This paper describes a solution for mobile heart monitoring. In part of hardware the authors focused on engineering problems of increasing the number of ECG leads and increasing the sampling rate. It potentially allows to increase the effectiveness and accuracy of localization and to decrease the influence of pacemaker pulses on the ECG signal recording respectively. Implementation of hardware and software parts is described. The method and software tool for wavelet-based analysis of ECG signals are proposed for arrhythmia detection task. Experimental results show that proposed wavelet-based method of ECG analysis can detect signs of arrhythmia. Results of wireless channel speed test confirm that the chosen hardware meets the requirements of wireless protocol bandwidth. Proposed solutions are suitable for portable heart monitoring systems.