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Biomedical subjects

D Vorwerk

Publications and source records attributed to D Vorwerk.

At least 37 records · Page 2Linked to original sources
PubMed1999

S-1 radiculopathy as a possible predisposing factor in focal myositis with unilateral hypertrophy of the calf muscles.

Associated with chronic S-1 radiculopathy, a 44-year-old man developed unilateral hypertrophy of the calf muscles. Electromyography revealed neurogenic alterations in the corresponding limb compatible with S-1 radiculopathy. In addition, MR-tomographic and bioptic findings were consistent with a focal inflammatory myopathy of the enlarged right gastrocnemius muscle. Predisposing factors for the localisation of a focal myositis are unknown. This case report highlights the diagnostic difficulties in distinguishing focal myositis and denervation hypertrophy following S-1 radiculopathy or secondary inflammation related to denervation. We consider the possibility that in our case the inflammatory process might have been triggered by electromyographically proven chronic denervation related to radiculopathy.

Adult↗
PubMed1999

Experimental treatment of early chronic iliac vein thrombosis with a modified hydrodynamic thrombectomy catheter: preliminary animal experience.

PURPOSE: To evaluate the efficacy and safety of a new hydrodynamic catheter for removal of chronic iliac vein thrombus. METHODS: Unilateral iliac vein thrombosis was induced in seven pigs by combining permanent coil and temporary balloon occlusion. Thrombectomy was performed with a new hydrodynamic catheter (10 F S.E.T.) 3 days after thrombus induction. After thrombectomy, the animals were killed and the iliac veins were examined histologically. RESULTS: Complete thrombectomy (100% thrombus removal) was achieved in three of seven animals, 75% removal in three of seven animals, and only 30% removal in one animal. The average thrombus removal was 75%. Successful re-establishment of flow was achieved in five of seven cases. Histologically, the thrombi were partially organized, meeting the histologic criteria for early chronic venous thrombosis. Minor venous wall damage caused by the thrombectomy procedure without acute hemodynamic consequences was observed in four of seven cases. CONCLUSION: The 10-F S.E.T. catheter was reasonably effective in removing chronic iliac vein thrombus with no hemodynamically significant complications.

Animals↗
PubMed1999

Improvement of haemocompatibility of metallic stents by polymer coating.

An alternative to open heart surgery in treating arterial diseases causing restricted blood flow is the implantation of intracoronary metallic stents. In spite of the advances in implantation and in spite of the excellent mechanical properties of metallic stents, there are still limitations because of the thrombogenicity of the metal. We have, hence, directed our attention to the coating of metallic stents with an ultrathin polymer layer by chemical vapor deposition (CVD) polymerization of 2-chloroparacyclophan. In a second step of surface modification the poly(2-chloroparaxylylene) layer is modified by treatment with a sulfur dioxide plasma in order to obtain a more hydrophilic surface with new functional groups. The results demonstrate the stable polymer coating of the stents and the improvement of haemocompatibility after treatment with sulfur dioxide plasma. Platelet adhesion is decreased from 85% for the metal surface to 20% for the CVD-coated and sulfur-dioxide-plasma treated surface.

Journal Article↗
PubMed1999

[The Perflex stent, a new balloon-expandable vascular stent: the initial clinical results].

PURPOSE: Clinical evaluation of a newly developed balloon-expandable vascular stent. METHOD: Participating in a multi-center study our clinic enrolled 12 patients with 15 iliac artery stenoses (Fontaine IIa-III) that were treated with the new stent. Three patients had bilateral stenoses. The mean ankle-brachial index (ABI) at rest was 0.76 +/- 0.25 (+/- 1 standard deviation), the mean ABI after exercise was 0.47 +/- 0.20. Indication for stent insertion was a residual trans-lesion pressure gradient > or = 10 mmHg after balloon angioplasty. Follow-up included clinical examination, measurements of the ABI at rest and after exercise, and colour duplex ultrasound (CDS) on the day of hospital dismissal and 1, 6 and 12 months after stent insertion. RESULTS: 16 stents were placed successfully. One stenosis was treated with two stents. Acute complications did not occur. The Fontaine stage increased by at least one stage in all patients. The ABI at rest rose to 0.91 +/- 0.26, the ABI after exercise to 0.86 +/- 0.29. During follow-up one stent occlusion, one stenosis proximal to a stent, and CDS-findings suggesting restenosis in two further stents were observed. CONCLUSIONS: It appears that the Perflex stent may be used in the iliac arteries with a success rate similar to other stents. However, this preliminary result has to be confirmed in a larger series and after a longer follow-up.

Aged↗
PubMed1999

Treatment of hemodialysis-related central venous stenosis or occlusion: results of primary Wallstent placement and follow-up in 50 patients.

PURPOSE: To analyze the effectiveness of stent placement as the primary treatment for central venous obstruction in patients undergoing hemodialysis. MATERIAL AND METHODS: Fifty-seven Wallstents were placed in 50 patients with symptomatic shunt dysfunction and arm swelling due to central venous obstruction. Technical success, complication, and patency rates were evaluated. RESULTS: Stent deployment was successful in all patients, and early rethrombosis (within 1 week) was noted in one patient (2%). Seventy-three episodes of reobstruction occurred and were treated percutaneously with angioplasty alone in 54 cases (74%). Nineteen cases (26%) necessitated additional stent placement. The 3-, 6-, 12-, and 24-month primary patency rates were 92%, 84%, 56%, and 28%, respectively. Cumulative overall stent patency was 97% after 6 and 12 months, 89% after 24 months, and 81% after 36 and 48 months. CONCLUSION: In the treatment of brachiocephalic and subclavian venous obstruction, stent placement shows excellent technical results and helps preserve vascular access for a substantial period. Multiple repeat interventions are, however, frequently required to maintain patency.

Adult↗
PubMed1998

[Dose and contrast medium reduction in intravenous digital subtraction angiography by bolus sequence].

PURPOSE: This study evaluates the dose area product, the amount of contrast media and the examination quality of the bolus chasing technique compared to the single-step technique in intravenous digital subtraction angiography. MATERIAL AND METHODS: 15 examinations each with bolus chasing and single-step technique were compared. The dose area product and the volume of contrast media were recorded. The examination quality was scored by two examiners. RESULTS: With bolus chasing the volume of the administered contrast media could be decreased on average by 114 ml (43%). The difference between the dose area product of bolus chasing (722 dGy/cm2) and single-step technique (1910 dGy/cm2) was significant. No significant difference in examination quality was found. CONCLUSIONS: The intravenous bolus chasing technique is a practicable method. Compared to the single-step technique it allows a remarkable dose reduction and a low consumption of contrast media without restriction of examination quality.

Angiography, Digital Subtraction↗
PubMed1998

[New TIPS placement in pregnancy in recurrent esophageal varices hemorrhage--assessment of fetal radiation exposure].

Recurrent variceal bleeding due to liver cirrhosis led to treatment with a transjugular intrahepatic portosystemic shunt (TIPS) in a pregnant woman at 20 weeks' gestation. Fetal radiation exposure was estimated to be less than 10 mSv. The use of a graduated catheter allowed measurement of field size and reliable determination of the patient's entrance dose. Radiation exposure of an approximated fetal dosage of 5.2 mSv did not justify abortion for medical reasons. Therefore, TIPS procedure is not generally contraindicated during pregnancy itself. TIPS placement may be a therapeutic option related to the severity of the underlying maternal disease, after radiation exposure of the fetus has been estimated.

Adult↗
PubMed1998

[Novel endoluminal stents for the treatment of arterial fistulas and perforations].

PURPOSE: To evaluate the use of polycarbonate-polyurethane (Corethane) stented grafts for the treatment of arteriovenous fistulas and arterial perforations. MATERIALS AND METHODS: 4 patients at the age of 34 to 81 underwent percutaneous insertion of corethane endoluminal grafts. Two patients had an arterial fistula--one iliaco-iliac, one brachio-brachial. Two patients underwent treatment to seal arterial perforations that occurred in the external iliac artery in one and in a femoral venous bypass in another. RESULTS: In all cases the communication or leakage was sealed by the endograft in place but had to be combined with a detachable balloon in om case. In three patients, a longer follow-up became available, one patient died three weeks after treatment from unrelated causes. While two stent grafts remained open for 15 and 24 months, one patient experienced stent graft occlusion three months after treatment. CONCLUSIONS: Corethane stent grafts are helpful to seal short-neck arteriovenous fistulas and arterial perforations even under emergency conditions.

Adult↗
PubMed1998

[Experimental model of early chronic pelvic vein thrombosis with occlusion spirals and thrombin].

PURPOSE: To create an early chronic venous thrombosis with good comparability to human venous thrombosis for evaluation of new thrombectomy systems. METHODS: Using a transjugular approach, three dacron-fibered occlusion coils were placed into the proximal common iliac vein of 7 pigs under general anesthesia. The coiled common iliac vein was blocked by the use of a balloon occlusion catheter, and 500 units of thrombin were injected into the "coil basket". One hour later, the balloon catheter was deflated and removed. After three days, the thrombus was controlled by phlebography and histology. RESULTS: The induction of thrombi was successful in all cases. The mean length of the thrombi was 60 mm and the mean diameter was 10 mm. Histologically, the thrombus consisted of a laminated plug of fibrin and platelets as well as clots in the sense of a mixed thrombus with signs of a beginning organization. Considering the cellular composition and the histological aspect, the thrombi met the criteria for early chronic venous thrombosis in humans. CONCLUSION: The presented experimental thrombus model is easy to perform and enables a good comparability to early chronic human venous thrombosis.

Animals↗
PubMed1998

Bedside testing (SimpliRED) in the diagnosis of deep vein thrombosis. Evaluation of 250 patients.

RATIONALE AND OBJECTIVES: The authors evaluate the sensitivity and specificity of a bedside test (SimpliRED) in the diagnosis of deep vein thrombosis compared with contrast phlebography. METHODS: Two hundred fifty patients, referred for phlebography, underwent bedside testing for detection of deep vein thrombosis. Contrast phlebography was performed immediately afterward. SimpliRED provides a clearly visible agglutination of the patient's red blood cells in the presence of elevated levels of cross-linked fibrin derivative (D-dimer), which is specific for fibrin breakdown. RESULTS: In 82 (32.8%) patients, deep vein thrombosis was confirmed venographically. An abnormal D-Dimer test was found in 79 of the 82 patients with thrombosis (sensitivity: 96.3%). The three patients who were diagnosed falsely as normal on agglutinin testing, had venograms which showed only an isolated calf thrombosis in small muscle veins (< 2 cm in diameter) not requiring treatment. One hundred of 168 patients without venographic thrombosis were diagnosed correctly by SimpliRED (specificity: 59.5%). The positive predictive value was 53.7%; the negative predictive value was 96.8%. CONCLUSIONS: All thrombotic disorders in the leg that required further treatment were identified correctly. SimpliRED is a very sensitive test with moderate specificity in the diagnosis of deep vein thrombosis. Therefore, further invasive testing is needed only in those patients in whom the D-dimer test is abnormal. A false-positive result of the bedside test may be nonspecific or due to elevated levels of fibrin split products, which can occur whenever the coagulation system has been activated by any of several conditions.

Adolescent↗
PubMed1998

Spondylodiskitic abscesses: CT-guided percutaneous catheter drainage.

PURPOSE: To determine whether computed tomographically (CT) guided percutaneous catheter drainage of spondylodiskitic abscesses is an appropriate and effective alternative to surgery. MATERIALS AND METHODS: CT-guided percutaneous catheter drainage was performed in 21 patients (16 men, five women; age range, 24-81 years) with 33 spondylodiskitic abscesses. Nine intradiskal, 12 paravertebral, and 12 psoas abscesses were drained with 5.6-14.0-F catheters. In 29 cases, the catheter was inserted by using the Seldinger technique in four cases, a trocar technique was used. All patients underwent follow-up CT or magnetic resonance imaging examinations for 6 months. RESULTS: Successful placement of the drainage catheter was achieved in each patient without procedural complications. The duration of drainage was 4-56 days (average duration, 26.8 days). Three of 33 catheters were changed because of insufficient drainage; one of the 33 catheters had to be reinserted because of dislocation. Two patients underwent surgery for stabilization of the spine with the drainage catheter in place. In 16 of the 21 patients, specific organisms were isolated; thus, definitive medical therapy was possible. Complete evacuation of all abscesses was achieved initially, with no evidence of recurrence during the follow-up. CONCLUSION: CT-guided percutaneous catheter drainage is an efficient and safe procedure in the management of spondylodiskitic abscesses.

Abscess↗
PubMed1997

[Color-coded duplex ultrasonography of the orbit in central vein thrombosis].

PURPOSE: To evaluate the haemodynamic findings of orbital vessels in patients with central retinal vein occlusion by colour coded duplex sonography. METHODS: In 24 patients suffering from central retinal vein occlusion, confirmed by ophthalmoscopy and fluorescence angiography, colour-coded duplex sonography of central retinal vein, central retinal artery, posterior ciliary arteries and ophthalmic artery of the affected, and the unaffected contralateral eye, was performed and compared to a control group (150 healthy subjects). RESULTS: In eyes with central retinal vein occlusion, the maximum velocity of the central retinal vein was on average 4.55 cm/s (+/-2.37 cm/s) and, as compared with the unaffected eye (mean: 6.56 +/- 1.47 cm/s) and the control group (5.97 +/- 2.37 cm/s), reduced significantly. In the affected eyes, the end diastolic velocity of the central retinal artery was reduced and the pulsatility index was increased significantly, compared with the unaffected eyes and the control group. Compared with the control group, the peak systolic and end diastolic velocities of the ophthalmic artery were significantly reduced. CONCLUSION: In conclusion, the findings assessed by colour-coded duplex sonography show a flow reduction in the central retinal vein and an increased arterial flow resistance in the retinal layer. There is good correlation with the angiographic results. Moreover, flow reductions in the ophthalmic artery, which are not seen in ophthalmological examinations, can be detected by this new examination technique.

Adult↗
PubMed1997

[The diagnosis of deep venous thromboses of the leg using a new rapid test (SimpliRED)].

PURPOSE: Evaluation of sensitivity and specificity of a bed-side test in the diagnosis of deep-vein thrombosis compared to contrast phlebography. METHODS: 122 patients, referred for phlebography, underwent bedside testing (SimpliRED) for detection of deep vein thrombosis. Contrast phlebography was confirmed immediately afterwards. SimpliRED provides a clearly visible agglutination of the patient's red blood cells in the presence of elevated levels of crosslinked fibrin derivatives (D-dimer) in the sample, being specific for fibrin breakdown. RESULTS: In 37 (30.3%) patients deep vein thrombosis could be confirmed. An abnormal D-dimer test was found in 35 of the 37 patients with thrombosis (sensitivity: 94.6%). Two patients who had not been identified by agglutinin testing, showed an isolated calf thrombosis in small muscle veins (< 2 cm in diameter) not requiring treatment. 55 of 85 patients without thrombosis in phlebography were stated correctly by SimpliRED (specificity: 64.7%). CONCLUSION: All thrombotic disorders in the leg with the need for further treatment were identified correctly. SimpliRED is a very sensitive test with moderate specificity in the diagnosis of deep vein thrombosis. Therefore, further invasive testing is needed only in such patients where the D-dimer test is abnormal. A false positive result of the bed-side test may be non-specific or due to elevated levels of fibrin split products, if the coagulation system is activated in several other conditions.

Adult↗
PubMed1997

[Sutureless vascular end-to-side anastomosis: an in-vivo test of a percutaneous concept in the animal model].

PURPOSE: To test a percutaneous concept for creation of a sutureless terminolateral vascular anastomosis in vivo. MATERIAL AND METHOD: By creating sideholes into the middle portion of a stent and a stent graft, both implants could be arranged in a Y-shaped configuration. An arteriovenous shunt was created in 3 sheep between the left carotid artery and the left external jugular vein. A stent graft was partially inserted into the venous lumen. Axial venous patency was restored by placing a stent through the sidehole into the graft lumen from an upstream puncture site. Graft patency was maintained by placing the sidehole of the stent at the bridging point between stent graft and stent with no stent struts crossing. Arterial end-to-end anastomosis was performed by retrograde placement of a stent graft into the arterial lumen. Both anastomoses were connected by a silicone tube. RESULTS: In all cases, a venous end-to-side anastomosis was created that was blood-tight and safely secured into the vascular lumen. CONCLUSION: Y-shaped configuration of stent and stent grafts through sideholes allows creation of sutureless end-to-side anastomoses in vivo.

Anastomosis, Surgical↗