternative in the postinterventional follow-up.

Mechanical thrombolysis of acute occlusion of both the superficial and the deep femoral arteries using a thrombectomy device.

OBJECTIVE: Our objective was to evaluate the efficacy of the Amplatz thrombectomy device for recanalization of acute occlusions of both the superficial and the deep femoral arteries. MATERIALS AND METHODS: Eighteen patients with acute occlusions of the femoral arteries (eight male, 10 female; 10-87 years old) were treated using the Amplatz thrombectomy clot macerator. The duration of occlusion was 16 +/- 8 hr. Eighteen patients underwent treatment of the deep femoral artery, and 16 patients had additional involvement of the superficial femoral artery. After primary recanalization of the deep femoral artery, the superficial femoral artery was also recanalized using the Amplatz thrombectomy device. Nine patients required additional aspiration thrombectomy of the tibial arteries, five patients required additional aspiration thrombectomy of side branches of the deep femoral artery, and 12 patients required additional local thrombolysis with urokinase. RESULTS: In 14 (78%) of 18 patients, recanalization of the deep femoral artery was complete without demonstrable residual thrombi. Arterial spasms were observed in five patients (28%). The rate of limb salvage was 94% at a mean follow-up interval of 8.9 +/- 4.1 months. In the 18 patients, the ankle-brachial pressure index went from a median value of 0.56 before therapy to a median value of 0.91 after therapy. No severe complications occurred. CONCLUSION: Mechanical thrombolysis in the deep femoral artery with the Amplatz thrombectomy device is an effective, rapid method of treatment and is rarely associated with complications. In cases of concomitant occlusion of the tibial arteries, recanalization should always be attempted because the deep femoral artery may provide a functionally decisive collateral artery between the iliac and tibial vasculature.

[Monitoring ischemia-/reperfusion syndrome in abdominal aortic aneurysm--conventional operation versus stent implantation]. / Monitoring des Ischämie-/Reperfusionssyndroms beim Bauchaortenaneurysma--Konventionelle Operation versus Stentimplantation.

From a biochemical point of view, our study corroborates the suggestion that implantation of a stent graft is less invasive than conventional surgery for infrarenal aortic aneurysm. In general, ischemia during open aortic surgery lasts shorter but affects a much greater part of the body than stent implantation. Eventration before, and more pronounced reperfusion following conventional repair cause marked intra-operative increases in TxB2, 6-keto-PGF1 alpha, and sICAM-1 levels. Thromboxane obviously is generated mainly in the reperfused tissues, whereas 6-keto-PGF1 alpha is produced in the eventrated bowel. sICAM-1 is released from both.

[Mechanically detachable minicoils attached to a wire for superselective embolization]. / Mechanische abwerfbare, am Draht fixierte Minispiralen zur superselektiven Embolisation.

PURPOSE: Evaluation of clinical usability and effectivity of newly developed, mechanically applicable minicoils attached to a wire for super-selective embolisation. MATERIAL AND METHODS: The new embolisation coils have been used in 16 patients aged between 28 and 90 years for the following indications: 4 haemorrhages in cases of advanced carcinoma of the cervix, one false aneurysm, 7 traumatic lesions and 4 arteriovenous fistulas. The minicoils are made of platinum and are attached to a guide wire with a connecting hook. Application is via a microcatheter in coaxial technique. RESULTS: Percutaneous embolisation has been successful in patients. Additional surgery has not been required in any of them. Manipulation of the system is relatively easy and embolisation is made possible under controlled circumstances. In one case a minicoil disappeared into a peripheral vessel, but could be recovered percutaneously. CONCLUSION: The minicoils allow super-selective embolisation but, for reasons of cost, should be reserved to such vascular regions where the risk of misplacing must be kept at a minimum. Basic experience with embolisation techniques is indispensable for the application of this method.

Stenting of central venous stenoses in hemodialysis patients: long-term results.

From November 1992 through July 1996, 15 Wallstents were implanted for the treatment of symptomatic central arm vein obstructions in 14 hemodialysis patients (10 subclavian, 2 brachiocephalic vein stenoses, 2 subclavian vein occlusions). There were no acute complications. All patients were investigated by clinical examination and color-duplex sonography at regular three month intervals. When recurrent swelling predicted restenosis, phlebography was also performed. During the follow-up, high grade stenoses at the central or peripheral ends of four stents were successfully treated with five overlapping stents, giving a total of 20 Wallstent implantations. Complete occlusion of another subclavian vein distally to the stent at 16 months required ligation of the patient's arteriovenous fistula. Life table analysis including all 20 stents revealed a cumulative primary one year (two year) stent patency of 70% (50%). The cumulative secondary one year (two year) stent patency was 100% (85%). We believe that in hemodialysis patients, PTA plus Wallstent implantation is a safe and effective procedure in the treatment of central venous stenoses and even shorter occlusions. Consequent follow-up allows for timely diagnosis and treatment of restenoses, thus guaranteeing long-term patency rates comparable to those of veno-venous bypass surgery.

[Atypical aortic coarctations in type I neurofibromatosis]. / Atypische Aortenkoarktationen bei Neurofibromatose Typ I.

From 1971 through 1996, 16 patients were operated on for atypical aortic coarctation. Three of them (two women, 18 and 27 years old, one boy, 13 years old) had typical signs of neurofibromatosis type I (NF1). All had renovascular hypertension due to suprarenal and/or interrenal aortic stenosis. Two had additional bilateral renal artery stenoses, one with a poststenotic aneurysm. In all patients a thoraco-abdominal aorto-aortic bypass was implanted. The renal artery stenoses were bridged by two aorto-renal, a prothesio-renal, and a spleno-renal bypass. Only one kidney had to be explanted 13 years after revascularization for a recurring hilar aneurysm after ex-situ reconstruction was found to be impossible. At their last follow-up examination (at 16, 14, and 9 years) all patients were normotensive without medication and had normal serum-creatinine measurements. Angiography or spiral-CT done in all patients showed normal function of all bypasses. In literature we found another 27 patients with neurofibromatosis operated on for atypical aortic coarctation. In these young and otherwise healthy patients, even complex reconstructions can be performed with a low rate of complications and excellent long-term results. Surgical therapy of all relevant stenoses (at best in a single procedure) is necessary for complete relief of renovascular hypertension. Consequent follow-up is advised for the detection of possible late complications, especially after exclusion of aneurysms.