Cardiovascular adaptations to transfusion/chelation therapy of homozygote sickle cell anemia

Cardiovascular function and dysfunction in sickle cell anemia

The 100th anniversary of the discovery of sickle cell anemia (SCA) as a distinct clinical entity by James B. Herrick in 1910 will soon be a reality. SCA continues to present opportunities for elemental observations of basic science and pathophysiologic clinical mechanisms-in particular, those associated with cardiopulmonary and circulatory disorders. Data indicate that cardiomegaly results from increased work caused by the anemia and that myocardial ischemia may result from the combined effects of severe anemia, microthrombi, and increased blood viscosity producing myocardial dysfunction, scarring, and elevated filling pressures. Sudden death has resulted from frank myocardial infarction and ischemia-induced rhythm disturbances. Myocardial injury may also be associated with bone marrow embolism. Mortality risk factors include systemic hypertension, pulmonary hypertension, and possibly subclinical electrical instability.

Evaluation of 107 patients with sickle cell anemia through tissue Doppler and myocardial performance index

BACKGROUND

Sickle-cell anemia (SCA) is associated with elevated cardiac output and cardiomegaly, as demonstrated in many studies. Recently, diastolic dysfunction and pulmonary hypertension have been shown to have poor prognoses in patients with SCA. New indexes of systolic and diastolic evaluation should be used to give more information on both the adult and the pediatric populations. The objectives of this study were to determine the systolic and diastolic function of both ventricles using load-independent parameters and to evaluate cardiac findings due to transfusion or chelation therapy in patients with SCA.

METHODS

We evaluated 107 patients with SCA, aged 3 to 18 years (mean age, 10.1 +/- 4.7 years). Physical exams, electrocardiography, and Doppler echocardiography were performed in all patients. These patients were compared with 70 normal children and adolescents.

RESULTS

Combined systolic and diastolic function of both ventricles was evaluated by the myocardial performance index (MPI). MPI values were higher both in the left ventricles (P = .00) and in the right ventricles (P = .00) of patients with SCA compared with controls. Diastolic function was evaluated by diastolic mitral valve flow and by tissue Doppler echocardiography. E-wave deceleration time was higher in patients than in controls. Patients were divided into 2 groups: group 1 consisted of 95 nontransfused patients and group 2 of 12 patients on chronic transfusion therapy. Group 1 patients demonstrated significantly larger left ventricular mass than those in group 2. Systolic and diastolic function did not differ between patients when an 8 g/dL cutoff value of hemoglobin was used.

CONCLUSION

This Doppler echocardiographic study showed that early abnormalities in systolic and diastolic function can occur at an early age in SCA, even among children and adolescents in New York Heart Association functional classes I and II.

Acquired coarctation of the aorta

Coarctation of the aorta is usually caused by a congenital narrowing of the aorta. This report describes two children who developed hypertension secondary to an acquired coarctation of the aorta. In one patient the coarctation was temporally related to umbilical artery catheterization and was associated with thrombosis and aneurysmal dilatation of the aorta. In the second patient, the coarctation occurred after surgical aortotomy during the removal of an intrathoracic neuroblastoma. Patients who have interventional damage to the aorta should be periodically examined for the appearance of a coarctation. Although an acquired coarctation of the aorta is an infrequent complication of invasive or surgical procedures, it should be identified since it represents a remediable cause of hypertension in children.

Cardiovascular effects of hypertransfusion therapy in children with sickle cell anemia

Thirteen children, age 1.9 to 14.8 years with documented sickle cell disease, underwent echocardiographic assessment of cardiac status while on and off periodic hypertransfusion therapy (HTX). Two to three units of washed packed red blood cells were transfused every 2-4 weeks in children with splenic sequestration crises, cerebrovascular accidents (CVA), aseptic necrosis of the femoral head, and miscellaneous complications of sickle cell disease to maintain hemoglobin (Hgb) concentrations of greater than or equal to 10 g/dl and % sickle hemoglobin (S Hgb) of less than or equal to 20%. This therapy administered over an average duration of 24 months resulted in normalization of left heart chamber enlargement and statistically significant decrease in heart rate, left ventricular mass, and cardiac output. Echocardiographically derived left ventricular function parameters remained normal on and off transfusion therapy. Changes in left ventricular diastolic dimension and cardiac output correlated with changes in % S Hgb (r = 0.59, p less than 0.001; and r = 0.54, p less than 0.001, respectively), and with changes in Hgb concentration (r = -0.78, r = -0.76, p less than 0.001). Expression of left heart abnormalities as a single composite function (Ydv), using multivariate regression analysis, allowed a comparison of cardiac status of 99 normal black controls, nontransfused sickle cell anemia (SCA) patients, and 13 study patients on and off HTX, and permitted serial assessment of cardiac status on and off treatment over 5 years in a single patient.(ABSTRACT TRUNCATED AT 250 WORDS)