1. From the Metropolitan Heart and Vascular Institute, Minneapolis, MN (D.F.), and the Division of Cardiovascular Diseases (D.F., K.K., M.M., I.S.S., R.E.E., J.K.O.), Department of Radiology (J.G., P.A., J.B.), and Department of Cardiothoracic Surgery (T.S., H.V.S.), Mayo Clinic, Rochester, MN.