da Costa Cássia Fré, Samesima Nelson, Pastore Carlos Alberto
Clinical Unit of Electrocardiography, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
PLoS One. 2017 Jan 17;12(1):e0169619. doi: 10.1371/journal.pone.0169619. eCollection 2017.
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.
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.
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.
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.
自上世纪初首次报道马的心电图记录以来，人们采用了不同的马心电图采集方法。本研究旨在确定马心电图电极的最佳定位方法以及平均心电轴（MEA）最可靠的计算方法。
我们评估了53匹临床健康的纯种马的心电图特征，其中38匹雄性，15匹雌性，年龄在2至7岁之间，均饲养在巴西圣保罗赛马俱乐部。每只动物记录两份心电图，一份使用杜波依斯导联定位系统，另一份使用基顶法。分析QRS波群振幅，使用两种计算方法，即第一种通过蒂利表，第二种通过三角计算，以获得上述两种电极定位方法在额面的MEA值。对两种方法的结果进行比较。
心电轴值存在显著差异：通过蒂利表获得的MEA，基顶法为+135.1°±90.9°，杜波依斯法为-81.1°±3.6°（p<0.0001）；通过三角计算获得的MEA，基顶法为-15.0°±11.3°，杜波依斯法为-79.9°±7.4°（p<0.0001）。此外，杜波依斯法在两种计算模式下的变化范围较小，无统计学或临床差异，而基顶法的变化范围较大。
杜波依斯法改善了纯种马心脏的集中程度，形成了似乎是真正的额面。无论采用哪种计算模式，它都是获得马心脏平均电轴最可靠的方法。
