1. From the Departments of Internal Medicine (Cardiovascular Section) (W.G.H., D.M.H., R.J.A., M.S.T.) and Radiology (W.G.H., C.A.H., K.M.L.), The Wake Forest University Baptist Medical Center, Winston-Salem, NC, and the Departments of Internal Medicine (Cardiovascular Division) (L.D.H., R.A.L., R.M.P.) and Radiology (G.D.C., J.P., R.M.P.), The University of Texas Southwestern Medical Center, Dallas.