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Heterogeneity of propagation of excitation in epicardium of pulmonary veins ostia in rabbit during cooling.

OBJECTIVE
The purpose of this research was to study the propagation of the excitation wave along epicardium in the area of the pulmonary veins ostia in rabbit in normal conditions and while cooling.


METHODS
The excitation wave spreading along epicardium in the area of pulmonary veins ostia in the left atrium at 36-37 degrees C and when cooling to 32 degrees C was studied by the method of electrocardiochronotopography in rabbit of Chinchilla species, five months age. The size of the registering surface of the electrode was 1.08 x 1.08 cm.


RESULTS
The time of depolarization when cooling from 36 degrees C to 32 degrees C changes unevenly in various zones of pulmonary veins. On the epicardium of pulmonary veins area at temperature reduction from 36 degrees C to 33 degrees C, change in the direction of excitation and essential reduction of depolarization time, and its significant increase under further cooling to 32 degrees C were observed. In the middle part of the left atrium at temperature reduction, change in the main direction of the excitation wave propagation, shift of the location of the areas of the latest depolarization were revealed and the front become more homogeneous.


CONCLUSION
In the area of the left atrium base the heterogeneity of the front of depolarization at temperature reduction was revealed.