Intracoronary radiation decreases the second phase of intimal hyperplasia in a repeat balloon angioplasty model of restenosis.
OBJECTIVE
Repeat balloon angioplasty is likely to induce intimal proliferation, which is associated with a higher restenosis rate. This study examined the effect of intracoronary ionizing radiation on restenotic lesions using repeat balloon injury in a normolipemic swine.


METHODS
Eight domestic normolipemic pigs underwent overstretch balloon angioplasty with a 3.5 mm balloon in the LAD and LCX, followed by repeat balloon injury at the same sites 4 weeks after the initial injury. At that time a high activity 192Iridium source was introduced immediately after the angioplasty by random assignment to deliver 14 Gy at 2 mm in eight of the injured coronary arteries (LAD and LCX). One month later the animals were killed and the coronary arteries pressure perfusion fixed. Serial sections were stained with H&E and VVG, then evaluated by histopathologic and morphometric techniques. Maximal intimal thickness (MIT), intimal area (IA), and intimal area corrected for the extent of injury (IA/FL) were measured in the irradiated and control arteries and were compared to control arteries with single injuries from previous studies.


RESULTS
Repeat balloon injury induced significant additional medial damage, which was associated with marked intimal hyperplasia in a concentric pattern. Intracoronary irradiation significantly decreased the total of neointima area formation (IA 93 + 0.35 mm2 compared to control 1.38 + 0.33 mm2 p < 0.01) and the MIT was also significantly reduced in the irradiated vessels (0.57 + 0.18 mm vs. 0.71 + 0.08 mm, p = 0.05).


CONCLUSIONS
Intracoronary irradiation immediately after the second balloon dilatation inhibits the intimal hyperplasia due to that injury. However, there was no effect on the existing neointima from the initial injury.
Waksman
R
R
Andreas Gruentzig Cardiovascular Center, Department of Medicine, Emory University School of Medicine, USA.
Robinson
K A
KA
Crocker
I R
IR
Gravanis
M B
MB
Cipolla
G D
GD
Seung
K B
KB
King
S B
SB
D000800:Angioplasty, Balloon / Q000009:adverse effects*; D000818:Animals; D003327:Coronary Disease / Q000532:radiotherapy*; D004195:Disease Models, Animal; D005260:Female; D006965:Hyperplasia / Q000532:radiotherapy; D012008:Recurrence; D013552:Swine; D017539:Tunica Intima / Q000473:pathology* / Q000528:radiation effects