Electrocardiography of southern elephant seal (Mirounga leonina) weanlings

The mean values for amplitude and duration of electrocardiogram intervals, cardiac rhythm, and mean frontal plane QRS-axis were measured in 18 free-living weanling southern elephant seals (Mirounga leonina) anesthetized with tiletamine-zolazepam. Animals were 30-50 days old and had been weaned about 3 wk earlier. All animals had a normal sinus rhythm. The mean P-wave duration per animal had a range of 0.06-0.09 sec, and mean PR interval and QT interval ranges were 0.08-0.12 sec and 0.25-0.26 sec, respectively. The amplitude of the R wave was 0.22 mV in a VR and 0.5 mV in DI. The electrical axis was between -60 degrees and +30 degrees in 13 of the weanlings. Electrocardiograms were also obtained from five anesthetized juveniles and one adult female. The electrical axis of juveniles was between 0 and 120 degrees, whereas the QRS vector for the adult female had an orientation of -150 degrees. This report is the first detailed description of the southern elephant seal electrocardiogram.