Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Abstract
Electrocardiograms (ECGs) are infrequently performed on captive elephants, and few large-scale studies have been reported in the literature. Obtaining ECGs from elephants is challenging due to their size, thick skin, and tendency to be in constant motion. Commonly encountered problems include inadequate leads, insufficient cable length, and poor signal conduction. Novel clamps were designed and used in this study. Quick-Grip® Handi-Clamp™ 2” Curved Bar Clamps (Irwin Industrial Tool Company, DeWitt, NE) were modified by replacing one end of the clamps with a copper plate, which was connected to a conducting wire and 1/8-inch mono in-line jack. Long ECG cables (71 cm) were used.
ECGs were performed on a total of 19 Asian elephants (Elephas maximus); tracings from 10 elephants were obtained with a PageWriter Trim II (Philips Medical Systems, Bothell, WA), and nine were obtained using a MAC 1200 (G.E. Healthcare, Waukesha, WI). A six-lead system was used. Four clamps were placed on the elephant: one in each inguinal skin fold, and one over each triceps. Alcohol was applied to the electrodes to maximize conduction of the signal. Readings were obtained with the elephants standing as well as in right lateral (RL) and/or left lateral (LL) recumbency. Continuous tracings were obtained with the paper speed at 25 mm/sec, waves amplified to 20 mm/mV, and filters set at the maximum values. Generally, the best tracings were obtained from Lead I with the elephant standing or in RL recumbency. A partial summary of the data is provided in Tables 1 and 2.
Table 1. Duration of elephant ECG waves and intervals in seconds. Ranges given with mean values±SD in parentheses; n=number of animals
|
Position
|
P range
|
P-R range
|
QRS range
|
T range
|
Q-T range
|
U range
|
|
Standing
n=9
|
0.08–0.28
(0.18±0.06)
|
0.28–0.54
(0.38±0.07)
|
0.09–0.20
(0.17±0.03)
|
0.20–0.39
(0.27±0.05)
|
0.56–0.86
(0.70±0.09)
|
0.24–0.36
(0.30±0.04)
|
|
RL recumbency
n=5
|
0.07–0.16
(0.11±0.03)
|
0.29–0.42
(0.35±0.05)
|
0.09–0.22
(0.17±0.04)
|
0.15–0.32
(0.23±0.06)
|
0.54–0.76
(0.62±0.08)
|
0.10–0.33
(0.20±0.06)
|
|
LL recumbency
n=7
|
0.10–0.26
(0.16±0.05)
|
0.26–0.44
(0.33±0.06)
|
0.11–0.24
(0.17±0.04)
|
0.19–0.42
(0.25±0.06)
|
0.56–0.84
(0.68±0.10)
|
0.18–0.32
(0.26±0.05)
|
Table 2. Amplitude of elephant ECG waves in millivolts. Ranges given with mean values±SD in parentheses; n=number of animals
|
Position
|
Heart rate
|
P range
|
QRS range
|
T range
|
U range
|
|
Standing
n=9
|
26–44
(38±6)
|
0.08–0.24
(0.13±0.04)
|
0.67–1.27
(0.94±0.18)
|
0.06–0.27
(0.16±0.06)
|
0.10–0.19
(0.13±0.04)
|
|
RL recumbency
n=5
|
34–41
(38±3)
|
0.04–0.16
(0.10±0.04)
|
0.69–1.25
(0.95±0.19)
|
0.08–0.2
(0.12±0.04)
|
0.05–0.2
(0.08±0.05)
|
|
LL recumbency
n=7
|
33–59
(44±8)
|
0.04–0.25
(0.11±0.05)
|
0.32–1.16
(0.78±0.26)
|
0.08–0.18
(0.13±0.03)
|
0.1–0.16
(0.14±0.02)
|