The cardiac function of dogs experimentally infected with Trypanosoma brucei infection was studied electrocardiographically. Ten mongrel dogs clinically free of cardiac abnormalities were used for the study. They were intra-peritoneally inoculated with 1 ml of Phosphate buffered saline diluted blood containing 1x106 of the federe strain of the parasite. A six lead electrocardiogram was taken in each of the dogs before and at 8th 16th and 24th days after inoculation of the parasites. Ventricular premature contraction, Atrio-ventricular blocks, polymorphic ventricular tachycardia, notched R wave, ST wave abnormalities and sinoventricular rhythm were displayed by the infected dogs. The infected dogs had elevated heart rate in all the six leads studied. At various times during the infection, QT and QTC of the infected dogs were significantly lower than the uninfected ones in leads II and AVF. At various days during the infection the QRS index was significantly wider than those of the uninfected dogs. T. brucei infected dogs have a lower variability of their RR index when compared to the uninfected ones. The R wave voltage was significantly reduced and T wave amplitude was significantly increased by the infection in lead AVL and lead I respectively. The result of this study has shown that T. brucei caused arrhythmia and ECG changes in dogs. The increased heart rate, reduced RR variability, and the shortened QT and QTC width seen during the infection reflects the enhanced state of the sympathetic activity in the infected dogs.
Key words: ECG, T. brucei, dogs, arrhythmia