Tissue Doppler echocardiography in patients with long QT syndrome

Congenital long QT syndrome (LQTS) is a well-defined clinical entity associated with a high mortality among untreated patients. Tissue Doppler (TD) echocardiography that has been recently introduced, facilitates wall motion analysis. Therefore, to further characterize myocardial velocity abnormalities associated with LQTS, using TD and conventional echocardiography, we compared control subjects and LQTS patients.

Ten patients with mild LQTS and 14 control subjects were examined with standard and TD echocardiography. We studied myocardial velocities in basal and mid-segments of the septal, lateral, inferior and anterior walls. Peak velocity and time intervals were measured in each segment. We confirmed previously described M-mode abnormalities, demonstrated by an increase of the wall thickening time index. TD analysis demonstrated increased systolic and diastolic peak velocities for all segments in LQTS patients. Regional isovolumic relaxation time and systolic velocity half time (VHT) were significantly longer in LQTS group associated with a prolonged late systolic phase, resulting in a plateau morphology.

We demonstrated that TD allows the characterization of myocardial velocity abnormalities in LQTS patients. TD measurements could become part of the routine clinical evaluation for patients potentially affected by the LQTS as a new phenotypic marker.