Cardioelectric Field on the Bird Body Surface during Activation of Atrial Myocardium

Cardioelectric field (CEF) on the body surface of birds (hen and pigeon) at the period of atrial excitation was studied by the method of the 64-channel synchronous electrocardiotopography. At the period of the atrial depolarization in the birds the zone of CEF negative potentials on the body surface is located cranially with respect to the zone of positive potentials. At the initial moments of P wave the minimum is located in the cranial (hen) or middle (pigeon) third of the dorsal body surface, while the maximum—in the area of the heart projection onto the ventral (hen) or left-lateral (pigeon) body surface. The maximum and minimum of the potential reach the greatest value at the period of the middle part of the P wave (near the peak), their amplitude being higher in pigeons. The distribution dynamics of the CEF potentials on the body surface is similar in different bird species and is characterized by stability in mutual disposition of positive and negative zones. The interspecies and intraspecies CEF variability on the body surface at the period of the atrial activation seems to be due to differences in the heart disposition in the chest. At the period of the atrial myocardium activation, CEF on the bird body surface reflects adequately projection of the potential distribution on epicardium and the sequence of spreading of excitation in the atrial myocardium, including that in the presence of several fronts of depolarization waves.