Abstract
This study examined the temporal responses in preventing neointimal proliferation of rabbit iliac arteries where 192Ir-HDR intra-vascular irradiation was carried out after PTA with a cutting balloon catheter. PTA was performed in both iliac arteries of twenty rabbits. Intravascular irradiation was performed on the same segment with PTA on the iliac artery of one side and the unirradiated side was studied as a control. The radiation dose was 12 Gy. Animals were euthanatized at 1, 2, 3, 4, 8, and 12 weeks after angioplasty. Histopathologic and morphometric analyses were then carried out.
PTA caused radial stretching of the artery and medial compression. Internal elastic lamina was cut with a cutting blade and deep dissections were made extending into the media. Histopathology showed that cellular accumulation repaired the dissection and neointimal proliferation followed. A striking reduction in the amount of neointimal proliferation in the irradiated arteries was observed compared with the control vessels. At a week, the neointima area had markedly increased to 0.63 ± 0.21 × 10-4 mm2 in the control arteries, while no evidence of neointimal proliferation was noted in the irradiated artery segments. At 2-4 weeks, a marked and statistically significant decrease in the neointima area was observed compared with the control arteries. The control arterial segments had a neointimal area of 9.06 ± 3.47 × 10-4 mm2. The neointimal area was 3.24 ± 1.61 × 10-4 mm2 in the irradiated artery (p<0.01). At 8-12 weeks as well, a significant difference was noted between the irradiated and the control arterial segments. The control arterial segments had a neointimal area of 9.18 ± 3.63 × 10-4 mm2, while the irradiated arterial segments had 3.51 ± 1.55 × 10-4 mm2.
From the above results, the 192Ir-HDR afterloading irradiation with a dose of 12 Gy can be considered sufficient for inhibiting neointimal proliferation in angioplastied rabbit iliac arteries with a cutting balloon catheter.
