CARDIAC STUDY BY DOBUTAMINE STRESS ECHOCARDIOGRAPHY IN THALASSEMIC PATIENTS

In patients with Thalassaemia Major the iron overload with alteration both of systolic and diastolic properties of left and right ventricles finally leads to symptoms of cardiac failure and is the most frequent cause of death in these patients (1). In the majority of asymptomatic thalassemic patients with normal myocardial mass it is possible to demonstrate an alteration of the diastolic function both with echocardiographic study and with radionuclide angiography (subclinical cardiac disease) (2,3) . We have also demonstrated in ''ex thalassemics'' with stable and heavy iron overload in the subclinical cardiac disease phase a subnormal systolic function and a slight impairment of the contractility state (4). Therefore our purpose was to evaluate cardiac performance emphasising the contractility properties of the left ventricle during moderate inotropic stimulation with dobutamine in thalassemic patients in subclinical cardiac disease. We are now also using this test to evaluate cardiac performance in adults thalassemic patients as a screening for marrow transplantation procedure. Dobutamine is a sympathomimetic drug (beta 1 agonist) that increases myocardial contractility and at high doses also systolic arterial blood pressure and heart rate. The half-life is extremely short and at low doses the drug has no major side effects. Continuous intravenous dobutamine infusion is largely used in the therapeutic field to treat cardiac failure and it is reported to be a very efficacious and safe therapeutic agent. Recently dobutamine stress echocardiography was reported to be an accurate non-invasive diagnostic technique for detecting cardiac dysfunction in adults with coronary artery disease (Dobutamine is used for this purpose at high dose to increase the myocardial oxygen consumption) (5,6). At low doses stress echocardiography is now starting to be used as a useful tool for detecting viable myocardium soon after acute myocardial infarction (7,8), to distinguish a reversible ischemic myocardial damage from ah irreversible one and finally to unmask abnormalities in cardiac function in asymptomatic doxorubicin treated long term survivors of childhood cancer (9).