The vector U loop of ventricular premature beats.

HERE have been no reports on the U vector loop or arc of ventricular premature beats. Recently a systematic study was carried out on the vectorcardiogram of ventricular premature beats. The QRS and T vector loop of the ventricular premature beats will be reported elsewhere. Since the U vector loop could not be studied in all these cases because of technical difficulties, and since it needs a description rather independent from the QRS and T loops it is described here as a different paper.