Cardiac abnormalities in children with sickle cell anemia

Sickle cell anemia (SCA) results in chronic volume overload of the heart due to hemodilution. Previous echocardiographic studies of cardiac function in children with SCA have not accounted for these abnormal loading conditions. The objectives of this study were to (1) determine how the degree of anemia and transfusion status relate to cardiac findings and (2) evaluate cardiac function using load-independent parameters of function. We evaluated 77 patients with SCA, ages 2 to 22 years (mean +/- SD = 11.7 +/- 4.7), using physical examination, electrocardiography, and echocardiography. We compared two groups of patients. Group 1 consisted of 57 non-transfused patients, and Group 2 consisted of 20 patients on a chronic transfusion protocol. Group 1 patients exhibited a significantly lower hemoglobin, higher cardiac output, and larger left ventricular (LV) end-diastolic dimension and LV mass than groups 2 (P < 0.05). However, the velocity of circumferential fiber shortening-wall stress index (a load-independent measure of systolic function) was normal and not statistically different between the two groups. Conversely, the LV myocardial performance index (a measure of combined systolic and diastolic function) was significantly higher in Group 2 (P < 0.001), possibly indicating impaired myocardial diastolic function. SCA in children results in a volume-overloaded heart with a significant increase in LV dimensions and mass, both proportional to the degree of anemia. Despite these abnormal loading conditions, systolic function is preserved. Patients on a chronic transfusion protocol may develop diastolic dysfunction despite iron chelation therapy.