[Vectorcardiographic manifestations of supraventricular ectopic rhythms].

In the presence of low right atrial rhythms, the eight-shaped PF loop is located in the first quadrant, the PH loop is rotating in a counterclockwise direction and PS can rotate in either course. When the rhythm originates in high left atrial regions, PF and PH loop loops can be found in the third quadrant of both planes and should have a clockwise rotation. When the pacemaker is located in low left atrial regions, the PF loop rotates in a counterclockwise direction, or with its branches superposed, and located in the second quadrant; PH is rotating clockwise in the third quadrant; PS with either a clockwise or a counterclockwise rotation, is situated above and slightly ahead of the E point. In the presence of a nodal rhythm, the P loops show a counterclockwise rotation or an eight-shaped configuration. In the absence of atrial enlargements, the PF loop can be seen in the first quadrant and the PH in the first or the fourth quadrant.