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 (

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.

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.

The precise determination of vascular lumen and stent diameters: correlation among calibrated angiography, intravascular ultrasound, and pressure-fixed specimens.

PURPOSE: Luminal diameters measured in vivo by calibrated-catheter angiography and by intravascular ultrasound were correlated with those obtained from pressure-fixed histologic cross-sections to determine the accuracy of both methods. METHODS: Angiographic and endosonographic diameter measurements were performed in the center of stents placed in the iliac arteries of 10 miniature pigs and were compared with luminal and stent diameters in postmortem, pressure-fixed, histologic cross-sections from identical locations. RESULTS: Compared with histologic diameters, magnification-corrected angiographic measurements still magnified vascular luminal diameters by 0.7 +/- 0.71 mm (r = 0.41, Pearson; p < 0.003, Wilcoxon, matched pairs), whereas intravascular ultrasound measurements proved to be almost identical to the histologic lumina (r = 0.95, Pearson; p > 0. 5, Wilcoxon, matched pairs). Similarly, stent diameters correlated well between endosonographic and histologic measurements (r = 0.91; p = 0.002), and less well between angiographic and histologic diameters (r = 0.62; p = 0.002). CONCLUSION: Since calibrated angiography still overestimates vascular lumina, endosonography is the preferred technique for accurate in vivo measurements.

Local intraarterial thrombolysis: in vitro comparison of various infusion catheters.

PURPOSE: Catheters are compared in vitro to evaluate the efficacy of thrombolysis during urokinase infusion within the thrombus. METHODS: Six catheters were introduced individually into human thrombus within a stenotic flow model. Urokinase was infused continuously into the thrombus. To quantify the efficacy of thrombolysis, pressure gradients were recorded proximal and distal to the thrombus and during the course of infusion. Uniformity of lysis was assessed radiographically. RESULTS: The fastest and most homogeneous thrombolysis was achieved with the EDM and the straight-flush catheter, shown by decreasing transthrombotic pressure gradients. All other catheter designs showed less homogeneous and delayed thrombolysis (p 0.7). CONCLUSION: The EDM catheter and the straight flush catheter achieved the most homogeneous and fastest thrombolysis, apparently due to the best urokinase distribution within the thrombus.

Local intraarterial thrombolysis: in vitro comparison between automatic and manual pulse-spray infusion.

PURPOSE: Manual and automatic pulse-spray infusion techniques are compared in vitro to evaluate the efficacy of thrombolysis and the distribution of urokinase and saline solution within thrombus using a pulse-spray catheter. METHODS: A pulse-spray catheter was introduced into a human thrombus within a stenotic flow model. Automatic and manual pulsed infusion of urokinase and automatic pulsed infusion of saline solution were compared. To quantify the efficacy of thrombolysis, pressure gradients were recorded proximal and distal to the thrombus and during the course of infusion. Distribution of infused urokinase was assessed radiographically. RESULTS: The fastest and most homogeneous dissolution of the thrombus was achieved with automatic pulsed infusion of urokinase, shown by decreasing transthrombotic pressure gradients (p < 0.001, Wilcoxon, matched pairs). Manual pulsed infusion of urokinase or saline solution resulted in inhomogeneous thrombus dissolution and delayed thrombolysis. CONCLUSION: Application of automatic pulse-spray injectors seems beneficial for more effective and homogeneous intraarterial pulse-spray thrombolysis when compared with conventional manual pulsed technique.

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.

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.

Outcome of patients with advanced neoplastic disease receiving vena caval filters.

PURPOSE: The authors examined the appropriateness and outcome of inferior vena caval (IVC) filter placements in patients with advanced malignancies and limited expected survival. PATIENTS AND METHODS: Over a 35-month period, 35 IVC filters were inserted in 34 adult patients with advanced neoplasms. Follow-up was as long as 28 months (mean, 5.2 months). Filter effectiveness, complications, recurrent pulmonary emboli, patient survival, and hospital discharge status were recorded. RESULTS: Twenty-eight patients (82%) were discharged home (n = 21) or to nursing facilities (n = 7) between 1 and 193 days (mean, 23 days) after filter insertion. Six patient (18%) died during hospitalization 1-95 days after filter insertion. The overall mean survival was 6.6 months; for patients with stage III and IV tumors mean survival was 8.0 and 5.5 months, respectively. Even among patients with stage IV disease, 59% survived longer than 3 months. There were no complications related to filter insertion and no clinical evidence of recurrent pulmonary emboli. In 14% of patients, filters enabled invasive therapeutic and palliative procedures to be performed. CONCLUSION: The presence of advanced neoplastic disease by itself should not be a deterrent to insertion of IVC filters, as most patients survived well beyond initial hospitalization.

Analysis of particle size generated during plaque ablation with a flashlamp pumped pulsed dye laser.

PURPOSE: To examine debris size generated during in vitro plaque ablation by laser energy and estimate the risk of peripheral embolization following laser angioplasty. METHODS: A flashlamp pumped pulsed dye laser of 480-nm wavelength was used to ablate calcified arteriosclerotic plaque, fibrous fatty plaque, and normal aortic wall on samples of human cadaver aortas. Each tissue sample was immersed in saline solution and treated with the same amounts of laser energy transmitted by a 320 microns-diameter glass fiber in direct tissue contact. The debris generated during plaque ablation was then separated from the supernatant and the particles were counted and analyzed for size. RESULTS: Depending on the underlying type of tissue and the setting of laser energy, a wide range of particles with sizes between 5.3 mm2 and 64 microns 2 was found in samples. The largest particles were found after ablation of calcified atherosclerotic plaque, whereas fibrous, fatty plaque and normal aortic wall showed smaller particles and a lesser amount of debris. CONCLUSION: Our study demonstrates that a considerable amount of debris is generated during laser angioplasty at 480 nm and that particle size is sufficient to cause potentially symptomatic embolic occlusions of mid- and small-sized peripheral arteries.

Comparison of mechanical deformation properties of metallic stents with use of stress-strain analysis.

PURPOSE: Elastic and plastic deformation properties of the Wallstent, Palmaz stent, and Strecker stent were evaluated quantitatively with an in vitro model simulating forces exerted by an eccentric lesion. MATERIALS AND METHODS: A miniaturized compression testing device was constructed. Stress-strain graphs were obtained for each stent, and the elastic moduli and yield points were calculated. RESULTS: There is a 21-fold range in the elastic modulus among the Wallstent, Palmaz stent, and Strecker stents. The Palmaz stent was the only device to exhibit permanent plastic deformation. The 10-mm Palmaz stent will undergo 15% focal eccentric narrowing at 0.75 atm of pressure; the "standard braid" and "less shortening braid" 10-mm Wallstents at 0.55 and 0.25 atm, respectively; and the 10-mm tantalum Strecker stent at 0.08 atm. Overlapping of stents doubles the stiffness of the Wallstent and the Strecker stent and doubles the yield point of the Palmaz stent. The 4-9 mm Palmaz stent is 30% more resistant to deformation than the larger 8-12-mm version when expanded to identical 8-mm diameters. CONCLUSIONS: The "standard braid" version of the 10-mm Wallstent provides 2.3-fold additional strength for resistant stenoses compared with the "less shortening braid." Overlapping or nesting of stents may permit full expansion should there be incomplete expansion or recoil of a single stent. The 4-9-mm Palmaz stent is preferable from the standpoint of allowing the use of a smaller (7-F instead of 9-F) introducer sheath and also for providing superior resistance to deformation. A purely elastic stent such as the Wallstent is preferable in locations where permanent plastic deformation may occur, such as the thoracic outlet.

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.

Evaluation of a prototype steerable angioscopic laser catheter in a canine model: a feasibility study.

To overcome some of the persisting technical problems related to laser angioplasty, a new catheter was designed and investigated in a canine model. This 5F catheter contained a deflectable tip for steerability, an angioscope, and a laser fiber. Catheter steerability, angioscopic function, and the effects of a 480 nm flash lamp pumped pulsed dye laser on normal canine vessel walls were evaluated. Steering, angioscopic guidance, and application of laser energy were easy and fast to perform in a bloodless vessel segment. Maintaining a condition of bloodlessness at the target site, critical to angioscopic guidance, proved to be the most difficult part in this prototype evaluation. It was noted that the 480 nm pulsed dye laser did not cause macroscopic alterations or perforations to the normal vessel wall. We conclude that a relatively simple deflection mechanism of a small-caliber angioscope provides the kind of aiming ability requisite for precise endovascular therapy. Complete bloodlessness of the area is necessary for both viewing and laser ablation at 480 nm.

Peripheral angioplasty balloon technology.

Changes in balloon and catheter technology have led to the development of smaller, more flexible, and less traumatic balloon dilatation systems. The physical principles that govern balloon angioplasty and the current status of balloon materials and catheter designs will be reviewed. A compilation of various angioplasty catheters is also summarized.

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.