[Embolotherapy: principles and indications]. / Grundlagen der Embolisation und anderer verschliessender Verfahren.

Vascular embolizations are complex and sophisticated procedures and can be a powerful alternative or useful adjunct to surgery in many clinical situations. Hemorrhage, vascular malformations, and tumors are the main indications for embolization procedures. Establishing the correct indication for intervention as well as the proper embolic agent and the most suitable catheterization technique requires advanced knowledge in interventional radiology, and an interdisciplinary approach is a prerequisite. A broad spectrum of microcatheters and embolization materials is available for these therapies. The desired level of occlusion and the individual vascular territory determine the choice of mechanical devices, particles, or liquid substances. Sclerosing agents and thrombin are used in special situations such as varicoceles and pseudoaneurysms.

[Endoluminal therapy of infrarenal abdominal aortic aneurysms: a new interventional technique]. / Die endoluminale Therapie des infrarenalen Bauchaorten-aneurysmas--ein neues interventionelles Verfahren.

PURPOSE: With a series of 31 transluminal stent-graft procedures, we assessed the feasibility and clinical effectiveness of a new stent-graft for the treatment of infrarenal abdominal aortic aneurysms (AAAs). METHODS: We treated the patients (male; mean age 71 years) with straight or bifurcated nitinol stents covered with woven dacron graft material for infrarenal eccentric saccular AAA (n = 4) or AAA involving the bifurcation and the common iliac arteries (n = 27). The 18-F delivery system was advanced via a surgical arteriotomy and the stent-graft was placed under fluoroscopic control. Follow-up period ranged from 8 days to 9 months. RESULTS: The implantation of the stent-grafts was technically successful in 30/31 cases. Procedure-related complications were acute hepatic failure due to gastric bleeding in a patient with liver cirrhosis, graft occlusion due to emboli originating from the left atrium (n = 1), macro-embolisation (n = 3), local haematoma (n = 1) and av-fistula (n = 1) requiring surgery. A post-implantation syndrome with leukocytosis and elevated C-reactive protein was observed in all patients. CONCLUSIONS: Endoluminal repair of infrarenal AAA with use of dacron covered nitinol stent-grafts is feasible, safe and clinically effective. However, careful long-term evaluation is necessary.

[Mid-term follow-up after placement of the new balloon-expendable VIP-stent into the iliac arteries]. / Mittelfristige Ergebnisse nach Implantation des neuen ballon-expandierbaren VIP-Stents in die Beckenarterien.

PURPOSE: To assess the effectiveness and mid-term patency of VIP balloon expandable stents in patients with iliac occlusive disease. MATERIAL AND METHODS: Between August and December 1997, 26 balloon-expandable VIP (Medtronic) stainless steel vascular stents were implanted in 19 patients with iliac occlusive disease. 22 lesions in common iliac (n = 11), external iliac (n = 5), common iliac plus contralateral external iliac (n = 1), and unilateral common and external iliac (n = 2) arteries were stented, allowing 20 limbs for assessment. There were 18 stenoses and 4 occlusions in 7 female and 12 male patients (mean age 65 years, range 45-80). RESULTS: All lesions were treated satisfactorily, yielding a technical success rate of 100%. Primary patency was 91% (20/22) at 6 months. In 2 lesions restenoses (90% and 70%) were observed, requiring repeated angioplasty. Color Doppler analysis at 12 months revealed no further restenoses. CONCLUSION: The new VIP balloon-expandable stents achieve very good initial technical success and good mid-term patency in the treatment of iliac occlusive disease.

[Infrarenal abdominal aortic aneurysm: endovascular repair with stent grafts]. / Infrarenales Bauchaortenaneurysma: Endovaskuläre Stent-Graft-Therapie.

As an alternative to surgery, endovascular therapy with stent grafts has become the second main treatment option for infrarenal abdominal aortic aneurysms. Unlike surgery, endovascular treatment with stent grafts is also applicable in patients unfit for open repair. Despite current improvements in endovascular repair devices, significant anatomic barriers still exclude this technique for a large number of patients. Computed tomography, magnetic resonance imaging, and ultrasound are essential for diagnostics, preintervention planning, and postintervention follow-up of abdominal aneurysms treated with stent grafts. This review covers etiology, pathology, and diagnostic aspects. Materials and methods for endovascular treatment of abdominal aortic aneurysms are presented in detail, and clinical results and complications are discussed.

Ultrasound examination of carotid and vertebral arteries.

Ultrasound is the most widespread diagnostic procedure in obstructive disease of the arteries supplying the brain. The combined non-invasive information on morphology and function makes duplex ultrasound the procedure of choice in screening and follow-up of carotid artery disease. This review deals with all relevant aspects of color duplex ultrasound of the carotids and the vertebral arteries. After a short introduction into the clinical background, the paper focuses on aspects of examination technique. In the main part of the review the relevant ultrasound findings in carotid artery disease are discussed. The different methods for grading stenoses of the internal carotid artery are explained in detail. Other relevant pathologies, such as vertebral artery disease, dissection and aneurysms, are briefly mentioned. The clinical value of ultrasound in the work-up of carotid and vertebral artery disease is briefly discussed in comparison with other imaging procedures.

Percutaneous endoprosthesis for treatment of aortic aneurysms.

The purpose of this study was to define the clinical utility of stent-grafts for endoluminal treatment of infrarenal abdominal aortic aneurysms (AAAs). In a prospective study involving three centers, bifurcated stent-grafts for endovascular repair of infrarenal AAAs were implanted in 295 patients. Patient selection was based on anatomic suitability. For analysis of the initial and follow-up results the patients were divided in three subgroups. Group 1 included patients treated between August 1994 and April 1996 with use of the original stent-graft device; group 2 comprised patients treated between May 1996 and December 1997 with the refined stent-graft device, and group 3 comprised patients treated with a newly designed bifurcated stent-graft device. In group 1 (n = 111) the primary technical success was 82%. The procedure had to be converted to surgery in four patients. Endoleaks immediately after the procedure were observed in 16 patients. The initial technical success in subgroup 2 (n = 159) was 96%. One patient required surgical repair, and five others had immediate perigraft flow due to reperfusion via lumbar arteries. For group 3 (n = 28) the primary technical success rate was 89%. Endoleaks due to back-bleeding via lumbar arteries were demonstrated in three patients. Minor and major complications related to the intervention, including two perioperative deaths, were observed in 24 patients (8%). Serious problems such as distal migration or disconnection of the stent-graft were detected during follow-up in five patients. Delayed aortic rupture occurred in three patients who survived after successful surgical repair. Based on the initial results and a limited follow-up of 35 months, we believe endoluminal repair of infrarenal AAA with use of bifurcated endografts may be a feasible alternative to conventional surgery, especially for patients at high surgical risk. However, at the present time there are major concerns with respect to the structural integrity of stent-graft material and the fate of the proximal aortic cuff in the long-term time frame.

[Histamine release and cardiovascular reactions to implantation of bone cement during total hip replacement]. / Histaminfreisetzung und kardiovaskuläre Reaktionen nach Implantation von Knochenzement bei totalem Hüftgelenkersatz.

Cardiovascular reactions to acrylic bone cement in patients with total hip replacement are a common complication. Hypotension and arrhythmias are the most frequently observed symptoms. Elderly patients with fractures of the femoral neck constitute a special risk group. In some patients these reactions can be fatal. The mechanisms suggested to explain these reactions are embolism of air, polymer or fat, reaction to the heat, and toxic or vasodilating effects of the acrylic monomer. In a pilot study and in a case report a significant rise of the plasma histamine was described following cementation of the femur. We therefore performed an investigation to find whether application of bone cement to the femur caused histamine release in elective hip surgery, and, independently of this, also investigated whether premedication with H1- + H2-antagonists had any effect on the cardiovascular reactions due to bone cement implantation into the femoral shaft in elderly patients with hip fracture. METHODS. Part I. In all, 40 patients, scheduled for elective surgical hip replacement were anesthetized by general or epidural anesthesia. Patients were continuously monitored by ECG. Blood pressure was recorded noninvasively at 2-min intervals during the study. Blood samples for the determination of the plasma histamine were taken immediately before implantation of the bone cement into the femur, and 2, 5, and 10 min after. Part II. A further group of 20 patients aged greater than or equal to 70 years with fractures of the femoral neck and in whom total hip replacement was planned were included in the study. In this group, 10 patients were randomly assigned to receive 4 mg clemastine + 400 mg cimetidine i.v. about 15 min before implantation of the bone cement. All patients were operated on under general anesthesia. ECG was monitored continuously and blood pressure was monitored at 2-min intervals during the study. Changes of the blood pressure and heart rate and therapeutic interventions following the implantation of the bone cement were documented. RESULTS. Part I. In 11 of the 40 patients (27.5%) plasma histamine increased by greater than 0.5 ng/ml (9 patients greater than 1 ng/ml). In comparable groups (patients with a control systolic blood pressure less than or equal to 130 mmHg) the histamine responders showed a significantly greater reduction in systolic blood pressure (-5.7 +/- 14.7 vs -17.7 +/- 8.6 mmHg). Part II. In the control group we observed a significantly greater fall in systolic blood pressure than in premedicated patients (41.5 +/- 25.4 vs 11.0 +/- 13.4 mmHg). In the control group 7 of the 10 patients required therapeutic interventions, while in the premedicated group only one therapeutic intervention was necessary (P less than 0.05). DISCUSSION. We have demonstrated that the implantation of acrylic bone cement into the femur may increase plasma histamine by greater than 1 ng/ml. In elderly patients with preexisting cardiac diseases or/and hypovolemia even moderate histamine release can cause serious, sometimes potentially fatal, cardiovascular complications. In this special risk group with hip fractures we found a significant reduction in the frequency of cardiovascular reactions to bone cement implantation in patients premedicated with H1 + H2 antagonists. Because we also observed significant falls in systolic blood pressure in premedicated patients, we assume that the pathogenesis of cardiovascular reactions to bone cement implantation is multifactorial. It may be that potentially lethal complications only occur if two or more of the predisposing factors (hypovolemia, myocardial insufficiency, arrhythmia, embolism, histamine release) are present simultaneously. Pre- and intraoperative measures therefore have to be instituted to eliminate all possible risk factors.

Two-center German experience with aortic endografting.

PURPOSE: To report the results of a two-center study of endovascular abdominal aortic aneurysm (AAA) exclusion using a polyester-covered nitinol stent-graft. METHODS: Candidates were evaluated with arteriography and computed tomography. Criteria for endovascular therapy were a proximal aortic neck > 10 mm in length and < 25 mm in diameter, no bilateral internal iliac artery involvement in the aneurysm, no markedly tortuous common iliac arteries (CIAs) or CIAs < 7 mm in diameter, and no superior mesenteric artery occlusive disease. Patients were treated with the Mialhe Stentor and Vanguard stent-grafts in either tube or bifurcated versions. RESULTS: Between August 1994 and November 1996, 149 patients (mean age 67 years, range 49 to 90) were admitted to the study. Overall primary technical success (aneurysm exclusion without endoleak) was 87% (130 patients): 78% (7 patients) for tube grafts and 88% (123 patients) for bifurcated endografts. The rate of local, remote, or systemic complications was 10.8%, with a 30-day mortality rate of 0.7%. During an average 13.5-month follow-up, there were no late deaths. Four of 20 endoleaks sealed spontaneously, 14 were treated with endoluminal techniques, and 2 remain untreated by patient request. Three graft limb thromboses occurred; one was treated surgically, one with lytic therapy, and one was untreated. Secondary patency was 96%. CONCLUSIONS: Endoluminal repair of infrarenal AAAs using straight or bifurcated grafts is a feasible alternative to conventional surgical repair. Longer follow-up and more experience with refined endograft models will elucidate the durability of this endovascular approach to treating AAAs.

Abdominal aortic aneurysms: preliminary technical and clinical results with transfemoral placement of endovascular self-expanding stent-grafts.

PURPOSE: To evaluate treatment of infrarenal abdominal aortic aneurysm (AAA) with a new endoluminal stent-graft. MATERIALS AND METHODS: In 26 male patients, straight or bifurcated nitinol stents covered with woven Dacron graft material were implanted to treat eccentric saccular AAA (n = 3) or AAA involving the bifurcation and common iliac arteries (n = 23), with follow-up from 8 days to 8 1/2 months. RESULTS: Implantation was technically successful in all but one of the 26 (96%) patients (leak of the stent-graft for more than 3 months necessitated implantation of an additional covered stent). In seven of the 26 patients, minor residual perfusion persisted immediately after implantation, but complete thrombosis occurred within 7 days. Five procedure-related complications occurred: distal embolization (n = 2); local hematoma, which necessitated surgery (n = 1); acute hepatic failure due to gastric bleeding, in a patient with liver cirrhosis (n = 1); and stent-graft occlusion due to emboli originating from the left atrium (n = 1). CONCLUSION: Exclusion of AAA from circulation was feasible, safe, and clinically effective with the new stent-graft.

Endoluminal stent-grafts for infrarenal abdominal aortic aneurysms.

BACKGROUND: The treatment of aortic aneurysms with endovascular stents or stent-graft prostheses is receiving increasing attention as an alternative to major abdominal surgery. To define the clinical value of this technique, we prospectively studied the use of stent-graft endoprostheses made of nitinol and covered with polyester fabric for the treatment of infrarenal abdominal aortic aneurysms. METHODS: We treated a total of 154 patients at three academic hospitals. Twenty-one patients with aortic aneurysms not involving the aortic bifurcation received straight stent-grafts, and 133 patients with aortic aneurysms involving the bifurcation and the common iliac arteries received bifurcated stent-grafts. After a unilateral surgical arteriotomy, the endoprostheses were advanced through the femoral arteries and placed under fluoroscopic guidance. Computed tomography and intraarterial angiography were performed during an average follow-up of 12.5 months. RESULTS: The primary success rate, defined as complete exclusion of the abdominal aortic aneurysm from the circulation, was 86 percent in the group receiving straight grafts and 87 percent in the group receiving bifurcated grafts. In three patients the procedure had to be converted to an open surgical operation. Minor (n=13) or major (n=3) complications associated with the procedure (including 1 death) occurred in 10 percent of the patients. All patients had a postimplantation syndrome, with leukocytosis and elevated C-reactive protein levels. CONCLUSIONS: Our results suggest that endovascular treatment of infrarenal abdominal aortic aneurysms is technically feasible and can effectively exclude abdominal aortic aneurysms from the circulation. With further refinement, endoluminal repair may emerge as an interventional strategy to treat infrarenal aortic aneurysms, especially in patients at high surgical risk.

Results of a European multicentre iliac stent trial with a flexible balloon expandable stent.

PURPOSE: to determine the 12 months success rate with a balloon expandable, flexible stainless steel stent in iliac artery obstructions. MATERIALS AND METHODS: one-hundred and twenty-six consecutive patients with iliac obstructive disease and who demonstrated an unsatisfactory angioplasty result with a post-dilatation gradient of at least 10 mmHg, or a primary occluded lesion were included in the study. Follow-up was by Doppler sonography, ankle pressures with and without exercise and clinical parameters. RESULTS: after stent placement, the mean percentage diameter stenosis decreased from 79 to 4%, with a mean intra-arterial pressure gradient of 3 mmHg. Primary stent patency was 94% at 6 months and 89% at 12 months. Primary clinical result at 6 months was 88% and at 12 months 81%. Primary assisted clinical result (after re-pta) at 6 and 12 months was 89 and 86%, respectively. The Ankle Brachial Index (ABI) after exercise at 1 month follow-up was reduced from 0.88 to 0.75, with minor deterioration at 6 months to 0.72, and at 12 months to 0.68. The 1, 6, and 12 months follow-up Piek Systolic Velocity (PSV) ratios across the stented lesions remained stable at a mean of 1.4, 1.6, and 1.6, respectively. However, respectively 44, 39 and 34% of the patients still experienced symptoms of claudication. CONCLUSIONS: the results presented here support the suggestion stenting to be an effective device in the treatment of iliac artery obstructive disease. This study also, confirms other study results concerning haemodynamic patency after iliac stenting on the indication of a 10 mmHg pressure gradient after pta and the discrepancy between good haemodynamic patency and clinical result.

Current practice of temporary vena cava filter insertion: a multicenter registry.

PURPOSE: To evaluate the current practice of temporary vena cava filter placement and its complications. MATERIALS AND METHODS: A multicenter registry was conducted from May 1995 until May 1997 using a standardized questionnaire. One hundred eighty-eight patients were evaluated. Patient characteristics, filter indications, filter characteristics, and complications were registered. RESULTS: Deep vein thrombosis was proven in 95.2% of the patients. Main filter indication was thrombolysis therapy (53.1%). Average filter time was 5.4 days. An Antheor filter was inserted in 56.4%, a Guenther filter in 26.6%, and a Prolyser filter in 17.%. Transfemoral filter implantation was slightly preferred (54.8%). Four patients died of pulmonary embolism (PE) during filter protection. Major filter problems were filter thrombosis (16%) and filter dislocation (4.8%). When thrombus was found in or at the filter before explantation, additional thrombolysis was performed in 16.7%, additional filter implantation in 10%, and thrombus aspiration in 6.7%; 4.8% of filters were replaced with permanent filters. DISCUSSION: Temporary vena cava filters are placed to prevent PE in a defined patient population. Despite their presence, PEs still occur in a small percentage. Problems of filter thrombosis and dislocation have to be solved. CONCLUSION: The results of this multicenter registry support the need for innovative filter design, as well as a randomized, prospective study.