Electrocardiography in anaesthetised red-eared sliders (Trachemys scripta elegans).

Electrocardiographic (ECG) values were measured in nine red-eared sliders (Trachemys scripta elegans), anaesthetised with either ketamine, ketamine/xylazine or ketamine/midazolam, for the purpose of cardiocentesis. Lead II traces were then recorded through three cutaneous electrodes. The ECG complexes consisted of small upright P waves, larger R waves and no Q or S wave deflections, very long QT intervals, small upright T waves, and a short TP interval. No SV waves were recorded. This pattern was similar to the ECGs reported in other reptilian species, and differs from mammalian ECGs in having lower amplitude waveforms, a much longer repolarisation phase (longer ST and QT intervals), and a considerably shorter TP interval. A significant correlation was found between the heart rate and the QT and ST intervals, a lower heart rate being associated with a longer period of repolarisation without significantly prolonging the depolarisation (P, PR and QRS) intervals.