Abstract
We studied serial electrocardiographic changes in murine myocarditis due to encephalomyocarditis (EMC) virus. After taking control electrocardiograms using standard extremity and 2 precordial leads, 86 mice were intraperitoneally inoculated with a 0.1 ml of the M variant of EMC virus suspension containing 100 TCID50. Electrocardiograms were recorded everyday from the 2nd to the 14th day, and thereafter once every 3-5 days until the 35th day. The cumulative incidence of myocarditis was 90% (77 out of 86). The control electrocardiogram showed a heart rate of 528 ± 87 beats/min (mean ± SD) and PR intervals of 0.03-0.05 sec, and significant rhythm or conduction disturbances were not found. Various electrocardiographic abnormalities, such as atrial (10%) and ventricular (21%) premature contractions, were noticed on the 4th to the 14th day. After 15-35 days arrhythmias still remained in 3 mice. The presence of arrhythmias in the chronic stage of myocarditis suggests that arrhythmias in some patients with no other clinical manifestations may be a sequela of the previous viral myocarditis. Thus, this study may contribute clinically to the clarification of the electrocardiographic characteristics in viral myocarditis.
