This book not only discusses clinical applications, but also links HRV to systems biology and theories of complexity.   This publication should be interesting for several groups of clinicians and scientists, including cardiologists, anesthesiologists, intensivists and physiologists. Heart Rate Variability is in principle easy and cheap, making it interesting for all kind of hospitals and private practice. The book will be an example of using translational medicine (bench to bedside) where newest theoretical results are linked to newest clinical research.