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Shen J, Fu H, Ding Y, Yuan Z, Xiang Z, Ding M, Huang M, Peng Y, Li T, Zha K, Ye Q. The role of iron overload and ferroptosis in arrhythmia pathogenesis. IJC HEART & VASCULATURE 2024; 52:101414. [PMID: 38694269 PMCID: PMC11060960 DOI: 10.1016/j.ijcha.2024.101414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/04/2024]
Abstract
Ferroptosis is a newly discovered form of programmed cell death triggered by intracellular iron overload, which leads to the accumulation of lipid peroxides in various cells. It has been implicated in the pathogenesis and progression of various diseases, including tumors, neurological disorders, and cardiovascular diseases. The intricate mechanism underlying ferroptosis involves an imbalance between the oxidation and antioxidant systems, disturbances in iron metabolism, membrane lipid peroxidation, and dysregulation of amino acid metabolism. We highlight the key molecular mechanisms governing iron overload and ferroptosis, and discuss potential molecular pathways linking ferroptosis with arrhythmias.
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Affiliation(s)
- Jingsong Shen
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Hengsong Fu
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Yanling Ding
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Ziyang Yuan
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Zeming Xiang
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Miao Ding
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Min Huang
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Yongquan Peng
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Tao Li
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Kelan Zha
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Qiang Ye
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
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Zhang T, Luo L, He Q, Xiao S, Li Y, Chen J, Qin T, Xiao Z, Ge Q. Research advances on molecular mechanism and natural product therapy of iron metabolism in heart failure. Eur J Med Res 2024; 29:253. [PMID: 38659000 PMCID: PMC11044586 DOI: 10.1186/s40001-024-01809-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 03/22/2024] [Indexed: 04/26/2024] Open
Abstract
The progression of heart failure (HF) is complex and involves multiple regulatory pathways. Iron ions play a crucial supportive role as a cofactor for important proteins such as hemoglobin, myoglobin, oxidative respiratory chain, and DNA synthetase, in the myocardial energy metabolism process. In recent years, numerous studies have shown that HF is associated with iron dysmetabolism, and deficiencies in iron and overload of iron can both lead to the development of various myocarditis diseases, which ultimately progress to HF. Iron toxicity and iron metabolism may be key targets for the diagnosis, treatment, and prevention of HF. Some iron chelators (such as desferrioxamine), antioxidants (such as ascorbate), Fer-1, and molecules that regulate iron levels (such as lactoferrin) have been shown to be effective in treating HF and protecting the myocardium in multiple studies. Additionally, certain natural compounds can play a significant role by mediating the imbalance of iron-related signaling pathways and expression levels. Therefore, this review not only summarizes the basic processes of iron metabolism in the body and the mechanisms by which they play a role in HF, with the aim of providing new clues and considerations for the treatment of HF, but also summarizes recent studies on natural chemical components that involve ferroptosis and its role in HF pathology, as well as the mechanisms by which naturally occurring products regulate ferroptosis in HF, with the aim of providing reference information for the development of new ferroptosis inhibitors and lead compounds for the treatment of HF in the future.
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Affiliation(s)
- Tianqing Zhang
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Li Luo
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Qi He
- People's Hospital of Ningxiang City, Ningxiang City, China
| | - Sijie Xiao
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Yuwei Li
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Junpeng Chen
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Tao Qin
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Zhenni Xiao
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China
| | - Qingliang Ge
- Department of Cardiology, Changde Hospital, Xiangya School of Medicine, Central South University, Hunan, China.
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Shizukuda Y, Rosing DR. Hereditary hemochromatosis with homozygous C282Y HFE mutation: possible clinical model to assess effects of elevated reactive oxygen species on the development of cardiovascular disease. Mol Cell Biochem 2024; 479:617-627. [PMID: 37133674 DOI: 10.1007/s11010-023-04726-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/31/2023] [Indexed: 05/04/2023]
Abstract
Hereditary hemochromatosis with the homozygous C282Y HFE mutation (HH-282H) is a genetic condition which causes iron overload (IO) and elevated reactive oxygen species (ROS) secondary to the IO. Interestingly, even after successful iron removal therapy, HH-282H subjects demonstrate chronically elevated ROS. Raised ROS are also associated with the development of multiple cardiovascular diseases and HH-282H subjects may be at risk to develop these complications. In this narrative review, we consider HH-282H subjects as a clinical model for assessing the contribution of elevated ROS to the development of cardiovascular diseases in subjects with fewer confounding clinical risk factors as compared to other disease conditions with high ROS. We identify HH-282H subjects as a potentially unique clinical model to assess the impact of chronically elevated ROS on the development of cardiovascular disease and to serve as a clinical model to detect effective interventions for anti-ROS therapy.
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Affiliation(s)
- Yukitaka Shizukuda
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
- Division of Cardiology, Department of Internal Medicine, Cincinnati VA Medical Center, Cincinnati, OH, 45220, USA.
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, 45267, USA.
| | - Douglas R Rosing
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
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Wood JC. Cardiac complications in thalassemia throughout the lifespan: Victories and challenges. Ann N Y Acad Sci 2023; 1530:64-73. [PMID: 37902424 PMCID: PMC10841366 DOI: 10.1111/nyas.15078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
Thalassemias are among the most common hereditary diseases in the world because heterozygosity offers protection against malarial infection. Affected individuals have variable expression of alpha or beta chains that lead to their unbalanced utilization during hemoglobin formation, oxidative stress, and apoptosis of red cell precursors prior to maturation. Some individuals produce sufficient hemoglobin to survive but suffer the vascular stress imposed by chronic anemia and ineffective erythropoiesis. In other patients, mature red cell formation is insufficient, and chronic transfusions are required-suppressing anemia and ineffective erythropoiesis but at the expense of iron overload. The cardiovascular consequences of thalassemia have changed dramatically over the previous five decades because of evolving treatment practices. This review summarizes this evolution, focusing on complications and management pertinent to modern patient cohorts.
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Affiliation(s)
- John C Wood
- Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA
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Electrophysiological properties and heart rate variability of patients with thalassemia major in Jakarta, Indonesia. PLoS One 2023; 18:e0280401. [PMID: 36638135 PMCID: PMC9838856 DOI: 10.1371/journal.pone.0280401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 12/28/2022] [Indexed: 01/14/2023] Open
Abstract
Beta thalassemia major (TM) is a common hereditary disease in Indonesia. Iron overload due to regular transfusion may induce myocardial iron deposition leading to electrophysiological dysfunction and functional disorders of the heart. Ventricular arrhythmia is one of the most common causes of sudden cardiac death in thalassemia patients. This cross-sectional study of 62 TM patients aged 10-32 years in Cipto Mangunkusumo General Hospital was done to assess their electrophysiological properties and heart rate variability, including 24- hour Holter monitoring, signal averaged electrocardiogram (SAECG) for detection of ventricular late potential (VLP), and determination of heart rate variability (HRV). We also assessed their 12-lead ECG parameters, such as P wave, QRS complex, QT/ QTc interval, QRS dispersion, and QT/ QTc dispersion. Iron overload was defined by T2-star magnetic resonance (MR-T2*) values of less than 20 ms or ferritin level greater than 2500 ng/mL. Subjects were grouped accordingly. There were significant differences of QTc dispersion (p = 0.026) and deceleration capacity (p = 0.007) between MR-T2* groups. Multivariate analysis showed an inverse correlation between QTc dispersion and MR-T2* values. There was a proportional correlation between heart rate deceleration capacity in the low MR-T2* group (p = 0.058) and the high ferritin group (p = 0.007). No VLPs were detectable in any patients. In conclusion, prolonged QTc dispersion and decreased heart rate deceleration capacity were significantly correlated with greater odds of iron overload among patients with Thalassemia major.
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Alipour MR, Pezeshkpour Z, Namayandeh SM, Sarebanhassanabadi M. Evaluation of ECG and echocardiographic findings in patients aged 2 to 18 years affected with thalassemia major. PROGRESS IN PEDIATRIC CARDIOLOGY 2021. [DOI: 10.1016/j.ppedcard.2021.101454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Joshi PK, Patel SC, Shreya D, Zamora DI, Patel GS, Grossmann I, Rodriguez K, Soni M, Sange I. Hereditary Hemochromatosis: A Cardiac Perspective. Cureus 2021; 13:e20009. [PMID: 34987900 PMCID: PMC8716004 DOI: 10.7759/cureus.20009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2021] [Indexed: 11/21/2022] Open
Abstract
Hereditary hemochromatosis (HH) is a common genetic metabolic disorder characterized by excessive iron absorption and elevated serum iron levels, which accumulate in various organs, such as the heart, pancreas, gonads, and damage these organs. There are only a few articles and clinical studies describing the characteristics of cardiac involvement in HH along with the significance of early diagnosis and management in preventing complications. In this review article, we have reviewed multiple pieces of literature and gathered available information regarding the subject. We compiled the data to investigate the importance of early detection of symptoms, regular monitoring, and prompt management with strict adherence to reverse or prevent complications. This article has reviewed different aspects of cardiac hemochromatosis, such as pathogenesis, clinical presentation, diagnosis, and management. Recognition of early symptoms, diagnosis of cardiac involvement with various modalities, and implementation of early treatment are essentially the foundation of better outcomes in HH.
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Chen H, Xia F, Chen X, Cai Y, Jin Z. Ablation of small conductance calcium-activated potassium type-2 channel (SK 2) delays occurrence of bupivacaine-induced cardiotoxicity in isolated mouse hearts. Hum Exp Toxicol 2021; 40:464-471. [PMID: 32909839 DOI: 10.1177/0960327120958102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bupivacaine is frequently used for conducting regional anesthesia. When accidentally injected or excessively absorbed into circulation, bupivacaine can induce severe arrhythmia and potentially lead to cardiac arrest. The specific mechanisms underlying this cardiotoxicity, however, remain to be clarified. We transfected HEK-293 cells to express the small conductance calcium-activated potassium type-2 channel (SK2), and used a whole-cell patch clamp method in order to explore how bupivacaine affected these channels. We subsequently used SK2 knockout mice to explore the relevance of SK2 channels in bupivacaine-induced cardiotoxicity in isolating mouse hearts, mounting them on a Langendorff apparatus, and perfusing them with bupivacaine. Using this system, arrhythmia, asystole, and cardiac functions were monitored. We observed dose-dependent inhibition of SK2 channels by bupivacaine: half-maximal inhibitory concentration (IC50) value = 18.6 μM (95% CI 10.8-32.1). When SK2 knockout (SK2 -/-) or wild-type (WT) mice were perfused with Krebs-Henseleit buffer (KHB), we did not observe any instances of arrhythmia. When SK2 -/- mice or WT were perfused with KHB containing bupivacaine (40 μM), the time to arrhythmia (Tarrhythmia) and time to asystole (Tasystole) were both significantly longer in SK2 -/- mice relative to WT mice (P < 0.001). Similarly, SK2 -/- mice exhibited a significantly longer time to 25%, 50%, and 75% reductions in heart rate (HR) and rate-pressure product (RPP) relative to WT mice following bupivacaine perfusion (P < 0.001). These results reveal that bupivacaine was able to mediate a dose-dependent inhibition of SK2 channels in HEK-293 cells, and deletion of SK2 channels can delay bupivacaine-induced cardiotoxicity in isolated mouse hearts.
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Affiliation(s)
- H Chen
- Department of Anesthesiology, the 89657First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - F Xia
- Department of Anesthesiology, the 89657First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - X Chen
- Department of Anesthesiology, the 89657First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Y Cai
- Department of Anesthesiology, the 89657First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Z Jin
- Department of Anesthesiology, the 89657First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
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Siri-Angkul N, Song Z, Fefelova N, Gwathmey JK, Chattipakorn SC, Qu Z, Chattipakorn N, Xie LH. Activation of TRPC (Transient Receptor Potential Canonical) Channel Currents in Iron Overloaded Cardiac Myocytes. Circ Arrhythm Electrophysiol 2021; 14:e009291. [PMID: 33417472 DOI: 10.1161/circep.120.009291] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Arrhythmias and heart failure are common cardiac complications leading to substantial morbidity and mortality in patients with hemochromatosis, yet mechanistic insights remain incomplete. We investigated the effects of iron (Fe) on electrophysiological properties and intracellular Ca2+ (Ca2+i) handling in mouse left ventricular cardiomyocytes. METHODS Cardiomyocytes were isolated from the left ventricle of mouse hearts and were superfused with Fe3+/8-hydroxyquinoline complex (5-100 μM). Membrane potential and ionic currents including TRPC (transient receptor potential canonical) were recorded using the patch-clamp technique. Ca2+i was evaluated by using Fluo-4. Cell contraction was measured with a video-based edge detection system. The role of TRPCs in the genesis of arrhythmias was also investigated by using a mathematical model of a mouse ventricular myocyte with the incorporation of the TRPC component. RESULTS We observed prolongation of the action potential duration and induction of early and delayed afterdepolarizations in myocytes superfused with 15 µmol/L Fe3+/8-hydroxyquinoline complex. Iron treatment decreased the peak amplitude of the L-type Ca2+ current and total K+ current, altered Ca2+i dynamics, and decreased cell contractility. During the final phase of Fe treatment, sustained Ca2+i waves and repolarization failure occurred and ventricular cells became unexcitable. Gadolinium abolished Ca2+i waves and restored the resting membrane potential to the normal range. The involvement of TRPC activation was confirmed by TRPC channel current recordings in the absence or presence of functional TRPC channel antibodies. Computer modeling captured the same action potential and Ca2+i dynamics and provided additional mechanistic insights. CONCLUSIONS We conclude that iron overload induces cardiac dysfunction that is associated with TRPC channel activation and alterations in membrane potential and Ca2+i dynamics.
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Affiliation(s)
- Natthaphat Siri-Angkul
- Department of Cell Biology and Molecular Medicine, Rutgers University, New Jersey Medical School, Newark (N.S.-A., N.F., J.K.G., L.-H.X.).,Cardiac Electrophysiology Research and Training Center (N.S.-A., S.C.C., N.C.), Chiang Mai University, Thailand.,Department of Physiology, Faculty of Medicine (N.S.-A., N.C.), Chiang Mai University, Thailand
| | - Zhen Song
- Department of Medicine (Cardiology), University of California, Los Angeles (Z.S., Z.Q.)
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, Rutgers University, New Jersey Medical School, Newark (N.S.-A., N.F., J.K.G., L.-H.X.)
| | - Judith K Gwathmey
- Department of Cell Biology and Molecular Medicine, Rutgers University, New Jersey Medical School, Newark (N.S.-A., N.F., J.K.G., L.-H.X.)
| | - Siriporn C Chattipakorn
- Cardiac Electrophysiology Research and Training Center (N.S.-A., S.C.C., N.C.), Chiang Mai University, Thailand
| | - Zhilin Qu
- Department of Medicine (Cardiology), University of California, Los Angeles (Z.S., Z.Q.)
| | - Nipon Chattipakorn
- Cardiac Electrophysiology Research and Training Center (N.S.-A., S.C.C., N.C.), Chiang Mai University, Thailand.,Department of Physiology, Faculty of Medicine (N.S.-A., N.C.), Chiang Mai University, Thailand
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers University, New Jersey Medical School, Newark (N.S.-A., N.F., J.K.G., L.-H.X.)
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Evaluation of electrocardiographic markers of cardiac arrhythmic events and their correlation with cardiac iron overload in patients with β-thalassemia major. Cardiol Young 2020; 30:1666-1671. [PMID: 32883379 DOI: 10.1017/s1047951120002498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Iron overload is associated with an increased risk of atrial and ventricular arrhythmias. Data regarding the relationship between electrocardiographic parameters of atrial depolarisation and ventricular repolarisation with cardiac T2* MRI are scarce. Therefore, we aimed to investigate these electrocardiographic parameters and their relationship with cardiac T2* value in patients with β-thalassemia major. In this prospective study, 52 patients with β-thalassemia major and 52 age- and gender-matched healthy patients were included. Electrocardiographic measurements of QT, T peak to end interval, and P wave intervals were performed by one cardiologist who was blind to patients' data. All patients underwent MRI for cardiac T2* evaluation. Cardiac T2* scores less than 20 ms were considered as iron overload. P wave dispersion, QTc interval, and the dispersions of QT and QTc were significantly prolonged in β-thalassemia major patients compared to controls. Interestingly, we found prolonged P waves, QT and T peak to end dispersions, T peak to end intervals, and increased T peak to end/QT ratios in patients with T2* greater than 20 ms. No significant correlation was observed between electrocardiographic parameters and cardiac T2* values and plasma ferritin levels. In conclusion, our study demonstrated that atrial depolarisation and ventricular repolarisation parameters are affected in β-thalassemia major patients and that these parameters are not correlated with cardiac iron load.
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Relation Between Cardiac T2* Values and Electrocardiographic Parameters in Children With Transfusion-dependent Thalassemia. J Pediatr Hematol Oncol 2020; 42:e610-e614. [PMID: 32032245 DOI: 10.1097/mph.0000000000001734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND/OBJECTIVES Cardiac T2* magnetic resonance imaging (MRI) is the gold standard to determine myocardial iron overload. As availability of Cardiac T2* is not uniform across developing nations, our strategy was to identify a more accessible and cost effective tool to assess myocardial iron accumulation. As children with transfusion-dependent thalassemia also experience various electrocardiographic abnormalities, we performed electrocardiography (ECG) as well as Cardiac T2* MRI on all children registered in our thalassemia unit. MATERIALS AND METHODS Forty-eight transfusion-dependent thalassemia children with transfusion burden ≥12 times/y (6 to 19 y) in the Thalassemia Unit of the Division of Hematology Oncology, Department of Pediatrics were enrolled. Patients were divided into 3 groups based on severity of T2* value, that is group I (T2*<10), group II (T2* 10 to 20), group III (T2*>20). A T2* value >20 was taken as normal. ECG and serum ferritin was also performed on the day of MRI. RESULTS Among the various ECG parameters, QRS duration, and QTc interval were significantly increased if cardiac iron overload was high with a P-value of 0.036 and 0.000, respectively. Also, high serum ferritin predicted a decline in T2* value with a P-value of 0.001. QT interval and QTc interval significantly correlated inversely with T2* (P=0.042, r=-0.295 and P=0.002, r=-0.446, respectively) but not QRS duration (P=0.05, r=-0.282). Serum ferritin also was found to have a significant inverse correlation with T2* value (P=0.000, r=-0.497). CONCLUSIONS Abnormalities on ECG, that is prolongation of QRS duration, QT interval, and QTc interval were significantly associated with cardiac iron overload, that is decrease in the value of Cardiac T2* in our study.
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Sun XR, Liu T, Liu XP. Type 1 Brugada phenotype induced by cardiac iron overload after blood transfusion. HeartRhythm Case Rep 2020; 6:187-190. [PMID: 32322493 PMCID: PMC7156983 DOI: 10.1016/j.hrcr.2019.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Xue-Rong Sun
- Heart Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Tong Liu
- Department of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China
| | - Xing-Peng Liu
- Heart Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
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Consequences of parenteral iron-dextran loading investigated in minipigs. A new model of transfusional iron overload. Blood Cells Mol Dis 2020; 83:102440. [PMID: 32353700 DOI: 10.1016/j.bcmd.2020.102440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/18/2020] [Accepted: 04/16/2020] [Indexed: 11/21/2022]
Abstract
Patients with blood transfusion-dependent anemias develop transfusional iron overload (TIO), which may cause cardiosiderosis. In patients with an ineffective erythropoiesis, such as thalassemia major, common transfusion regimes aim at suppression of erythropoiesis and of enteral iron loading. Recent data suggest that maintaining residual, ineffective erythropoiesis may protect from cardiosiderosis. We investigated the common consequences of TIO, including cardiosiderosis, in a minipig model of iron overload with normal erythropoiesis. TIO was mimicked by long-term, weekly iron-dextran injections. Iron-dextran loading for around one year induced very high liver iron concentrations, but extrahepatic iron loading, and iron-induced toxicities were mild and did not include fibrosis. Iron deposits were primarily in reticuloendothelial cells, and parenchymal cardiac iron loading was mild. Compared to non-thalassemic patients with TIO, comparable cardiosiderosis in minipigs required about 4-fold greater body iron loads. It is suggested that this resistance against extrahepatic iron loading and toxicity in minipigs may at least in part be explained by a protective effect of the normal erythropoiesis, and additionally by a larger total iron storage capacity of RES than in patients with TIO. Parenteral iron-dextran loading of minipigs is a promising and feasible large-animal model of iron overload, that may mimic TIO in non-thalassemic patients.
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Arrhythmias and Sudden Cardiac Death in Beta-Thalassemia Major Patients: Noninvasive Diagnostic Tools and Early Markers. Cardiol Res Pract 2019; 2019:9319832. [PMID: 31885907 PMCID: PMC6914907 DOI: 10.1155/2019/9319832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/03/2019] [Accepted: 08/19/2019] [Indexed: 11/24/2022] Open
Abstract
Beta-thalassemias are a group of inherited, autosomal recessive diseases, characterized by reduced or absent synthesis of beta-globin chains of the hemoglobin tetramer, resulting in variable phenotypes, ranging from clinically asymptomatic individuals to severe anemia. Three main forms have been described: heterozygotes, homozygotes β+, and homozygotes β°. Beta-thalassemia major (β-TM), the most serious form, is characterized by an absent synthesis of globin chains that are essential for hemoglobin formation, causing chronic hemolytic anemia. Cardiac complications represent a leading cause of mortality in β-TM patients, although an important and progressive increase of life expectancy has been demonstrated after the introduction of chelating therapies. Iron overload is the primary factor of cardiac damage resulting in thalassemic cardiomyopathy, in which diastolic dysfunction usually happens before systolic impairment and overt heart failure (HF). Although iron-induced cardiomyopathy is slowly progressive and it usually takes several decades for clinical and laboratory features of cardiac dysfunction to manifest, arrhythmias or sudden death may be present without signs of cardiac disease and only if myocardial siderosis is present. Careful analysis of electrocardiograms and other diagnostic tools may help in early identification of high-risk β-TM patients for arrhythmias and sudden cardiac death.
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Gualdani R, Guerrini A, Fantechi E, Tadini-Buoninsegni F, Moncelli MR, Sangregorio C. Superparamagnetic iron oxide nanoparticles (SPIONs) modulate hERG ion channel activity. Nanotoxicology 2019; 13:1197-1209. [PMID: 31437063 DOI: 10.1080/17435390.2019.1650969] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as diagnostic agents in magnetic resonance imaging (MRI), for drug delivery vehicles and in hyperthermia treatment of tumors. Although the potential benefits of SPIONs are considerable, there is a distinct need to identify any potential cellular damage associated with their use. Since human ether à go-go-related gene (hERG) channel, a protein involved in the repolarization phase of cardiac action potential, is considered one of the main targets in the drug discovery process, we decided to evaluate the effects of SPIONs on hERG channel activity and to determine whether the oxidation state, the dimensions and the coating of nanoparticles (NPs) can influence the interaction with hERG channel. Using patch clamp recordings, we found that SPIONs inhibit hERG current and this effect depends on the coating of NPs. In particular, SPIONs with covalent coating aminopropylphosphonic acid (APPA) have a milder effect on hERG activity. We observed that the time-course of hERG channel modulation by SPIONs is biphasic, with a transient increase (∼20% of the amplitude) occurring within the first 1-3 min of perfusion of NPs, followed by a slower inhibition. Moreover, in the presence of SPIONs, deactivation kinetics accelerated and the activation and inactivation I-V curves were right-shifted, similarly to the effect described for the binding of other divalent metal ions (e.g. Cd2+ and Zn2+). Finally, our data show that a bigger size and the complete oxidation of SPIONs can significantly decrease hERG channel inhibition. Taken together, these results support the view that Fe2+ ions released from magnetite NPs may represent a cardiac risk factor, since they alter hERG gating and these alterations could compromise the cardiac action potential.
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Affiliation(s)
- Roberta Gualdani
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy.,Institute of Neuroscience, Laboratory of Cell Physiology, Université Catholique de Louvain , Brussels , Belgium
| | - Andrea Guerrini
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | - Elvira Fantechi
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | | | - Maria Rosa Moncelli
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | - Claudio Sangregorio
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy.,ICCOM-CNR and INSTM , Sesto Fiorentino , Italy
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16
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Shizukuda Y, Rosing DR. Iron overload and arrhythmias: Influence of confounding factors. J Arrhythm 2019; 35:575-583. [PMID: 31410226 PMCID: PMC6686354 DOI: 10.1002/joa3.12208] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/24/2019] [Accepted: 05/15/2019] [Indexed: 12/11/2022] Open
Abstract
Arrhythmias as a cardiac complication of iron overload (IO) have been well described for decades in the clinical literature. They are assumed to be directly associated with the myocardial accumulation of iron. However, the influence of heart failure and elevated oxidative stress, which are major arrhythmogenic confounding factors associated with IO on arrhythmias, has not been critically reviewed in the published literature. A comprehensive narrative review of published articles in PubMed was conducted to address the influence of confounding factors of IO on arrhythmias. The previous data may have been largely confounded by the other cardiac complications of IO, particularly heart failure. The previous studies on IO-related arrhythmias lack proper age-gender-matched control subjects and/or comparison groups with properly controlled confounding factors to assess accurately their etiology and clinical significance. Given the above considerations, further mechanistic investigations to clarify the etiology and clinical relevance of IO-induced arrhythmias are needed. In addition, investigations to develop arrhythmia management strategy specific to IO, are warranted.
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Affiliation(s)
- Yukitaka Shizukuda
- Cardiovascular BranchNational Heart, Lung, and Blood InstituteBethesdaMaryland
- Cincinnati VA Medical CenterCincinnatiOhio
- Division of Cardiovascular Health and DiseaseUniversity of CincinnatiCincinnatiOhio
| | - Douglas R. Rosing
- Cardiovascular BranchNational Heart, Lung, and Blood InstituteBethesdaMaryland
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17
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Yamauchi A, Kamiyoshi A, Sakurai T, Miyazaki H, Hirano E, Lim HS, Kaku T, Shindo T. Development of a mouse iron overload-induced liver injury model and evaluation of the beneficial effects of placenta extract on iron metabolism. Heliyon 2019; 5:e01637. [PMID: 31193082 PMCID: PMC6515419 DOI: 10.1016/j.heliyon.2019.e01637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/16/2019] [Accepted: 04/30/2019] [Indexed: 12/11/2022] Open
Abstract
Hepatic iron deposition is seen in cases of chronic hepatitis and cirrhosis, and is a hallmark of a poorer prognosis. Iron deposition is also found in non-alcoholic steatohepatitis (NASH) patients. We have now developed a mouse model of NASH with hepatic iron deposition by combining a methione- and choline-deficient (MCD) diet with an iron-overload diet. Using this model, we evaluated the effects of human placenta extract (HPE), which has been shown to ameliorate the pathology of NASH. Four-week-old male C57BL/6 mice were fed the MCD diet with 2% iron for 12 weeks. In liver sections, iron deposition was first detected around the portal vein after 1 week. From there it spread throughout the parenchyma. Biliary iron concentrations were continuously elevated throughout the entire 12-week diet. As a compensatory response, the diet caused elevation of serum hepcidin, which accelerates excretion of iron from the body. Accumulation of F4/80-positive macrophages was detected within the sinusoids from the first week onward, and real-time PCR analysis revealed elevated hepatic expression of genes related inflammation and oxidative stress. In the model mice, HPE treatment led to a marked reduction of hepatic iron deposition with a corresponding increase in biliary iron excretion. Macrophage accumulation was much reduced by HPE treatment, as was the serum oxidation-reduction potential, an index of oxidative stress. These data indicate that by suppressing inflammation, oxidative stress and iron deposition, and enhancing iron excretion, HPE effectively ameliorates iron overload-induced liver injury. HPE administration may thus be an effective strategy for treating NASH.
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Affiliation(s)
- Akihiro Yamauchi
- Department of Cardiovascular Research, Shinshu University Graduate School of Medicine, Matsumoto, Japan.,Japan Bio Products Co., Ltd., Tokyo, Japan
| | - Akiko Kamiyoshi
- Department of Cardiovascular Research, Shinshu University Graduate School of Medicine, Matsumoto, Japan
| | - Takayuki Sakurai
- Department of Cardiovascular Research, Shinshu University Graduate School of Medicine, Matsumoto, Japan
| | | | | | | | | | - Takayuki Shindo
- Department of Cardiovascular Research, Shinshu University Graduate School of Medicine, Matsumoto, Japan
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18
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Siri-Angkul N, Xie LH, Chattipakorn SC, Chattipakorn N. Cellular Electrophysiology of Iron-Overloaded Cardiomyocytes. Front Physiol 2018; 9:1615. [PMID: 30498456 PMCID: PMC6249272 DOI: 10.3389/fphys.2018.01615] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/25/2018] [Indexed: 01/07/2023] Open
Abstract
Iron, the most abundant transition metal element in the human body, plays an essential role in many physiological processes. However, without a physiologically active excretory pathway, iron is subject to strict homeostatic processes acting upon its absorption, storage, mobilization, and utilization. These intricate controls are perturbed in primary and secondary hemochromatoses, leading to a deposition of excess iron in multiple vital organs including the heart. Iron overload cardiomyopathy is the leading cause of mortality in patients with iron overload conditions. Apart from mechanical deterioration of the siderotic myocardium, arrhythmias reportedly contribute to a substantial portion of cardiac death associated with iron overload. Despite this significant impact, the cellular mechanisms of electrical disturbances in an iron-overloaded heart are still incompletely characterized. This review article focuses on cellular electrophysiological studies that directly investigate the effects of iron overload on the function of cardiac ion channels, including trans-sarcolemmal and sarcoplasmic reticulum Ca2+ fluxes, as well as cardiac action potential morphology. Our ultimate aim is to provide a comprehensive summary of the currently available information that will encourage and facilitate further mechanistic elucidation of iron-induced pathoelectrophysiological changes in the heart.
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Affiliation(s)
- Natthaphat Siri-Angkul
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand.,Department of Cell Biology and Molecular Medicine, Rutgers University - New Jersey Medical School, Newark, NJ, United States.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers University - New Jersey Medical School, Newark, NJ, United States
| | - Siriporn C Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand.,Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| | - Nipon Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
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Barbero U, Fornari F, Guarguagli S, Gaglioti CM, Longo F, Doronzo B, Anselmino M, Piga A. Atrial fibrillation in β-thalassemia Major Patients: Diagnosis, Management and Therapeutic Options. Hemoglobin 2018; 42:189-193. [DOI: 10.1080/03630269.2018.1488724] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Umberto Barbero
- Royal Brompton and Harefield Hospital, Imperial College London, London, UK
- Cardiology Unit, SS. ma Annunziata Hospital, Savigliano, Italy
| | - Federico Fornari
- Dipartimento of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga, Torino, Italy
| | - Silvia Guarguagli
- Royal Brompton and Harefield Hospital, Imperial College London, London, UK
| | - Carmen Maria Gaglioti
- Dipartimento of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga, Torino, Italy
| | - Filomena Longo
- Dipartimento of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga, Torino, Italy
| | | | - Matteo Anselmino
- Cardiology Unit, Città della Salute e della Scienza Hospital, University of Turin, Turin, Italy
| | - Antonio Piga
- Dipartimento of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga, Torino, Italy
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20
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Zhang H, Zhabyeyev P, Wang S, Oudit GY. Role of iron metabolism in heart failure: From iron deficiency to iron overload. Biochim Biophys Acta Mol Basis Dis 2018; 1865:1925-1937. [PMID: 31109456 DOI: 10.1016/j.bbadis.2018.08.030] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 07/25/2018] [Accepted: 08/22/2018] [Indexed: 12/11/2022]
Abstract
Iron metabolism is a balancing act, and biological systems have evolved exquisite regulatory mechanisms to maintain iron homeostasis. Iron metabolism disorders are widespread health problems on a global scale and range from iron deficiency to iron-overload. Both types of iron disorders are linked to heart failure. Iron play a fundamental role in mitochondrial function and various enzyme functions and iron deficiency has a particular negative impact on mitochondria function. Given the high-energy demand of the heart, iron deficiency has a particularly negative impact on heart function and exacerbates heart failure. Iron-overload can result from excessive gut absorption of iron or frequent use of blood transfusions and is typically seen in patients with congenital anemias, sickle cell anemia and beta-thalassemia major, or in patients with primary hemochromatosis. This review provides an overview of normal iron metabolism, mechanisms underlying development of iron disorders in relation to heart failure, including iron-overload cardiomyopathy, and clinical perspective on the treatment options for iron metabolism disorders.
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Affiliation(s)
- Hao Zhang
- Division of Cardiology, Department of Medicine, Canada; Mazankowski Alberta Heart Institute, Canada
| | - Pavel Zhabyeyev
- Division of Cardiology, Department of Medicine, Canada; Mazankowski Alberta Heart Institute, Canada
| | - Shaohua Wang
- Mazankowski Alberta Heart Institute, Canada; Division of Cardiac Surgery, Department of Surgery, University of Alberta, Edmonton, Canada
| | - Gavin Y Oudit
- Division of Cardiology, Department of Medicine, Canada; Mazankowski Alberta Heart Institute, Canada.
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21
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WITHDRAWN: Cardiac Complications in Patients with Thalassemia Major in Iran: A Meta-Analysis Study. PROGRESS IN PEDIATRIC CARDIOLOGY 2017. [DOI: 10.1016/j.ppedcard.2017.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Fradette C, Rozova A, Stilman A, Tsang YC, Allison MJ, Tricta F. Randomized, Blinded, Placebo- and Positive-Controlled Crossover Study to Determine the Effect of Deferiprone on the QTc Interval in Healthy Subjects. Clin Pharmacol Drug Dev 2017; 7:22-32. [PMID: 28394491 DOI: 10.1002/cpdd.352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/16/2017] [Indexed: 12/27/2022]
Abstract
This study evaluated whether deferiprone, an oral iron chelator, acts to prolong the QT interval. Fifty healthy volunteers received single doses of each of the following: therapeutic dose of deferiprone (33 mg/kg), supratherapeutic dose (50 mg/kg), placebo, or moxifloxacin, a positive control known to significantly prolong QT interval. Following each dose, subjects underwent cardiac monitoring, pharmacokinetics assessments, and safety assessments. Based on the QT interval obtained using the Fridericia correction for heart rate (QTcF), the upper bound of the 1-sided 95% confidence interval of the mean difference between deferiprone and placebo was <10 milliseconds (the threshold of concern defined by authorities) at all time points for both doses: maximum difference of 3.01 milliseconds for the therapeutic dose and 5.23 milliseconds for the supratherapeutic dose. The difference in dQTcF between moxifloxacin and placebo demonstrated that the study was adequately sensitive to detect a significant prolongation of QTcF. The concentration-response correlation analyses revealed some weak but statistically significant trends of increase in dQTcF and ddQTcF with increasing exposure to deferiprone, but these trends should have no clinical consequence even at the recommended maximum dosage. In conclusion, there was no clinically meaningful effect on QTc interval following single therapeutic or supratherapeutic doses of deferiprone.
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23
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Iron citrate reduces high phosphate-induced vascular calcification by inhibiting apoptosis. Atherosclerosis 2016; 254:93-101. [DOI: 10.1016/j.atherosclerosis.2016.09.071] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 08/31/2016] [Accepted: 09/29/2016] [Indexed: 11/21/2022]
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24
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Russo V, Rago A, Papa AA, Nigro G. Electrocardiographic Presentation, Cardiac Arrhythmias, and Their Management in β-Thalassemia Major Patients. Ann Noninvasive Electrocardiol 2016; 21:335-42. [PMID: 27324981 DOI: 10.1111/anec.12389] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Beta-thalassemia major (β-TM) is a genetic hemoglobin disorder characterized by an absent synthesis of globin chains that are essential for hemoglobin formation, causing chronic hemolytic anemia. Clinical management of thalassemia major consists in regular long-life red blood cell transfusions and iron chelation therapy to remove iron introduced in excess with transfusions. Iron deposition in combination with inflammatory and immunogenic factors is involved in the pathophysiology of cardiac dysfunction in these patients. Heart failure and arrhythmias, caused by myocardial siderosis, are the most important life-limiting complications of iron overload in beta-thalassemia patients. Cardiac complications are responsible for 71% of global death in the beta-thalassemia major patients. The aim of this review was to describe the most frequent electrocardiographic abnormalities and arrhythmias observed in β-TM patients, analyzing their prognostic impact and current treatment strategies.
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Affiliation(s)
- Vincenzo Russo
- Second University of Naples - Monaldi Hospital, Naples, Italy
| | - Anna Rago
- Second University of Naples - Monaldi Hospital, Naples, Italy
| | | | - Gerardo Nigro
- Second University of Naples - Monaldi Hospital, Naples, Italy
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25
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Duyuler S, Türker Duyuler P, Batur MK. Impact of Iron and Homocysteine Levels on T Peak-to-End Interval and Tp-e/QT Ratio in Elite Athletes. Ann Noninvasive Electrocardiol 2016; 21:557-565. [PMID: 27019094 DOI: 10.1111/anec.12365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Electrocardiography (ECG) is frequently used in preparticipation evaluation of competitive athletes. Repolarization heterogeneities on ECG is a well-known indicator for malignant ventricular arrhythmias and sudden cardiac death. We aimed to investigate the effect of iron and homocysteine levels on arrhythmogenic indicators, T peak-to-end (Tp-e) interval, and Tp-e/QT ratio in elite athletes. METHODS A total of 72 players (48 football and 24 basketball) with a mean age of 25.4 ± 5.0 years were included to the analysis. Blood biochemistry, homocysteine level, and iron parameters (transferrin saturation and serum iron) were obtained by standard methods. Duration of QRS, QT interval, and Tp-e interval were measured manually on the precordial leads and Tp-e/QT ratio was calculated. RESULTS Baseline demographic and clinical characteristics of the study population were compared in two groups according to the median value of Tp-e/QT = 0.219. Both iron and transferrin saturations were higher in the above median group (P = 0.001 and P = 0.002, respectively), however, homocysteine levels were not statistically different among two groups (P = 0.405). In correlation analysis, both serum iron and transferrin saturation were significantly correlated with Tp-e interval (r = 0.368; P = 0.001 and r = 0.394; P = 0.00, respectively) and Tp-e/QT ratio (r = 0.357; P = 0.002 and r = 0.372; P = 0.001, respectively). Multiple stepwise regression analysis revealed that transferrin saturation was an independent predictor of Tp-e interval and Tp-e/QT ratio (β = 0.325; P = 0.002 and β = 0.372; P = 0.001, respectively). CONCLUSION This study showed an independent relationship between iron status and Tp-e interval and Tp-e/QT ratios of elite sport players which were also not correlated with serum homocysteine levels.
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Affiliation(s)
- Serkan Duyuler
- Department of Cardiology, Acıbadem Ankara Hospital, Ankara, Turkey.
| | - Pınar Türker Duyuler
- Department of Cardiology, Ankara Numune Education and Research Hospital, Ankara, Turkey
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26
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Early Cardiac Involvement and Risk Factors for the Development of Arrhythmia in Patients With β-Thalassemia Major. J Pediatr Hematol Oncol 2016; 38:5-11. [PMID: 26583617 DOI: 10.1097/mph.0000000000000467] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Cardiac iron overload is the most serious complication in thalassemia; even patients treated with intensive chelation suffer at a certain point from cardiomyopathy and arrhythmia. AIM The aim of the study was to identify indicators of cardiac dysfunction in thalassemia as well as risk factors associated with the development of arrhythmia. PATIENTS AND METHODS A total of 45 patients with β-thalassemia major were enrolled in this cross-sectional study. Patients were divided into 2 groups according to the absence (group A) or the presence of arrhythmia (group B). Cardiac parameters in thalassemic groups were evaluated using 24-Holter recording, Stress electrocardiogram, and M-mode echocardiography. Serum ferritin and Cardiac T2* were used to assess the iron status. RESULTS Group B showed significantly higher values of cardiac T2* and serum ferritin (P<0.05). Group B patients had significantly higher maximum heart rate with significant attacks of bradycardia and ST segment changes. In addition, they achieved a lower percentage of maximum age predicted heart rate and lower values of maximum metabolic equivalents (P<0.05). Significantly higher values of the left atrial diameter, the interventricular septum diameter, and the left-ventricle posterior wall diameter (P<0.05) were identified in group B. CONCLUSIONS The increase in left atrial diameter, interventricular septum diameter, and left-ventricle posterior wall diameter seems to be related to the development of arrhythmia in patients with thalassemia, especially supraventricular arrhythmias.
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Elshrif MM, Cherry EM. Electrophysiological properties under heart failure conditions in a human ventricular cell: a modeling study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:4324-9. [PMID: 25570949 DOI: 10.1109/embc.2014.6944581] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Heart failure (HF) is one of the major diseases across the world. During HF the electrophysiology of the failing heart is remodeled, which renders the heart more susceptible to ventricular arrhythmias. In this study, we quantitatively analyze the effects of electrophysiological remodeling of the major currents of human ventricular myocytes on the dynamics of the failing heart. We develop a HF model using a modified version of a recently published model of the human ventricular action potential, the O'Hara-Virag-Varro-Rudy (OVVR) model. The proposed HF model incorporates recently available HF clinical data. It can reproduce most of the action potential (AP) properties of failing myocytes, including action potential duration (APD), amplitude (APA), notch (APN), plateau (APP), resting membrane potential (RMP), and maximum upstroke velocity (dV/dtmax). In addition, the model reproduces the behavior of the [Na+], concentration and [Ca(2)+]i dynamics. Moreover, the HF model exhibits alternans with a fast pacing frequency and can induce early afterdepolarizations (EADs). Additionally, blocking the late sodium current shortens the APD and suppresses EADs, in agreement with experimental findings. The dynamics of the proposed model are assessed through investigating the rate dependence of the AP and the dynamics of the major currents. The steady-state (S-S) and S1-S2 restitution curves along with accommodation to an abrupt change in cycle length were evaluated. Our study should help to elucidate the roles of alterations in electrophysiological properties during HF. Also, this HF cellular model could be used to study HF in a realistic geometry and could be embedded into a model of HF electromechanics to investigate electrical and mechanical properties simultaneously during HF.
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28
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Italia K, Colah R, Ghosh K. Experimental animal model to study iron overload and iron chelation and review of other such models. Blood Cells Mol Dis 2015; 55:194-9. [DOI: 10.1016/j.bcmd.2015.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/11/2015] [Indexed: 01/03/2023]
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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30
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Elshrif MM, Shi P, Cherry EM. Representing variability and transmural differences in a model of human heart failure. IEEE J Biomed Health Inform 2015; 19:1308-20. [PMID: 26068919 DOI: 10.1109/jbhi.2015.2442833] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
During heart failure (HF) at the cellular level, the electrophysiological properties of single myocytes get remodeled, which can trigger the occurrence of ventricular arrhythmias that could be manifested in many forms such as early afterdepolarizations (EADs) and alternans (ALTs). In this paper, based on experimentally observed human HF data, specific ionic and exchanger current strengths are modified from a recently developed human ventricular cell model: the O'Hara-Virág-Varró-Rudy (OVVR) model. A new transmural HF-OVVR model is developed that incorporates HF changes and variability of the observed remodeling. This new heterogeneous HF-OVVR model is able to replicate many of the failing action potential (AP) properties and the dynamics of both [Ca(2+)]i and [Na(+)]i in accordance with experimental data. Moreover, it is able to generate EADs for different cell types and exhibits ALTs at modest pacing rate for transmural cell types. We have assessed the HF-OVVR model through the examination of the AP duration and the major ionic currents' rate dependence in single myocytes. The evaluation of the model comes from utilizing the steady-state (S-S) and S1-S2 restitution curves and from probing the accommodation of the HF-OVVR model to an abrupt change in cycle length. In addition, we have investigated the effect of chosen currents on the AP properties, such as blocking the slow sodium current to shorten the AP duration and suppress the EADs, and have found good agreement with experimental observations. This study should help elucidate arrhythmogenic mechanisms at the cellular level and predict unseen properties under HF conditions. In addition, this AP cell model might be useful for modeling and simulating HF at the tissue and organ levels.
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31
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Bayar N, Kurtoğlu E, Arslan Ş, Erkal Z, Çay S, Çağırcı G, Deveci B, Küçükseymen S. Assessment of the relationship between fragmented QRS and cardiac iron overload in patients with beta-thalassemia major. Anatol J Cardiol 2014; 15:132-6. [PMID: 25252297 PMCID: PMC5336998 DOI: 10.5152/akd.2014.5188] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Objective: Beta-thalassemia major (TM) is a genetic hemoglobin disorder causing chronic hemolytic anemia. Since cardiac insufficiency and arrhythmias are the primary causes of mortality in such patients, monitoring of cardiac iron load is important in management of the disorder. The purpose of this study was to investigate the importance of fragmented QRS (fQRS) and its relation to the cardiac T2* value for the evaluation of cardiac iron load in TM patients. Methods: This retrospective study included 103 TM patients. The patients’ T2* values, measured by cardiac MRI and 12-lead surface ECGs, were interpreted. The cardiac T2* values under 20 were considered as cardiac iron overload. The relationship between the cardiac T2* value and fQRS in ECG was investigated. Results: The median age of the patients was 22.6±6.6 years. All patients were on regular blood transfusions and iron chelators. The patients had no risk factors for coronary artery disease. In 50 (48%) patients fQRS was detected, and in 37 (74%) of these the T2* values were low. 86% of patients with cardiac involvement (37) had fQRS, but 22% of patients with non-involvement (13) had fQRS (p<0.001). Conclusion: Since cardiac involvement is the primary cause of mortality in TM patients, the early diagnosis of cardiac dysfunction is of vital importance. The search for fQRS in the ECGs of these patients, particularly when cardiac T2* values cannot be determined and followed, is a non-expensive and easy-to-attain method for therapy management.
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Affiliation(s)
- Nermin Bayar
- Clinic of Cardiology, Antalya Education and Research Hospital; Antalya-Turkey.
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Sripetchwandee J, KenKnight SB, Sanit J, Chattipakorn S, Chattipakorn N. Blockade of mitochondrial calcium uniporter prevents cardiac mitochondrial dysfunction caused by iron overload. Acta Physiol (Oxf) 2014; 210:330-41. [PMID: 24034353 DOI: 10.1111/apha.12162] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 07/15/2013] [Accepted: 08/29/2013] [Indexed: 12/24/2022]
Abstract
AIM Iron overload in the heart can lead to iron-overload cardiomyopathy and cardiac arrhythmia. In the past decades, growing evidence has suggested that cardiac mitochondrial dysfunction is associated with the development of cardiac dysfunction and lethal arrhythmias. Despite these facts, the effect of iron overload on cardiac mitochondrial function is still unclear. In this study, we determined the effects of iron overload on the cardiac mitochondrial function and the routes of cardiac mitochondrial iron uptake. We tested the hypothesis that iron overload can lead to cardiac mitochondrial dysfunction and that mitochondrial calcium uniporter (MCU) plays a major role for cardiac mitochondrial iron uptake under iron-overload condition. Cardiac mitochondrial function was assessed via the determination of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) production and mitochondrial membrane potential changes. METHODS Isolated cardiac mitochondria from male Wistar rats were used in this study. To determine the routes for cardiac mitochondrial iron uptake, isolated mitochondria were exposed to MCU blocker (Ru360), mitochondrial permeability transition pore (mPTP) blocker (cyclosporin A) and an iron chelator (deferoxamine). RESULTS We found that (i) iron overload caused cardiac mitochondrial dysfunction, indicated by increased ROS production, mitochondrial membrane depolarization and mitochondrial swelling; and (ii) only MCU blocker completely protected cardiac mitochondrial dysfunction caused by iron overload. CONCLUSIONS These findings strongly suggest that MCU could be the major route for iron uptake into cardiac mitochondria. The inhibition of MCU could be the novel pharmacological intervention for preventing iron-overload cardiomyopathy.
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Affiliation(s)
- J. Sripetchwandee
- Cardiac Electrophysiology Research and Training Center; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Cardiac Electrophysiology Unit; Department of Physiology; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
| | - S. B. KenKnight
- Cardiac Electrophysiology Research and Training Center; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Cardiac Electrophysiology Unit; Department of Physiology; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
| | - J. Sanit
- Cardiac Electrophysiology Research and Training Center; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Cardiac Electrophysiology Unit; Department of Physiology; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
| | - S. Chattipakorn
- Cardiac Electrophysiology Research and Training Center; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Faculty of Dentistry; Chiang Mai University; Chiang Mai Thailand
| | - N. Chattipakorn
- Cardiac Electrophysiology Research and Training Center; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Cardiac Electrophysiology Unit; Department of Physiology; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
- Biomedical Engineering Center; Chiang Mai University; Chiang Mai Thailand
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Spatial repolarization heterogeneity detected by magnetocardiography correlates with cardiac iron overload and adverse cardiac events in beta-thalassemia major. PLoS One 2014; 9:e86524. [PMID: 24475137 PMCID: PMC3903540 DOI: 10.1371/journal.pone.0086524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 12/10/2013] [Indexed: 11/19/2022] Open
Abstract
Background Patients with transfusion-dependent beta-thalassemia major (TM) are at risk for myocardial iron overload and cardiac complications. Spatial repolarization heterogeneity is known to be elevated in patients with certain cardiac diseases, but little is known in TM patients. The purpose of this study was to evaluate spatial repolarization heterogeneity in patients with TM, and to investigate the relationships between spatial repolarization heterogeneity, cardiac iron load, and adverse cardiac events. Methods and Results Fifty patients with TM and 55 control subjects received 64-channel magnetocardiography (MCG) to determine spatial repolarization heterogeneity, which was evaluated by a smoothness index of QTc (SI-QTc), a standard deviation of QTc (SD-QTc), and a QTc dispersion. Left ventricular function and myocardial T2* values were assessed by cardiac magnetic resonance. Patients with TM had significantly greater SI-QTc, SD-QTc, and QTc dispersion compared to the control subjects (all p values<0.001). Spatial repolarization heterogeneity was even more pronounced in patients with significant iron overload (T2*<20 ms, n = 20) compared to those with normal T2* (all p values<0.001). Loge cardiac T2* correlated with SI-QTc (r = −0.609, p<0.001), SD-QTc (r = −0.572, p<0.001), and QTc dispersion (r = −0.622, p<0.001), while all these indices had no relationship with measurements of the left ventricular geometry or function. At the time of study, 10 patients had either heart failure or arrhythmia. All 3 indices of repolarization heterogeneity were related to the presence of adverse cardiac events, with areas under the receiver operating characteristic curves (ranged between 0.79 and 0.86), similar to that of cardiac T2*. Conclusions Multichannel MCG demonstrated that patients with TM had increased spatial repolarization heterogeneity, which is related to myocardial iron load and adverse cardiac events.
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Said Othman KM, Elshazly SA, Heiba NM. Role of non-invasive assessment in prediction of preclinical cardiac affection in multi-transfused thalassaemia major patients. ACTA ACUST UNITED AC 2013; 19:380-7. [PMID: 24225039 DOI: 10.1179/1607845413y.0000000140] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
BACKGROUND The principal cause of mortality and morbidity in β-thalassemia major (β-TM) is the iron overload as these patients receive about 20 times the normal intake of iron, which leads to iron accumulation and damage in the liver, heart, and endocrine organs. Chronically transfused patients used to die from cardiac iron overload in their teens and twenties. Monitoring of iron status through cardiac magnetic resonance imaging (CMRI) has replaced the conventional methods of assessment, yet this modality is not readily available in centers where the disease distribution is maximal. Objectives The aim of this work is to study some simple non-invasive tools and their abilities to predict preclinical cardiac affection reflecting cardiac iron deposition (CID) in multi-transfused β-TM patients taking the T2* CMRI as a gold standard reference test. METHODS One hundred consecutive multi-transfused, clinically stable β-TM patients with age ranging from 16 to 30 years (mean ± SD, 21.1 ± 3.9) were included in this study. Assessment of serum ferritin, serum hepcidin, and high-sensitivity C-reactive protein as well as cardiac assessment by echo-doppler and 24-hour Holter were used to predict CID, and consequently predict preclinical cardiac affection, in reference to CMRI results as the standard method of cardiac iron assessment. RESULTS According to CMRI results, patients were subdivided into a group of 42 patients with detectable myocardial iron (T*≤ 20 ms) and a group of 58 patients with no detectable myocardial iron (T* > 20 ms). No differences in age, gender, or distribution of splenectomized patients were observed between both groups. Patients with detectable myocardial iron received significantly higher number of transfusions per year than those with no detectable myocardial iron (mean ± SD, 14.6 ± 1.7 vs. 12.5 ± 1.7; P < 0.001) yet comparable levels of serum ferritin, serum hepcidin, and hepcidin/ferritin ratio (P > 0.05) were noted. Cardiac iron detection was associated with significantly lower heart rate (mean ± SD, 75 ± 6.1 vs. 80 ± 6.9; P < 0.001), lower left ventricular ejection fraction (LVEF) (mean ± SD 60.1 ± 3.2 vs. 70.1 ± 2.8; P < 0.001), and higher total number of premature ventricular contractions (PVCs) (median 78 vs. 14; P < 0.001). The group with CID comprised significantly more patients with left ventricular diastolic dysfunction (15/42, 35.7% vs. 3/58, 5.2%; P < 0.001); PVCs ≥10/hour (13/42, 31% vs. 2/58, 3.4%; P < 0.001); episodes of sinus pauses (6/42, 14.3% vs. 1/58, 1.7%; P < 0.05); episodes of high-grade atrio-ventricular block (5/42, 11.9% vs. 1/58, 1.7%; P < 0.05) compared to the group with no (CID). In presence of normal LVEF, detection of 10 or more PVCs per hour was the most predictive of cardiac iron loading with a positive predictive value of 86.7% and specificity of 96.6%, and the highest likelihood ratio (9.09). Detection of more than 22 PVCs/24 hours had the best sensitivity (81%) and the best negative predictive value (84%). The positive likelihood ratio of the studied parameters was highest in case of presence of PVCs ≥10/hour and lowest in case of average heart rate with a cut-off level of ≤77.5 bpm (9.09 and 1.46, respectively). CONCLUSION Our results support our hypothesis that monitoring β-TM patients with echo and Holter electrocardiogram can help in the detection of preclinical cardiac affection in centers lacking cardiac MRI; however, due to relatively low sensitivity they can not fully replace CMRI. Further work is needed to identify additional simple parameters that can form a diagnostic model with adequate sensitivity.
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Bavbek N, Yilmaz H, Erdemli HK, Selcuki Y, Duranay M, Akçay A. Correlation between iron stores and QTc dispersion in chronic ambulatory peritoneal dialysis patients. Ren Fail 2013; 36:187-90. [PMID: 24059284 DOI: 10.3109/0886022x.2013.836750] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIM We aimed to investigate the QT dispersion and corrected QT (QTc) dispersion which are suggested as the signals of ventricular arrhythmias, in patients on maintenance CAPD and to evaluate the correlation between iron stores and these electrocardiographic parameters. MATERIALS AND METHOD Fifty-eight patients on maintenance CAPD and 19 healthy age- and sex-matched adults without cardiac disease were included. The PD patients were divided into two groups according to whether their computerized measurements of QTc dispersion were longer than 65 ms. RESULTS Although QT interval was statistically significantly shorter in control group (34 ± 28 vs. 43 ± 34 ms; p < 0.05), there was no significant difference in regards to the QTc, QT dispersion and QTc dispersion between two groups. PD patients with QTc dispersion longer than 65 ms had higher levels of serum ferritin (p = 0.038) and transferrin saturation (TSAT; p = 0.022) than the others. QTc dispersion were positively correlated with ferritin (r = 0.469, p < 0.01) and TSAT (r = 0.430, p < 0.01) in CAPD patients. CONCLUSION Although prolonged QTc, QT dispersion and QTc dispersion were suggested as the markers of ventricular arrhythmias we did not find any significant difference in regards to these parameters between control patients and CAPD patients. But the high body iron stores in these patients increase the risk of increased QT dispersion. The concern over iron overload in dialysis patients is not only because of its oxidative toxicity, but also its precipitation of arrhythmias, which may be measured by the surrogate marker of QTc dispersion.
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Affiliation(s)
- Nuket Bavbek
- Department of Nephrology, Turgut Ozal University Medical School , Ankara , Turkey
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King JH, Huang CLH, Fraser JA. Determinants of myocardial conduction velocity: implications for arrhythmogenesis. Front Physiol 2013; 4:154. [PMID: 23825462 PMCID: PMC3695374 DOI: 10.3389/fphys.2013.00154] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/10/2013] [Indexed: 12/19/2022] Open
Abstract
Slowed myocardial conduction velocity (θ) is associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. θ is determined by the ion channel and physical properties of cardiac myocytes and by their interconnections. Thus, θ is closely related to the maximum rate of action potential (AP) depolarization [(dV/dt)max], as determined by the fast Na+ current (INa); the axial resistance (ra) to local circuit current flow between cells; their membrane capacitances (cm); and to the geometrical relationship between successive myocytes within cardiac tissue. These determinants are altered by a wide range of pathophysiological conditions. Firstly, INa is reduced by the impaired Na+ channel function that arises clinically during heart failure, ischemia, tachycardia, and following treatment with class I antiarrhythmic drugs. Such reductions also arise as a consequence of mutations in SCN5A such as those occurring in Lenègre disease, Brugada syndrome (BrS), sick sinus syndrome, and atrial fibrillation (AF). Secondly, ra, may be increased due to gap junction decoupling following ischemia, ventricular hypertrophy, and heart failure, or as a result of mutations in CJA5 found in idiopathic AF and atrial standstill. Finally, either ra or cm could potentially be altered by fibrotic change through the resultant decoupling of myocyte–myocyte connections and coupling of myocytes with fibroblasts. Such changes are observed in myocardial infarction and cardiomyopathy or following mutations in MHC403 and SCN5A resulting in hypertrophic cardiomyopathy (HCM) or Lenègre disease, respectively. This review defines and quantifies the determinants of θ and summarizes experimental evidence that links changes in these determinants with reduced myocardial θ and arrhythmogenesis. It thereby identifies the diverse pathophysiological conditions in which abnormal θ may contribute to arrhythmia.
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Affiliation(s)
- James H King
- Physiological Laboratory, Department of Physiology, Development and Neuroscience, University of Cambridge Cambridge, UK
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Herren AW, Bers DM, Grandi E. Post-translational modifications of the cardiac Na channel: contribution of CaMKII-dependent phosphorylation to acquired arrhythmias. Am J Physiol Heart Circ Physiol 2013; 305:H431-45. [PMID: 23771687 DOI: 10.1152/ajpheart.00306.2013] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The voltage-gated Na channel isoform 1.5 (NaV1.5) is the pore forming α-subunit of the voltage-gated cardiac Na channel, which is responsible for the initiation and propagation of cardiac action potentials. Mutations in the SCN5A gene encoding NaV1.5 have been linked to changes in the Na current leading to a variety of arrhythmogenic phenotypes, and alterations in the NaV1.5 expression level, Na current density, and/or gating have been observed in acquired cardiac disorders, including heart failure. The precise mechanisms underlying these abnormalities have not been fully elucidated. However, several recent studies have made it clear that NaV1.5 forms a macromolecular complex with a number of proteins that modulate its expression levels, localization, and gating and is the target of extensive post-translational modifications, which may also influence all these properties. We review here the molecular aspects of cardiac Na channel regulation and their functional consequences. In particular, we focus on the molecular and functional aspects of Na channel phosphorylation by the Ca/calmodulin-dependent protein kinase II, which is hyperactive in heart failure and has been causally linked to cardiac arrhythmia. Understanding the mechanisms of altered NaV1.5 expression and function is crucial for gaining insight into arrhythmogenesis and developing novel therapeutic strategies.
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Affiliation(s)
- Anthony W Herren
- Department of Pharmacology, University of California Davis, Davis, California
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Nguemo F, Fleischmann BK, Gupta MK, Šarić T, Malan D, Liang H, Pfannkuche K, Bloch W, Schunkert H, Hescheler J, Reppel M. The L-type Ca2+ channels blocker nifedipine represses mesodermal fate determination in murine embryonic stem cells. PLoS One 2013; 8:e53407. [PMID: 23320083 PMCID: PMC3539992 DOI: 10.1371/journal.pone.0053407] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Accepted: 11/28/2012] [Indexed: 01/20/2023] Open
Abstract
Dihydropyridines (DHP), which nifedipine is a member of, preferentially block Ca(2+) channels of different cell types. Moreover, influx of Ca(2+) through L-type Ca(2+) channels (LTCCs) activates Ca(2+) signaling pathways, which in turn contribute to numerous cellular processes. Although LTCCs are expressed in undifferentiated cells, very little is known about its contributions to the transcriptional regulation of mesodermal and cardiac genes. This study aimed to examine the contribution of LTCCs and the effect of nifedipine on the commitment of pluripotent stem cells toward the cardiac lineage in vitro. The murine embryonic stem (ES, cell line D3) and induced pluripotent stem (iPS, cell clone 09) cells were differentiated into enhanced green fluorescence protein (EGFP) expressing spontaneously beating cardiomyocytes (CMs). Early treatment of differentiating cells with 10 µM nifedipine led to a significant inhibition of the cardiac mesoderm formation and cardiac lineage commitment as revealed by gene regulation analysis. This was accompanied by the inhibition of spontaneously occurring Ca(2+) transient and reduction of LTCCs current density (I(CaL)) of differentiated CMs. In addition, nifedipine treatment instigated a pronounced delay of the spontaneous beating embryoid body (EB) and led to a poor surface localization of L-type Ca(2+) channel α(1C) (Ca(V)1.2) subunits. Contrary late incubation of pluripotent stem cells with nifedipine was without any impact on the differentiation process and did not affect the derived CMs function. Our data indicate that nifedipine blocks the determined path of pluripotent stem cells to cardiomyogenesis by inhibition of mesodermal commitment at early stages of differentiation, thus the proper upkeep Ca(2+) concentration and pathways are essentially required for cardiac gene expression, differentiation and function.
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Affiliation(s)
- Filomain Nguemo
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Bernd K. Fleischmann
- Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, Germany
| | - Manoj K. Gupta
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Tomo Šarić
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Daniela Malan
- Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, Germany
| | - Huamin Liang
- Department of Physiology, Huazhong University of Science and Technology, Tongji Medical College, Wuhan, China
| | - Kurt Pfannkuche
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, German Sport University, Cologne, Germany
| | | | - Jürgen Hescheler
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Michael Reppel
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
- Department of Cardiology, Medical University of Lübeck, Lübeck, Germany
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Lopin KV, Gray IP, Obejero-Paz CA, Thévenod F, Jones SW. Fe²⁺ block and permeation of CaV3.1 (α1G) T-type calcium channels: candidate mechanism for non-transferrin-mediated Fe²⁺ influx. Mol Pharmacol 2012; 82:1194-204. [PMID: 22973060 DOI: 10.1124/mol.112.080184] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Iron is a biologically essential metal, but excess iron can cause damage to the cardiovascular and nervous systems. We examined the effects of extracellular Fe²⁺ on permeation and gating of Ca(V)3.1 channels stably transfected in HEK293 cells, by using whole-cell recording. Precautions were taken to maintain iron in the Fe²⁺ state (e.g., use of extracellular ascorbate). With the use of instantaneous I-V currents (measured after strong depolarization) to isolate the effects on permeation, extracellular Fe²⁺ rapidly blocked currents with 2 mM extracellular Ca²⁺ in a voltage-dependent manner, as described by a Woodhull model with K(D) = 2.5 mM at 0 mV and apparent electrical distance δ = 0.17. Extracellular Fe²⁺ also shifted activation to more-depolarized voltages (by ∼10 mV with 1.8 mM extracellular Fe²⁺) somewhat more strongly than did extracellular Ca²⁺ or Mg²⁺, which is consistent with a Gouy-Chapman-Stern model with surface charge density σ = 1 e(-)/98 Ų and K(Fe) = 4.5 M⁻¹ for extracellular Fe²⁺. In the absence of extracellular Ca²⁺ (and with extracellular Na⁺ replaced by TEA), Fe²⁺ carried detectable, whole-cell, inward currents at millimolar concentrations (73 ± 7 pA at -60 mV with 10 mM extracellular Fe²⁺). With a two-site/three-barrier Eyring model for permeation of Ca(V)3.1 channels, we estimated a transport rate for Fe²⁺ of ∼20 ions/s for each open channel at -60 mV and pH 7.2, with 1 μM extracellular Fe²⁺ (with 2 mM extracellular Ca²⁺). Because Ca(V)3.1 channels exhibit a significant "window current" at that voltage (open probability, ∼1%), Ca(V)3.1 channels represent a likely pathway for Fe²⁺ entry into cells with clinically relevant concentrations of extracellular Fe²⁺.
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Affiliation(s)
- Kyle V Lopin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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Di Loreto P, Ronco C, Vescovo G. Long QT, alteration of calcium-phosphate product, prevalence of ventricular arrhythmias and sudden death in peritoneal dialysis patients: a Holter study. ITALIAN JOURNAL OF MEDICINE 2012. [DOI: 10.1016/j.itjm.2011.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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The Association between Myocardial Iron Load and Ventricular Repolarization Parameters in Asymptomatic Beta-Thalassemia Patients. Adv Hematol 2012; 2012:170510. [PMID: 22666259 PMCID: PMC3361145 DOI: 10.1155/2012/170510] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 01/28/2012] [Accepted: 02/06/2012] [Indexed: 12/17/2022] Open
Abstract
Previous studies have demonstrated impaired ventricular repolarization in patients with β-TM. However, the effect of iron overload with cardiac T2* magnetic resonance imaging (MRI) on cardiac repolarization remains unclear yet. We aimed to examine relationship between repolarization parameters and iron loading using cardiac T2* MRI in asymptomatic β-TM patients. Twenty-two β-TM patients and 22 age- and gender-matched healthy controls were enrolled to the study. From the 12-lead surface electrocardiography, regional and transmyocardial repolarization parameters were evaluated manually by two experienced cardiologists. All patients were also undergone MRI for cardiac T2* evaluation. Cardiac T2* score <20 msec was considered as iron overload status. Of the QT parameters, QT duration, corrected QT interval, and QT peak duration were significantly longer in the β-TM group compared to the healthy controls. Tp − Te and Tp − Te dispersions were also significantly prolonged in β-TM group compared to healthy controls. (Tp − Te)/QT was similar between groups. There was no correlation between repolarization parameters and cardiac T2* MRI values. In conclusion, although repolarization parameters were prolonged in asymptomatic β-TM patients compared with control, we could not find any relation between ECG findings and cardiac iron load.
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Detterich J, Noetzli L, Dorey F, Bar-Cohen Y, Harmatz P, Coates T, Wood J. Electrocardiographic consequences of cardiac iron overload in thalassemia major. Am J Hematol 2012; 87:139-44. [PMID: 22052662 DOI: 10.1002/ajh.22205] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 09/22/2011] [Accepted: 09/27/2011] [Indexed: 11/11/2022]
Abstract
Iron cardiomyopathy is a leading cause of death in transfusion-dependent thalassemia major (TM) patients and MRI (T2*) can recognize preclinical cardiac iron overload, but, is unavailable to many centers. We evaluated the ability of 12-lead electrocardiography to predict cardiac iron loading in TM. 12-lead electrocardiogram and cardiac T2* measurements were performed prospectively, with a detectable cardiac iron cutoff of T2*less than 20 ms. Patients with and without cardiac iron were compared using two-sample statistics and against population norms using age and gender-matched Z-scores. 45/78 patients had detectable cardiac iron. Patients having cardiac iron were older and more likely female but had comparable liver iron burdens and serum ferritin. Increased heart rate (HR) and prolonged corrected QT interval (QT(c)) were present, regardless of cardiac iron status. Repolarization abnormalities were the strongest predictors of cardiac iron, including QT/QT(c) prolongation, left shift of T-wave axis, and interpretation of ST/T-wave morphology. Recursive partitioning of the data for females using T-axis and HR and for males using QT, HR, and T-axis produced algorithms with AUROC's of 88.3 and 87.1, respectively. Bradycardia and repolarization abnormalities on 12-lead electrocardiography were the most specific markers for cardiac iron in thalassemia major. Changes in these variables may be helpful to stratify cardiac risk when cardiac MRI is unavailable. However, diagnostic algorithms need to be vetted on larger and more diverse patient populations and longitudinal studies are necessary to determine reversibility of the observed abnormalities.
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Affiliation(s)
- Jon Detterich
- Division of Cardiology, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
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Pennell DJ, Carpenter JP, Roughton M, Cabantchik ZI. On improvement in ejection fraction with iron chelation in thalassemia major and the risk of future heart failure. J Cardiovasc Magn Reson 2011; 13:45. [PMID: 21910880 PMCID: PMC3180261 DOI: 10.1186/1532-429x-13-45] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 09/12/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Trials of iron chelator regimens have increased the treatment options for cardiac siderosis in beta-thalassemia major (TM) patients. Treatment effects with improved left ventricular (LV) ejection fraction (EF) have been observed in patients without overt heart failure, but it is unclear whether these changes are clinically meaningful. METHODS This retrospective study of a UK database of TM patients modelled the change in EF between serial scans measured by cardiovascular magnetic resonance (CMR) to the relative risk (RR) of future development of heart failure over 1 year. Patients were divided into 2 strata by baseline LVEF of 56-62% (below normal for TM) and 63-70% (lower half of the normal range for TM). RESULTS A total of 315 patients with 754 CMR scans were analyzed. A 1% absolute increase in EF from baseline was associated with a statistically significant reduction in the risk of future development of heart failure for both the lower EF stratum (EF 56-62%, RR 0.818, p < 0.001) and the higher EF stratum (EF 63-70%, RR 0.893 p = 0.001). CONCLUSION These data show that during treatment with iron chelators for cardiac siderosis, small increases in LVEF in TM patients are associated with a significantly reduced risk of the development of heart failure. Thus the iron chelator induced improvements in LVEF of 2.6% to 3.1% that have been observed in randomized controlled trials, are associated with risk reductions of 25.5% to 46.4% for the development of heart failure over 12 months, which is clinically meaningful. In cardiac iron overload, heart mitochondrial dysfunction and its relief by iron chelation may underlie the changes in LV function.
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Affiliation(s)
- DJ Pennell
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London UK
- National Heart and Lung Institute, Imperial College, London UK
| | - JP Carpenter
- Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London UK
- National Heart and Lung Institute, Imperial College, London UK
| | - M Roughton
- Department of Statistics, University College London, UK
| | - ZI Cabantchik
- Life Sciences Institute, Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
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Kim D, Jensen JH, Wu EX, Feng L, Au WY, Cheung JS, Ha SY, Sheth SS, Brittenham GM. Rapid monitoring of iron-chelating therapy in thalassemia major by a new cardiovascular MR measure: the reduced transverse relaxation rate. NMR IN BIOMEDICINE 2011; 24:771-777. [PMID: 21190261 PMCID: PMC3138893 DOI: 10.1002/nbm.1639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 10/11/2010] [Accepted: 10/12/2010] [Indexed: 05/30/2023]
Abstract
In iron overload, almost all the excess iron is stored intracellularly as rapidly mobilizable ferritin iron and slowly exchangeable hemosiderin iron. Increases in cytosolic iron may produce oxidative damage that ultimately results in cardiomyocyte dysfunction. Because intracellular ferritin iron is evidently in equilibrium with the low-molecular-weight cytosolic iron pool, measurements of ferritin iron potentially provide a clinically useful indicator of changes in cytosolic iron. The cardiovascular magnetic resonance (CMR) index of cardiac iron used clinically, the effective transverse relaxation rate (R(2)*), is principally influenced by hemosiderin iron and changes only slowly over several months, even with intensive iron-chelating therapy. Another conventional CMR index of cardiac iron, the transverse relaxation rate (R(2)), is sensitive to both hemosiderin iron and ferritin iron. We have developed a new MRI measure, the 'reduced transverse relaxation rate' (RR(2)), and have proposed in previous studies that this measure is primarily sensitive to ferritin iron and largely independent of hemosiderin iron in phantoms mimicking ferritin iron and human liver explants. We hypothesized that RR(2) could detect changes produced by 1 week of iron-chelating therapy in patients with transfusion-dependent thalassemia. We imaged 10 patients with thalassemia major at 1.5 T in mid-ventricular short-axis planes of the heart, initially after suspending iron-chelating therapy for 1 week and subsequently after resuming oral deferasirox. After resuming iron-chelating therapy, significant decreases were observed in the mean myocardial RR(2) (7.8%, p < 0.01) and R(2) (5.5%, p < 0.05), but not in R(2)* (1.7%, p > 0.90). Although the difference between changes in RR(2) and R(2) was not significant (p > 0.3), RR(2) was consistently more sensitive than R(2) (and R(2)*) to the resumption of iron-chelating therapy, as judged by the effect sizes of relaxation rate differences detected. Although further studies are needed, myocardial RR(2) may be a promising investigational method for the rapid assessment of the effects of iron-chelating therapy in the heart.
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Affiliation(s)
- Daniel Kim
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, NY 10016, USA.
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Rose RA, Sellan M, Simpson JA, Izaddoustdar F, Cifelli C, Panama BK, Davis M, Zhao D, Markhani M, Murphy GG, Striessnig J, Liu PP, Heximer SP, Backx PH. Iron overload decreases CaV1.3-dependent L-type Ca2+ currents leading to bradycardia, altered electrical conduction, and atrial fibrillation. Circ Arrhythm Electrophysiol 2011; 4:733-42. [PMID: 21747058 DOI: 10.1161/circep.110.960401] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Chronic iron overload (CIO) is associated with blood disorders such as thalassemias and hemochromatosis. A major prognostic indicator of survival in patients with CIO is iron-mediated cardiomyopathy characterized by contractile dysfunction and electrical disturbances, including slow heart rate (bradycardia) and heart block. METHODS AND RESULTS We used a mouse model of CIO to investigate the effects of iron on sinoatrial node (SAN) function. As in humans, CIO reduced heart rate (≈20%) in conscious mice as well as in anesthetized mice with autonomic nervous system blockade and in isolated Langendorff-perfused mouse hearts, suggesting that bradycardia originates from altered intrinsic SAN pacemaker function. Indeed, spontaneous action potential frequencies in SAN myocytes with CIO were reduced in association with decreased L-type Ca(2+) current (I(Ca,L)) densities and positive (rightward) voltage shifts in I(Ca,L) activation. Pacemaker current (I(f)) was not affected by CIO. Because I(Ca,L) in SAN myocytes (as well as in atrial and conducting system myocytes) activates at relatively negative potentials due to the presence of Ca(V)1.3 channels (in addition to Ca(V)1.2 channels), our data suggest that elevated iron preferentially suppresses Ca(V)1.3 channel function. Consistent with this suggestion, CIO reduced Ca(V)1.3 mRNA levels by ≈40% in atrial tissue (containing SAN) and did not lower heart rate in Ca(V)1.3 knockout mice. CIO also induced PR-interval prolongation, heart block, and atrial fibrillation, conditions also seen in Ca(V)1.3 knockout mice. CONCLUSIONS Our results demonstrate that CIO selectively reduces Ca(V)1.3-mediated I(Ca,L), leading to bradycardia, slowing of electrical conduction, and atrial fibrillation as seen in patients with iron overload.
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Affiliation(s)
- Robert A Rose
- Department of Physiology, University Health Network, University of Toronto, Toronto, Ontario, Canada
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Russo V, Rago A, Pannone B, Papa AA, Di Meo F, Mayer MC, Spasiano A, Russo MG, Golino P, Calabrò R, Nigro G. Dispersion of repolarization and beta-thalassemia major: the prognostic role of QT and JT dispersion for identifying the high-risk patients for sudden death. Eur J Haematol 2011; 86:324-31. [PMID: 21255082 DOI: 10.1111/j.1600-0609.2011.01579.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vincenzo Russo
- Chair of Cardiology, Second University of Naples, Naples, Italy.
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Neven E, De Schutter TM, Behets GJ, Gupta A, D'Haese PC. Iron and vascular calcification. Is there a link? Nephrol Dial Transplant 2011; 26:1137-45. [PMID: 21325349 DOI: 10.1093/ndt/gfq858] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Iron deficiency is frequently seen in patients with end-stage renal disease, particularly in those treated by dialysis, this is because of an impairment in gastrointestinal absorption and ongoing blood losses or alternatively, due to an impaired capacity to mobilize iron from its stores, called functional iron deficiency. Therefore, these patients may require intravenous iron to sustain adequate treatment with erythropoietin-stimulating agents. Aside from this, they are also prone to vascular calcification, which has been reported a major contributing factor in the development of cardiovascular disease and the increased mortality associated herewith. Several factors and mechanisms underlying the development of vascular calcification in chronic kidney diseased patients have been put forward during recent years. In view of the ability of iron to exert direct toxic effects and to induce oxidative stress on the one hand versus its essential role in various cellular processes on the other hand, the possible role of iron in the development of vascular calcification should be considered.
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Affiliation(s)
- Ellen Neven
- Laboratory of Pathophysiology, Faculties of Medicine and Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Belgium
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Murphy CJ, Oudit GY. Iron-Overload Cardiomyopathy: Pathophysiology, Diagnosis, and Treatment. J Card Fail 2010; 16:888-900. [DOI: 10.1016/j.cardfail.2010.05.009] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 05/11/2010] [Accepted: 05/11/2010] [Indexed: 01/31/2023]
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ModuleNet: An R package on regulatory network building. CHINESE SCIENCE BULLETIN-CHINESE 2010. [DOI: 10.1007/s11434-010-3278-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Zacharski LR, McKernan L, Metzger ME, Malone MG, Samnotra V, Bhargava A, Steiner PR, Rauwerdink CA, Ornstein DL, Cornell CJ. Remission of paroxysmal atrial fibrillation with iron reduction in haemophilia A. Haemophilia 2010; 16:726-30. [PMID: 20236353 DOI: 10.1111/j.1365-2516.2010.02218.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
SUMMARY Two male first cousins with mild haemophilia A had baseline factor VIII levels of 12-15% and experienced bleeding requiring coagulation factor infusion therapy with trauma and surgical procedures. Both the patients with haemophilia A also had electrocardiographically documented symptomatic paroxysmal atrial fibrillation (PAF) for several years that had become resistant to pharmacological suppression. Radiofrequency ablation was considered in both the cases but deferred considering refusal of consent by the patients to undergo the procedure. Remission of arrhythmias has been reported in patients with iron-overload syndromes. Body iron stores assessed by serum ferritin levels were elevated in both men but neither had the C282Y or H63D genes for haemochromatosis. Calibrated reduction of iron stores by serial phlebotomy, avoiding iron deficiency, was followed by remission of symptomatic PAF in both cases. Iron reduction may be an effective treatment for arrhythmias apart from the classic iron-overload syndromes and deserves further study particularly in patients with bleeding disorders who might be at risk for arrhythmias and other diseases of ageing.
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Affiliation(s)
- L R Zacharski
- Section of Hematology/Oncology, Department of Medicine, Dartmouth Hitchcock Medical Center, Lebanon, NH, USA.
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