RESUMO
Previous studies, using M mode echocardiography, provided unexpected evidence of a mechanical alteration in patients with long QT syndrome. The aim of this study was to evaluate entire left ventricular [LV] wall motion characteristics in patients with long QT syndrome using tissue Doppler imaging. We enrolled 17 patients with congenital long QT syndrome [11 female and 6 male, aged 21 to 45 years. 10 subjects without cardiac disease were also selected as control group. Two-dimensional tissue Doppler imaging [TDI] recording of the LV was obtained from the basal and mid-segments from apical four-chamber, two-chamber, and long-axis views. 'Myocaridal Contraction Duration' [MCD] was defined as the time from start of R wave on ECG to end of S wave on TDI. MCD was measured in the six LV wall positions: septal, anteroseptal, lateral, inferior, posterior and anterior positions. LV contractility dispersion was significantly greater in long QT syndrome patients compared to control group [0.051 +/- 0.011 vs. 0.016 +/- 0.06; P<0.001]. Our study evaluated left ventricular dispersion of contractility duration in patients with long QT syndrome. This mechanical dispersion may be a reflection of the inhomogeneity of repolarisation in the long QT syndrome