Comparison of global dispersion with local dispersion of ventricular repolarization measured with monophasic action potential mapping technique in swine

AIM To evaluate whether the global dispersion of ventricular repolarization(DVR) can be estimated from the measurements between a few adjacent or remote sites.METHODS Monophasic action potentials(MAPs) were recorded from(75±12) left ventricular endocardial sites in 10 pigs by using the CARTO mapping system.End-of-repolarization time(EORT) and MAP duration(MAPD) were calculated at each site and ten sets of 3-dimensional repolarization maps were constructed.Global DVRs in EOR and MAPD were compared with the adjacent DVR in areas 2 cm~2 and remote DVRs between 2 MAPs with the greatest activation time difference(remote DVR1) and between the apical and laterobasal left ventricle(remote DVR2).RESULTS The adjacent DVRs in EOR and MAPD were significantly smaller than the global ones [(15±4 and 12±4) ms vs (84±31 and 77±26) ms respectively,P(0.01))].Both the two remote DVR parameters,(42±19 and 23±14) ms for remote DVR1 and(25±16 and 18±11) ms for remote DVR2,were markedly greater than the adjacent ones(P0.01),but still significantly smaller than the global DVR values(P0.01).CONCLUSION Global DVR can not be satisfactorily estimated from MAP recordings from a few adjacent or remote sites.Obtaining global information is of great importance in evaluating DVR.