摘要: <正> Freqency-domain Correlative cardiogram （FCG） is a new method in diagnosing coronary heart diseases. There were few experimental data about its reliability. In order to evaluate the sensitivity and specificity of FCG and offer experimental evidences for diagnosing at the early stage of coronary heart diseases, changes of FCG were observed after acute ischemia caused by ligating left circumflex coronary arteries in animals. Action potentials （AP） of ventricular myocardial cells were recorded in situ with floating microelectrodes placed on the surfaces of the heart according to Woodbury. The ECG and the FCG were recorded with an HBD-II Multi-domain Cardiac Signals Automatic Diagnostic Instrument which synchronously samples routine ECG V5 （X channel） and II （Y channel） for a continous 125 seconds. After 10 minutes occlusion, the action potential amplitude （APA） and the O phase upstroke rate （Vmax） were slowed down; APD₃₀ and APD₅₀ were significantly shortened. The ST segment and the T wave of the ECG were elevated. The main changes in the FCG were that the first peaks of the power spectrum function （Gxx, Gyy） were significantly increased in amplitude, the R waves in the autocorrelation function （Vxx, Vyy） and the cross correlation function （Vxy） were increased in amplitude, that the small waves between the R waves disappeared and that the declines of the R waves amplitude were not evident. The AP, the ECG and the FCG returned nearly to normal after 10 minutes reperfusion. The changes of the FCG after ligation of dog left circumflex coronary arteries were similar to those recorded from rabbits. These results suggest that the FCG is sensitive to the changes of myocardial electrical activities in the early stage of coronary artery occlusion.