[Determination of the specific points in the atrial excitation sequence on the P loop of the VCG by using the parameters of a differentially amplified ECG].

Ninety-eight normal subjects and 31 patients with right, left or bilateral atrial enlargement were examined, with differentially-amplified atrial electrocardiogram (DAECG) and intensified atrial vectorcardiogram recorded simultaneously. Atrial complex DAECG permitted an accurate determination of the following sequence of specific atrial activation points on the P loop of vectorcardiogram: activation along the right atrium only (before the left atrium is included), the origin of left atrial activation, the termination of right atrial activation and the maximum vector of the left atrium. Determining the maximum vector according to the most distant point on the P loop is not practicable, because of its ambiguous representation of atrial activation processes. For most normal subjects and all patients, with right atrial enlargement, the maximum vector point on the P loop coincides with the termination point of right atrial activation, while in cases of left atrial enlargement it coincides with the maximum vector point on the P loop coincides with the termination point of right atrial activation, while in cases of left atrial enlargement it coincides with the maximum vector point of the left atrium.