1. From the Divisions of Cardiology and Cardiothoracic Surgery (N.M.R., D.A.F., R.O.B.), Northwestern University Feinberg School of Medicine, and Institute for Bioengineering and Nanoscience in Advanced Medicine (S.R.S.), Northwestern University, Chicago, Ill, and Department of Molecular Biology and Biochemistry (M.S., D.R., T.S.), Department of Cardiology and Cardiothoracic Surgery (J.D., T.O., A.J.T.), and Electron Microscopy Laboratory (M.S.), Mayo Clinic, Rochester, Minn.