STUDIES ON APPLICATIONS OF ELECTROCARDIOGRAM IN HORSES : I. THE LEAD METHOD AND ELECTROCARDIOGRAM WITH SPECIAL REFERENCE TO CONFIGURATIONS AND MEASUREMENTS OF WAVES IN THE LIMB LEAD

Abstract

Configurations and calculations in the limb lead were conducted in normal horses as a part of project in electrocardiographic studies. The results thus obtained are summarized as follows. 1. Cardiac displacement may be observed in the limb lead by the directions of recordings of R_ and R_ waves. Although 40% of dropped heart and 30% of transversed heart were observed, 30% could not be classified to any types. 2. The intricate triphasic waves in P wave were found in from 70 to 80%. Appearance of this type was found usually in normal horses in the limb lead. 3. Isoelectric waves in the PR(PQ) were shown in from 70 to 80%, but other cases indicated descending, ascending and vibratory. No appearances of isoelectric waves were ever found in the latter cases, except for the presence of disturbances, in the results of calculations of PR(PQ) intervals. Therefore, it will be thought that the measurement of PR(PQ) intervals in disturbances of auriculoventricular conduction has an important significance. 4. Notchings on the down or upstroke were found 20% in R_I, 10% in R_ and 20% in R_, and then, notchings of the apex of R waves in R_ and R_ were seen 20 and 30% respectively. The appearance of notching in negative R, except for R_I, seemed to have some correlations with the cardiac displacement. 5. Arc curved S waves were found in 80% in lead I, 66% in lead II and 90% in lead III. They appeared on the terminal part of the downstroke of R and succeeded to RS-T segments. 6. In RS-T segments or junctions, each 60% in leads I and II, and 80% in lead III indicated isoelectric types. In other cases were found the types of descending, ascending and slight vibratory to the zero line. 7. Monophasic negative waves were always observed in the T wave of lead I. In leads II and III, 66 and 90% of them indicated monophasic positive waves. Other cases were the diphasic which showed positive deflections after negative. 8. The amplitudes in each wave were higher in the mean values than those of LANNEK & RUTQVIST. The authors considered that such results may be ascribed to the position differences of electrodes. The mean values of durations and intervals nearly approached the results reported by DUKES & BATT and by LANNEK & RUTQVIST