Design and architecture of a multiple patients wireless ECG monitoring system is proposed, which is based on wireless link through network and emerging standards for low rate personal area networks (LR-WPANS) such as IEEE 802.15.4 and zigbee. The system includes an ECG signal acquisition board (110) transmitting the signals to a sensor module with wireless transmitter, that is worn by a patient. A wireless multi-patient receiver is remotely located and connected to a computer for access of the data, analysis and display. Also proposed is a reliable, scalable and energy aware multi-tree routing (EAMTR) for increasing the network lifetime and performance in the LR-WPANS. A light-weight algorithm for ECG feature extraction and automatic cardiac arrhythmia detection with alarm system is proposed.