Rotation, Velocity and Deformation Imaging in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is regarded as one of the most common inherited cardiac diseases. In a number of population studies the prevalence of HCM is estimated in the general population to be at least 1 in 500. HCM is inherited with an autosomal dominant Mendelian pattern, variable expressivity, and age-related (and incomplete) penetrance. Clinical diagnosis of HCM requires confirmation of phenotypic expression, that is an unexplained increase in left ventricular (LV) wall thickness (≥15 mm in adults) associated with a nondilated LV chamber with cardiac imaging (usually echocardiography). Phenotype positive patients may show different patterns of LV hypertrophy: reverse septal curvature, sigmoidal and apical forms have been described. Relatives identified with pathogenic mutations (gene carriers) but without evidence of the disease phenotype comprise a new HCM subgroup, designated as genotype positive-phenotype negative individuals. The risk of eventually developing LV hypertrophy in this group is currently uncertain. In this thesis we investigated the value of speckle tracking echocardiographically (STE)-derived global and regional LV rotation and strain in HCM mutation gene carriers and patients, both in systole and diastole. In the first part of this thesis STE analysis of myocardial velocity, rotation and strain in systole and diastole is introduced. In Chapter 2 a literature review of LV twist mechanics in cardiomyopathies is presented. Analysis of LV twist mechanics may provide substantial pathophysiological understanding in a variety of cardiomyopathies. In the second part of this thesis the feasibility of STE is studied. In Chapter 3 it is shown with a moving phantom model that mitral annular velocities can be accurately determined by STE in an angle independent way. In Chapter 4 the feasibility, observer variability and test-retest variability of LV twist measurements by STE is described. The method appeared to be feasible in approximately