Spatial Correlation of Action Potential Duration and Diastolic Dysfunction in Transgenic and Drug-induced LQT2 Rabbits
Abstract
Enhanced dispersion of action potential duration (APD) is a major contributor to long-QT-(LQTS)-related arrhythmias.We aimed at investigating spatial correlations of regional heterogeneities in cardiac repolarization and mechanical function in LQTS.Female transgenic LQT2 (n=11) and wildtype (LMC) rabbits (n=9/10 without/with E4031) were subjected to phase contrast MRI to assess regional myocardial velocities. In the same rabbits' hearts, monophasic APDs were assessed in corresponding segments.In LQT2 and E4031 rabbits, APD was longer in all LV segments (p<0.01) and APD dispersion was greater than in LMC (p<0.01). In diastole, peak radial velocities (Vr) were reduced in LQT2 and E4031 compared to LMC in base and mid (cm/s, LQT2, -3.36±0.4, p<0.01, E4031, -3.24±0.6, p<0.0001, LMC, -4.42±0.5) - indicating an impaired diastolic function. Regionally heterogeneous diastolic Vr correlated with APD (LQT2, CC 0.38