Electric currents applied during the refractory period can modulate cardiac contractility in vitro and in vivo.

Daniel Burkhoff MD PhD , Itzik Shemer , Bella Felzen , Juichiro Shimizu , Yuval Mika , Marc Dickstein , David Prutchi , Nissim Darvish 3 and Shlomo A. Ben-Haim 2,5 Divisions of Circulatory Physiology and Cardiology, Cardiac Physiology Laboratory, Department of Medicine, Columbia University, N.Y., Impulse Dynamics, Tirat HaCarmel 39120, Israel, Department of Physiology and Biophysics, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, P.O.B. 9649, Haifa 31096, Israel, Department of Anesthesiology, Columbia University, N.Y., Harvard-Thorndike Arrhythmia Institute, Beth-Israel Hospital, 330 Brookline Ave, Boston, Massachusetts 02215, USA