Detection of vulnerable coronary plaques by color fluorescent angioscopy.
OBJECTIVE
This study was carried out to detect vulnerable coronary plaques by color fluorescent angioscopy.


BACKGROUND
Collagen fibers (CFs) mainly provide mechanical support to coronary plaques. Oxidized low-density lipoprotein (Ox-LDL) induces macrophage proliferation, which in turn destroy CFs while accumulating lipids. As such, demonstration of the absence of CFs, deposition of lipids, and the Ox-LDL may suggest plaque instability.


METHODS
Fluorescence of the major components of the atherosclerotic plaques was examined by fluorescent microscopy using a 345-nm band-pass filter and 420-nm band-absorption filter (A-imaging). Fluorescence of Ox-LDL was examined using a 470-nm band-pass filter and 515-nm band-absorption filter (B-imaging) and Evans blue dye as an indicator. Fluorescence in 57 excised human coronary plaques was examined by A-imaging color fluorescent angioscopy. Oxidized LDL in 31 excised coronary plaques and in 12 plaques of 7 patients was investigated by B-imaging color fluorescent angioscopy.


RESULTS
Collagen I, collagen IV, and calcium exhibited blue, light blue, and white autofluorescence, respectively. In the presence of beta-carotene which coexists with lipids in the vascular wall, collagen I and IV exhibited green, collagen III and V white, cholesterol yellow, cholesteryl esters orange fluorescence. Oxidized LDL exhibited reddish brown fluorescence in the presence of Evans blue dye. Therefore, coronary plaques exhibited blue, green, white-to-light blue, or yellow-to-orange fluorescence based on plaque composition. Histological examination revealed abundant CFs without lipids in blue plaques; CFs and lipids in green plaques; meager CFs and abundant lipids in white-to-light blue plaques; and the absence of CFs and deposition of lipids, calcium, and macrophage foam cells in the thin fibrous cap in yellow-to-orange plaques, indicating that the yellow-to-orange plaques were most vulnerable. Reddish brown fluorescence characteristic of Ox-LDL was observed in excised coronary plaques, as also in patients.


CONCLUSIONS
Color fluorescent angioscopy provides objective information related to coronary plaque composition and may help identify unstable plaques.
Uchida
Yasumi
Y
Japan Foundation for Cardiovascular Research, Funabashi and Tokyo, Japan. uchiy@ta2.so-net.ne.jp
Uchida
Yasuto
Y
Kawai
Seiji
S
Kanamaru
Ryohei
R
Sugiyama
Yukou
Y
Tomaru
Takanobu
T
Maezawa
Yoshiro
Y
Kameda
Noriaki
N
D000368:Aged; D017546:Angioscopy; D001344:Autopsy; D015415:Biomarkers / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002784:Cholesterol / Q000032:analysis; D003094:Collagen / Q000032:analysis; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels / Q000737:chemistry* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D008077:Lipoproteins, LDL / Q000032:analysis; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011237:Predictive Value of Tests; D019207:beta Carotene / Q000032:analysis
D015415:Biomarkers; D005456:Fluorescent Dyes; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D019207:beta Carotene; D003094:Collagen; D002784:Cholesterol; D002118:Calcium