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Biomedical subjects

D Vorwerk

Publications and source records attributed to D Vorwerk.

At least 91 records · Page 5Linked to original sources
PubMed1994

Ulcerated plaques and focal aneurysms of iliac arteries: treatment with noncovered, self-expanding stents.

OBJECTIVE: We studied the value of noncovered, self-expanding stents for treatment of ulcerated plaques and focal aneurysms of iliac arteries. MATERIALS AND METHODS: Seventeen patients with ulcerated plaques (n = 13) and aneurysms (n = 5) were treated with noncovered, self-expanding Wallstent endoprostheses. A total of 18 lesions were stented. The lesions were in the common iliac artery (n = 10), the external iliac artery (n = 3), or affected parts of both arteries (n = 5). Their mean length was 3.5 +/- 1.0 cm. All lesions were accompanied by stenosis of the affected arterial segment. RESULTS: Occlusion of ulcerations or aneurysms occurred immediately in three cases and thereafter in the remaining 15 cases, as shown by angiographic follow-up. Embolization did not occur. Follow-up revealed a 4-year cumulative patency of 82%, with reobstruction of the stent in three cases. CONCLUSION: Noncovered stents are a rational approach to treating circumscribed aneurysms and ulcerated plaques of the iliac arteries. The stent regularly smoothens the vessel wall by sealing the ulcerated area or aneurysm immediately or soon after stent placement.

Aortic Dissection↗
PubMed1994

[Percutaneous radiologic techniques in therapy of choledocholithiasis].

Interventional radiology offers a variety of techniques for percutaneous manipulation of intrahepatic and extrahepatic bile duct stones via the T-tube be tract and the transhepatic route, including extraction, fragmentation, transpapillary expulsion of stones into the duodenum, and chemolysis. These techniques can be combined with extracorporeal lithotripsy, balloon dilatation and electroincision of stenoses and implantation of metallic stents. Removal of stones via the T-tube tract is just as successful as endoscopic stone manipulation and leaves the papilla of Vater intact. Percutaneous transhepatic stone manipulation is more difficult and potentially more dangerous, and is restricted to patients where the endoscopic approach is not possible or operative techniques have been exhausted.

Combined Modality Therapy↗
PubMed1994

Efficacy SH U 508 A (Levovist) as blood pool enhancer in the Doppler evaluation of multiple vascular regions.

SH U 508 A (Levovist) as a blood pool enhancer to investigate multiple vascular regions with Doppler ultrasonography. Thirty patients with sub-optimal cardiac or peripheral vascular Doppler exams received 75 intravenous contrast bolus injections in all to investigate the intensity and the duration of Doppler signal enhancement after the i.v. administration of an echo contrast agent - i.e., SH U 508 A (Levovist) by Schering AG, Berlin, Germany. All cases exhibited Doppler enhancement and the investigator's "diagnostic confidence" increased from 35% (precontrast) to 91% (post-contrast) (p < 0.05). Audio Doppler intensity was measured quantitatively and more than 16 dB enhancement was demonstrated in all the vascular regions under investigation (p < 0.05). Enhancement lasted more than 60 seconds in the peripheral vessels and 120 seconds in the heart vessels. No clinically relevant adverse reactions were ever observed. To conclude, i.v., -administered SH U 508 A (Levovist) is a valuable means of increasing cardiac, femoral arterial and transcranial (cerebral arterial) Doppler signal intensity. Enhancement is durable and improves the clinical diagnostic confidence in the patients with suboptimal Doppler findings.

Adult↗
PubMed1993

[Superselective kidney artery embolization as therapy of choice in bleeding of benign origin].

Over a period of 15 years selective embolization of the renal artery was performed in 22 patients (15 men, 7 women; mean age 47.5 [5-73] years), using a percutaneously introduced coaxial technique with a 3F catheter. Tissue glue (N-butyl-2-cyanoacrylate) was employed in 18 cases, spiral wire in two, detachable balloon in three and gel-foam in one case. The bleeding had been iatrogenic in 20 cases, in one it was the result of a traffic accident, while in another the bleeding was from an angioma. The procedure was successful at the first attempt in 21 patients, permanently arresting bleeding in 18. There were three complications, transitory and not requiring treatment in two. In one patient gel-foam embolization went to a wrong site and a nephrectomy had to be performed.--This form of selective embolization is the treatment of choice in traumatic injury to a renal vessel.

Adolescent↗
PubMed1993

[Internal bile duct drainage using self-expanding metal stents in benign and malignant bile duct obstruction].

Within a 4-year period, 24 patients were treated by internal biliary drainage using self-expanding wall stents. In 3 patients, a benign and in 21 patients a malignant obstruction were present. The stents were successfully placed in all cases with an incomplete tumour coverage in three cases. Complete relief of icteric symptoms was seen in 18 out of 24 cases. Acute complications requiring additional treatment occurred in 5 patients. Average survival time was 93 days for malignant disease and 26 months for benign lesions. Cumulative patency after 200 days was 63% for stents placed in malignant obstructions. Stents in benign obstructions remained open in all cases.

Aged↗
PubMed1993

[Treatment of stenosed or occluded hemodialysis shunts. Results of percutaneous angioplasty and combined radiologic-surgical therapy].

The results of all recanalisations of stenosed and occluded haemodialysis shunts over a period of three years are reported; there were 112 percutaneous angioplasties and 40 combined radiological-surgical procedures. In 13% of cases a metallic endoprosthesis (wall stent) and in 3% Simpson's atherectomy catheter was used. The functional results were retrospectively evaluated for all 152 interventions which involved 60 orthoptic Brescia-Cimino shunts and 19 PTFE prostheses. In addition, the primary and total functions of the treated shunts were calculated. Cumulative function rate (percentage at a given time of effective shunts) for Brescia-Cimino shunts at one year was 80% and after two years 68.5%; for the PTFE prosthesis the corresponding figures were 83.8 and 75.5% respectively. The average number of interventions per patient was 2.3 with a range of 1-7. Total functional rate of all shunts following the first percutaneous procedure after one year was 78.2%, for combined radiological-surgical procedures for the treatment of acute thromboses it was 68%. Comparison with the results of surgical treatment reported in the literature confirms the effectiveness of percutaneous or combined treatment of stenosed or acutely occluded haemodialysis shunts. The outstanding advantage of radiological intervention is its repeatability.

Angioplasty, Balloon↗
PubMed1992

Percutaneous embolectomy: in vitro investigations of the self-expanding tulip sheath.

A self-expanding sheath with a tulip-shaped distal end was designed for performance of percutaneous embolectomy. Its ability to retrieve clots was tested in an in vitro flow model; results were compared with those obtained with a conventional 10-F sheath. Simulated embolectomy of clots weighing 0.1-1.5 g was performed with a 0.75-mL Fogarty balloon on a 4-F catheter. The clot material that embolized distally during the procedure was sampled and quantified. No effective embolectomy was performed via a conventional sheath. With the tulip sheath, however, complete clot removal was achieved unless the clot size exceeded the tulip volume. On the basis of results of in vitro testing, the tulip design is promising for use in several applications during percutaneous interventions.

Catheterization↗
PubMed1991

[The implantation of self-expanding metal prostheses (stents) into the bronchial system in central neoplasms].

This paper reports the use of an endobronchial metallic prosthesis (wall stent) for palliative management of 6 patients with central neoplasms and life-threatening airway obstruction. In five of six patients implantation of the stent resulted in improvement of their dyspnoea. However, functional data showed only a slight amelioration. In case of endobronchial growth, tumour may protrude easily through the meshwork of the stent. Therefore, use of the stent in these patients only seems appropriate if combination with other forms of therapy (radiation, laser) is possible. The easy feasibility of stent implantation and the lack of severe side effects and migration indicate that the stent may be an effective means in patients suffering from peribronchial tumour compression.

Airway Obstruction↗
PubMed1991

[The percutaneous removal of osteoid osteomas via CT-guided drilling].

Osteoid osteomas were removed by CT-guided core drill excision of the nidus in 4 patients. All osteoid osteomas were located in the lower extremity and included cortical lesions in the femur (n = 2), and the tibia (n = 1) and one spongious lesion in the navicular bone of the foot. Nidus diameter ranged from 2 to 3 mm. The patients were discharged after the procedure same day or next day depending on the kind of anaesthesia performed. Follow-up periods ranged from 6 to 56 months and revealed no signs of recidivation. CT-guided core-drill excision of the nidus seems to be a very promising alternative to surgical procedures because of its high cost-effectiveness and minimal invasiveness.

Adolescent↗
PubMed1991

In vitro ablation of normal and diseased vascular tissue by a fiber-transmitted holmium laser.

An in vitro study was performed to test the ablative potential of a fiber-transmitted pulsed holmium laser (2.1 microns) applied to normal vascular wall, lipomatous plaques, and calcified plaques. Different fluences per pulse of 42, 80, 205, and 315 J/cm2 were used. Ablation of normal tissue and lipomatous plaques was achieved with all power settings. Effective ablation of calcified plaques, however, occurred only after a minimum fluence of 205 J/cm2, and the effect was significantly less pronounced compared to ablation of soft lesions.

Angioplasty, Laser↗
PubMed1991

Pancreatic enhancement after low-dose infusion of Mn-DPDP.

Enhancement of the pancreas was demonstrated after low-dose (10 mumol/kg) infusion of a new contrast agent for magnetic resonance (MR) imaging, manganese dipyridoxal-diphosphate (Mn-DPDP). To the authors' knowledge, this has not been described previously. The enhancement reached a maximum of 98% +/- 13% (standard deviation) during a long period (greater than 6 hours). Mn-DPDP seems to have potential as a selective contrast agent in MR imaging of the pancreas.

Contrast Media↗
PubMed1991

Iliac artery stenosis or obstruction after unsuccessful balloon angioplasty: treatment with a self-expandable stent.

Obstruction or stenosis of the iliac artery was treated by placement of a self-expandable stent in 91 patients. A total of 100 lesions was treated. All patients had had poor results of balloon angioplasty including residual stenosis, iliac occlusion, and dissection. The stent used in all cases was a self-expandable stainless steel endoprosthesis mounted on a 7- or 9-French catheter and covered by an invaginated tubular rolling membrane. The diameter of the expanded stent varied from 7 to 12 mm. A total of 129 stents was placed. Technical success was 97%. Thromboses occurred immediately after placement in two patients and within the first month in six; these were mainly due to residual obstruction. Eighty-two (93%) of 88 patients with a follow-up longer than 3 months had no recurrent symptoms. Restenosis caused by intimal hyperplasia inside the stent occurred in 10 patients; these required repeated intervention in only four cases. In the remaining six patients, no further complications occurred. Our results show that self-expanding endoprostheses are of value for improving the results of inadequate percutaneous transluminal angioplasty.

Adult↗
PubMed1991

[Intravascular ultrasound for support in percutaneous interventional treatment].

The potential of intravascular ultrasound (IVUS) as an adjunct to angiography was investigated in 54 interventional procedures (13 venous lesions, 41 arterial lesions: stent placement in 31, atherectomy in 7, balloon dilation in 6, thrombectomy in 5, placement of vena cava filters in 3, foreign body retrieval in 2 cases). IVUS offered additional information to angiography in 30 cases; the therapeutic concept was changed because of IVUS findings in 18 cases. Severity of dissections or stenoses was more accurately depicted by IVUS compared to angiography. IVUS allowed an exact measurement of vessel diameter and a correct positioning of stents and caval filters.

Catheterization, Peripheral↗
PubMed1991

[Indications for the implantation of vascular endoprostheses (stents)].

Percutaneous endoprostheses were recently introduced as an adjunctive therapy for arterial occlusive disease. Clinical experience in 137 patients showed encouraging technical success in the follow-up results in patients with iliac lesions. A low patency rate in femoral arteries, however, restricts stent implantation to selected cases. So far, indications for lesions located elsewhere have not yet been fully accepted. Because long-term follow-up data are not yet available, stent placement should be applied to a subset of lesions that are not amenable to balloon angioplasty alone.

Arterial Occlusive Diseases↗
PubMed1990

[Percutaneous vascular endoprotheses for occlusions or stenoses of hemodialysis shunts].

In ten patients (four men and six women, mean age 51.7 [26-79] years), with six occlusions and five stenoses of a haemodialysis shunt or shunt-draining subclavian vein, a self-expanding intravascular stent was implanted percutaneously after balloon-dilatation. The implantation was successful in 9 of 11 instances, but the shunt thrombosed in two within 24 hours (in one of the patients, with antithrombin III deficiency, the shunt had to be abandoned). After an average observation period of 7.8 (1-14) months, ten shunts have remained open and suitable for dialysis. A further stent had to be implanted in one of the patients because of stenosis distal to the first stent. In three patients intima hyperplasia within the stent necessitated percutaneous balloon dilatation and/or atherectomy.

Adult↗