الفهرس 
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Abstract
SUMMARY
C
ardiovascular complications are well recognized in patients with β-thalassemia major (β-TM) and sickle cell disease (SCD) due to iron overload. Techniques for assessing MIO and its response to chelation therapy are essential or the best management of hemoglobinopathies’ induced cardiovascular complications. Vitamin D deficiency is prevalent in patients with transfusion-dependent thalassemia and there is an association between vitamin D and left ventricular function and iron overload in thalassemia. However, the relationship between vitamin D and cardiac iron remains unclear and role of vitamin D in cardiac disease in SCD and β-TM needs to be assessed.
Therefore, this study assessed vitamin D status in children and adolescents with SCD and β-TM in relation to cardiac complications using echocardiography and cardiac magnetic resonance (CMR) T2*.
The study included 76 patients with chronic hemolytic anemia without symptomatic cardiac or pulmonary disease (41 patients with SCD and 35 patients with -TM); 43 males and 33 females recruited from the regular attendants of the Pediatric Hematology Clinic, Pediatric Hospital, Ain Shams University.. The mean age of SCD patients was 14.8 ± 2.7 years (range, 10-18 years) while patients with had a mean age 15.1 ± 2.9 years (range, 8-18 years).
All included patients were subjected to detailed medical history and thorough clinical examination with special emphasis on anthropometric measures, disease duration, evidence of renal, hepatic or cardiac disease, history of splenectomy, transfusion history and chelation therapy.
Laboratory investigations included; complete blood count (CBC), liver and kidney function tests as well as analysis of lactate dehydrogenase (LDH) and indirect bilirubin as markers of hemolysis. Serum ferritin level was measured at study with calculation of the mean value of the last year prior to the study in order to know the ferritin trend. Urinary albumin excretion (UAE) was assessed in an early morning fasting urine sample as albumin-to-creatinine ratio to detect micro- or macro-albuminuria. Vitamin D levels were assessed by Radio-immune assay. Liver iron concentration (LIC) was assessed by magnetic resonance imaging (MRI). Screening for pulmonary hypertension and cardiovascular abnormalities was performed by the non-invasive doppler echocardiograpghy and cardiac magnetic resonance (CMR) was used to assess cardiac T2* and myocardial iron concentration.
In this study, among the studied patients, cardiac disease was found in 6 SCD patients (14.6%) and 13 -TM patients (37.1%). The incidence of splenectomy and cardiac disease was significantly higher in -TM patients than those with SCD. Transfusion index was significantly higher in patients with -TM than those with SCD. The incidence of patients receiving combined chelation was significantly higher among patients with -TM compared with SCD group. WBC count was significantly higher in patients with SCD compared with -TM patients while the latter group had higher incidence of hemolysis as shown by higher indirect bilirubin and LDH. ALT was significantly higher while serum albumin was lower in -TM patients.
As regards echocardiographic parameters, systolic and diastolic cardiac functions were significantly impaired in -TM patients as shown by increased Tei index as well as decreased ejection fraction and fractional shortening. Cardiac T2* was significantly lower while myocardial iron concentration (MIC) was significantly higher in -TM patients compared with SCD group while serum ferritin and LIC showed no significant difference.
Vitamin D levels were decreased in both SCD and -TM patients than reference levels; however, SCD patients had significantly lower vitamin D levels than -TM group. Vitamin D levels were significantly higher among males while it was significantly decreased among those with pulmonary hypertension risk and nephropathy in the SCD group. In -TM group, vitamin D levels were significantly lower in patients with cardiac disease and those with serum ferritin levels ≥ 2500 µg/L. There was a significant evidence of diastolic dysfunction in SCD and -TM patients who had low serum vitamin D level < 20 ng/mL
There were significant negative correlations between vitamin D levels and each of ALT, serum creatinine, serum ferritin, LIC while vitamin D levels were positively correlated to cardiac T2* among -TM patients.
CONCLUSION
from this study, we may conclude that:
Systolic and diastolic cardiac functions were significantly impaired in pediatric patients with β-TM compared with SCD which is linked to high myocardial iron concentration in those patients.
Vitamin D deficiency is prevalent in both β-TM and SCD.
Low vitamin D levels were associated with cardiac dysfunction in children and adolescents with SCD and β-TM.
Vitamin D deficiency in those patients was linked to cardiac iron overload leading to iron induced cardiomyopathy. Vitamin D deficiency in those patients was linked to cardiac iron overload leading to iron induced cardiomyopathy.
RECOMMENDATIONS
Therefore, we may recommend the following:
Supplementation of vitamin D should be considered for thalassemia and SCD patients, particularly for those with vitamin D deficiency.
Proper chelation and good compliance are mandatory to improve cardiac disease, iron overload and consequently, vitamin D status in β-TM patients.
Use of cardiac magnetic resonance imaging to guide chelation therapy in patients with transfusion-dependent hemoglobinopathies.