Background. QT interval dispersion (QTd) is conventionally interpreted as a result of repolarization heterogeneity
in ventricular myocardium. However, another concept of QTd origin has been discussed recently, suggesting that
different projections of the repolarization vector into individual ECG leads could be responsible for the differences
in QT interval duration. Moreover, the reproducibility could be influenced by factors both electrocardiographic (T
wave amplitude, U wave) and extracardiac (noise, ECG measures). In the presented study we have followed the QTd
in two groups of patients with proved changes of an electric heart field.
Methods and Results. Studied groups: 1. Control group, 2. Healthy pregnant women, 3. Patients treated with
dosulepine. QT interval was measured from 80 unipolar chest leads used for body surface potential mapping. The
QTdwas significantly higher in both experimental groups in comparison with the control group (p<0.001). Significant
correlation was found between the QTd and dosulepine plasma level (p<0.001). Also amplitude of the T wave loop
was in both groups decreased and its width increased (both p<0.001).
Conclusions. If appropriate procedure of measurement is used, the QTd is significantly increased in many physiological
and pathological states. Clinical relevancy of borderline increased values has to be interpreted very carefully.
QT dispersion, vectorcardiography, dosulepine, body surface potential mapping.