[Spatial characteristics of the P loop in normal subjects and in patients with an enlarged right atrium].

The studies performed have shown that: 1) using automatic reproduction of 10-20-fold magnified images of P-loop it is possible to learn its configuration, duration, recording direction, position and orientation of its moment vectors; 2) using digital computer list output of curves it is possible to determine numerical values of PXYZ-loop parameters and its vector and scalar characteristics; 3) for the diagnosis of right atrial dilatation (RAD) the assessment of vector values is more important than their orientation by azimuth and elevation angles; 4) the increase beyond normal (M + 2 sigma) of space vector values of PXYZ-loop - P0.25 greater than 0.16 mV, -Pmax greater than 0.22 mV and SP area greater than or equal to 0.03 mV.mV (3 mm2) reflects the initial stage of RAD; 5) changes of normal initial/final vector ratio (-P0,025 greater than or equal to -P0,075 - in normal subjects and P0,075 greater than or equal to P0,025 in patients with RAD) indicate the advanced stage of RAD.