The invention is related to a device and method for cordless recording, telecommunication transmission, and processing of three special ECG leads by the means of the mobile device (1) and diagnostic-calibration center (2) where the reconstruction of standard ECG leads is performed. Reconstruction parameters are determined previously by calibration for each patient. In urgent situation, a patient (3) performs recording of three special ECG leads with the mobile device (1), and sends the memorized data to the diagnostic-calibration device (2) via a cellular telephone (4). The patient can trace the process of recording and sending the data with the help of sound and light indicators. Diagnostic-calibration center (2) is equipped with a PC computer (6) connected to a receiving cellular telephone (7) and calibration ECG device (8) with 14 electrodes. Ten electrodes are grouped into a standard 12-channel ECG cable, while the remaining four are used for recording of three special ECG leads and are grouped into a separate box (9) with integrated electrodes arranged identically as the integrated electrodes on the mobile device (1).