An analysis of electrocardiogram of alligator sinensis

Abstract 1. 1. ECG were recorded to determine the direction of atrial and ventricular depolarized waves and ventricular repolarized wave from Standard Limb Leads and Augmented Unipolar Limb Leads. 2. 2. Statistical analysis was made, using six crocodiles at a measuring temperature of 22–25°C, on the time values and amplitudes of the waves from Standard Lead II as well as time duration of cardiac cycles concerning the initial heart rates, the R-T/R-R values and electrical axis of the QRS complex. The upward part of R waves generally displayed a variable notch. R wave's time values and the direction of normal T wave differed from those reported concerning Alligator mississipiensis . 3. 3. With extended voluntary apnoea, the amplitude and direction of P and T waves would change, resulting in an inverted P wave and an upright T wave. With R-R time extended, the values of R-T/R-R decreased substantially. 4. 4. Along with the decrease of heart rates under voluntary dives, ECG T wave amplitude and direction changed, showing a relationship of T wave and breathing similar to that when the crocodiles were on land.