USE OF FLUORESCENT LATEX MICROSPHERES TO MEASURE CORONARY BLOOD-FLOW DISTRIBUTION

Radioactive microspheres have long been in use to measure blood flow d istribution to various vascular beds. Their drawbacks are the short ha lf-lives of the radioactive material, the need for appropriate care in handling and disposing of such material, and their relative expensive ness. We investigated the use of fluorescent microspheres as indicator s of coronary blood flow distribution in a canine model. Radioactive ( I-125) microspheres were used as a comparison standard. Four colors of fluorescent microspheres were used: blue, yellow-green, orange, and r ed, having emission frequencies ranging from 385 to 605 nM. The experi ments were carried out in dogs under pentobarbital anesthesia, in whic h the microspheres were given during pump perfusion of the left circum flex artery with the animal's own blood. The hearts were removed, fixe d for 3 days in 10% formalin, and sectioned. Samples from the endocard ial, myocardial, and epicardial layers were read on a gamma counter. T he fluorescent microspheres were extracted from the same tissues into ethyl acetate, and read in a fluorescence spectrophotometer at the app ropriate excitation/emission frequencies. Comparable results were obta ined from the two methods, with good sensitivity and resolution of dye colors, using the fluorescent microspheres. (C) 1993 Wiley-Liss, Inc.