Demographic transition and the decreasing number of medical experts in rural areas create a growing demand for tele-medicine systems that allow remote patient monitoring. Especially in the context of heart diseases, the possibility to transmit electrocardiograph (ECG) data in a streaming mode is of high interest. However, available cellular networks with protocols like GPRS, EDGE or UMTS are highly unreliable due to frequent connection interruptions and high bandwidth variations for data traffic. In this paper, we present a system suitable for live ECG-streaming over UMTS. We describe a usability experiment of the system within the context of the Berlin-Marathon, a huge event with 40.000 participants - 5 of them carrying devices with our software for live ECG streaming. The systems successfully demonstrated the use of near-field Bluetooth communication between electronic health care devices and a home broker in conjunction with mobile communication via UMTS. The forthcoming Fontane system builds upon experiences collected with the current prototype. We present these experiences and discusses some of the challenges of live streaming of medical data across unreliable heterogeneous networks.