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

Area of Science:

• Veterinary Cardiology
• Herpetology
• Comparative Physiology

Background:

• Electrocardiography (ECG) is crucial for assessing cardiac function across species.
• Understanding reptilian cardiac physiology, particularly ECG characteristics, is less established than in mammals.
• Red-eared sliders (Trachemys scripta elegans) are common models for reptilian research.

Purpose of the Study:

• To characterize the electrocardiographic (ECG) values in red-eared sliders (Trachemys scripta elegans).
• To compare ECG patterns between red-eared sliders and other reptilian and mammalian species.
• To investigate the relationship between heart rate and ECG intervals, specifically repolarization phases.

Main Methods:

• Nine red-eared sliders were anesthetized using ketamine, ketamine/xylazine, or ketamine/midazolam.
• Lead II ECG traces were recorded using three cutaneous electrodes.
• Analysis focused on ECG complex morphology, QT intervals, ST intervals, and TP intervals.

Main Results:

• ECG complexes showed small upright P waves, larger R waves, no Q or S deflections, very long QT intervals, small upright T waves, and a short TP interval.
• Reptilian ECG patterns differed from mammalian ECGs, characterized by lower amplitude waveforms, a much longer repolarization phase (longer ST and QT intervals), and a considerably shorter TP interval.
• A significant negative correlation was found between heart rate and QT/ST intervals; lower heart rates were associated with longer repolarization periods.

Conclusions:

• The study established characteristic ECG parameters for red-eared sliders, highlighting distinct reptilian cardiac repolarization.
• These findings underscore significant physiological differences in cardiac repolarization between reptiles and mammals.
• The correlation between heart rate and repolarization intervals provides insights into cardiac regulation in this species.