Application of Vectocardiography in Cattle

Abstract

Even if the anatomical cardiac axis is not identical to its electrical axis, it is well known that in various species, the cardiac morphological changes are reflected on the angle of electrical cardiac axis. In this way, it has been shown in man (1, 2), dog (3, 4) and horse (5, 6), that cardiac vectors amplitude and orientation are modified by growth, training or pathological ventricular hypertrophy induced by various cardiac disorders including right and left valvulopathy, hindrances in systemic blood circulation accompanying extracardial diseases and hypertension in pulmonary circulation. By contrast, in the bovine species, electrocardiography consisted up to now in a purely qualitative analysis of the cardiac electrical activity, whereas vectocardiographic studies were still lacking in this species. It was thus of great interest to perfect a vectocardiography technique for cattle. On the other hand, in ungulae, depolarisation pattern of the heart is specific because of a particular organisation of the Purkinje fibers in the myocardium (7). Accordingly, several specific lead systems have been developed in the horse to quantify tridimensional vectocardiographic parameters. Because of the similarities between cardiac electric activity and between heart position within the thorax in horse and cattle (7), the validity of four of these equine lead systems was compared when transposed in calves.