M.M. Galagudza - Doctor of Science (Medicine), head of Institute of Experimental Medicine (Almazov Federal Heart, Blood and Endocrinology Centre). E-mail: galagoudza@mail.ru
K.V. Zaichenko - Doctor of Science (Technology), professor, head of the department of medical radioelectronics of St. Petersburg State University of aerospace instrumentation. E-mail: kvz_41@aanet.ru

The potential for refinement of ECG-diagnostics of ischemia, including early verification of ischemic heart disease and determination of the stage of the ischemic injury, was investigated in the present study. The characterization of the ECG signal parameters at the different stages of the experiment was performed using the technique of ultrahigh resolution electrocardiography (UHR-ECG). This technique enables to register both low-magnitude and high-frequency (HF) components of the electrogram (EG). Myocardial ischemia was elicited in the anesthetized male Wistar rats retaining systemic neurohumoral influences on the heart by means of left coronary artery ligation. Experiments were performed using mechanical lung ventilation and microsurgical technique. For verification of the reproducibility of ischemia, both anatomical area at risk and infarct size were determined after the end of the experiment. During the experiments, the ECG was registered by the prototype computer-assisted electrocardiograph - SVR-2K - for UR-ECG and control electrocardiograph - Cardiotechnika-8?. The electrocardiogram was registered in low- (LF) and high-frequency (HF) channels of - SVR-2K - during the entire period of myocardial ischemia-reperfusion injury. We assessed both quantitative and qualitative characteristics of the ECG in order to identify the parameters of ECG (or ECG-markers) which are most closely correlated with the early phases of ischemia, and also for confirmation of the presence of predictive and informative signs of schemia in the HF and LF areas of the ECG spectrum. A comparison of ECG and spectral characteristics of ECG obtained prior to left coronary artery ligation (normal state) was done with the postischemic values. The analysis of the components of ECG spectrum in the HF channel has revealed significant changes during ischemia. The spectral power of the HF components of ECG has been significantly attenuated starting from the beginning of ischemia. It should be noted that on the first minute after coronary artery ligation the LF channels of both electrocardiographs failed to detect any visible changes of the signals as compared with baseline while the analysis of the spectral composition of the HF components according to the technique of the UR-ECG has revealed the substantial decrease in the spectral power of the HF-components of ECG. The described changes in the spectral characteristics of ECG were reproducible among all animals of the experimental group. In conclusion, the application of the UHR-ECG with subsequent spectral analysis in the HF-channel gives the opportunity for decisive verification of the signs of myocardial ischemia already after 60 seconds after coronary artery ligation in the experimental settings.

 

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