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Spectral profiles of acute and healed myocardial radiofrequency ablation lesions

A spectral approach to differentiate between acute and healed myocardial lesions was explored. The long‐term goal of these studies is improved treatment of atrial fibrillation using percutaneous RF catheters. The epicardial surface of excised rat hearts was illuminated by continuous wavelength spectrum via an optical fiber coupled to a spectrofluorometer. Emitted, scattered and reflected light was acquired by a high sensitivity CCD camera. Spectra were separated into three groups: unablated tissue, acute and healed RF lesions. Structure of the lesions was confirmed by cytopathology. Spectra between all three groups differed significantly throughout the 300–800nm range. The largest difference was observed in the 300–400nm illumination range accounting for the loss of NADH fluorescence in acute lesions, but not in healed tissue. In the 400–620nm illumination range both acute and healed epicardial lesions exhibited significantly higher intensity compared to control tissue. In the 620–800nm range difference between three groups diminished. The results point to a possibility of in situ visualization of acute and chronic lesions based on the spectral differences in reflected and emitted light. The sensitivity and specificity of lesion identification can be further increased by ratiometry of images acquired at different illumination wavelengths (Supported by the NIH HL095828 & NSF CBET1231549)