[Use of body surface heart potential mapping for registration of electrical phenomenal in the atrium]

Research on body surface potential mapping concerned predominantly the ventricular excitation process. There is only very limited data available documenting surface potential distribution during atrial electric events. The goal of this study was to establish the pattern and criteria of the atrial potential maps in the healthy population, which is substantial for a prospective usefulness of the noninvasive registrations of surface maps in atrial arrhythmias. A group of 54 subjects in whom there was no clinical evidence of cardiac dysfunction underwent a procedure of body surface potential mapping. The recordings were performed using the HPM-7100 system simultaneously from 87 leads covering the entire thorax. Isopotential maps registered during the P wave were subjected to the statistical analysis by means of the own system "Heart Map" enabling the qualitative and quantitative estimation of the atrial maps. To avoid a problem of variable heart rate, a time standardization, by the division of the P wave into 10 time intervals, was applied. In order to eliminate an interindividual variability of heart location in the thorax, a distribution of the constituent values without subordinating them to the individual electrodes was proposed. In consequence, the group-mean isopotential maps of the wave P for the normal subjects were created. According to the migration of the maximum throughout the thoracic surface during the P wave, three phases of the isopotential atrial maps were determined: phase 1 (P1-P4) comprising initial 40% of the P wave, phase 2 (P5,P6)-next 20% of the P wave and phase 3 (P7-P10)-the terminal 40% of the P wave duration. These phases reflect the successive sequences of atrial excitation. During the whole atrial depolarization the minimum of potential, changing its value, was located around lead D7. Furthermore, in the results of the analysis of the constituent values sequences, for the P wave time intervals the additional quantitive parameters were calculated, i.e. areas designated by positive and negative potential and the ratio of these areas. The presented findings revealed that surface maps give the precious insight into spread of atrial excitation. Establishing of the distribution pattern and the criteria of the atrial potential maps for normals enables to undertake the further research on the use of this technique in a various atrial pathology.