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Query: UMLS:C0018801 (heart failure)
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Most patients diagnosed with secondary hemochromatosis have had repeated blood transfusions. Cardiac failure accounts for approximately one-third of the deaths associated with hemochromatosis. Liver dysfunction or hormonal disorders such as diabetes generally precede cardiac failure. A 23-year-old woman with hemochromatosis had, despite significant left ventricular dysfunction, liver function within the normal range on biochemical evaluation. She was treated for congestive heart failure and given desferoxamine intravenously. She did not have primary hemochromatosis, and had not received multiple blood transfusions or iron supplement. As a child the patient had been diagnosed with congenital non-spherocytic hemolytic anemia not requiring transfusion; thus, this is a unique case of secondary hemochromatosis.
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PMID:Cardiac dysfunction because of secondary hemochromatosis caused by congenital non-spherocytic hemolytic anemia. 1121 22

Iron-overload cardiomyopathy is a restrictive cardiomyopathy that manifests itself as systolic or diastolic dysfunction secondary to increased deposition of iron in the heart and occurs with common genetic disorders such as primary hemochromatosis and beta-thalassemia major. Although the exact mechanism of iron-induced heart failure remains to be elucidated, the toxicity of iron in biological systems is believed to be attributed to its ability to catalyze the generation of oxygen-free radicals. In the current investigation, the dose-dependent effects of chronic iron-loading on heart tissue concentrations of iron, glutathione peroxidase (GPx) activity, free-radical production, and cardiac dysfunction were investigated in a murine model of iron-overload cardiomyopathy. It was shown that chronic iron-overload results in dose-dependent (a) increases in myocardial iron burden, (b) decreases in the protective antioxidant enzyme GPx activity, (c) increased free-radical production, and (d) increased mortality. These findings show that the mechanism of iron-induced heart dysfunction involves in part free radical-mediated processes.
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PMID:Iron-overload cardiomyopathy: evidence for a free radical--mediated mechanism of injury and dysfunction in a murine model. 1123 11

During the last decades efforts regarding dietary iron supply focused mostly on the prevention of deficiencies, especially during growth and pregnancy. Correspondingly, homeostatic mechanisms increase intestinal iron absorption in iron deficiency, but its downregulation at high intake levels seems insufficient to prevent accumulation of high iron stores at high intake. There is no regulated iron excretion in overload. Excess of pharmaceutical iron may cause toxicity and therapeutic doses may cause gastrointestinal side effects. Chronic iron excess, e.g. in primary and secondary hemochromatosis, may lead to hepatic fibrosis, diabetes mellitus and cardiac failure. Chronic intake of 50-100 mg Fe/day of highly bioavailable iron with home-brewed beer in sub-Saharan Africans lead to cirrhosis and diabetes. Applying a safety factor of 2 would lead to an upper safe level of 25-50 mg Fe/day for this endpoint of conventional iron toxicity. However, beyond this kind of damage iron is known to catalyze the generation of hydroxyl radicals from superoxide anions and to increase oxidative stress which, in turn, increases free iron concentration. This self-amplifying process may cause damage to lipid membranes and proteins, which relates radical generation and organ damage after ischemia-reperfusion events to available free iron in clinical and experimental settings. Correspondingly, epidemiological studies as well as observations in heterozygotes for hereditary hemochromatosis suggest that the risk of atherosclerosis and acute myocardial infarction is related to body iron stores, though there is conflicting epidemiological evidence as well. The most recent and best controlled studies, however, support the hypothesis that iron stores are related to cardiovascular risk. Iron-amplified oxidative stress may also increase DNA damage, oxidative activation of precancerogens and support tumor cell growth. This is supported by experimental, clinical and epidemiological observations. Due to these mechanisms high iron stores may present a health hazard. Though this has not been finally proven, available evidence strongly recommends not to increase iron intake beyond physiological requirements. To avoid iron deficiency symptoms, on the other hand, care must be taken to meet recommended daily intake.
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PMID:Safety aspects of iron in food. 1142

BACKGROUND: Myocardial reflectivity is abnormally increased in patients with thalassemia major under transfusion treatment, probably due to myocardial iron deposits and/or secondary structural changes. Such increased reflectivity has been detected by both qualitative and subjective analysis of two-dimensional echocardiographic (2-D echo) images and quantitative assessment of integrated backscatter amplitude with noncommercially available ultrasound prototypes. The purpose of this study was to assess the acoustic properties of myocardium in patients with beta-thalassemia major and iron overload by means of quantitative computerized offline textural analysis of conventionally recorded 2-D echo images, and to compare textural data with other qualitative (visual assessment) and quantitative (ultrasound backscatter analysis) approaches for myocardial ultrasound tissue characterization simultaneously applied to these patients. METHODS AND RESULTS: Thirty-five young patients with thalassemia major, without clinical signs of cardiac failure, and 20 age and sex matched normal controls were studied by echocardiography. Each patient was receiving blood transfusion every 2-3 weeks. Two-dimensional echo images, obtained with a commercially available echocardiograph using the parasternal long-axis view, were digitized off line and analyzed by first and second order texture algorithms applied to regions of interest in the myocardium (septal and posterior wall). The mean gray level value was higher in thalassemic patients than in controls on both the septum (110 +/- 25 vs 57 +/- 13, arbitrary units on a 0-255 scale; P < 0.01) and posterior wall (91 +/- 25 vs 67 +/- 18; P < 0.01). Among second order statistical parameters, contrast and angular second moment significantly (P < 0.01) differentiated septal and posterior walls of patients and controls. In thalassemic patients, no consistent correlation was found between wall texture parameters and hematologic (years of transfusions and chelation, number of transfusions), 2-D echo (posterior wall thickness, left ventricular end-diastolic diameter), and Doppler (transmitral E/A waves ratio) parameters. Myocardial walls with visually assessed increased echo reflectivity showed a trend toward higher values of mean gray level when compared with myocardial segments with qualitatively assessed normal reflectivity (septum: 121 +/- 26 vs 106 +/- 24; posterior wall: 105 +/- 23 vs 87 +/- 23). Although radiofrequency integrated backscatter has been demonstrated to be capable of identifying thalassemic patients, no significant correlation was found between mean gray level (by texture analysis) and radiofrequency data (septum: r = 0.03; posterior wall: r = 0.09; P = NS for both). CONCLUSIONS: Myocardial walls affected by hemochromatosis show ultrasound image texture alterations that may be quantified with digital image analysis techniques and appear mostly unrelated to hematologic and conventional, as well as radiofrequency-based, echocardiographic parameters. These changes in quantitatively evaluated echo reflectivity are present even before the development of clinical and echocardiographic signs of cardiac dysfunction. (ECHOCARDIOGRAPHY, Volume 13, January 1996)
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PMID:Quantitative Texture Analysis in Two-Dimensional Echocardiography: Application to the Diagnosis of Myocardial Hemochromatosis. 1144 99

Patients with beta thalassemia major present with severe anemia and need continuous transfusion therapy. The consequent iron overload leads to hemochromatosis. Initial cardiac involvement can be present in thalassemic patients without clinical manifestations of heart failure. The purpose of this study was to assess the contractile reserve of the left ventricle in patients with normal baseline two-dimensional (2-D) echocardiographic findings using low dose dobutamine echocardiography. The underlying hypothesis was that, at an early stage, structural impairment of the myocardial wall due to myocardial iron deposits and/or secondary fibrotic changes could be so subtle so as not to impair resting systolic function, but is severe enough to blunt or even exhaust the contractile response to inotropic stimulation. Twenty-four consecutive patients (13 men and 11 women; ages 18 +/- 3.8 years) with beta thalassemia major undergoing evaluation for bone marrow transplantation entered the study. By selection, all were asymptomatic, without clinical signs of cardiac failure, and had normal regional and global systolic function at baseline echocardiographic study. A control group of 16 age and sex matched subjects was also studied. All underwent baseline, 2-D, and Doppler study, as well as dobutamine stress (up to 5 &mgr;g/kg per min) 2-D echocardiographic study. Patients and controls showed comparable values of indexes of global (ejection fraction: 0.64 +/- 0.06 vs 0.65 +/- 0.05, P = NS) and regional (systolic thickening of posterior wall: 90 +/- 34 vs 91 +/- 34%, P = NS) function at baseline. Left ventricular diastolic filling was evaluated with Doppler echocardiography. Peak flow velocity in early diastole was increased in thalassemic patients compared to controls (114 +/- 16 vs 96 +/- 18 cm/sec, P < 0.01), and flow velocity deceleration time was reduced (139 +/- 17 vs 157 +/- 20 msec, P < 0.01). At peak dobutamine, thalassemic patients showed a blunted contractile response compared to controls for indexes of both global (ejection fraction: 0.62 +/- 0.06 vs 0.69 +/- 0.05, P < 0.01) and regional (% systolic thickening of posterior wall: 91 +/- 36 vs 130 +/- 39%, P < 0.01) function. When individual patient analysis was performed, echocardiographic parameters were beyond the 95% confidence limits obtained from normal controls in 5 (21%) of the 24 study patients by one or more Doppler diastolic indexes, in 6 (25%) by indexes of contractile reserve, and in 11 (46%) by one of either diastolic function or contractile reserve indexes. These data demonstrate that the "iron heart" of asymptomatic thalassemic patients is a weak heart. Even if the regional and global systolic functions are similar to normals under resting conditions, the application of an inotropic challenge unmasks the weakness of these hearts, which can be identified at an earlier stage of their natural history through the blunted contractile response following the infusion of low dose dobutamine. The information on contractile reserve is not redundant, but rather incremental and in addition to that provided by Doppler echocardiographic indexes, which may be abnormal in these patients. (ECHOCARDIOGRAPHY, Volume 13, September 1996)
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PMID:Reduced Left Ventricular Contractile Reserve Identified by Low Dose Dobutamine Echocardiography as an Early Marker of Cardiac Involvement in Asymptomatic Patients with Thalassemia Major. 1144 56

Iron depletion was suggested to be protective against the development of ischemic heart disease. Population studies have led to conflicting results, and such an association has not been addressed in patients with heart failure due to cardiomyopathy. We studied the distribution of hemochromatosis-related mutations in 319 patients with heart failure due to cardiomyopathy of different etiologies. The genotypic distribution showed a significantly higher prevalence of heterozygotes for the C282Y mutation in patients with ischemic cardiomyopathy than in patients with cardiomyopathy of nonischemic etiologies (p = 0.0036). The frequency of the D63 mutation was not significantly different between ischemic versus nonischemic groups. In multiple logistic regression models adjusted for age, sex, ethnicity, and different degrees of disease progression, there was a strong and significant association of the C282Y mutation with ischemic cardiomyopathy compared with the nonischemic group (odds ratio 6.64, 95% confidence interval 1.71 to 25.73, after adjustment). In our sample, genetic variation in the HFE gene was associated with ischemic cardiomyopathy. Such association merits further study regarding its value as a prognostic marker in patients with ischemic heart disease.
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PMID:Hemochromatosis gene variants in patients with cardiomyopathy. 1154 59

Hemochromatosis is a genetic disease of iron overload due to intestinal hyperabsorption of iron. It is one of the most prevalent autosomal recessive diseases in Caucasian populations. Hemochromatosis causes severe visceral and metabolic complications at adulthood, which include cirrhosis, diabetes, arthropathy and cardiac failure. A major breakthrough has been the discovery, in 1996, of the HFE gene which is strongly associated with the phenotypic expression of the disease. This discovery has, very quickly, provided a powerful genetic blood test which permits, in most cases, to establish the diagnosis in a non invasive way (i.e. without a liver biopsy). Hemochromatosis can be cured by repeated venesections provided the diagnosis has been detected sufficiently early. Moreover, an efficient preventive strategy can be applied to family members and should now be proposed to the general population. Finally, the identification of the HFE gene has paved the way for the identification of new iron overload entities.
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PMID:Hemochromatosis at the intersection of classical medicine and molecular biology. 1155 26

The prevention of anthracycline cardiotoxicity is particularly important in children who can be expected to survive for decades after cancer chemotherapy with these agents. The rapid increase in clinical toxicity at doses greater than 550 mg/m(2) of doxorubicin (DOX) has made this dose the limiting one in order to avoid DOX-induced cardiac failure. However, arbitrary dose limitation is inadequate because of variability of individual tolerance. Decreasing myocardial concentrations of anthracyclines (ANT) and their metabolites and schedule modification of administration can reduce anthracycline cardiotoxicity. Anthracycline structural analogues such as epirubicin, idarubicin and mitoxantrone have been used in clinical practice. In addition, the liposomal ANT, which can be incorporated into a variety of liposomal preparations, are a new class of agents that may permit more specific organ targeting of ANT, thereby producing less cardiac toxicity. Much interest has focused on the administration of ANT in conjunction with another agent that will selectively attenuate the cardiotoxicity. As is known, the ANT chelate iron and the DOX-iron complex catalyzes the formation of extremely reactive hydroxyl radicals. Many agents, such as dexrazoxane (DEX), able to remove iron from DOX, have been investigated as anthracycline cardioprotectors. Clinical trials of DEX have been conducted in children and significant short-term cardioprotection with no evidence of interference with antitumor activity has been demonstrated. Whether long-term cardiac toxicity will also be avoided in surviving patients has not yet been determined.
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PMID:Recent advances in the prevention of anthracycline cardiotoxicity in childhood. 1156 84

Chronic inflammation is a common feature of end-stage renal disease (ESRD) that is gaining increasing attention as a major cause of morbidity and mortality. It is well established that ESRD per se carries a heightened risk of inflammatory disorders and other co-morbid conditions, but it should also be pointed out that dialysis treatment per se can bring additional risk factors for inflammation, such as impure dialysate or bio-incompatible membranes. Inflammation has recently been associated with atherosclerosis and malnutrition in ESRD, and this link has led to the development of the malnutrition, inflammation, atherosclerosis (MIA) hypothesis. This describes a syndrome whereby raised levels of pro-inflammatory cytokines (such as IL-1, IL-6 and TNF-alpha) are a common link between malnutrition, inflammation and atherosclerosis. Also, anaemia appears to be an important element linking elevated cytokine levels with poor patient outcomes. Several mechanisms for cytokine-induced anaemia have been proposed, including intestinal bleeding, impaired iron metabolism and suppression of bone marrow erythropoiesis and erythropoietin production. These effects suggest that pro-inflammatory cytokines may also be an important cause of lack of response to recombinant human erythropoietin (rh-Epo) therapy. In the light of this putative role of pro-inflammatory cytokines, anti-cytokine agents may prove useful to optimize efficacy of rh-Epo in anaemic chronic renal failure patients. Other potential therapeutic strategies include minimizing exposure to causes of inflammation from various co-morbid conditions, such as persistent infections and chronic heart failure.
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PMID:The role of inflammation in the anaemia of end-stage renal disease. 1159 Feb 55

Hereditary hemochromatosis (HH) is a common inborn error of iron metabolism characterized by excess dietary iron absorption and iron deposition in several tissues. Clinical consequences include hepatic failure, hepatocellular carcinoma, diabetes, cardiac failure, impotence, and arthritis. Despite the discovery of the mutation underlying most cases of HH, considerable uncertainty exists in the mechanism by which the normal gene product, HFE, regulates iron homeostasis. Knockout of the HFE gene clearly confers the HH phenotype on mice. However, studies on HFE expressed in cultured cells have not yet clarified the mechanism by which HFE mutations lead to increased dietary iron absorption. Recent discoveries suggest other genes, including a second transferrin receptor and the circulating peptide hepcidin, participate in a shared pathway with HFE in regulation of iron absorption. This review summarizes our current understanding of the relationship between iron stores and absorption and presents models to explain the dysregulated iron homeostasis in HH.
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PMID:Mechanisms of iron accumulation in hereditary hemochromatosis. 1182 84


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