Pulmonary hypertension is defined in children  as a mean pulmonary arterial pressure greater than 25 mmHg at rest or 30 mmHg during physical activity , with increased pulmonary artery capillary wedge pressure and an increased pulmonary vascular resistance greater than 3 Woods units × M2. it is the main cause of morbidity and mortality in the group of thalassemia , if no treatment leads to right ventricular  heart failure and death . The development of pulmonary artery hypertension( PAH) is assumed to be the result of many multifactorial pathogenic mechanisms  including chronic hemolysis, iron overload , hypercoagulability , and erythrocyte dysfunction as a result of splenectomy , inflammation  and nitric oxide depletion . PAH symptoms are non-specific , their signs consist of right ventricular lift , an accentuated pulmonary component of the second heart sound, a (gallop rhythm) right ventricular third heart sound, and parasternal heave meaning a hypertrophied right ventricle. The diagnosis of PAH requires a clinical suspicion based on symptoms and physical examination .Echocardiography is frequently used to screen for PAH, monitor progression over time and allow identification of patients for whom diagnostic right heart catheterization is warranted and its treatment includes hemoglobinopathy specific treatment(regular blood transfusion and appropriate iron chelation therapy , hydroxyurea , L carnitin therapy)  and PAH specific therapy (Sildenafil citrate , Bosentan , Riociguat or  sometime, it used  Epoprostenol  therapy which given  as continuous infusion , it antithrombotic agent that  inhibits  hypoxic pulmonary vasoconstriction and antiproliferative  properties)