RESEARCH COMMUNICATIONS OF THE 28th ECVIM-CA CONGRESS

The mean electrical axis (MEA) of the QRS complex is the average of all the instantaneous mean electrical vectors occurring sequentially during ventricular depolarization, and it ranges from +40° to +100° in healthy dogs. In humans, indeterminate QRS axis (iQRS axis) is defined as the impossibility to calculate the MEA of the QRS due to biphasic complexes with equal or nearly equal positive and negative components in all the six limb leads. The iQRS axis is a rare condition in humans and it occurs when the MEA is perpendicular to the frontal plane. In humans, iQRS axis has been found in healthy subjects and in patients with ventricular hypertrophy. The aim of this study was to describe the prevalence of the iQRS axis in dogs, looking for associations between iQRS and age, body weight, thoracic morphotype as well as presence of cardiac diseases.