Simultaneous recording of ECGs from disease-free rats, using a cathode ray oscilloscope and a direct writing instrument.

Abstract

Simultaneous recording of electrocardiograms of rats, using a direct‐writing heatstylus electrocardiograph and a cathode ray oscilloscope, demonstrates that reliable records can be obtained with the former instrument. The response characteristics of the direct‐writing machine were shown to be very favourable for an instrument of its kind, the recorder output being 3 db down at 175 c/s; thereafter, there is a slow fall off so that even at 200 c/s a 50 per cent response was given.Using the direct‐writing machine, a strain difference in the ECG pattern has been found. This can be explained in terms of anatomical differences which in man are known to influence ECG patterns.The comparison between the two instruments was made on animals free of chronic murine pneumonia and other common laboratory diseases. Subsequently, when animals from a diseased colony were examined, abnormalities were found in the form of a recurring tremor. It may be concluded that the rat is quite suitable for experimental ECG studies, and that direct‐writing instruments are available having the characteristics necessary for reliable recording of rat ECGs, due consideration being given to the information normally supplied by an electrocardiogram.