Abstract: An apparatus and method for detecting electrical activity in areas of tissue. The apparatus (1) includes a main catheter (5), multifibered endoscope (10), light filtering means (30, 42, 52), photodetectors (40, 50) and a signal processor (60). The apparatus is used to detect electrical activity by first infusing both an electrically sensitive dye and an electrically insensitive reference dye into the subject tissue and then detecting the intensity of light emitted from both dyes. The wavelength of light emitted from each dye is different. The intensity of light emitted from each dye is similar for non-electrically active tissue and moving tissue but different for electrically active tissue. The intensity of light from the two dyes as separately recorded by the photodetectors is compared by a signal processor to eliminate noise attributable to movement within the area of tissue and arrive at a accurate calculation of electrical activity within the area of tissue.

Abstract: A method of detecting and recording action-potential-related fluorescent changes from a remote tissue situs which has been treated with a voltage-sensitivity dye. The method utilizes a single optical fiber to both direct excitation light to the remote tissue situs and receive emitted fluorescence from the remote tissue situs. The emitted fluorescence from the remote tissue situs is directed to a photomultiplier or photodiode which produces a resulting fluorescence-related signal which is analyzed. The method and related apparatus eliminates signal noise and allows accurate recording and analysis of action-potential-related fluorescent changes.