Use of selective vasodilation in treatment of sickle cell disease

Individuals with sickle cell disease and its genetic variants demonstrate a modest to severe hemolytic anemia. They are also prone to both acute and chronic vaso- occlusive phenomena, which may lead to irreversible tissue damage, organ failure, and premature death. To better understand these vaso-occlusive phenomena, it would be useful to determine the extent to which arteriolar mi- crovascular obstruction might contribute to the pathogenesis of sickle cell disease. We studied the hematologic and ocular effects of orally administered nifedipine in several steady-state patients and compared these with a case- control group of patients not receiving nifedipine. In the nifedipine-treated patients, a striking reversal in ischemic retinal and conjunctival changes was observed, as well as a significant improvement in color vision performance. In addition, the treated subjects showed a slight but significant decline in the levels of both indirect serum bilirubin and plasma hemoglobin, suggesting a concurrent amelioration in the rate of hemolysis. These observations are consistent with the hypothesis that inappropriate vasoconstriction, or frank vasospasm, perhaps in response to the altered rheology of red cells containing polymerized hemoglobin S, may play an important role in the pathophysiology of sickle cell disease. Furthermore, selective vasodilation may prove to be a useful adjunctive approach to the treatment of the manifestations of the sickle syndromes.