This study investigated the occurrence of changes in the electrical rotation direction of the QRS complex during 10-minute vectorcardiogram (VCG) recordings. Data from 40 patients were analyzed, obtained in collaboration with the Instituto Dante Pazzanese de Cardiologia (São Paulo, Brazil). The sample was selected by convenience and included individuals undergoing clinical follow-up, routine evaluations, or participating as research volunteers.
VCGs were acquired using the ECGPC system (TEB, Brazil) at a sampling rate of 1200 samples per second, with eight electrodes positioned according to the Frank lead system. Recordings were separated into the horizontal and frontal planes, and the QRS rotation was classified into three categories: clockwise, counterclockwise, or figure-eight. Each heartbeat within the recordings was individually reviewed to identify changes in rotation direction compared to the preceding beat. Among the 40 exams analyzed, 19 presented rotation variations: 12 in the frontal plane, 6 in the horizontal plane, and 1 in both planes. A total of 121 beats exhibited a change in rotation pattern, with 58 associated with the figure-eight configuration. Additionally, two beats showing rotation changes were related to extrasystolic events.
The identification and classification of these variations were based solely on the morphology of the VCG without introducing clinical interpretations. These data provide a quantitative description of the frequency and distribution of QRS rotation changes during Frank lead VCG acquisition, offering a basis for further studies exploring the physiological relevance of these observations.