Pre-existing Stent Research Articles

Impact of Preoperative Ureteral Stenting on Outcome of Ureteroscopic Treatment for Urinary Lithiasis

Sparse published data exist on the impact of preexistent ureteral stents on the success of ureteroscopic stone surgery. We investigated the impact of a preexistent ureteral stent in relation to a number of parameters and outcomes of ureteroscopic management for urinary lithiasis. We retrospectively evaluated a cohort of patients undergoing ureteroscopy for renal and ureteral calculi. Data were abstracted on stone side, size, number and site, patient demographics, total stone burden, ureteral access sheath use, preoperative ureteral stent, ureteroscope type and outcome. Statistical analysis was done. The success rate of 1 and 2 ureteroscopic procedures was 86.9% and 97.3%, respectively. Primary analysis included data on 221 initial procedures. The single procedure success rate for stone site was 91.9% for the distal ureter, 89.7% for the proximal ureter, 83.3% for the renal pelvis, 80.5% for the lower pole and 82.4% for the interpolar/upper pole. Success was negatively associated with primary stone size (p = 0.020), total stone number (p = 0.001) and cumulative stone burden (p <0.001). Stone site was not a predictor of success (p = 0.394). A preexistent stent was positively associated with success but it was not statistically significant (adjusted OR 2.22; 95% CI 0.88, 5.63; p = 0.254). Secondary analysis in patients who initially underwent flexible ureteroscopy yielded results consistent with those of primary analysis. Results show that ureteropyeloscopic lithotripsy and stone extraction may be performed with a high success rate. Success was significantly inversely related to stone size, cumulative stone burden and number of stones. Success was positively related to a preexisting ureteral stent but not significantly so.

CURATIVE ENDOVASCULAR RECONSTRUCTION OF CEREBRAL ANEURYSMS WITH THE PIPELINE EMBOLIZATION DEVICE

The Pipeline embolization device (PED) (Chestnut Medical Technologies, Inc., Menlo Park, CA) is a new microcatheter-delivered endovascular construct designed to achieve the curative reconstruction of the parent arteries giving rise to wide-necked and fusiform intracranial aneurysms. We present our initial periprocedural experience with the PED and midterm follow-up results for a series of 53 patients. Patients harboring large and giant wide-necked, nonsaccular, and recurrent intracranial aneurysms were selected for treatment. All patients were pretreated with dual antiplatelet medications for at least 72 hours before surgery and continued taking both agents for at least 6 months after treatment. A control digital subtraction angiogram was typically performed at 3, 6, and 12 months. Fifty-three patients (age range, 11-77 years; average age, 55.2 years; 48 female) with 63 intracranial aneurysms were treated with the PED. Small (n = 33), large (n = 22), and giant (n = 8) wide-necked aneurysms were included. A total of 72 PEDs were used. Treatment was achieved with a single PED in 44 aneurysms, with 2 overlapping PEDs in 17 aneurysms, and with 3 overlapping PEDs in 2 aneurysms. The mean time between the treatment and last follow-up digital subtraction angiogram was 5.9 months (range, 1-22 months). Complete angiographic occlusion was achieved in 56%, 93%, and 95% of aneurysms at 3 (n = 42), 6 (n = 28), and 12 (n = 18) months, respectively. The only aneurysm that remained patent at the time of the 12-month follow-up examination had been treated previously with stent-supported coiling. The presence of a preexisting endoluminal stent may have limited the efficacy of the PED reconstruction in this aneurysm. No aneurysms demonstrated a deterioration of angiographic occlusion during the follow-up period (i.e., no recanalizations). No major complications (stroke or death) were encountered during the study period. Three patients (5%), all with giant aneurysms, experienced transient exacerbations of preexisting cranial neuropathies and headache after the PED treatment. All 3 were treated with corticosteroids, and these symptoms resolved within 1 month. Endovascular reconstruction with the PED represents a safe, durable, and curative treatment of selected wide-necked, large and giant cerebral aneurysms. The rate of complete occlusion at the time of the 12-month follow-up examination approached 100% in the present study. To date, no angiographic recurrences have been observed during serial angiographic follow-up.

Abstract No. 207: Internal Iliac Artery Embolization Prior to EVAR: Comparison of the AMPLATZER® Vascular Plug to Conventional Coils

Internal iliac artery (IIA) embolization is routinely performed prior to endovascular repair of aortoiliac and isolated common iliac artery (CIA) aneurysms. The purpose of this study was to compare main trunk IIA embolization using the AMPLATZER® Vascular Plug (AVP) to conventional coil embolization with regards to cost, procedure time, number of angiographic runs, and late development of an endoleak. We retrospectively reviewed 34 cases between September 2004 and July 2008 of main trunk IIA embolization prior to endovascular stent graft repair of either aortoiliac (21) or isolated CIA aneurysms (8), or revision of preexisting endovascular stent grafts (5). In 14 patients embolization was performed with the AVP, and in the remaining 20 patients, embolization was performed with conventional coils. In each case, the total number of plugs/coils and their cost were determined. Procedure time and number of angiographic runs, both from initial IIA catheterization to vessel occlusion, were reviewed. There was no significant difference in average IIA diameter between the two groups. IIA occlusion was obtained with a single AVP in 12 of the 14 patients, and with two AVPs in the remaing two. An average of 7.8 (+/- 3.7) coils were used in the 20 patients undergoing coil embolization. Average cost of embolization with the AVP was $443.39, significantly lower than the $621.12 average cost of coil embolization (P value 0.035). Average time from initial IIA catheterization to vessel occlusion was also significantly decreased when the AVP was used over coils (23.7 vs 34.7 minutes, P value 0.035). No statistically significant difference in number of angiographic runs was noted. Follow-up CT angiograms were available in 12/14 patients who underwent AVP embolization, and in 17/20 patients who underwent coil embolization (mean followup 10.7 months), none of which demonstrated the presence of endoleak related to the IIA or distal iliac limb. In patients undergoing endovascular stent graft repair of aortoiliac or CIA aneurysms, successful IIA embolization can be performed both at a lower cost and with shorter procedure time with the AVP as compared to conventional coils.

Construction-related Differences Seen in Ureteral Access Sheaths: Comparison of Reinforced Versus Nonreinforced Ureteral Access Sheaths

Ureteral access sheaths (UASs) are used to facilitate ureteroscopic procedures. Difficulties with use have been reported. Manufacturers have redesigned these devices to ameliorate these problems, including reinforcement of the sheath wall. This study compared reinforced (RUASs) and nonreinforced UASs (NRUASs) of the same manufacturer to determine whether RUASs expedite ureteroscopy and how relevant the reinforced structure is in terms of overall success. We prospectively followed up patients undergoing ureteroscopy for urolithiasis with 1 of 2 UASs; the Applied NRUAS and the Applied RUAS. The demographics, operative parameters, and outcomes were assessed. Statistical analysis was performed. A total of 98 UASs were used in 68 male and 30 female patients (47 NRUASs and 51 RUASs). No significant differences were found between the groups in terms of demographic parameters, operative parameters, or successful sheath deployment. The overall success rate for sheath deployment was 95%. A pre-existing stent was significantly associated with successful deployment (P = .004). The sheath-specific limitations included kinking (NRUASs, 10%) and sheath angulation/deformity (RUASs, 21%). The mean follow-up time was 43.4 months; and 93.9% of the patients had radiologic follow-up. No ureteral strictures were noted. No significant difference was found in the overall success rates between the use of Applied NRUASs and RUASs. The presence of a pre-existing stent was significantly associated with successful sheath deployment. Each UAS design had its own unique limitations, seen with low frequency. Successful sheath use might relate to both the sheath itself and the patient/operative parameters.

A Result with Newly-Developed Covered Metallic Stent, ComVi Stent

Background & Aim: Covered metallic stent was an effective endoprosthesis for the management of unresectable distal biliary malignancies. However, the high incidence of complications such as cholecystitis, pancreatitis and migrations could not be well controlled by pre-existing stent. We report a trial of newly-developed ComVi stent (Taewoong Medical Co., Ltd. Korea). ComVi stent is made of two nitinol braided stents and e-PTFE membrane. Membrane is fixed between the two stents and nitinol stents are exposed to inner and outer surface. The weak axial force (the force stent being straight) is unique mechanical character of this stent. Patients & Methods: We placed ComVi stent endoscopically in 36 cases with unresectable distal biliary malignancies between May 2005 and November 2006. The causative diseases were pancreatic cancer in 27, metastatic node in 7, gallbladder cancer in 1 and bile duct cancer in 1. Mean age was 72 (45-88). Male-female ratio was 15:21. Result: Eighteen patients were alive at the analysis. Mean observation period was 234 days and mean stent patency duration was 181 days. Total complications were 11 (32%), re-obstructions in 10 (23%) and cholecystitis in 1 (3%). Other complications such as pancreatitis or migrations were not observed. Causes of the re-obstruction were sludge in 3 and food impaction in 7. Mean patency of re-obstructed stents was 54 days. All complications were observed within 6 months after ComVi stent placement. On the other hand, there was no complication after 6 months up until from the stent placement. Conclusion: ComVi stent showed good patency duration and low incidence of complications. We considered that early obstructions by food impaction were caused by exposed wire both inner and outer of stent, and could be prevented with caution.

Placement of PEG tubes through previously placed self-expanding esophageal metal stents☆

Background: Self-expanding metal stents are frequently used to palliate patients with malignant dysphagia and close tracheoesophageal fistulae. Despite proper stent positioning and deployment, in a subset of patients there is no improvement in dysphagia, closure of tracheoesophageal fistulae, or resolution of anorexia. Such patients may require a PEG tube. It has been suggested that PEG placement through a preexisting esophageal stent is problematic because of the risks of gastrostomy tube impaction within the stent and resultant stent migration. Methods: Case records were retrospectively reviewed of 9 consecutive patients with indwelling esophageal self-expanding metal stents undergoing attempted PEG. Observations: PEG tube placement was successful in all patients. In 1 patient, the stent migrated distally into the stomach during PEG placement. This was managed endoscopically without further complication. Conclusions: PEG placement in patients with previously placed esophageal self-expanding metal stents is a relatively safe and feasible procedure, although stent migration may occur.

Placement of PEG tubes through previously placed self-expanding esophageal metal stents

Background: Self-expanding metal stents are frequently used to palliate patients with malignant dysphagia and close tracheoesophageal fistulae. Despite proper stent positioning and deployment, in a subset of patients there is no improvement in dysphagia, closure of tracheoesophageal fistulae, or resolution of anorexia. Such patients may require a PEG tube. It has been suggested that PEG placement through a preexisting esophageal stent is problematic because of the risks of gastrostomy tube impaction within the stent and resultant stent migration. Methods: Case records were retrospectively reviewed of 9 consecutive patients with indwelling esophageal self-expanding metal stents undergoing attempted PEG. Observations: PEG tube placement was successful in all patients. In 1 patient, the stent migrated distally into the stomach during PEG placement. This was managed endoscopically without further complication. Conclusions: PEG placement in patients with previously placed esophageal self-expanding metal stents is a relatively safe and feasible procedure, although stent migration may occur.