Evaluation of isovolumic myocardial motions in human subjects using tissue velocity echocardiography

Sammanfattning: Colour-coded tissue velocity imaging (TVE) with Echocardiography is an established method for evaluation of the global cardiac function and of the regional myocardial movements. The TVE-technique allows measurements of velocity and deformation variables from any discrete point in the myocardial wall during the cardiac cycle with high temporal and longitudinal spatial resolution. Even the rapid kinetic events during the isovolumic phases can be analysed which has been reported to be involved in the process of pre and postsystolic ventricular reshaping. However, the optimal sampling requirements for a proper rendering of the tissue velocity variables and the effect of different temporal smoothing filters incorporated in the WE software have not yet been established. The aims for current thesis were to establish optimal values for temporal resolution and also to study the effect of temporal filtering algorithms on colour-coded tissue derived duration and velocity variables registered at the base of left ventricle in apical views. After ensuring adequate sampling rate and temporal filter width for the myocardial velocity profiles the isovolumic periods were analysed in fortynine healthy subjects to describe normal reference values in the base of four different cardiac walls. The influence of gender and age were also studied for isovolumic time, velocity variables as well their respectively amplitude motion. The reproducibility for the longitudinal and radial myocardial velocity and displacement variables was studied and varied between 5-12% (CV). The temporal resolution should at least 100 frames/s for a proper rendering of the myocardial velocity variables during the entire cardiac cycle. Increased temporal filter width affected the results by decreased myocardial velocities and the effect was most pronounced during the rapid isovolumic events. The longitudinal motions of left ventricular wall showed biphasic patterns during the isovolumic contraction and relaxation periods and the segmental velocities and displacements differs among the four walls. The relative myocardial isovolumic displacement was most pronounced in anterior wall (5.0 of the total longitudinal myocardial shortening). Except prolonged duration of the TVE-IVRT in the older age group, no other larger gender and age differences occurred.