[1] Univ Texas, SW Med Ctr, Echocardiog Labs, Div Cardiol, Dallas, TX 75216 USA
[2] Johns Hopkins Univ, Med Ctr, Baltimore, MD 21218 USA
[3] Deaconess Nashoba Hosp, Ayer, MA USA
[4] Thomas Jefferson Univ, Philadelphia, PA 19107 USA
[5] Tufts Univ New England Med Ctr, Boston, MA 02111 USA
[6] Cleveland Clin Fdn, Cleveland, OH 44195 USA
[7] Bowman Gray Med Ctr, Winston Salem, NC USA
[8] Oklahoma Cardiovasc & Hypotens Ctr, Oklahoma City, OK USA
[9] Vet Affairs Med Ctr, E Orange, NJ USA
[10] Orange Cty Heart Inst & Res Ctr, Orange, CA USA
[11] Univ Calif San Francisco, San Francisco, CA 94143 USA
[12] Washington Univ, Med Ctr, St Louis, MO USA
[13] Univ Massachusetts, Med Ctr, Worcester, MA USA
[14] NIH, Bethesda, MD 20892 USA
[15] Massachusetts Gen Hosp, Boston, MA 02114 USA
[16] Vanderbilt Univ, Nashville, TN USA
[17] Indiana Univ, Indianapolis, IN 46204 USA
[18] Res Hlth Inc, Houston, TX USA
[19] Univ Oregon, Hlth Sci Ctr, Portland, OR USA
[20] Univ Calif San Diego, San Diego, CA 92103 USA