DISPERSION OF REGIONAL WALL-MOTION ABNORMALITY IN PATIENTS WITH LONG QT SYNDROME

Objective-To examine the left ventricular regional wall motion abnorma lity and to evaluate dispersion of this abnormality in patients with l ong QT syndrome.Design-Left ventricular short axis images at basal and middle levels were recorded on videotape and digitised to reconstruct digitised M mode echocardiograms, from which left ventricular wall th ickness curves were obtained. The wall thickening time (ThT) was defin ed as the period in which the instantaneous wall thickness exceeded 90 % of the maximum wall thickness. ThT was measured at three segments in each of the septal and free wall sides of the left ventricle, a total of 12 segments. To examine the mechanical dispersion of the left vent ricle, the difference between the maximum and minimum ThT of 12 segmen ts in each subject was obtained. Patients-Light patients with congenit al long QT syndrome (averaged QTc interval (SD) 509 (27) ms(1/2)) and 10 control subjects (QTc interval 397 (26) ms(1/2)) were examined. Res ults-The averaged ThT values of the 12 segments pooled from all subjec ts were correlated with the QT intervals (r = 0.72, p < 0.005). Thus t he averaged ThT in the long QT syndrome patients was longer than in th e control subjects (p < 0.005). The segmental variation of ThT in the patients was greater than in the control subjects (p < 0.001). The dis persion of ThT in the patients was therefore larger than in control su bjects (p < 0.005). However, the pattern of ThT variation in the patie nts varied according to the individual subject. Conclusions-There is n ot only electrical but also mechanical dispersion in the left ventricl e of long QT syndrome patients. Regional assessment of ventricular wal l motion may allow quantification of the spatial variation of wall mot ion abnormality.