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Arterial Applications of Vascular Radiotherapy
Persistent benefit at 6-month follow-up. ] Am Coli CardioI1995;25:1451-1456. 9. Fischel! TA, Kharma BK, Fischell DR, et al. Low-dose beta-particle emission from "stent" wire results in complete, localized inhibition of smooth muscle cell proliferation. Circulation 1994;90:2956-2963. 10. Brenner D], Miller RC, Hal! E]. The radiobiology of intravascular irradiation. Int] Radiat Oneal BioI Phys 1996;36:805-810. 11. Fischer-Dzoga K, Dimitrievich GS, Schaffner T. Effect of hyperlipidemic serum and irradiation on wound healing in primary quiescent cultures of vascular cells. Exp Molec Pathol 1990;52:1-12. 12. Weinberger], Amols H, Ennis RD, Schwartz A, Wiedermann ]G, Marboe C. Intracoronary irradiation: Dose response for the prevention of restenosis in swine. Int] Radiat Oncol BioI Phys 1996;36:767-775. 13. Vodovotz Y, Robinson K, Cook L]A, Wink DA, Mitchell ]B, Waksman R. Effect of radiation on the expression of transforming growth factor-B1 in restenotic lesions following balloon angioplasty and injury in swine. In: Waksman R, Leon MB, eds. Advances in Cardiovascular Radiation Therapy. Washington, DC, February 1997:19. 14. Scott NA, Cipolla GD, Ross CE, et al. Identification of a potential role for the adventitia in vascular lesion formation after balloon overstretch injury of porcine coronary arteries. Circulation 1996;93:2178-2187. 15. Clowes AW, Clowes MM. Kinetics of cellular proliferation after arterial injury. Lab Invest 1985;52:611616. 16. Banai S, Shou M, Correa R, et al. Rabbit ear model of injury-induced arterial smooth muscle proliferation. Circ Res 1991;69:748-756 17. Wilensky RL, March KL, Gradus-Pizlo I, Sandusky G, Fineberg N, Hathaway DR. Vascular injury, repair, and restenosis after percutaneous transluminal angioplasty in the atherosclerotic rabbit. Circulation 1995;92:2995-3005. 18. Mayberg MR, Luo Z, London S, Gajdusek C, Rasey]S. Radiation inhibition of intimal hyperplasia after arterial injury. Rad Res 1995;142:212-220. 19. Kovalic ]], Perez CA. Radiation therapy following keloidectomy: A 20-year experience. Int ] Radiat Oncol BioI Phys 1989;17:77-80. 20. Laird ]R, Carter A], Kufs WM, et al. Inhibition of neointimal proliferation with low-dose irradiation from a beta-particle-emitting stent. Circulation 1996; 93:529-536.
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21. Fischell TA, Carter A], Laird]R. The beta-particleemitting radioisotope stent (Isostent): Animal studies and planned clinical trials. Am ] Cardiol 1996; 78(suppl 3A):45-50.
4:20 pm Devices for Vascular Brachytherapy Patricia E. Cole, PhD, MD
4:45 pm Arterial Applications of Vascular Radiotherapy Mohsin Saeed, MD
5:05 pm Venous Applications of Vascular Radiotherapy Franklin j. Miller, MD, and Todd Lessie, MD University of Utah Salt Lake City, Utah Experimental 32p Irradiation for Transjugular Intrahepatic Portosystemic Shunting In Swine Transjugular intrahepatic portosystemic shunting (TIPS) created a major change in the treatment of portal hypertension as a cause of variceal hemorrhage in the early and mid 1990's. Because of stenosis occurring on the hepatic vein end of the stent as well as within the stent, however, frequent maintenance has led to a decrease in the number of procedures perfOlmed during the past 2-3 years. Because porto-caval shunting including TIPS has never led to increased survival of these patients, but does decrease the frequency of bleeding and its severity, there has been a gradual return to sclerotherapy for control of esophageal bleeding. Studies on cost for both TIPS and sclerotherapy show similar expenditures. Until a method can be found to slow the progression of stent stenosis, TIPS will likely be used less frequently in the immediate future compared with use during the years 1991-1995. One of the approaches for addressing intimal hyperplasia in arteries after stenting has been to deliver a gamma or beta source to the artery. Laberge has described similar histopathologic findings in TIPS shunts. The myofibroblastic response seen in liver explants has some features of the myointimal hyperplasia seen in arteries after angioplasty and stenting. The purpose of this study was to determine whether TIPS cellular response could be influenced by beta irradiation. 32p is readily available and was chosen as an energy source. Eleven swine (30-35 kg) with normal portal pressures were divided into two groups after successful TIPS placement. Six swine underwent intraluminal 32p irradiation (15 Gy) of the hepatic parenchymal and venous outflow tracts at the time of the TIPS. The 32p was applied through a PTA balloon within the tract for 35 minutes. Five animals with TIPS served as controls; all animals in both groups were sacrificed at 28 days to evaluate TIPS patency as well as the cellular response within the TIPS tract. Using thermoluminescent dosimeters (TLDs), the 32p source was calculated to deliver 15 Gy to the wall of the tract with 3-4 mm of penetration. Beyond this distance of 3-4 mm from the stent wall or the hepatic vein, less than 1 Gy is delivered to the liver parenchyma. At the time of restudy (28 days), all stents (except one treated
442
21. Fischell TA, Carter A], Laird]R. The beta-particleemitting radioisotope stent (Isostent): Animal studies and planned clinical trials. Am ] Cardiol 1996; 78(suppl 3A):45-50.
4:20 pm Devices for Vascular Brachytherapy Patricia E. Cole, PhD, MD
4:45 pm Arterial Applications of Vascular Radiotherapy Mohsin Saeed, MD
5:05 pm Venous Applications of Vascular Radiotherapy Franklin j. Miller, MD, and Todd Lessie, MD University of Utah Salt Lake City, Utah Experimental 32p Irradiation for Transjugular Intrahepatic Portosystemic Shunting In Swine Transjugular intrahepatic portosystemic shunting (TIPS) created a major change in the treatment of portal hypertension as a cause of variceal hemorrhage in the early and mid 1990's. Because of stenosis occurring on the hepatic vein end of the stent as well as within the stent, however, frequent maintenance has led to a decrease in the number of procedures perfOlmed during the past 2-3 years. Because porto-caval shunting including TIPS has never led to increased survival of these patients, but does decrease the frequency of bleeding and its severity, there has been a gradual return to sclerotherapy for control of esophageal bleeding. Studies on cost for both TIPS and sclerotherapy show similar expenditures. Until a method can be found to slow the progression of stent stenosis, TIPS will likely be used less frequently in the immediate future compared with use during the years 1991-1995. One of the approaches for addressing intimal hyperplasia in arteries after stenting has been to deliver a gamma or beta source to the artery. Laberge has described similar histopathologic findings in TIPS shunts. The myofibroblastic response seen in liver explants has some features of the myointimal hyperplasia seen in arteries after angioplasty and stenting. The purpose of this study was to determine whether TIPS cellular response could be influenced by beta irradiation. 32p is readily available and was chosen as an energy source. Eleven swine (30-35 kg) with normal portal pressures were divided into two groups after successful TIPS placement. Six swine underwent intraluminal 32p irradiation (15 Gy) of the hepatic parenchymal and venous outflow tracts at the time of the TIPS. The 32p was applied through a PTA balloon within the tract for 35 minutes. Five animals with TIPS served as controls; all animals in both groups were sacrificed at 28 days to evaluate TIPS patency as well as the cellular response within the TIPS tract. Using thermoluminescent dosimeters (TLDs), the 32p source was calculated to deliver 15 Gy to the wall of the tract with 3-4 mm of penetration. Beyond this distance of 3-4 mm from the stent wall or the hepatic vein, less than 1 Gy is delivered to the liver parenchyma. At the time of restudy (28 days), all stents (except one treated