[Types of Conduction Disturbances in Pulmonary Veins]

Recently, the notion that in 60-80 % of cases the origin of the pulmonary veins (PV) is the place of origin of atrial fibrillation (AF) has become widespread. It has been shown that in this area, under the action of norepinephrine (HA), in the absence of stimulation, an intrinsic rhythm appears. Using two-channel microelectrode leads (from the mouth and distal part of the PV) in rats weighing 350-450 grams, it was found that: 1) in the distal part of PV there are cells with depolarized resting potential (RP) up to -50 mV, which under normal conditions are not excitable; 2) in 17 experiments out of 23, various blocks of excitation conduction along PV were revealed; 3) in 8 experiments out of 23, a reflected excitation wave - echo from PV - was recorded. Myocardium of PV is an extremely heterogeneous medium with a strong variance in the duration of the action potential and variable rate of conduction, which contributes to the occurrence of different types of conduction blocks and causes echoes and other rhythm disturbances.