gms | German Medical Science

Atrial fibrillation is the most common of all sustained cardiac arrhythmias. Recent clinical studies have shown that pulmonary veins are an important source of ectopic beats, which can initiate paroxysmal tachyarrhythmias and atrial fibrillation, especially in the presence of certain cardioactive agents. The left atrium consists predominantly of myocardial cells but may occasionally contain subsidiary pacemaker cells. The excitation wave spreading in epicardium in the area of falling the pulmonary veins into the left atrium at 36-37^oС and at cooling to 30^oС was studied by the method of electrocardiochronotopography in rabbit (Shinshila), of five months age. It was established that at 36-37^oС the excitation wave in epicardium spreads from inter-atrial septum along myocardial sleeve bending around the pulmonary veins, to the dorsal side of the left atrium. In this area the front of excitation branches off, dividing into two waves, one moves to the base of left auricle, the second depolarizes directly the area of vessels. At heart cooling, the direction of spreading the front of the excitation wave in epicardium in the area of falling the pulmonary veins into the left atrium does not change, but the time of depolarization of this area is changed. At cooling from 36^oС to 33^oС the time of depolarization of the area under study decreases, at further reduction of the temperature there occurs increase of the excitation time and the front becomes more homogeneous. The work is supported by the grant of the scientific school of the academician M.P.Roshchevsky SciSch-5118.2006.4, grant RFFI 05-04-49296, International Russian-Taiwan project 05-04-90586.