Adult patients with hypertension not controlled by medical therapy (hypertension defined as systolic blood pressure greater than 150 millimeters of mercury or diastolic pressure greater than 90 millimeters of mercury despite optimal medical management). Pediatric patients must have BP WNL for age. NOTE: blood pressure within the upper limit of normal is defined as: blood pressure less than or equal to the 95th percentile for age, height, and gender, and measured, and not be receiving medication for treatment of hypertension.