Abstract 2907: Regional Heterogeneity of Torsion in Hypertrophic Cardiomyopathy
Background: The newly developed Two-Dimensional Tissue Tracking (2DTT)technique can trace regional myocardial tissue using pattern matching method without a limitation in the Doppler angle correction. The 2DTT has a capability to clinically evaluate cardiac regional torsions. Our objective was to characterize regional heterogeneity of left ventricular (LV) torsion using 2DTT in hypertrophic cardiomyopathy (HCM).
Methods: Ten patients with nonobstructive HCM and 10 normal subjects were studied. We acquired LV basal and apical short-axis views using Hitachi EUB-8500 ultrasound machine equipped with 2DTT software. Total 8 points were manually placed on anterior, lateral, posterior and septum both at endo- and epicardium in each base and apex. The movements of these points were automatically tracked by the system throughout a cardiac cycle. LV torsion was measured as the difference of rotation at basal and apical plane in each of the 8 regions.
Results: The HCM septal and lateral wall demonstrated significantly greater endocardial torsions as compared to the normals (septal, 20.1±4.8 vs 11.2±1.6°, p=0.0002; lateral, 17.6±6.5 vs 10.6±1.1°, p=0.001). In the HCM group, each endocardial region showed significantly greater torsion than that did the epicardial region (p<0.05, respectively), on the other hand, this transmural difference was not present in normal group.
Conclusions: LV torsion shows regional heterogeneity in HCM, which may reflect altered patterns of intramural fiber strain due to regional fiber disarray in HCM.