Dose-response study of intracoronary beta-radiation with 32P in balloon- and stent-injured coronary arteries in swine.
OBJECTIVE
A dose-response study was performed in swine to investigate the vascular effects of 32P over a broad range of doses in order to define the therapeutic window of intracoronary radiotherapy (ICR) with 32P.


METHODS
A total of 131 porcine arteries were subjected to balloon injury or stenting followed by 0-36 Gy of ICR from a centered 32P source wire to 1 mm beyond lumen surface or a sham ICR procedure. Animals were euthanized at 4 weeks, and vessels were harvested for histomorphometry.


RESULTS
In the balloon-injured arteries, doses of 7 and 9 Gy did not impact restenosis. At doses of 14-36 Gy, neointima was markedly reduced, with mild dilatation at the highest dose, 36 Gy. In the stent-injured arteries, the lowest dose of 9 Gy failed to reduce neointimal growth, while 14-26 Gy showed the most favorable response.


CONCLUSIONS
ICR with 32P features a broad therapeutic window. Doses of 14-26 Gy to 1 mm beyond lumen surface provided an optimal combination of efficacy and safety. Doses of 7 and 9 Gy were generally ineffective, suggesting a minimum threshold for ICR with 32P to effectively inhibit restenosis.
Kałuza
G L
GL
Methodist DeBakey Heart Center and Baylor College of Medicine, Houston, TX 77030, USA.
Raizner
A E
AE
Mazur
W
W
Schulz
D G
DG
Zymek
P T
PT
Nguyen-Ho
P
P
Tio
F O
FO
Fajardo
L F
LF
Ali
N M
NM
D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D001918:Brachytherapy; D023903:Coronary Restenosis / Q000517:prevention & control* / Q000532:radiotherapy; D003331:Coronary Vessels / Q000293:injuries*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008297:Male; D010761:Phosphorus Radioisotopes / Q000627:therapeutic use*; D015607:Stents; D013552:Swine
D010761:Phosphorus Radioisotopes