[1] NHLBI, Sickle Cell Vasc Dis Sect, NIH, Bethesda, MD 20892 USA
[2] Childrens Natl Med Ctr, Dept Cardiol, Washington, DC 20010 USA
[3] Univ Michigan, Med Ctr, Ann Arbor, MI USA
[4] NHLBI, Pulm & Vasc Med Branch, Bethesda, MD 20892 USA
[5] Howard Univ, Ctr Sickle Cell Dis, Washington, DC 20059 USA
[6] Johns Hopkins Univ, NHLBI, Bethesda, MD USA
[7] Univ Pittsburgh, Vasc Med Inst Pulm, Pittsburgh, PA USA
[8] Howard Univ, Ctr Sickle Cell Dis, Potomac, MD USA