NADH as an Endogenous Marker of Cardiac Tissue Injury at the Site of Radiofrequency Ablation

Abstract

Atrial fibrillation (AF) remains the most commonly occurring cardiac arrhythmia; its incidence is associated with a lower quality of life including a higher rate of morbidity & mortality. Percutaneous left atrial catheter ablation for the purpose of eliminating AF has become a common treatment option and is currently being investigated for superiority over medical therapy in a large clinical trial. RFA produces lesions that can block the spread of electrical activity from the sites of abnormal activity including pulmonary veins. Today, there are limited means for real time monitoring of tissue injury during the RFA procedure. To address this need, we explored the fluorescence of endogenous NADH as a possible live marker of tissue injury during the ablation procedure. Studies were conducted in blood-free and blood-perfused isolated rat hearts. Epicardial RFA lesions were seen as areas of low NADH fluorescence which encompassed both irreversible and reversibly damaged tissue. Their size significantly exceeded TTC negative staining (TTC - Triphenyl Tetrazolium Chloride, a redox indicator used to differentiate between metabolically active and inactive tissues). Real-time monitoring of NADH fluorescence allowed visualization of gaps of viable tissue between the RFA lesions. Dual recordings of NADH and epicardial electrical activity linked these gaps to the occurrence of post-ablation reentries. We conclude that fluorescence of endogenous NADH can assist visualization of injured epicardial tissue near the tip of the RFA catheter lesions.