Physiology and pathophysiology of iron cardiomyopathy in thalassemia.
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.
Wood
John C
JC
Division of Cardiology, Mailstop 34, Childrens Hospital of Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027, USA. jwood@chla.usc.edu
Enriquez
Cathleen
C
Ghugre
Nilesh
N
Otto-Duessel
Maya
M
Aguilar
Michelle
M
Nelson
Marvin D
MD
Moats
Rex
R
Coates
Thomas D
TD
D002021:Buffers; D002302:Cardiac Output; D006332:Cardiomegaly / Q000209:etiology; D009202:Cardiomyopathies / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D015913:Chelation Therapy; D003131:Combined Modality Therapy; D006321:Heart / Q000503:physiopathology; D006801:Humans; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000627:therapeutic use; D019190:Iron Overload / Q000209:etiology / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008954:Models, Biological; D010084:Oxidation-Reduction; D013318:Stroke Volume; D013789:Thalassemia / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism / Q000628:therapy; D065227:Transfusion Reaction; D014655:Vascular Resistance
D002021:Buffers; D007502:Iron Chelating Agents; D007501:Iron