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Pizzo E, Cervantes DO, Ketkar H, Ripa V, Nassal DM, Buck B, Parambath SP, Di Stefano V, Singh K, Thompson CI, Mohler PJ, Hund TJ, Jacobson JT, Jain S, Rota M. Phosphorylation of cardiac sodium channel at Ser571 anticipates manifestations of the aging myopathy. Am J Physiol Heart Circ Physiol 2024; 326:H1424-H1445. [PMID: 38639742 DOI: 10.1152/ajpheart.00325.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 03/12/2024] [Accepted: 04/02/2024] [Indexed: 04/20/2024]
Abstract
Diastolic dysfunction and delayed ventricular repolarization are typically observed in the elderly, but whether these defects are intimately associated with the progressive manifestation of the aging myopathy remains to be determined. In this regard, aging in experimental animals is coupled with increased late Na+ current (INa,L) in cardiomyocytes, raising the possibility that INa,L conditions the modality of electrical recovery and myocardial relaxation of the aged heart. For this purpose, aging male and female wild-type (WT) C57Bl/6 mice were studied together with genetically engineered mice with phosphomimetic (gain of function, GoF) or ablated (loss of function, LoF) mutations of the sodium channel Nav1.5 at Ser571 associated with, respectively, increased and stabilized INa,L. At ∼18 mo of age, WT mice developed prolonged duration of the QT interval of the electrocardiogram and impaired diastolic left ventricular (LV) filling, defects that were reversed by INa,L inhibition. Prolonged repolarization and impaired LV filling occurred prematurely in adult (∼5 mo) GoF mutant mice, whereas these alterations were largely attenuated in aging LoF mutant animals. Ca2+ transient decay and kinetics of myocyte shortening/relengthening were delayed in aged (∼24 mo) WT myocytes, with respect to adult cells. In contrast, delayed Ca2+ transients and contractile dynamics occurred at adult stage in GoF myocytes and further deteriorated in old age. Conversely, myocyte mechanics were minimally affected in aging LoF cells. Collectively, these results document that Nav1.5 phosphorylation at Ser571 and the late Na+ current modulate the modality of myocyte relaxation, constituting the mechanism linking delayed ventricular repolarization and diastolic dysfunction.NEW & NOTEWORTHY We have investigated the impact of the late Na current (INa,L) on cardiac and myocyte function with aging by using genetically engineered animals with enhanced or stabilized INa,L, due to phosphomimetic or phosphoablated mutations of Nav1.5. Our findings support the notion that phosphorylation of Nav1.5 at Ser571 prolongs myocardial repolarization and impairs diastolic function, contributing to the manifestations of the aging myopathy.
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Affiliation(s)
- Emanuele Pizzo
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Daniel O Cervantes
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Harshada Ketkar
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, United States
| | - Valentina Ripa
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Drew M Nassal
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, United States
| | - Benjamin Buck
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Sreema P Parambath
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, United States
| | - Valeria Di Stefano
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Kanwardeep Singh
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Carl I Thompson
- Department of Physiology, New York Medical College, Valhalla, New York, United States
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Columbus, Ohio, United States
| | - Thomas J Hund
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Jason T Jacobson
- Department of Physiology, New York Medical College, Valhalla, New York, United States
- Department of Cardiology, Westchester Medical Center, Valhalla, New York, United States
| | - Sudhir Jain
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York, United States
| | - Marcello Rota
- Department of Physiology, New York Medical College, Valhalla, New York, United States
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Sillanmäki S, Vainio HL, Ylä-Herttuala E, Husso M, Hedman M. Measuring Cardiac Dyssynchrony with DENSE (Displacement Encoding with Stimulated Echoes)-A Systematic Review. Rev Cardiovasc Med 2023; 24:261. [PMID: 39076380 PMCID: PMC11270089 DOI: 10.31083/j.rcm2409261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/18/2023] [Accepted: 06/26/2023] [Indexed: 07/31/2024] Open
Abstract
Background In this review, we introduce the displacement encoding with stimulated echoes (DENSE) method for measuring myocardial dyssynchrony using cardiovascular magnetic resonance (CMR) imaging. We provide an overview of research findings related to DENSE from the past two decades and discuss other techniques used for dyssynchrony evaluation. Additionally, the review discusses the potential uses of DENSE in clinical practice. Methods A search was conducted to identify relevant articles published from January 2000 through January 2023 using the Scopus, Web of Science, PubMed and Cochrane databases. The following search term was used: (DENSE OR 'displacement encoding with stimulated echoes' OR CURE) AND (dyssynchrony* OR asynchron* OR synchron*) AND (MRI OR 'magnetic resonance' OR CMR). Results After removing duplicates, researchers screened a total of 174 papers. Papers that were not related to the topic, reviews, general overview articles and case reports were excluded, leaving 35 articles for further analysis. Of these, 14 studies focused on cardiac dyssynchrony estimation with DENSE, while the remaining 21 studies served as background material. The studies used various methods for presenting synchronicity, such as circumferential uniformity ratio estimate (CURE), CURE-singular value decomposition (SVD), radial uniformity ratio estimate (RURE), longitudinal uniformity ratio estimate (LURE), time to onset of shortening (TOS) and dyssynchrony index (DI). Most of the dyssynchrony studies concentrated on human heart failure, but congenital heart diseases and obesity were also evaluated. The researchers found that DENSE demonstrated high reproducibility and was found useful for detecting cardiac resynchronisation therapy (CRT) responders, optimising CRT device settings and assessing right ventricle synchronicity. In addition, studies showed a correlation between cardiac fibrosis and mechanical dyssynchrony in humans, as well as a decrease in the synchrony of contraction in the left ventricle in obese mice. Conclusions DENSE shows promise as a tool for quantifying myocardial function and dyssynchrony, with advantages over other cardiac dyssynchrony evaluation methods. However, there remain challenges related to DENSE due to the relatively time-consuming imaging and analysis process. Improvements in imaging and analysing technology, as well as possible artificial intelligence solutions, may help overcome these challenges and lead to more widespread clinical use of DENSE.
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Affiliation(s)
- Saara Sillanmäki
- Institute of Medicine, University of Eastern Finland, 70210 Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, 70029 Kuopio, Finland
| | - Hanna-Liina Vainio
- Institute of Medicine, University of Eastern Finland, 70210 Kuopio, Finland
| | - Elias Ylä-Herttuala
- Diagnostic Imaging Center, Kuopio University Hospital, 70029 Kuopio, Finland
- A.I. Virtanen Institute, University of Eastern Finland, 70210 Kuopio, Finland
| | - Minna Husso
- Diagnostic Imaging Center, Kuopio University Hospital, 70029 Kuopio, Finland
| | - Marja Hedman
- Institute of Medicine, University of Eastern Finland, 70210 Kuopio, Finland
- Diagnostic Imaging Center, Kuopio University Hospital, 70029 Kuopio, Finland
- Heart Center, Kuopio University Hospital, 70029 Kuopio, Finland
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Cervantes DO, Pizzo E, Ketkar H, Parambath SP, Tang S, Cianflone E, Cannata A, Vinukonda G, Jain S, Jacobson JT, Rota M. Scn1b expression in the adult mouse heart modulates Na + influx in myocytes and reveals a mechanistic link between Na + entry and diastolic function. Am J Physiol Heart Circ Physiol 2022; 322:H975-H993. [PMID: 35394857 PMCID: PMC9076421 DOI: 10.1152/ajpheart.00465.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/09/2022] [Accepted: 03/23/2022] [Indexed: 11/22/2022]
Abstract
Voltage-gated sodium channels (VGSCs) are macromolecular assemblies composed of a number of proteins regulating channel conductance and properties. VGSCs generate Na+ current (INa) in myocytes and play fundamental roles in excitability and impulse conduction in the heart. Moreover, VGSCs condition mechanical properties of the myocardium, a process that appears to involve the late component of INa. Variants in the gene SCN1B, encoding the VGSC β1- and β1B-subunits, result in inherited neurological disorders and cardiac arrhythmias. But the precise contributions of β1/β1B-subunits and VGSC integrity to the overall function of the adult heart remain to be clarified. For this purpose, adult mice with cardiac-restricted, inducible deletion of Scn1b (conditional knockout, cKO) were studied. Myocytes from cKO mice had increased densities of fast (+20%)- and slow (+140%)-inactivating components of INa, with respect to control cells. By echocardiography and invasive hemodynamics, systolic function was preserved in cKO mice, but diastolic properties and ventricular compliance were compromised, with respect to control animals. Importantly, inhibition of late INa with GS967 normalized left ventricular filling pattern and isovolumic relaxation time in cKO mice. At the cellular level, cKO myocytes presented delayed kinetics of Ca2+ transients and cell mechanics, defects that were corrected by inhibition of INa. Collectively, these results document that VGSC β1/β1B-subunits modulate electrical and mechanical function of the heart by regulating, at least in part, Na+ influx in cardiomyocytes.NEW & NOTEWORTHY We have investigated the consequences of deletion of Scn1b, the gene encoding voltage-gated sodium channel β1-subunits, on myocyte and cardiac function. Our findings support the notion that Scn1b expression controls properties of Na+ influx and Ca2+ cycling in cardiomyocytes affecting the modality of cell contraction and relaxation. These effects at the cellular level condition electrical recovery and diastolic function in vivo, substantiating the multifunctional role of β1-subunits in the physiology of the heart.
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Affiliation(s)
| | - Emanuele Pizzo
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Harshada Ketkar
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Sreema P Parambath
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Samantha Tang
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Eleonora Cianflone
- Department of Physiology, New York Medical College, Valhalla, New York
- Molecular and Cellular Cardiology, Department of Medical and Surgical Sciences, Magna Graecia University, Catanzaro, Italy
| | - Antonio Cannata
- School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | | | - Sudhir Jain
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Jason T Jacobson
- Department of Physiology, New York Medical College, Valhalla, New York
- Department of Cardiology, Westchester Medical Center, Valhalla, New York
| | - Marcello Rota
- Department of Physiology, New York Medical College, Valhalla, New York
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Vij A, Malhotra S. Left ventricular regional asynchrony: Earliest marker for ischemic cardiomyopathy? J Nucl Cardiol 2021; 28:1051-1054. [PMID: 32901419 DOI: 10.1007/s12350-020-02355-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 10/23/2022]
Affiliation(s)
- Aviral Vij
- Division of Cardiology, Cook County Health, Chicago, IL, USA
- Division of Cardiology, Rush Medical College, Chicago, IL, USA
| | - Saurabh Malhotra
- Division of Cardiology, Cook County Health, Chicago, IL, USA.
- Division of Cardiology, Rush Medical College, Chicago, IL, USA.
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Malhotra S. Dyssynchrony as a marker of adverse prognosis among patients with coronary artery disease and heart failure. J Nucl Cardiol 2020; 27:1633-1636. [PMID: 31722082 DOI: 10.1007/s12350-019-01945-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 10/21/2019] [Indexed: 10/25/2022]
Affiliation(s)
- Saurabh Malhotra
- Cook County Health, Chicago, IL, USA.
- Rush Medical College, Chicago, IL, USA.
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Ghosh GC, Ghosh RK, Bandyopadhyay D, Chatterjee K, Aneja A. Ranolazine: Multifaceted Role beyond Coronary Artery Disease, a Recent Perspective. Heart Views 2019; 19:88-98. [PMID: 31007857 PMCID: PMC6448470 DOI: 10.4103/heartviews.heartviews_18_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ranolazine is a piperazine derivative approved as an antianginal. Primarily used as a second-line antianginal in stable coronary artery disease. Ranolazine blocks the late Na + current and prevents the rise of cytosolic calcium. It decreases myocardial wall tension and improves coronary blood flow. Ranolazine is effective in atrial fibrillation (AF) as an adjunct to electrical or pharmacological cardioversion. It can be used in combination with amiodarone or dronedarone. It has also been used in AF arising after coronary artery bypass grafting surgery. Role of ranolazine is also being evaluated in pulmonary arterial hypertension, diastolic dysfunction, and chemotherapy-induced cardiotoxicity. Ranolazine has some anti-glycemic effect and has shown a reduction of hemoglobin A1c in multiple trials. The antianginal effect of ranolazine has also been seen to be more in patients with diabetes compared to those without diabetes. Ranolazine is being evaluated in patients with the peripheral arterial disease with intermittent claudication and hypertrophic cardiomyopathy. Pilot studies have shown that ranolazine may be beneficial in neurological conditions with myotonia. The evidence-base on the use of ranolazine in various conditions is rapidly increasing with results of further trials eagerly awaited. Accumulating evidence may see ranolazine in routine clinical use for many conditions beyond its traditional role as an antianginal.
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Affiliation(s)
- Gopal Chandra Ghosh
- Department of Cardiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Raktim Kumar Ghosh
- MetroHealth Medical Center, Case Western Reserve University, Heart and Vascular Institute, Cleveland, OH, USA
| | | | - Krishnarpan Chatterjee
- Department of Cardiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Ashish Aneja
- MetroHealth Medical Center, Case Western Reserve University, Heart and Vascular Institute, Cleveland, OH, USA
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Malhotra S, Pasupula DK, Sharma RK, Saba S, Soman P. Relationship between left ventricular dyssynchrony and scar burden in the genesis of ventricular tachyarrhythmia. J Nucl Cardiol 2018; 25:555-569. [PMID: 29110290 DOI: 10.1007/s12350-017-1095-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/25/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND Left ventricular (LV) ejection fraction (EF) has poor predictive value for ventricular tachyarrhythmia (VT). Other parameters such as LV dyssynchrony (LVD), and LV scar burden have also been individually associated with VT, but the interplay of these factors in the genesis of VT has not been explored. This retrospective study sought to evaluate the relationship between LVD and imaging characteristics of the myocardial substrate in predicting VT. METHODS We identified 183 patients (150 men; mean age: 64 ± 14 years and mean LVEF: 23% ± 7%), who received an implantable cardioverter defibrillator (ICD) for primary prevention and who underwent a gated single-photon emission computed tomography (GSPECT) myocardial perfusion scan prior to ICD implantation. LVD was determined by phase analysis of the GSPECT images. Occurrence of VTs was established through routine ICD interrogations and review of electronic medical records. RESULTS LVD was present in 136 (74%) patients. VT occurred in 48 (26%) patients. Ninety-eight percent of patient who experienced VT had LVD. Patients without LVD had a significantly better survival free of both sustained and non-sustained VT (HR, 95% CI 4.90, 2.12-11.20; P < 0.0001). The combination of LVD and myocardial scar occupying > 6% of LV myocardium accounted for 83% of all VT events. CONCLUSIONS LVD assessment by GSPECT is strongly associated with incident VT in patients with low LVEF. The combination of LVD and scar burden predicted the majority of VT events.
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Affiliation(s)
- Saurabh Malhotra
- Division of Cardiovascular Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Deepak K Pasupula
- Department of Internal Medicine, University of Pittsburgh Medical Center at McKeesport, McKeesport, PA, USA
| | - Ravi K Sharma
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Samir Saba
- Division of Cardiology, Heart and Vascular Institute, University of Pittsburgh Medical Center, A-429 Scaife Hall, 200 Lothrop Street, Pittsburgh, PA, 15213, USA
| | - Prem Soman
- Division of Cardiology, Heart and Vascular Institute, University of Pittsburgh Medical Center, A-429 Scaife Hall, 200 Lothrop Street, Pittsburgh, PA, 15213, USA.
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Antagonism of Nav channels and α1-adrenergic receptors contributes to vascular smooth muscle effects of ranolazine. Sci Rep 2015; 5:17969. [PMID: 26655634 PMCID: PMC4674695 DOI: 10.1038/srep17969] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/10/2015] [Indexed: 12/19/2022] Open
Abstract
Ranolazine is a recently developed drug used for the treatment of patients with chronic stable angina. It is a selective inhibitor of the persistent cardiac Na+ current (INa), and is known to reduce the Na+-dependent Ca2+ overload that occurs in cardiomyocytes during ischemia. Vascular effects of ranolazine, such as vasorelaxation,have been reported and may involve multiple pathways. As voltage-gated Na+ channels (Nav) present in arteries play a role in contraction, we hypothesized that ranolazine could target these channels. We studied the effects of ranolazine in vitro on cultured aortic smooth muscle cells (SMC) and ex vivo on rat aortas in conditions known to specifically activate or promote INa. We observed that in the presence of the Nav channel agonist veratridine, ranolazine inhibited INa and intracellular Ca2+ calcium increase in SMC, and arterial vasoconstriction. In arterial SMC, ranolazine inhibited the activity of tetrodotoxin-sensitive voltage-gated Nav channels and thus antagonized contraction promoted by low KCl depolarization. Furthermore, the vasorelaxant effects of ranolazine, also observed in human arteries and independent of the endothelium, involved antagonization of the α1-adrenergic receptor. Combined α1-adrenergic antagonization and inhibition of SMCs Nav channels could be involved in the vascular effects of ranolazine.
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Abstract
: We used the isolated working rat model to evaluate the effect of therapeutic concentrations (5-10 μM) of ranolazine on contractile performance, oxygen consumption, irreversible ischemic injury, and sarcoplasmic reticulum (SR) function. Ischemic injury was induced by 30 minutes of global ischemia followed by 120 minutes of Langendorff reperfusion and evaluated on the basis of triphenyltetrazolium chloride staining. SR function was determined on the basis of [H]-ryanodine binding, the kinetics of calcium-induced calcium release, measured by quick filtration technique, and oxalate-supported calcium uptake. In working hearts, ranolazine significantly reduced oxygen consumption (P = 0.031), in the absence of significant changes in contractile performance, and decreased irreversible ischemic injury (P = 0.011), if administered either before ischemia-reperfusion (25.4% ± 4.7% vs. 42.7% ± 6.0%) or only at the time of reperfusion (20.2% ± 5.2% vs. 43.7% ± 9.9%). In SR experiments, treatment with ranolazine determined a significant reduction in [H]-ryanodine binding (P = 0.029), because of decreased binding site density (369 ± 9 vs. 405 ± 12 fmol/mg), and in the kinetics of SR calcium release (P = 0.011), whose rate constant was decreased, whereas active calcium uptake was not affected. Ranolazine effectiveness at reperfusion and its ability to module SR calcium release suggest that this drug might be particularly useful to induce cardioprotection during coronary revascularization interventions, although the relevance of the effects on calcium homeostasis remains to be determined.
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Serial myocardial perfusion imaging: defining a significant change and targeting management decisions. JACC Cardiovasc Imaging 2015; 7:79-96. [PMID: 24433711 DOI: 10.1016/j.jcmg.2013.05.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 05/20/2013] [Accepted: 05/30/2013] [Indexed: 12/22/2022]
Abstract
Myocardial perfusion imaging (MPI) with gated single-photon emission tomography provides important information on the extent and severity of myocardial perfusion abnormalities, including myocardial ischemia. The availability of software for automated quantitative assessment of myocardial perfusion in an objective and more reproducible manner than visual assessment has allowed MPI to be particularly effective in serial evaluation. Serial testing using MPI is widely used in guiding patient care despite the lack of well-defined appropriateness use criteria. This should not be surprising because ischemic heart disease is a life-long malady subject to dynamic changes throughout its natural course and particularly following man-made interventions that may improve or worsen the disease process, such as medical therapy and coronary revascularization. Serial MPI has filled an important clinical gap by providing crucial information for managing patients with changes in clinical presentations or in anticipation of such changes in patients with stable symptoms. In the research arena, serial MPI has been widely applied in randomized controlled trials to study the impact of various medical and interventional therapies on myocardial perfusion, as well as the relative merits of new imaging procedures (hardware and/or software), radiotracers, and stressor agents. Serial testing, however, unlike initial or 1-time testing, has more stringent requirements and is subject to variability because of technical, procedural, interpretational, and biological factors. The intrinsic variability of MPI becomes important in interpreting serial tests in order to define a true change in a given patient and to guide clinical decision making. The purpose of this first comprehensive review on this subject is to illustrate where serial MPI may be useful clinically and in research studies, and to highlight strategies for addressing the various issues that are unique to serial testing in order to derive more valid and robust data from the serial scans.
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Horvath B, Bers DM. The late sodium current in heart failure: pathophysiology and clinical relevance. ESC Heart Fail 2014; 1:26-40. [PMID: 28834665 DOI: 10.1002/ehf2.12003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 07/13/2014] [Accepted: 07/14/2014] [Indexed: 12/19/2022] Open
Abstract
Large and growing body of data suggest that an increased late sodium current (INa,late ) can have a significant pathophysiological role in heart failure and other heart diseases. The first goal of this article is to describe how INa,late functions under physiological circumstances. The second goal is to show the wide range of cellular mechanisms that can increase INa,late in cardiac disease, and also to describe how the up-regulated INa,late contributes to the pathophysiology of heart failure. The final section of the article discusses the possible use of INa,late -modifying drugs in heart failure, on the basis of experimental and preclinical data.
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Affiliation(s)
- Balazs Horvath
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| | - Donald M Bers
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
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Pourrier M, Williams S, McAfee D, Belardinelli L, Fedida D. CrossTalk proposal: The late sodium current is an important player in the development of diastolic heart failure (heart failure with a preserved ejection fraction). J Physiol 2014; 592:411-4. [PMID: 24488066 DOI: 10.1113/jphysiol.2013.262261] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Abstract
The effective treatment of coronary artery disease targets two distinct goals, controlling symptomatic angina and decreasing the adverse events associated with ischemia. Traditional anti-anginal and anti-ischemic drugs function by altering the determinants of myocardial oxygen supply or demand, usually by altering loading conditions, changing the heart rate, or impacting contractility. Blockade of the late inward sodium current, late I(Na), offers another target for the treatment of ischemia. Blockade of late I(Na) reduces the sodium and calcium overload that follows ischemia. This improves myocardial relaxation and reduces left ventricular diastolic stiffness, in turn enhancing myocardial contractility and perfusion. Ranolazine, a late I(Na) inhibitor, has been shown to provide both anti-anginal and anti-ischemic benefits without significant alterations in the heart rate and blood pressure in patients with stable coronary artery disease. When evaluated in patients with acute coronary syndrome, ranolazine has been shown to decrease recurrent ischemia, but not significantly reduce the risk of death or myocardial infarction. This review will address the rationale that inhibition of the late sodium current is beneficial in reducing cardiac dysfunction during ischemia, and discuss the clinical studies supporting the use of ranolazine for its anti-anginal and anti-ischemic effects.
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Madonna R, Cevik C, Nasser M. Electrical plasticity and cardioprotection in myocardial ischemia--role of selective sodium channel blockers. Clin Cardiol 2013; 36:255-61. [PMID: 23529949 DOI: 10.1002/clc.22113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/11/2013] [Indexed: 11/08/2022] Open
Abstract
The concept of electrical protection of the ischemic myocardium is in constant evolution and has recently been supported by experimental and clinical studies. Historically, antiplatelet agents, angiotensin-converting enzyme inhibitors, β-blockers, and statins have been all proposed as drugs conferring anti-ischemic cardioprotection. This was supported by the evidence consistently indicating that all these drugs were capable of reducing mortality and the risk of repeat myocardial infarction. The electrical plasticity paradigm is, however, a novel concept that depicts the benefits of improved sodium channel blockade with drugs such as ranolazine and cariporide. Although it has been hypothesized that the protective role of ranolazine depends on decreased fatty acid β-oxidation affecting preconditioning, we speculate against such a hypothesis, because inhibition of β-oxidation requires higher concentrations of the drug, above the therapeutic range. Rather, we discuss the key role of calcium overload reduction through inhibition of the late sodium current (I(Na)). Mechanisms driving cardioprotection involve the block of a cascade of complex ionic exchanges that can result in intracellular acidosis, excess cytosolic calcium, myocardial cellular dysfunction, and eventually cell injury and death. In this review we discuss the studies that demonstrate how electrical plasticity through sodium channel blockers can promote cardioprotection against ischemia in coronary heart disease.
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Affiliation(s)
- Rosalinda Madonna
- Texas Heart Institute and St. Luke's Episcopal Hospital, Department of adult cardiiology, Houston, Texas, USA.
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Abstract
Ranolazine is currently approved for use in chronic angina. The basis for this use is likely related to inhibition of late sodium channels with resultant beneficial downstream effects. Randomized clinical trials have demonstrated an improvement in exercise capacity and reduction in angina episodes with ranolazine. This therapeutic benefit occurs without the hemodynamic effects seen with the conventional antianginal agents. The inhibition of late sodium channels as well as other ion currents has a central role in the potential use of ranolazine in ischemic heart disease, arrhythmias, and heart failure. Despite its QTc-prolonging action, albeit minimal, clinical data have not shown a predisposition to torsades de pointes, and the medication has shown a reasonable safety profile even in those with structural heart disease. In this article we present the experimental and clinical data that support its current therapeutic role, and provide insight into potential future clinical applications.
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Affiliation(s)
- Nael Hawwa
- Internal Medicine Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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