1. From Department of Cardiothoracic Surgery (F.A.T., F.R., F.L., G.T.D., N.B.I., D.C.M.), Division of Cardiovascular Medicine (D.L.), Stanford University School of Medicine, Stanford, Calif; and Laboratory of Cardiovascular Physiology and Biophysics (G.T.D., N.B.I.), Research Institute of the Palo Alto Medical Foundation, Palo Alto, Calif.