Apical Transverse Motion Is Associated with Interventricular Mechanical Delay and Decreased Left Ventricular Function...

Apical transverse motion (ATM) is associated with electromechanical dyssynchrony in adult dilated cardiomyopathy (DCM). Bundle branch block electromechanical dyssynchrony is uncommon in pediatric DCM, but ATM and its association with ventricular function have not been characterized.

Fifty-six children with DCM were retrospectively studied. Using echocardiography, ATM was assessed visually and by speckle-tracking longitudinal displacement of the interventricular septal and left ventricular (LV) lateral walls in opposite directions. Doppler tissue imaging-derived displacement and velocities were used to time the onset and peak LV and right ventricle motion, from which intra- and interventricular delays were calculated to assess their association with ATM. The timing of aortic valve opening and closure in relation to onset and peak LV displacement was used as a measure of LV mechanical efficiency.

LV ATM was observed in 35 of 56 patients (62.5%), occurring in two patterns: 45% had ATM (interventricular septum displacing toward the lateral wall and lateral wall displacing toward the mitral annulus during systole), and 18% showed reverse ATM (r-ATM; lateral wall displaced toward the apex and interventricular septum displaced toward the septal annulus during systole). Both patterns were associated with increased interventricular but not intraventricular mechanical delay (controls: 2 msec, ATM 16 msec, r-ATM 8 msec, both P < .05 vs control subjects). Patients with ATM or r-ATM had lower LV ejection fractions (19% vs 29%, P < .05) and higher mechanical inefficiency compared with those without ATM. Survival was not statistically different in those with ATM or r-ATM compared with those without ATM or r-ATM.

In pediatric DCM, ATM is associated with LV dysfunction, mechanical inefficiency, and interventricular mechanical delay.