Effects of intracoronary radiation on thrombosis after balloon overstretch injury in the porcine model.
BACKGROUND
The main complications of PTCA remain thrombosis and restenosis. Recent studies have demonstrated reduction in the neointimal hyperplasia after intracoronary radiation (IR) with doses of 10 to 25 Gy of ionizing radiation delivered by either beta- or gamma-emitters to injured vessels. The purpose of this study was to examine the effect of ionizing radiation on the thrombosis rate (TR) of injured porcine coronary arteries.


RESULTS
Thirty-four juvenile swine (63 coronary arteries) were subjected to overstretch balloon injury followed by IR with doses of 0 to 18 Gy of either beta- or gamma-radiation. Two weeks after treatment, tissue sections were perfusion-fixed, stained with hematoxylin-eosin and Verhoeff-van Gieson's stain, and analyzed for presence of a thrombus, thrombus morphology, and neointima formation by computer-assisted histomorphometry techniques. Although the overall TR increased dose-dependently from 0 to 18 Gy prescribed dose, luminal thrombi decreased. Thrombus area also decreased with increasing radiation dose, whether assessed at the prescription point or at the luminal surface, which corresponded to decreased intimal area. Furthermore, luminal thrombi present after IR tended to consist mostly of fibrin and thus were less organized than in controls.


CONCLUSIONS
These results suggest that IR induces thrombosis but does not necessarily compromise the lumen. Strategies for reducing TR may further decrease intimal area as well as increasing the safety of this therapy.
Vodovotz
Y
Y
Vascular Brachytherapy Institute, Cardiovascular Research Foundation Washington Hospital Center,Washington, DC 20010, USA.
Waksman
R
R
Kim
W H
WH
Bhargava
B
B
Chan
R C
RC
Leon
M
M
D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D000818:Animals; D001610:Beta Particles; D001918:Brachytherapy; D003328:Coronary Thrombosis / Q000209:etiology / Q000517:prevention & control*; D003331:Coronary Vessels / Q000293:injuries / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006965:Hyperplasia; D011868:Radioisotopes / Q000627:therapeutic use; D012211:Rhenium / Q000627:therapeutic use; D013552:Swine; D017539:Tunica Intima / Q000293:injuries / Q000473:pathology / Q000528:radiation effects; D014947:Wounds and Injuries / Q000473:pathology / Q000532:radiotherapy; D014980:Xenon Radioisotopes / Q000627:therapeutic use; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
D011868:Radioisotopes; D014980:Xenon Radioisotopes; D015021:Yttrium Radioisotopes; D012211:Rhenium