A similar pilot study has already been conducted in adults and is now being tried in children to gather preliminary data for a grant submission. No safety issues were found in the adult pilot study. This study will evaluate the effect of different doses of propanolol. The risks of this study involve the risks of three (3) blood draws and the risks of propanolol. In order to minimize the risks children with sickle cell disease and asthma will be excluded because asthma is a contraindication to the use of propanolol. In addition, patients will not be hypertensive or bradycardic.