Only recently has it been appreciated that children with homozygous sickle cell anemia (SS) may have a clinically occult elevation of the tricuspid regurgitant jet velocity (TRJV). 1 The case presented in this report demonstrates not only occult elevation of TRJV but that symptomatic SS-associated pulmonary hypertension may occur during childhood, masquerading as acute chest syndrome, and can be difficult to treat.
CASE REPORTA boy was diagnosed with SS on newborn screening. By 5 years of age, he had 6 hospital admissions for presumptive reactive airway disease and 3 for acute chest syndrome. At 6 years of age, his pulmonary function tests revealed mild restrictive disease (forced vital capacity, 76% predicted) with early obstructive impairment (forced expiratory flow, 25% to 75%, 43% predicted) and responsiveness to a bronchodilator. Room air pulse oximetry was 99%. Therapy for reactive airway disease was prescribed.The child had a presumed fourth episode of acute chest syndrome at 7 years of age. At 7½ years, he presented with fatigue, tachypnea, chest pain, retractions, wheezing, hepatomegaly (4 cm), and pulse oximetry of 71% to 79%. Hemoglobin and reticulocyte counts were baseline: 6.9 g/dL and 39 %, respectively. Chest radiography revealed severe cardiomegaly and biventricular hypertrophy on the ECG. An echocardiogram showed mild biatrial, biventricular, and pulmonary artery dilation with a TRJV of 3.4 m/s and estimated right ventricular systolic pressure of 50 mm Hg on room air, reducing to 45 mm Hg with oxygen. Oxygen, red cell transfusion, furosemide, bronchodilators, and nasal steroids were administered and at discharge, he was receiving 0.75 L oxygen continuously to maintain pulse oximetry >90%. Subsequent TRJVs, hemoglobin, reticulocyte counts, and treatment are shown in the Figure. Two weeks after presentation, the TRJV remained elevated and pulmonary function tests showed forced vital capacity and forced expiratory flow 25% to 75%, both 58% predicted, without response to albuterol. An evaluation to exclude thrombophilia revealed a normal protein C activity, free protein S, antithrombin III, vonWillebrand antigen and activity, and negative D-dimer. Prothrombin G20210A and Factor V Leiden mutations and antiphospholipid antibodies were absent. L-Arginine was prescribed at 4.5 g/d (0.18 g/kg per day) delivered as Arginaid (Novartis Oncology; East Hanover, NJ), and oxygen was continued. Four and one-half months from presentation, the TRJV remained elevated and a transcranial Doppler ultrasound showed a mean flow of 178 m/s in the left middle cerebral artery. Therapy was commenced with monthly minor antigen-matched, red cell transfusions; hydroxyurea therapy was refused by the family.One month after his first transfusion, the room air pulse oximetry was 91% and our patient was as active as his classmates, so only nocturnal oxygen was continued. The adenoids were removed for obstructive sleep apnea diagnosed by sleep study. The abdominal ultrasound showed a few gallstones, but, because he was asymptomatic,...