Spectral Changes Caused By Radiofrequency Ablation Of Cardiac Tissue

Each type of .ssue exhibited dis.nct EEMs that underwent reproducible changes in fluorescence and diffuse reflectance upon RF abla.on (leF panel shows representa.ve EEMS, n=3-4). Specifically, RF resulted in a reduc.on of the NADH fluorescence peak in ventricular muscle EEMs (360/460nm excita.on/emission maxima, graph corresponds to the white doYed line on the boYom sets of EEMs). It also led to a broadening of collagen fluorescence peaks in the aorta. RF led to an increase in diffuse reflectance (seen as increased width of the EEM diagonal line) in all three .ssue types. Thermal coagula.on of heme-containing proteins, including different forms of myoglobin, led to a weaker absorp.on in the Soret band range (410-430nm). The laYer was par.cularly no.ceable in ventricular .ssue but was also significant in the leF atrial .ssue. The major changes caused by RF abla.on of ventricular .ssue are shown on the boYom right. AFer deriving an average EEM values from 4 unablated and 4 ablated sites of the ventricular .ssue, fluorescence mask was applied and difference EEM was then ploYed (note different LUT scale with blue being no change) METHODS: Light was delivered and acquired through a fiberop.c bundle pressed against excised pieces of porcine heart using FluoroMax 3 spectrofluorometer. Excita.on emission matrices (EEMs) from ventricular muscle, endocardial surface of leF atria, and aorta were acquired from 300-600 nm range. Values from different pieces of porcine .ssue were averaged to reveal the differences with p<0.05 considered significant. SPECTRAL CHANGES CAUSED BY RADIOFREQUENCY ABLATION OF CARDIAC TISSUE