A new bipolar precordial electrocardiographic lead configuration for specific evaluation of atrial depolarization in healthy dogs.

The Lewis lead is an EGC configuration used to detect atrial activity and its relationship with ventricular activity. However, no equivalent configuration has been proposed in veterinary medicine. Therefore, this study explored new bipolar lead configurations to evaluate atrial depolarization and investigated their characteristics by comparing them with conventional leads. The authors hypothesized that a lead with a high absolute value of the P wave (|P|) and a high ratio of the P wave to the QRS complex (|P|/|QRS|) might be an appropriate configuration. 6 laboratory Beagles were used. Electrocardiograms were recorded using bipolar limb leads (I, II, III, aVL, aVF, and aVR) and unipolar precordial leads (C2, C3, C4, C5, C6, M1, M2, M5, M6, 1st-R, CV6LL, and V10) in the standing position. The new bipolar leads were attached in the following configuration: the negative electrode was attached to M6, and the positive electrode was sequentially applied to M1 and M2. The leads were named M6M1 and M6M2. The waveforms obtained using the new bipolar leads M6M1 and M6M2 showed significantly higher |P|/|QRS| and |P| values than those obtained using conventional limb leads and precordial leads. The new leads achieved a specific enhancement of atrial activity conducted at a reduced ventricular amplitude and increased atrial amplitude, similar to the Lewis lead in human medicine. These findings suggest that M6M1 and M6M2 could be supplemental lead configurations to identify P waves without amplifying the QRS waves compared to conventional methods.