P:URPOSE: 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.

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.

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.

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.

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 </= 0.001, Friedmann-Test, Schaich-Hamerle). There was no significant difference in the efficacy of thrombus dissolution between the EDM and the straight-flush catheter (Wilcoxon, matched pairs, 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.

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.

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.

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.