Influence of cardiac shape on left ventricular twist

The dynamic interaction between subendocardial and subepicardial fibre helices in the left ventricle (LV) leads to a twisting deformation, which has an important role in LV function. This study sought to assess the influence of cardiac shape on LV twist in the normal and dilated human heart. The study comprised 45 dilated cardiomyopathy (DCM) patients and 60 for age- and gender-matched healthy volun-teers. Speckle tracking echocardiography was used to determine basal and apical LV peak systolic rotation (Rotmax) and instantaneous LV peak systolic twist (Twistmax). LV sphericity index was calculated by dividing the LV maximal long-axis internal dimension by the maxi-mal short-axis internal dimension at end-diastole. A parabolic relation between the sphericity index and apical Rotmax or Twistmax was identified in the total study population (R2 0.56 and R2 0.54, respectively; both P 0.001) and healthy volunteers (R2 0.39 and R2 0.25, respectively; both P 0.001), whereas these relation