Abstract 14825: Apical Rotation is an Important Contributor to Left Ventricular Diastolic Function: Observation During Apical Immobilization Using Starfish™ Positioner
Background: The helical arrangement of myocardial fibers leads to left ventricular (LV) twist that is thought to play an important role in cardiac function. Although there are a lot of studies to reveal the rotational difference depending on various physiological conditions and disease states of the heart, it is not well known how twist affects systolic or diastolic function precisely.
Methods: In 15 open-chest dogs, apical and basal short axis images were acquired using GE Vivid 7 at baseline and during the use of an apical suction device (StarfishTM) to limit apical rotation. LV pressure was measured by a micromanometer catheter. Stroke volume was measured by an ultrasonic flow probe around the ascending aorta. Peak radial strain, peak rotation, peak twist, peak systolic twisting rate (TR), peak untwisting rate during isovolumic relaxation period (URIVR) and peak untwisting rate after mitral valve opening (URE) were determined using speckle tracking echocardiography.
Results: By immobilizing the apex with gentle suction, apical rotation significantly decreased (by −50 ± 27%) and basal rotation slightly increased, resulting in a significant decrease in twist. Tau was prolonged and LV end-diastolic pressure (LVEDP) increased. TR and URIVR decreased. LV systolic pressure, peak positive and negative dP/dt, stroke volume, radial strain and URE were not changed. There was a stronger correlation between tau and URIVR (r = 0.63, p=0.0006) than that between peak positive dP/dt and TR (r = 0.46, p=0.01).
Conclusion: When the apex of the heart was immobilized using an apical suction device, diastolic function was impaired with reduction of apical rotation and URIVR but systolic function was not changed. Apical rotation contributes greater to diastolic function than to systolic function.
- © 2010 by American Heart Association, Inc.