Abstract 1872: Transmural Dispersion of Repolarization in Human Ventricular Wall
Transmural dispersion of repolartization (DR) has been studied in numerous animal models. Some studies presented evidence of midmyocardial population of M-cells that possess distinctly long action potential duration (APD). We aimed to investigate APD and DR in explanted failing human left ventricles (LV). We optically mapped APD in coronary-perfused human LV wedge preparations (n=4) using CMOS camera in presence of blebbistatin (BB, 10 μM). Microelectrode recordings were used to validate BB in human LV. RESULTS: During slow pacing (S1S1=2,000ms), APD at the endo-, mid-, and epicardium was 586±27ms, 578±19ms, and 496±14ms, respectively. Maximum APD gradient was 24±5 ms/mm, DR was 35±6 ms. Progressive decrease in S1S1 up to functional refractory period (460±26 ms) induced an inhomogeneous shortening of APD (up to 350±26 ms, 352±36 ms and 346±30 ms, respectively), decrease in APD gradient and DR (4±3 ms/mm and 20±4 ms, respectively, p<0.01) We present for the first time evidence of transmural APD gradient in failing human LV. However, we could not confirm presence of distinct population of M-cells that were found in several animal models.