Tomokuni Shiraishi

Radiofrequency ablation combined with CO2 injection for treatment of retroperitoneal tumor: protecting surrounding organs against thermal injury.

OBJECTIVE The objective of this study was to separate target tumors from adjacent structures by injecting carbon dioxide (CO2) around the tumor to avoid thermal injury and the heat-sink effect from the blood vessel during percutaneous radiofrequency ablation. CONCLUSION We successfully achieved complete ablation of a retroperitoneal tumor without thermal injury. Imaging-guided percutaneous CO2 injection is useful for preventing thermal injury while achieving complete ablation of the tumor during radiofrequency ablation.

Transcatheter embolization for peripheral pseudoaneurysms with n-butyl cyanoacrylate

The purpose of this study is to evaluate the clinical efficacy of transcatheter embolization for pseudoaneurysms of peripheral arteries with n-butyl cyanoacrylate (NBCA). From November 2000 to February 2008, 17 patients with 18 pseudoaneurysms were treated by transcatheter embolization at our affiliated hospitals. The locations of the pseudoaneurysms were right hepatic artery (n=3), renal artery (n=5), splenic artery (n=2), gastroduodenal artery (n=2), common hepatic artery (n=1), pancreatic arcade (n=1), external iliac artery (n=1), internal iliac artery (n=1), internal thoracic artery (n=1), and left gastric artery (n=1). We assessed technical success rate, embolization methods, and clinical course in this study. The technical success rate was 94.4% (17/18 cases). Embolization methods were isolation (n=17) and packing (n=1). Only NBCA was used in 14 cases, both coils and NBCA were used in four cases. Six patients were in shock prior to the procedure, but all patients recovered immediately after embolization procedure including transfusion. None of the patients died of procedure-related factors or had notable postoperative complications, but three patients died within a week of the procedure because of deterioration of the underlying disease. In conclusion, transcatheter embolization of pseudoaneurysms with NBCA is a safe and effective technique for treatment.

Efficacy of carbon dioxide for diagnosis and intervention in patients with failing hemodialysis access

Background: Carbon dioxide (CO2) is the only proven safe intravascular contrast agent in renal failure and contrast allergy. The use of CO2 as a contrast agent for the evaluation of failing dialysis fistulas has the potential to preserve residual renal function by eliminating the use of contrast material or decreasing the amount used for fistulograms. Purpose: To evaluate the feasibility of fistulography using CO2 for diagnosis and intervention in patients with failing hemodialysis access. Material and Methods: Dialysis access failure occurred in 94 patients (54 men, 40 women; mean age, 65 years; range, 32–89 years) on 146 occasions. CO2 was used as the first-choice contrast agent for fistulography and PTA. Fistulography was performed with the injection of CO2 in the brachial artery using a power injector. Results: Interventional treatment was indicated in 141 accesses. In 115 of these 141 cases, intervention was performed using CO2 fistulography alone. When the access flow stopped or decreased very much due to an occlusion and severe stenosis, we could not visualize the access by CO2 fistulography, or could not perform CO2 fistulography. For those cases, iodinated contrast fistulography was performed. When the vascular rupture, dissection, or clot formation occurred during intervention, iodinated contrast fistulography was performed. In three patients with arteriovenous fistula, manual injection of CO2 into the brachial artery resulted in reflux of the gas into the thoracic aorta causing transient loss of consciousness. Conclusion: CO2 is a useful contrast agent in the diagnosis and intervention of failing hemodialysis access, eliminating or limiting the use of iodinated contrast material. Caution should be exercised to prevent CO2 reflux into the aorta when injecting the gas into the brachial artery.

Transcatheter Coil Embolization for Steal Syndrome in Patients with Hemodialysis Access

Background: Drainage of large amounts of shunt blood into deep veins via collaterals reduces resistance to venous outflow and decreases blood flow to the artery distal to the arterial anastomotic site, potentially resulting in steal syndrome. Purpose: To evaluate the effectiveness of transcatheter coil embolization for collateral veins of hemodialysis access in the treatment of steal syndrome. Materials and Methods: Five hemodialysis patients (four male, one female; mean age 58.8 years, range 40–71 years) with symptomatic steal syndrome were treated. Steal syndrome was diagnosed based on decreased or absent distal pulse, coolness, pain, abnormal skin color, ischemic ulceration of digits, numbness, sensory impairment, or motor impairment. Coil embolization was performed to block collaterals communicating with deep veins, with conscious sedation and local anesthesia. Fistulography was performed before, immediately after, and 1 month after embolization. Ultrasonography was performed 2 days after embolization. Symptoms and signs were assessed 2 days after embolization. Clinical findings related to steal syndrome and access failure were observed at each hemodialysis. Results: Blood flow in the collaterals was successfully blocked by coil embolization in all patients. Distal pulse, coolness, pain, and skin color improved in all patients. Numbness, sensory impairment, and motor impairment were unimproved in two patients. In all patients, hemodialysis following embolization was performed normally. The mean observation period after embolization was 33 months (range 9–75 months). Conclusion: Coil embolization of collaterals that drain shunt blood into deep veins is effective for steal syndrome for hemodialysis access originating in the brachial artery.

Percutaneous Transluminal Cutting-Balloon Angioplasty for Hemodialysis Access Stenoses Resistant to Conventional Balloon Angioplasty

Purpose: To examine the value of cutting-balloon percutaneous transluminal angioplasty (PTA) for hemodialysis access with residual stenosis after conventional balloon PTA. Material and Methods: Angioplasty with conventional balloons was performed on 48 hemodialysis access stenoses in 28 patients. If the balloon waist still remained at the rated burst pressure, the balloon was reinflated up to three times. Fifteen of 48 stenoses had residual stenoses of more than 30% after conventional balloon PTA. In these 15 stenoses, additional cutting-balloon PTA was performed. Results: The mean residual percent diameter stenoses before and after conventional balloon PTA were 77.6±3.4% and 48.6±8.5%, respectively. Additional cutting-balloon PTA decreased the mean residual percent diameter to 27.9±10.0%, and the cutting balloon was completely inflated without complication. In 12 patients, the 6-month primary patency rate (±SE) was 90.0% (9.5), and the 1-year primary patency rate (±SE) was 25.0% (14.8). Conclusion: Additional cutting-balloon PTA was found useful for reducing residual stenosis.

Transcatheter arterial embolization therapy in cases of recurrent and advanced gynecologic cancer.

Transcatheter internal iliac arterial embolization therapy (TAE) using Gelfoam particles was performed in 24 patients with recurrent gynecologic cancer and ten patients with advanced gynecologic cancer who had previously undergone radiotherapy. The tumor showed complete response (CR) to the therapy in six patients, partial response (PR) in 12, minor response (MR) in three, and no changes (NC) in 13 patients, with the response rate (CR + PR) of 52.9% (18 of 34). No serious or prolonged side effects were encountered except for vesicovaginal fistula in three patients and renal failure in one. The median duration of survival was 299 days, and the 1‐year cumulative survival rate was 32.5%. The factors that were associated with favorable outcome after TAE were good general condition, no distant metastases, tumors <5 cm in diameter, and responses to the therapy of PR or better. Thus, TAE appears useful for the treatment of recurrent and advanced gynecologic malignancies.

Portopulmonary venous anastomosis in balloon‐occluded retrograde transvenous obliteration for the treatment of gastric varices

Several reports have described portopulmonary venous anastomosis (PPVA). However, in balloon‐occluded retrograde transvenous obliteration (BRTO), attention has not been paid to paradoxical embolism. The objective of this study was to investigate the existence of a right–left shunt due to PPVA when the drainage vein is occluded by a balloon during BRTO.

Advanced vulvar carcinoma treated with internal iliac arterial embolization therapy after radiotherapy

Two patients with vulvar carcinoma are reported who were treated with internal iliac transcatheter arterial embolization and radiotherapy. Patient 1 had T3N3M0 vulvar carcinoma. The lesion remaining after radiotherapy was treated by bilateral internal iliac arterial embolization. Vulvectomy was then performed, and the resected specimen showed no residual malignant cells. This patient is alive without recurrence 4 years 7 months after operation. Patient 2 (T3N0M0 vulvar carcinoma) underwent radiotherapy, and the remaining malignant tumor disappeared after bilateral internal iliac artery embolization. This patient has remained disease free without vulvectomy for 3 years after treatment.