1. From the Division of Interventional Radiology (D.Y.S., M.A.A.J.B., M.D.D., L.V.H.), Department of Cardiothoracic Surgery (M.D.D., D.C.M., R.V., S.C.M., R.S.M.), Department of Anesthesia (P.J.A.S.), and Department of Biostatistics (J.R.), Stanford University Medical Center, Stanford, Calif.