Abstract: A patient monitoring system which includes a portable device and a central station. The portable device includes an ECG and a photo-plethysmograph connected to the patient; arrhythmia analysis apparatus; an expert system for determining if a pre-established critical parameter set has been exceeded; and a wireless wide area communication device for automatically contacting the central station via a public cellular phone network when the critical parameter set has been exceeded. When the central station is contacted, the patient's ECG waveforms, measurements, and trends, are sent to the central monitoring station and a two way voice channel between the patient and the central station is automatically opened.