Résumé
There is no consensus about the exact nature of the pulmonary dysfunction in children with thalassemia major [TM]. Pulmonary vascular involvement by microthrombosis was suggested as a cause of pulmonary hypertension and/or abnormal pulmonary function test [PFT]. The aim of this work was to, [1] determine the predominant abnormality of PFT in children with TM, [2] detect the potential pulmonary hypertension [PH] and/or other forms of cardiac dysfunction, and [3] investigate whether exercise tolerance would be predominantly affected by cardiac, and or pulmonary abnormalities.Twenty five children with TM aged 8-15 year were investigated by echocardiography, lung function, carbon monoxide diffusion and coefficient by single breath method [DLcoSB], and exercise testing a few days after transfusions. All have had regular transfusions and chelation with deferoxamine and none had chronic pulmonary disease symptoms. Twelve healthy children underwent the same investigations as control group. The results proved that three TM children [12%] had severe restrictive lung disease, 9 [36%] had moderate restrictive and 3 [12%] had mild restrictive abnormality during lung function. DLcoSB was below cent predicted value in 48% of TM children, 91.6% of them had restrictive lung function. DLcoSB was normal in control group. Echocardiographic abnormalities were left ventricular dysfunction [LVD] in 11 TM children, 4 of them had PH. Two of the patient with PH had right ventricular dysfunction [RVD]. Significant decrease in exercise capacity was seen in all children with TM but none of the control group. Severe exercise impairment due to ventilatory limitation was observed in 4 [16%], moderately severe exercise impairment due to cardiac limitation was observed in 13 TM children [56%], and 7 TM children [28%] had mild exercise impairment due to cardiac limitation. 14 TM children [54%] had mild to moderate cardiac limitation to exercise without echocardiographic abnormalities
Conclusion: Restrictive lung disease is the predominant abnormality of PF in children with TM. LVD, and PH are common finding in children with TM. Moderate to severe exercise impairment due to abnormal cardiac response was the most frequent observation in TM children with or without echocardiographic abnormalities, while ventilatory limitation to exercise was less frequent. The early detection of cardiac abnormalities and lung limitation may have important therapeutic and prognostic implications in children with TM. Further studies would be warranted to establish the long term reproducibility of indices derived from exercise testing as tool to detect early cardiac dysfunction in the course of this disease in children