[1] Brigham & Womens Hosp, Div Cardiovasc, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Kagawa Univ, Dept Cardiovasc Physiol, Kagawa, Japan
[4] Stanford Univ, Sch Med, Div Cardiovasc Med, Falk Cardiovasc Res Ctr, Stanford, CA 94305 USA
[5] Vet Affairs Boston Healthcare Syst, Boston, MA 02115 USA