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. 2017 Jan 17;12(1):e0169619.
doi: 10.1371/journal.pone.0169619. eCollection 2017.

Cardiac Mean Electrical Axis in Thoroughbreds-Standardization by the Dubois Lead Positioning System

Cássia Fré da Costa  1 , Nelson Samesima  1 , Carlos Alberto Pastore  1
Affiliations

Cardiac Mean Electrical Axis in Thoroughbreds-Standardization by the Dubois Lead Positioning System

Cássia Fré da Costa et al. PLoS One. .

Abstract

Background: Different methodologies for electrocardiographic acquisition in horses have been used since the first ECG recordings in equines were reported early in the last century. This study aimed to determine the best ECG electrodes positioning method and the most reliable calculation of mean cardiac axis (MEA) in equines.

Materials and methods: We evaluated the electrocardiographic profile of 53 clinically healthy Thoroughbreds, 38 males and 15 females, with ages ranging 2-7 years old, all reared at the São Paulo Jockey Club, in Brazil. Two ECG tracings were recorded from each animal, one using the Dubois lead positioning system, the second using the base-apex method. QRS complex amplitudes were analyzed to obtain MEA values in the frontal plane for each of the two electrode positioning methods mentioned above, using two calculation approaches, the first by Tilley tables and the second by trigonometric calculation. Results were compared between the two methods.

Results: There was significant difference in cardiac axis values: MEA obtained by the Tilley tables was +135.1° ± 90.9° vs. -81.1° ± 3.6° (p<0.0001), and by trigonometric calculation it was -15.0° ± 11.3° vs. -79.9° ± 7.4° (p<0.0001), base-apex and Dubois, respectively. Furthermore, Dubois method presented small range of variation without statistical or clinical difference by either calculation mode, while there was a wide variation in the base-apex method.

Conclusion: Dubois improved centralization of the Thoroughbreds' hearts, engendering what seems to be the real frontal plane. By either calculation mode, it was the most reliable methodology to obtain cardiac mean electrical axis in equines.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Disposition of electrodes by the Dubois method.
The illustration depicts the disposition of electrodes by the Dubois method.
Fig 2
Fig 2. Base-apex electrodes positioning.
The illustration depicts the disposition of electrodes by the base-apex method.
Fig 3
Fig 3. Graphic representation of the cardiac axis.
Cardiac axes measured in Thoroughbreds from ECGs acquired by Dubois and base-apex methods, by Tilley tables and trigonometric calculations, with range of variation expressed in degrees.
Fig 4
Fig 4. Disposition of electrodes by the Einthoven method.
The illustration depicts the disposition of electrodes by the Einthoven’s method.
Fig 5
Fig 5
Tracings with the three electrode positioning methods: Panel A. base-apex; Panel B. Dubois; and Panel C. Einthoven. Three ECG tracings illustrating the different amplitudes and directions of mean electrical axes obtained with the different electrode positioning methods.
See this image and copyright information in PMC

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