By Ary L. Goldberger,
MD, FACC, Professor of Medicine, Harvard Medical School, Director,
Margret and H.A. Rey Institute for Nonlinear Dynamics in Physiology and
Medicine, Beth Israel Deaconess Medical Center, Boston, MA; Zachary D. Goldberger,
MD, MS, FACC, FHRS, Associate Professor of Medic..