Fully-Integrated Heart Rate Variability Monitoring System with an Efficient Memory

Heart rate variability is a strong indicator of a number of medical conditions. Current HRV systems typically determine R-R intervals from pre-recorded ECG signals, which include a large amount of redundant data. In this paper we describe a more efficient HRV monitoring and assessment system on chip. By applying digital techniques to store the difference between every two adjacent R-R intervals in a single-port synchronous, high-performance SRAM, up to 24 hours of continuous ECG data can be stored on chip with a fixed resolution of 1 ms. The system has been tested for functionality, synthesized and laid out in a commercial 0.18mum CMOS process in a 2.5times2.5 mm² hardware core with less than 155muW power consumption. Such a system can enable HRV monitoring with home based health care and implantable devices