[Electro-vectorcardiographic analysis of the negative, diphasic and bifid T wave in right precordial leads in young subjects].

Morphology, genesis and incidence of isolated T wave abnormalities on right precordial leads of healthy young individuals were studied in this work. ECG were obtained from 1510 healthy subjects aged 14 to 40 years consecutively submitted to a cardiological evaluation in order to assess their fitness for sport. In 510 of them a VCG was made too. The results showed that T waves were rarely negative beyond V1 (0.46%) and even more rarely negative from V1 to V3 (0.13%); diphasic T waves were present in 2.38% and bifid T waves in 6.15% of our cases. The T loop of VCG tended to be more posteriorly displaced and evolved from a counterclockwise to a clockwise rotation as the presence of negative T waves spread toward left on precordial leads. The "+-" type of diphasic T wave corresponded to a counterclockwise rotation of the T loop, the "-+" type to a clockwise rotation. Bifid T waves were associated with figure of eight or "arched" T loops of VCG. The T loops of those subjects who underwent a second evaluation after several years tended to be displaced more anteriorly, with counterclockwise rotation. The causes of these T wave abnormalities have not been clearly explained yet, even if a slight delay in the right final vectors was present in the majority of our cases.