Abstract
BACKGROUND: Despite the availability of several mapping technologies for investigating the electrophysiologic mechanisms of atrial fibrillation (AF), an experimental tool enabling high-resolution mapping of electrical impulses on the endocardial surface of the intact left atrium is lacking. OBJECTIVE: The purpose of this report is to present a new optical mapping approach implementing a steerable cardio-endoscope in isolated hearts. METHODS: The system consists of a direct or side-view endoscope coupled to a 532-nm excitation laser for illumination and a CCD camera for imaging of potentiometric dye fluorescence (di-4-ANEPPS, 80 x 80 pixels, 200-800 frames/s). The cardio-endoscope was aimed successively at diverse posterior left atrial locations to obtain high-resolution movies of electrical wave propagation and detailed endocardial anatomic features in the presence and absence of atrial stretch. RESULTS: We present several examples of high-resolution endoscopic posterior left atrial recordings of wave propagation patterns during both sinus rhythm and AF with signal-to-noise ratio similar to conventional optical mapping systems. We demonstrate the endoscope's ability to visualize highly organized AF sources (rotors) at specific locations on the posterior left atrium and posterior left atrium-pulmonary vein junctions. We present video images of waves emanating from such sources as they propagate into pectinate muscles in the left atrial appendage. In particular, we demonstrate this approach is ideally suited for studying the effects of atrial stretch on AF dynamics. CONCLUSION: In isolated hearts, cardio-endoscopic optical mapping of electrical activity should enable comprehensive evaluation of AF activity in the posterior left atrium, the role of local anatomy on AF dynamics, and the efficacy of pharmacologic and ablative interventions.