Radiation dose reduction in fluoroscopic procedures: left varicocele embolization as a model.

OBJECTIVES: To investigate the effect of a radiation reduction program on total dose, fluoroscopy dose per second corrected for body habitus and degree of collimation in left varicocele embolizations (LVE). METHODS: A radiation reduction program for LVE was implemented, consisting of a technique minimizing fluoroscopy time, using low-dose presets, virtual collimation, and virtual patient positioning. Height, weight, fluoroscopy time, kerma area product (KAP) and reference air kerma (Ka,r) were recorded for 100 consecutive cases satisfying the inclusion criteria. For each patient, a device specific dose correction factor, determined using a phantom, was used to standardize the KAP to that of the cylindrical diameter of the standard man and a collimation index was derived from the KAP and Ka,r. RESULTS: Median fluoroscopy time was 3 minutes (mean 4.5, range 1-23.8). Median KAP was 0.54 Gy/cm(2) (mean 0.82, range 0.12-6.52). There was a significant decrease in KAP/second corrected for cylindrical diameter (p < 0.001) and the collimation index (p < 0.001) over time. CONCLUSIONS: This study shows that a dedicated dose reduction program can achieve very low total radiation dose rates for LVE. The significant decrease in collimation index and standardized KAP per second during this study suggest a learning curve for collimation. KEY POINTS: • Left varicocele embolization can be performed with very low radiation doses. • The most effective real time radiation reduction measure is collimation. • There is a learning curve to achieving optimal collimation.

[Bile lake post Kasai hepatoportoenterostomy in biliary atresia].

In this case report we describe a boy with extrahepatic biliary atresia who underwent a Kasai hepatoportoenterostomy at six weeks of age. Beginning several weeks post-op, he had recurrent cholangitis inadequately controlled by various antibiotic prophylaxis regimens. Imaging revealed the development of several bile lakes in the liver hilum. Due to the recurrent nature of his cholangitis, and some evidence of acutely impaired biliary drainage, he underwent a refashioning of his portoenterostomy with resultant improved drainage. However, shortly thereafter, the patient developed ongoing fever and anemia. Culture of the bile lake aspirate grew multiresistant Klebsiella and a 6 week course of parenteral meropenume controlled his fever and his anemia improved. Following treatment cessation his fever and anemia returned. A biliary drain was inserted into his larger bile lake and following another course of parenteral antibiotics he has remained free of clinically detected cholangitis despite ongoing contamination of drained bile fluid. The development of bile lakes after Kasai hepatoportoenterostomy is not an uncommon finding. This have been associated with worse prognosis including increased incidence of cholangitis. Often, conservative treatment with prophylactic antibiotics suffices, however, in rare cases, more aggressive intervention may be considered including percutaneous bile drainage or surgical management. The benefit of these management strategies must be balanced with the potential gain regarding quality of life and delaying transplant, on an individual basis.

Stent grafts for central venous occlusive disease in patients with ipsilateral hemodialysis access.

PURPOSE: To assess long-term outcomes of stent grafts in patients with symptomatic central venous stenoses and occlusions ipsilateral to hemodialysis grafts or fistulas. MATERIALS AND METHODS: The study included 52 of 55 consecutive patients with symptomatic stenoses of the central veins draining upper limb dialysis access grafts or fistulas treated with stent grafts. Indications for stent grafts were poor angioplasty results, rapid recurrence, or total occlusion. Endpoints were lesion patency and access patency following intervention. Mean follow-up was 25 months with a median of 24 months and 1.25 additional procedures per patient year. Patency rates were calculated using Kaplan-Meier analysis. RESULTS: All stent grafts were successfully deployed. The lesion patency rates at 6, 12, 24, and 36 months after intervention were 60%, 40%, 28%, and 28%. The access patency rates at 6, 12, 24, and 36 months after intervention were 96%, 94%, 85%, and 72%. There was one major complication and no minor complications. In 40 patients (77%), the internal jugular vein confluence was covered by the stent graft. In five patients, the dialysis circuits became occluded, with no clinical sequelae in four; one patient was lost to follow-up. The contralateral brachiocephalic vein was covered in three patients (6%), preventing contralateral access construction in one patient. CONCLUSIONS: Central vein stent graft placement in patients with hemodialysis access is associated with prolonged access patency. Coverage of major vein confluences, which occurred in 83% of the patients in this series, can compromise future access and should be avoided whenever possible by careful technique.

Stent graft treatment for hemodialysis access aneurysms.

BACKGROUND: Aneurysms that develop in arteriovenous accesses as a result of repeated punctures are sometimes complicated by infection or ischemia causing sloughing of the overlying skin, which may endanger the access and risk major bleeding and other complications. Surgical revision may necessitate the temporary use of a central venous catheter until dialysis can be resumed via the access. We used stent grafts in selected patients for the exclusion of access aneurysms. METHODS: Twenty of 63 patients requiring access revision for complication of an aneurysm from February 2005 to December 2009 underwent ambulatory endovascular stent graft deployment. Indications included signs of impending rupture, questionable viability of overlying skin, pain, infection, and limitation of cannulation sites by the size or number of the aneurysms. Endovascular treatment always included angioplasty of associated outflow or central vein stenoses at the same ambulatory session. RESULTS: Twenty patients with complicated access aneurysms were treated by endovascular stent graft exclusion at an average of 4.8 ± 4.3 years (range, 0.2 to 16.1 years) after access construction: nine graft pseudoaneurysms, nine native vein aneurysms, and two acute iatrogenic pseudoaneurysms. Six patients had skin erosion over the aneurysm, and 12 had painful aneurysms and clinical signs of compromised blood supply to the skin. Another two patients with an acute giant false aneurysm occurring during endovascular procedures were treated in the same interventional session by the stenting technique to control bleeding. All the aneurysms underwent endovascular exclusion without complications. Only one infected puncture site failed to heal within 2 months of stenting and was closed surgically 10 months later due to persistent localized graft infection, but with no further bleeding episodes. Only one aneurysm did not reabsorb within 3 months. Patients with painful skin ischemia had immediate pain relief. All patients also had stenosis in the draining veins necessitating additional percutaneous transluminal angioplasty. Only one patient required hospitalization (for intravenous antibiotic treatment of staphylococcal sepsis). No patients required a central catheter for hemodialysis. One access occluded due to cephalic arch stenosis in a noncompliant patient. Functional patency was 87% at 12 months, with a median follow-up of 15 months (range, 6.3 to 55.5 months). CONCLUSION: Endovascular treatment with stent grafts in complicated access aneurysms is a simple, safe and rapid ambulatory procedure that enables treatment of both the aneurysm and its accompanying draining vein stenosis. It enables continued cannulation of the existing access and avoids the use of central catheters.

Shortening and migration of Wallstents after stenting of central venous stenoses in hemodialysis patients.

PURPOSE: To report our results for the placement of central venous stents in patients undergoing hemodialysis. METHODS: Ten Wallstents (Schneider, Bülach, Switzerland) were placed in 10 patients with shunt thrombosis, shunt dysfunction or arm swelling associated with central vein stenosis or occlusion. Technical success, patency and complications were evaluated. RESULTS: Stent deployment was successful in all cases. In seven cases (70%) there was significant delayed stent shortening. In two of these cases there was also stent migration. All these cases required additional stents. Primary patency rates at 6, 12 and 24 months were 66%, 25% and 0. Twenty-three additional procedures (percutaneous transluminal angioplasty or stenting) were required to achieve secondary patency rates at 6, 12 and 24 months of 100%, 75% and 57%. CONCLUSION: Stent placement in the central veins of dialysis patients has a high technical success rate resulting in symptomatic relief and preservation of access. Repeat interventions are required to maintain patency. Significant delayed shortening of the Wallstent occurred in 70% of patients which may have affected the patency rates. Strategies are suggested to avoid this problem.