Regional differences in shape and load in normal and diseased hearts studied by three dimensional tagged magnetic resonance imaging

Objectives: We aimed to characterize regional geometry in relation to load in two groups of patients with hypertrophic cardiomyopathy (HCM) and right ventricular pressure overload (RVPO) in relation to a group of subjects wit h normal left ventricular (LV) function. Background: Both these diseases ar e associated with marked changes in LV shape and function, which have not b een studied with detailed three dimensional tools. Methods: Three dimension al (3D) tagged magnetic resonance imaging (MRI) was used to characterize th e 3D geometry and regional stresses of the left ventricles in patients with HCM and RVPO. Curvatures, stresses, wall thickness, and endocardial motion were calculated from surface and volume elements. Results: Hearts with RVP O exhibited more circumferential and meridional flattening of the septum th an normal and HCM hearts. The stress indices were lowest in the HCM hearts, compared to normal and RVPO hearts, due to the larger thicknesses. There w as a more significant difference between lateral wall motion and other regi onal wall motions in the HCM and RVPO hearts as compared to normal hearts. Conclusions: It is suggested that curvature and stress mapping by 3D tagged MRI can be used as an important clinical tool for characterizing and disti nguishing between healthy and diseased hearts. The results provided here va lidated previous knowledge on HCM and RVPO known from planary imaging metho ds.