Abstract 10719: Left Ventricular Rotation is a Function of Helical Myocardial Architecture and Related to Circumferential Myocardial Shortening
Background: We noticed rotational left ventricular (LV) motion in our experiments using freshly harvested pig hearts driven passively by calibrated pulsatile pump, and sought to evaluate this observation.
Methods: We studied 10 freshly harvested pig hearts using a custom designed pulsatile heart model in water bath to facilitate ultrasound scanning. Each pig heart was driven passively by injecting a known volume into the LV cavity at a constant controlled rate (60/min) by a calibrated pump through clear plastic tubing with a latex balloon in the LV cavity secured at the mitral annulus. Pulsatile LV motion was scanned with a matrix transducer on a Siemens SC 2000 ultrasound system to acquire full volume 3D image loops at frame rate >30 volumes per second. Studies were conducted at 5 stroke volumes (30-70ml). Images were analyzed offline for segmental strain and rotation using a new 4D motion analysis program.
Results: Despite no external rotation, the 4D program detected counterclockwise apical and clockwise basal rotation with pulsatile LV motion. Apical rotation and fractional shortening (circumferential strain) increased with the increase in stroke volume (p<0.05). There was no significant change in basal LV rotation at all stroke volumes studied.
Conclusions: LV twist is an intrinsic myocardial function that can be explained on the basis of oblique helical orientation of myocardial fibers.
- © 2011 by American Heart Association, Inc.