Automatic detection of conduction block based on time-frequency analysis of unipolar electrograms

It is commonly thought that lethal tachyarrhythmias, such as ventricular fi brillation (VF), are perpetuated by functional reentry, which occurs when a n activation wave blocks and rotates around tissue that is excitable (i.e., functional block), Electrograms recorded near these regions typically cont ain two sequential deflections representing activation on either side of th e block. By detecting these "double potentials," we hypothesize that functi onal block can be detected by a single electrode, Methods: Unipolar electro grams were recorded from a 24 x 21 mapping array on the intact ventricular epicardium of five pigs during electrically-induced VF, The short time Four ier Transform (STFT) of each electrogram was analyzed to identify double po tentials, To evaluate the performance of the STFT algorithm, conduction blo ck was located in activation maps using a minimum conduction velocity crite rion (10 cm/s) and then compared to the results of the STFT algorithm, Resu lts: The STFT algorithm detected conduction block with a sensitivity of 0.7 4 +/- 0.12 and a specificity of 0.99 +/- 0.00. Conclusion: We have develope d an automated algorithm that can detect functional block during VF from a single electrode recording, Possible applications include fast, objective i dentification of block in mapping data and realtime localization of reentra nt substrates using mapping catheters.