PubMed Health⌕ Search

Biomedical subjects

D Vorwerk

Publications and source records attributed to D Vorwerk.

At least 19 recordsLinked to original sources
PubMed2005

[Chitosan pads vs. manual compression to control bleeding sites after transbrachial arterial catheterization in a randomized trial].

PURPOSE: Until now, no mechanical closure devices were available to achieve fast and secure hemostasis for vessel closure after catheterization of small arterial vessels. MATERIAL AND METHODS: Eighty patients were randomized to evaluate the effect on hemostasis by use of a chitosan pad (Chito-Seal, Abbott Vascular Devices, Galway/Ireland) in comparison to manual compression after diagnostic transbrachial arterial catheterization. Hemostasis after three minutes and one hour as well as local development of a hematoma after one and twenty-four hours were assessed. RESULTS: The use of chitosan pads significantly decreased the bleeding time in the first three minutes after manual compression time (p < 0.01). Significant decrease in bleeding risk at three minutes by use of the chitosan closure pads was also found in subgroups of patients with hypertension (p < 0.001) or diabetes (p < 0.01) and also in patients under anticoagulation therapy (p < 0.01). In addition, long-term protection from bleeding complications such as the risk of hematoma was decreased by the use of chitosan closure pads one hour (p < 0.01) or twenty-four hours (p < 0.001) after catheter removal. CONCLUSION: The use of an intravascular anchor or suture system is not safely applicable in these vessels due to the small diameter of the brachial artery. Our results document a significant improvement in hemostasis by using chitosan pads in these cases.

Angiography↗
PubMed2003

[Guidelines of the German Radiological Society for percutaneous vertebroplasty].

In many countries, percutaneous vertebroplasty became a widely accepted therapeutic option in osteoporotic and neoplastic fractures of the vertebral bodies which is employed in more and more patients. Under image guidance the method can be safely performed and provides a high success rate regarding stabilization of vertebral fractures and pain relief. Due to the increasing interest in vertebroplasty in Germany the German Radiological Society-Working Group on Interventional Radiology decided to produce guidelines for percutaneous vertebroplasty. This guidelines are based on the recent standard of knowledge and represent a guide for practical performance of this procedure. Based on the technical development of the method, indications and implementation of the method in multimodal therapy regimens may change over the next years. Therefore, this guidelines are not a rigid body of rules but a basis for an ongoing development adjusted to the scientific progress and the interdisciplinary discussion.

Age Factors↗
PubMed2003

[A novel hirudin coating of vascular endoprostheses: experimental results].

PURPOSE: Does hirudin coating improve the patency of iliac artery endoprostheses in comparison to non-hirudin-coated endoprostheses? MATERIALS AND METHODS: Nitinol stents and stentgrafts covered with polytetrafluoroethylene (PTFE) were coated with the polymer polyamino-p-xylylene-co-poly-p-xylylene using chemical vapor deposition (CVD) technique. Hirudin was covalently bound to the surface of the endoprostheses via the amino-group. External factors (mounting of the prosthesis, sterilization, storage time and temperature, release) affecting the hirudin activity were evaluated in vitro. Five types of prostheses were compared in vivo: (1) plain and (2) CVD- and hirudin-coated stents; (3) plain, (4) CVD-coated, and (5) CVD- and hirudin-coated PTFE-stentgrafts. In 20 sheep, 16 protheses of each type were inserted in arteries pretreated with a Fogarty maneuver. The animals were followed for either 1 (n = 10) or 6 (n = 10) months. Immediately after implantation and after 1, 3, and 6 months, intravascular ultrasound (IVUS) and angiography were performed. The vascular specimens were analyzed histologically. RESULTS: Within 10 weeks, the hirudin activity of coated stents dropped 60 % due to external factors; the activity of coated PTFE stentgrafts dropped 20 %. After 1, 3, and 6 months, IVUS and histology revealed a significantly reduced patency of the hirudin-coated stentgrafts compared to the other prostheses. Only IVUS showed a significantly reduced patency of hirudin coated stents after 1 and 3 months compared to plain and CVD-coated PTFE-stentgrafts. The reduced patency was caused by neointimal hyperplasia. CONCLUSIONS: In an experimental setting, hirudin coating did not improve the patency of vascular endoprostheses.

Angiography↗
PubMed2003

[Transbrachial selective carotid DSA in outpatients: safety and efficacy].

PURPOSE: To describe safety and efficacy of transbrachial selective carotid digital subtraction angiography (DSA) in outpatients. MATERIALS AND METHODS: From July 1999 to November 2001, selective carotid angiography was performed in 141 outpatients preferably using a left brachial arterial approach. The average age of the patients was 68 years (range: 39 - 89 years). After flush aortography through a 4F-pigtail catheter, bilateral selective common carotid artery (CCA) catheterization was performed with 4F-Sidewinder-1 or Sidewinder-2 catheters. In 49 patients, Doppler-sonography was performed before or after arteriography. A total of 41 patients underwent carotid surgery. RESULTS: Selective catheterization of the CCA was successful in 96 % of the cases. The diagnostic quality of the opacified aorta and CCA images was good to excellent. The overall complication rate did not exceed 2.1 %, and severe complications were not observed. One patient showed transient neurological symptoms and another mild nausea and agitation, probably as toxic reaction to the contrast medium. A single local hematoma developed after unsuccessful puncture of the brachial artery. CONCLUSION: Transbrachial selective carotid DSA is safe, reliable and well-tolerated in outpatients and achieves a superimposition-free CCA visualization.

Adult↗
PubMed2003

[Evolution of inflammatory parameters after fibroid embolization].

PURPOSE: To describe the rise of classical laboratory tests for inflammation following transarterial uterine fibroid embolization (UFE) in order to monitor the normal course following UFE. MATERIALS AND METHODS: In 20 females, white blood cell (WBC) count and C-reactive protein (CRP) were determined before and up to 5 days after UFE. With the exception of one noninflammatory complication, the post-procedure course was uneventful in all patients. The measured values were correlated with both the total uterine volume and the amount of instilled embolizing agent. RESULTS: Following UFE, an increase in the WBC count to an average maximum of 10.8 +/- 3.5/wL (range 5.9 - 18.6/wL) was found. In 13 of 20 patients, the WBC count was above normal on at least one day following UFE. The increase reached the maximum on the third post-interventional day and subsided within 5 days after the UFE. The CRP values increased significantly to an average maximum of 41.9 +/- 28.8 mg/l. The maximum was found on the 2nd post-interventional day in 8 patients, on the 3rd day in 11 patients and on the 4th day in one patient. No correlation to the total uterine volume or to the amount of the instilled embolizing agents was detected. CONCLUSION: Following uncomplicated UFE, a steep increase in CRP occurs with no or only a mild increase in the WBC count, which does not indicate an infected fibroid. The maximum is reached on the 3rd or 4th post-interventional day, followed by a decline in CRP and normalization of the WBC count.

Adult↗
PubMed2002

[New international networks in radiology graduate and continuing education: www.eurorad.org--a EAR Project for online publication of radiological data].

Eurorad (www.eurorad.org) is a joint project of EAR and has support of 27 national and 8 subspeciality radiology societies. Eurorad is the first noncommercial radiological publication that is exclusively based on the internet as a communication line with all steps of submission, reviewing and publication being performed online. Eurorad wants to build up a huge and exhaustive case file of diagnostic and interventional radiology. Like all scientific publications, Eurorad bases on an editor in chief and 13 section editors who are responsible for organizing each section of Eurorad. Each section has a number of peer reviewer with an overall total of more than 100. For submission and publication, all cases are structured in the same manner with case report, method and discussion. For the time being, Eurorad hosts 779 cases, of whom 346 are free available on the net. The actual rejection rate is 4.5%, other cases are under review.

Curriculum↗
PubMed2002

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.

Adult↗
PubMed2002

[Simple localization of peripheral pulmonary nodules - CT-guided percutaneous hook-wire localization].

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) is an alternative approach to small intrapulmonary nodules, if transbronchial or percutaneous biopsy have failed. We investigated the feasibility and effectiveness of the percutaneous CT-guided placement of hook-wires to localize such nodules before video-assisted thoracoscopy. SUBJECTS AND METHODS: 19 patients with new by diagnosed intrapulmonary nodules underwent CT-guided hook-wire localization by application of a X-Reidy -Set (Cook, Inc., Bjaeverskov, Denmark). The average age of the patient was 63 years (range: 19 - 80 years), the mean distance between the nodule and the pleura visceral was 7.58 mm (range: 0 - 25 mm) and the mean diameter was 11.58 mm (range: 5 - 25 mm). After localization, the patients underwent a VATS resection of the lesion within a mean time of 30 min (range 10 - 48 min). RESULTS: In all cases, resection of the nodules was successful. In 4 older patients the marking was complicated by poor cooperability. At the end of manipulation the end of the hook was distanced from the nodule. But also in these cases, resection was successfully performed. 8 patients developed an asymptomatic pneumothorax: 5 of them in a minor (max. 1.5 cm rim), three of them in a moderate (max. 3 cm rim) dimension. In 4 patients, in whom the tumor was hit directly by the needle, local bleeding occurred. In one case, haemoptoe was present. In no patient did a dislocation of the hookwire-system occur. CONCLUSION: CT-guided placement of a hook-wire system is a simple and reasonable procedure which facilitates safe VATS resection of small pulmonary nodules.

Adult↗
PubMed2001

Percutaneous interventions for treatment of iliac artery stenoses and occlusions.

Balloon angioplasty is still the main workhorse for percutaneous interventions in the iliac arteries. It is simple to perform, cost-effective, and remarkably safe. If an adequate hemodynamic result has been achieved, patency is acceptable. To monitor the quality of success, intraarterial pressure monitoring is an important tool. Balloon angioplasty may be followed by stent insertion in case of insufficient luminal gain after inadequate balloon angioplasty or occurrence of significant dissection. Percutaneous treatment of chronic iliac occlusions is technically challenging. For chronic occlusions (duration exceeding 3 months), balloon angioplasty alone, thrombolysis with subsequent balloon angioplasty, and elective stenting or mechanical passage of the occlusion followed by primary stent implantation have been described as alternative techniques. In case of in-stent stenosis, directional atherectomy or balloon dilatation is recommended. Stent grafts allow percutaneous exclusion of isolated iliac aneurysms, iatrogenic perforation, rupture, and arteriovenous fistulas, but these cases are rare. Some authors increasingly favor the use of endoluminal graft systems for treating atherosclerotic disease in iliac arteries, but insufficient data are available to prove the benefit of stent grafts in patients with atherosclerotic disease.

Angioplasty, Balloon↗
PubMed2001

[Use of a new tiltable angiography table for diagnostic and interventional CO2 angiography].

A new tiltable angiographic table was tested for its applicability during carbon dioxide angiography in 11 patients. A change of position could be performed easily without delaying the procedure time and improved image quality in 8 patients while carbon dioxide was applied as contrast agent. The new tiltable angio table--originally designed for surgical procedures performed within the angiosuite--proved to be of use also during percutaneous diagnostic procedures, particularly with carbon dioxide as a contrast agent.

Angiography↗
PubMed2001

Prototype percutaneous thrombolytic device: preclinical testing in subacute inferior vena caval thrombosis in a pig model.

PURPOSE: To develop an animal model of subacute inferior vena caval (IVC) thrombosis and apply this model in evaluating the safety and efficacy of a prototype percutaneous thrombolytic device for restoring patency. MATERIALS AND METHODS: In 11 pigs, a stent with a ligature in the middle was placed in the IVC. Thrombin was injected to induce thrombosis. Hemostasis was achieved by using an occlusion balloon. The stent was ligated to prevent thrombus migration. Five to 8 days after thrombus induction, the ligature was broken and the stent fully deployed. In 10 animals, thrombectomy was performed by using the percutaneous thrombolytic device. A vena caval filter was inserted at the beginning of each declotting procedure. Thrombus removal percentage was estimated and pulmonary angiograms obtained to detect embolism before and after thrombectomy. The IVC was analyzed histologically. To determine thrombus composition, one animal was sacrificed without thrombectomy. Concerning procedural safety, failure of the stent delivery system, stent migration, and venous perforation due to balloon inflation and the stent placement or thrombectomy procedure were evaluated. RESULTS: Thrombus creation was successful in all animals. Fragmentation led to 75%--100% thrombus removal with flow restoration in all cases. There were no episodes of stent delivery failure, stent migration, or venous perforation. No significant pulmonary embolism was observed. In one case, a vessel dissection was identified at histologic examination. CONCLUSION: In this animal model of IVC thrombosis, the percutaneous thrombolytic device is effective and safe for clot removal.

Animals↗
PubMed2000

Comparison of two stent-grafts with different porosity: in vivo studies in a sheep model.

PURPOSE: To compare two stent-grafts with a polyurethane-carbonate (PUC) polymer lining of different pore size and water permeability in the iliac arteries of sheep. MATERIALS AND METHODS: Two stent-grafts with an inner PUC-lining of normal and low water permeability (normal, 1,200 mL/min/cm2; low, 280 mL/min/cm2; pressure gradient, 20 mm Hg) were implanted in each of 16 sheep. Hoop strength was two times higher in low-permeable than in normal-permeable stent-grafts. Patency was monitored with use of angiography and intravascular ultrasound (IVUS) after 1, 3, and 6 months. The sheep were killed after 1 or 6 months. Specimens were studied histologically. IVUS and histologic data were analyzed statistically. RESULTS: IVUS measurements showed a wider patent lumen of the low- compared to the normal-permeable prostheses at all time points (P < .03). This is likely due to the greater hoop strength of the low-permeable stent-graft. After 1 month, both types of prostheses demonstrated complete transprosthetic tissue penetration and were covered with neointima and endothelium. The neointimal area was greater in low- than in normal-permeable stent-grafts (1 month, P < .005; 6 months, P < .03). CONCLUSIONS: Presumably, the higher permeability of the normal-permeable stent-grafts led to the reduced neointimal area by improving transprosthetic capillary ingrowth and endothelialization.

Angiography↗
PubMed2000

Suramin inhibits proliferation of human arterial smooth muscle cells in vitro: potential drug for prevention of restenosis by local drug delivery.

PURPOSE: Suramin is known to inhibit proliferation of various tumor cells. This study was performed to investigate the effect of suramin on proliferating human arterial smooth muscle cells (HASMC) and thus to examine its suitability for the prevention of restenosis. METHOD: Proliferation of HASMC was stimulated with human whole blood serum (HWBS), as well as with platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF). Proliferation was assessed by measuring DNA synthesis and cell viability was assessed by measuring mitochondrial activity. RESULTS: Suramin exerted a strong attenuating effect on the proliferation stimulators HWBS, PDGF, and bFGF. A suramin concentration of 0.5 mmol/L, which is approximately twice the dosage used for systemic application, was sufficient for complete neutralization of proliferation stimulation by 10% HWBS added to the cell culture medium. CONCLUSION: The authors' data demonstrate a strong proliferation inhibiting effect of suramin on HASMC in vitro. Because it is known to interact not only with one but with a multitude of relevant growth factors, these results make suramin a most interesting substance for local application for prevention of hyperplastic neointima formation.

Arteries↗
PubMed2000

Percutaneous treatment of thrombosed primary arteriovenous hemodialysis access fistulae.

BACKGROUND: We reviewed the efficacy of percutaneous intervention in acute thrombotic occlusion of native arteriovenous (AV) fistulae for hemodialysis. METHODS: Eight-one percutaneous procedures were performed in 54 patients presenting with a clotted native dialysis fistula. There were 60 cases of a long-segment thrombosis of the fistula. In 20 cases, a small thrombus usually caused by an underlying severe stenosis was observed. A proximal arterial occlusion was seen in one case. Treatment depended on clot size and included balloon dilation (N = 20), mechanical thrombectomy with various devices (N = 58), as well as pharmacomechanical thrombolysis (N = 3). RESULTS: Full restoration of flow was established in 72 cases (88.9%). Early reobstruction within 14 days occurred in eight cases (11.1%). Primary patency rates after a 1-, 3-, 6-, and 12-month period were 74, 63, 52, and 27%, respectively. Overall fistula patency was 75% after 3 months, 65% after 6 months, 51% after 12 months, and 22% after 24 months. CONCLUSIONS: Acute thrombotic occlusion of native AV fistulae is a major complication of hemodialysis. The results of treatment are believed to be less successful than thrombosis treatment in synthetic grafts. Our results, however, indicate the efficacy of percutaneous treatment in native fistulae, and demonstrate comparable technical results and patency rates.

Adult↗
PubMed2000

[Endoluminal vascular prostheses].

Endoluminal vascular prostheses that can be implanted by percutaneous routes represent the most recent development in vascular interventional radiology. Various commercially available types of prosthesis are presented and the construction principles and applications are described. At present secure indications for the implantation of endoluminal prostheses are limited to the elimination of aneurysms and arteriovenous fistulae of the large vessels near the trunk in sections that do not cross a joint. The wide use in peripheral occlusive diseases cannot yet be recommended because confirmed data are not available.

Biocompatible Materials↗
PubMed2000

[Temporary implantation of a metal stent in Vater's ampulla. Evaluation of early changes of the bile ducts in an animal study].

PURPOSE: Evaluation of temporary stent implantation in the papilla of vater and the subsequent alterations of the bile ducts in a controlled animal study. MATERIAL AND METHODS: In seven domestic pigs the papilla of vater was stented with a nitinolelastalloy-strecker stent over a period of three days. The microscopic and macroscopic changes of the biliary tract and the serologic parameters were judged. RESULTS: In three cases a slight widening of the peripheric bile ducts was found. With the exception of a mild elevation of lactate dehydrogenase the serological parameters remained normal. The explantation of the stent two possible in six cases. A thickening of the outer layers of the bile ducts and a low to middle grade injury of the mucosa were found histologically. CONCLUSION: A temporary stent implantation in the papilla of vater is feasible. The mucosal injuries caused by the temporary stent placement may be fully repairable. The method seems to be suitable for prolonged dilatation of benign stenoses.

Alloys↗