Is the Normal Heart Rate Chaotic?

In its issue of June 2009, Chaos has published a special section containing nine papers that address the question "Is the normal heart rate chaotic?". The discussion was initiated last year as a joint effort of Chaos and PhysioNet, which provided a collection of fifteen 20-24 hour RR interval time series derived from three PhysioBank ECG databases as a common focus for investigation of this question.