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Physiology and Pathophysiology of Iron Cardiomyopathy in Thalassemia
aDivision of Pediatric Cardiology, Childrens Hospital of Los Angeles, Los Angeles, California 90027, USA bDepartment of Pediatric Radiology, Childrens Hospital of Los Angeles, Los Angeles, California 90027, USA cDivision of Pediatric Hematology, Childrens Hospital of Los Angeles, Los Angeles, California 90027, USA
Address for correspondence: John C. Wood, M.D., Ph.D., Division of Cardiology, Mailstop 34, Childrens Hospital of Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027. Voice: 323-669-5470; fax: 323-669-7317. jwood{at}chla.usc.edu
Iron cardiomyopathy remains the leading cause of death in patients with thalassemia major. Magnetic resonance imaging (MRI) is ideally suited for monitoring thalassemia patients because it can detect cardiac and liver iron burdens as well as accurately measure left ventricular dimensions and function. However, patients with thalassemia have unique physiology that alters their normative data. In this article, we review the physiology and pathophysiology of thalassemic heart disease as well as the use of MRI to monitor it. Despite regular transfusions, thalassemia major patients have larger ventricular volumes, higher cardiac outputs, and lower total vascular resistances than published data for healthy control subjects; these hemodynamic findings are consistent with chronic anemia. Cardiac iron overload increases the relative risk of further dilation, arrhythmias, and decreased systolic function. However, many patients are asymptomatic despite heavy cardiac burdens. We explore possible mechanisms behind cardiac iron-function relationships and relate these mechanisms to clinical observations.
Key Words: iron • heart • MRI • ejection fraction • cardiac function • T2* This article has been cited by other articles:
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