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K H Barth

Publications and source records attributed to K H Barth.

At least 19 recordsLinked to original sources
PubMed2000

Hydrodynamic thrombectomy system versus pulse-spray thrombolysis for thrombosed hemodialysis grafts: a multicenter prospective randomized comparison.

PURPOSE: To evaluate the safety and efficacy of a hydrodynamic thrombectomy system in a prospective, multicenter randomized comparison with pulse-spray thrombolysis in hemodialysis grafts. MATERIALS AND METHODS: Nine centers enrolled 120 adult patients with recently (</=14 days) thrombosed hemodialysis grafts. Graft venography was used to confirm occlusion in 62 patients randomly assigned to thrombectomy and 58 to thrombolysis. For thrombolysis, a mixture of 5,000 U of heparin and 250,000 U of urokinase was distributed throughout the thrombus, first to the venous then to the arterial graft end. For thrombectomy, the catheter was passed in the same sequence. Technical success was removal of 80% or more of thrombus. Clinical success was technical success plus the ability to dialyze. Also assessed were total procedure time, thrombus treatment time, procedure-related blood loss, other complications, and 30- and 90-day outcomes. RESULTS: Patient demographics were comparable. Technical success rates were 95% (59 of 62) for thrombectomy and 90% (52 of 58) for thrombolysis (P: =.31). Clinical success rates were 89% (55 of 62) and 81% (47 of 58), respectively (P: =.24). At 30 days, 69% (43 of 62) and 66% (38 of 58), respectively, could be dialyzed through the graft (P: =.70); at 90 days, the rates were 40% (25 of 62) and 41% (24 of 58), respectively (P: =.91). None of these differences or those for procedure-related blood loss and early and late complications were statistically significant. Thrombus treatment times of 16.8 minutes for thrombectomy and 23.4 minutes for thrombolysis were significantly different (P: <.01). CONCLUSION: The hydrodynamic thrombectomy system is at least as efficacious and safe as pulse-spray thrombolysis but shortens thrombus treatment time.

Adult↗
PubMed1999

Effects of nitinol Strecker stent placement on vascular response in normal and stenotic porcine iliac arteries.

PURPOSE: This experimental study was conducted to evaluate neointimal thickness, lumen diameters, and histologic changes in normal and stenotic porcine iliac arteries following placement of self-expanding nitinol Strecker stents. MATERIALS AND METHODS: Neointimal trauma causing slight vascular stenosis was induced unilaterally within external iliac arteries of 12 swines by means of endothelial abrasion and high cholesterol diet. Nitinol Strecker stents were placed within the stenotic and the normal contralateral vascular segments. For histopathologic evaluation, the pigs were killed 12 or 24 weeks after stent placement and luminal diamters were evaluated angiographically. RESULTS: Excluding one occlusion, 15% narrowing of the lumen diameter was induced unilaterally (P = .002). Initial luminal gain after stent placement was greater for stenotic than for normal arteries. The amount of neointima thickness was not different between stenotic and normal vessels (P > .05). Comparing vascular diameters before stent placement and at follow-up, luminal loss due to neointima proliferation was 22% within normal arteries (P = .0002), while a luminal gain by 15% was found within the stenotic arteries (P = .008). Maturation of neointima and endothelial coverage were complete after 24 weeks. CONCLUSIONS: Even though nitinol Strecker stents induce excessive neointimal proliferation, stenotic arteries seem to profit from great early luminal gain resulting in 15% of vascular expansion at follow-up while slight stenosis is induced within normal iliac arteries.

Alloys↗
PubMed1999

Initial results from uterine fibroid embolization for symptomatic leiomyomata.

PURPOSE: To evaluate the safety and short-term efficacy of uterine fibroid embolization (UFE) in patients with symptomatic uterine fibroids. MATERIALS AND METHODS: Bilateral UFE was performed in 61 patients with symptomatic uterine leiomyomata during a 16-month period. Imaging was performed before the procedure and at 3 months and 1 year after the procedure. Questionnaires were obtained at regular intervals after the procedure to assess patient outcome. RESULTS: All procedures but one were technically successful. Mean clinical follow-up was 8.7 months. Minor complications occurred in five patients during the follow-up period. All were treated without permanent sequelae. Menstrual bleeding was improved in 89%, with 81% of patients moderately to markedly improved. Pelvic pain and pressure was improved in 96% of patients, with moderate to marked improvement in 79%. At initial imaging follow-up (mean, 4.4 months postprocedure), median uterine volume decreased 34% (P = .0001) and the median dominant fibroid volume decreased 50% (P = .0001). Imaging at 1 year (mean, 12.3 months) after the procedure showed continued reduction with a median uterine volume reduction of 48% (P = .0002) and median dominant fibroid volume decrease of 78% (P = .0002). CONCLUSION: In the authors' initial clinical experience, UFE appears effective in controlling symptoms and substantially reducing fibroid volume with few complications.

Adult↗
PubMed1996

Paired comparison of vascular wall reactions to Palmaz stents, Strecker tantalum stents, and Wallstents in canine iliac and femoral arteries.

BACKGROUND: Palmaz stents, Strecker stents, and Wallstents, all used clinically, differ substantially in their physical characteristics, yet how differently the vascular wall reacts to them has not been demonstrated conclusively. We therefore undertook a side-by-side comparison. METHODS AND RESULTS: One stent was implanted into each canine external iliac and/or the flexing portion of the proximal femoral artery. In 9 dogs, Palmaz stents were placed vis-à-vis Strecker stents, with follow-up of 2 and 4 months. In 7 dogs, Palmaz stents were placed vis-à-vis Wallstents, with 4 months of follow-up. Angiographic midstent luminal diameters immediately after placement and at follow-up as well as midstent cross-sectional areas of neointima were compared for significant differences. In addition, neointimal maturation, medial atrophy, and stent-related trauma were assessed. Angiographically, all arteries remained open. The degree of luminal narrowing by recoil and neointima never reached 50% and was modest for Palmaz stents and Wallstents (P = .33) but significantly higher for Strecker stents (P < .0001 compared with Palmaz stents). This corresponded histologically to a significantly thicker neointima (P = .003) over Strecker than over Palmaz stents but not between Palmaz stents and Wallstents (P = .18). Neointimal buildup was generally more pronounced in the femoral artery segments than in the iliac segments. Maturation of the neointima over Palmaz stents was much further advanced than over Strecker stents and slightly more advanced than over Wallstents. Pressure-related atrophy of the tunica media was least for Strecker stents and more pronounced but similar for Wallstents and Palmaz stents. Wallstent wire ends caused some wall trauma; several femoral Palmaz stent struts protruded through the media. CONCLUSIONS: The lower-hoop-strength, higher-profile tantalum Strecker stent is affected by vascular wall recoil and evokes a greater degree of neointima formation than the lower-profile, higher-hoop-strength Palmaz stent and Wallstent. Medial atrophy is pronounced outside the latter two stents. The rigid Palmaz stent can penetrate through the vascular wall in flexing arteries.

Animals↗
PubMed1995

Radiological intervention in upper and lower gastrointestinal bleeding.

The role of angiography in acute upper GI tract bleeding is less a diagnostic than a therapeutic one because it provides a guide to selective embolization of either the left gastric artery, or the gastroduodenal artery and its two principal branches, the pancreaticoduodenal and the right gastroepiploic artery. Angiographic catheter techniques may also provide substantial diagnostic and therapeutic support for the management of acute lower GI bleeding from a variety of bleeding sources. The advantages are minimal invasion and relatively low risk. The intermittent nature of GI bleeding often interferes with the ability of angiography to demonstrate the source of bleeding. However, at times angiographic techniques provide the only reasonable means of localizing and controlling bleeding.

Adult↗
PubMed1994

Insertion of Groshong central venous catheters utilizing fluoroscopic techniques.

Groshong central line indwelling catheters are extensively used in gynecologic oncology patients for administration of chemotherapy, intravenous fluids, and pain medications. They are easy to maintain and have a good safety record. We report on the placement of these central venous catheters under direct fluoroscopic visualization as a method which is safe, inexpensive, and efficacious in high-risk patients. Fluoroscopic visualization during insertion provides several advantages: visualization of bony landmarks, placement of the guidewire into the subclavian vein and superior vena cava under direct visualization, and confirmation of appropriate distal placement of the Groshong catheter. Patient advantages include the following: (1) avoidance of unnecessary punctures to access the subclavian vein; (2) verification of guidewire placement to avoid cephalic placement; (3) passage of the guidewire only as far as the right atrium to avoid potential dysrrhythmias secondary to right ventricular irritation; and (4) a savings of approximately 60% over insertion in the general operating room. Thirty patients had placement under fluoroscopic visualization in the angiography suite of Georgetown University Hospital. The average age of the patients was 58 years (42-78). Sixteen patients had ovarian cancer, 6 had endometrial cancer, 5 had cervical cancer, and 3 had other gynecologic malignancies. Fifteen patients had catheters placed for chemotherapy, 14 for hydration, and 1 for pain control. Ten patients had had previous central venous catheters: 6 had been removed for infection, 2 for thrombus, 1 for completion of chemotherapy, and 1 for catheter kinkage. All 10 with previous catheters had successful placement of catheters in the angiography suite. Complications from insertion were minimal with one asymptomatic pneumothorax and one proximal port in an extravascular position. We present the technique of fluoroscopic insertion of Groshong catheters which is an effective method of placement in high-risk patients.

Adult↗
PubMed1992

Injection characteristics and downstream contrast material distribution of flush aortography catheters: in vitro study.

Performance of 11 commercially available 4- and 5-F aortic flush catheters was evaluated with respect to the extent of upstream injection, catheter motion, and downstream homogeneity of a 10-, 15-, and 20-mL/sec bolus of 76% meglumine sodium diatrizoate at room temperature. Tests were made in a pulsatile aortic flow model containing circulating fluid isoviscous to blood. The injection process was recorded on videotape. Homogeneity of the contrast material bolus was determined spectrophotometrically from samples collected from the center and each of the four quadrants of the vessel lumen. Upstream contrast material injection between 1.5 and 7 cm in length emerged from all catheters; it was lowest with one of the "tennis racket" designs from one and a new spiral end-loop design (Halo) from another manufacturer. All catheters, except the most rigid and largest-caliber catheter (5.8 F) showed considerable shaft motion at the higher injection rates. Downstream contrast material mixing homogeneity was always best at the highest injection rate but altogether was better for the Halo catheter than for any other catheter tested. It is concluded that all tested 4- and 5-F aortic flush catheters show some undesirable features, but certain design modifications improve performance and comparative testing is helpful to distinguish such features.

Aortography↗
PubMed1992

Gadolinium-enhanced magnitude contrast MR angiography of popliteal and tibial arteries.

To evaluate the efficacy of gadopentetate dimeglumine in MR angiography of the lower extremities, a flow phantom, seven healthy volunteers, and seven patients with peripheral vascular disease were studied with a magnitude contrast (MC) technique. The combination of an MC rephase-dephase gradient-refocused-echo pulse sequence, a 40-cm-long transmit-receive coil, and intravenous administration of a bolus of gadopentetate dimeglumine improved MR angiographic quality in the phantom, volunteers, and patients. Gadolinium enhancement decreased deleterious saturation effects and improved images of the popliteal and tibioperoneal arteries in the volunteers and patients. However, in some cases, venous overlap, imaging artifacts, and suboptimal visualization of subtle lesions limited interpretation. The authors conclude that gadolinium enhancement combined with an MC subtraction pulse sequence appreciably improves MR angiography of lower extremity arteries.

Arterial Occlusive Diseases↗
PubMed1990

Autoantigens in human neuroblastoma cells.

Neuroblastoma cells are frequently used as targets in studies of autoimmune diseases of the nervous system. We examined the human neuroblastoma cell line, LAN-5, for the presence of autoantigens that react with naturally occurring autoantibodies in human sera. Antibodies to the HNK-1 and Gal(beta 1-3)GalNAc epitopes, which have been implicated in human autoimmune neuropathy and motor neuron disease, respectively, immunostained the surface of the neuroblastoma cells, and antibodies to the 200 kDa high molecular weight neurofilament protein (NFH) immunostained the cytoplasm and cell processes. The NHK-1 and Gal(beta 1-3)GalNAc epitopes were associated with several glycoprotein bands in Western blots of the neuroblastoma cells, and the HNK-1 epitope was also shared by a glycolipid which co-migrated with 3-sulfoglucuronyl paragloboside (SGPG) from peripheral nerve, indicating that SGPG is synthesized in neuronal cells. Northern blot analysis revealed a single RNA band of 4800 bp for NFH in normal brain but two RNA species of 4800 and 3800 bp in both neuroblastoma and adrenal cells, confirming their common origin. The neuroblastoma cells appear to contain antigens that bind to naturally occurring autoantibodies in human serum and might therefore be useful for detecting and investigating the effects of anti-neuronal antibodies. The antibody populations being investigated, however, should be distinguished from other autoantibodies which might be present in the patients' serum.

Antibodies, Monoclonal↗