Left ventricular coordinate systems

Three-dimensional kinematics of radiopaque markers in anterior, posterior, septal, and lateral regions of a major equatorial plane were evaluated in anesthetized dogs by biplane fluoroscopy. Stationary coordinate systems measured marker locations recorded during diastole and systole from a contractile origin at the center of contraction at end systole and from a geometric origin at the intersection with the equatorial plane of the ventricular long axis at end diastole. A time-indexed system measured marker locations at end diastole and at end systole, respectively, from the locations of the geometric origin at end diastole and end systole. Compared to the stationary system with the geometric origin, both the stationary system with the contractile origin and the time-indexed system reduced the variability of the radial components of the contractile displacements between ventricular regions. In contrast to the other two systems, the system with the contractile origin reduced circumferential components to values not significantly different from zero. These results indicate that 1) abnormally contracting regions of the ventricle may be located and their size measured by determining the region where the radial component differs from that in the rest of the equatorial plane and 2) rotation in a major equatorial plane of the ventricle is significant, but the influence of rotation can be minimized by referencing ventricular dimensions to a coordinate system with an origin at the center of contraction.