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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Brugada syndrome is an inherited arrhythmogenic and nonstructural heart disease that may cause syncope and sudden cardiac death (SCD). It is characterized by ST segment elevation in the right precordial leads (V1-V3) and male predominance. Mutation on SCN5A encoding the alpha-subunit of the sodium channel is seen in 20%-30% of patients with the syndrome. Because of low penetrance of gene mutation, clinical manifestations and prognosis can be variable in individuals. Therefore, asymptomatic population with Brugada-type electrocardiogram (ECG) exists in community and SCD risk stratification of the individual can be problematic. Although understanding of the cellular mechanism of the syndrome has advanced, there are conflicting data about its prevalence and prognosis. Population-based genetic epidemiology studies with longer follow-up periods may be able to elucidate clinical outcome of the syndrome, particularly asymptomatic patients.
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PMID:Brugada syndrome and Brugada-type electrocardiogram. 1843 88

A 51-year-old woman presented with an episode of syncope. Upon further review she was found to have a typical Brugada type pattern on her electrocardiogram. She did not have evidence for structural heart disease. At electrophysiological testing she was found to have marked infrahisian conduction disease and had easily inducible polymorphic ventricular tachycardia. She underwent implantation of a dual-chamber implantable cardioverter defibrillator (ICD) and family screening was recommended. Genetic analysis revealed a novel nonsense mutation in the gene encoding for the sodium channel (SCN5A). Five months after ICD implantation the patient had an episode of ventricular fibrillation documented on ICD interrogation. This case is unique as it is consistent with an overlap syndrome, namely both Brugada Syndrome and distal atrioventricular (AV) conduction disease secondary to a novel SCN5A mutation in a young female. This finding highlights the phenotypic heterogeneity of novel SCN5A mutations.
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PMID:Brugada syndrome with marked conduction disease: dual implications of a SCN5A mutation. 1843 84

By 2050, atrial fibrillation (AF) will be present in 2% of the general population and in a far higher proportion of elderly patients. Currently, we are content with rate control and anticoagulation in elderly asymptomatic patients, whereas in younger patients with symptomatic recurrent AF, pulmonary vein isolation is the treatment of choice. However, in a large number of patients, there remains a genuine choice between anti-arrhythmic therapy to suppress the arrhythmia and rate control to control the ventricular rate. This review provides a contemporary evidence-based insight into the buoyant development of new anti-arrhythmic agents, exploring new mechanisms of action or novel combinations of established anti-arrhythmic activity. An attractive prospect for AF therapy is the introduction of agents with selective affinity to ion channels specifically involved in atrial repolarization, so-called atrial repolarization-delaying agents. Presently, there are several potential anti-arrhythmic drugs with this mode of action, which are currently in pre-clinical and clinical development. Vernakalant is in the most advanced phase of investigation and its intravenous formulation has recently been recommended for approval for pharmacological cardioversion of AF. However, although this agent has some electrophysiological effects which are specific to the atria, it has others which affect both the atria and the ventricles. Other drugs, such as XEND0101, block a single atrial-specific membrane current. The success of such agents depends critically on their atrial electrophysiological selectivity, freedom from cardiac adverse effects, and general safety. Other possibilities include modified analogues of traditional anti-arrhythmic drugs with additional novel mechanisms of action and less complex metabolic profiles. Dronedarone is an investigational agent with multiple electrophysiological effects, which is devoid of iodine substituents and is believed to have a better side effect profile than its predecessor amiodarone. The development portfolio of dronedarone is practically complete and approval for several indications in AF may soon be assessed. Innovative anti-arrhythmic agents with unconventional anti-arrhythmic mechanisms, such as stretch receptor antagonism, sodium-calcium exchanger blockade, late sodium channel inhibition, and gap junction modulation, have not yet reached clinical studies in AF. Gene- and cell-based therapies, which can selectively target individual currents, could provide ideal one-time only curative therapy for arrhythmias, and the first proof-of-concept studies have been reported. There is accumulating evidence in support of the anti-arrhythmic effects of non-anti-arrhythmic drugs. Treatments with angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, statins, and omega-3 fatty acids all seem promising, over and above any effect related to the treatment of underlying heart disease. However, despite exciting results from animal experiments and promising outcomes from retrospective analyses, there is no robust evidence of specific effects of these drugs to transform current clinical practice.
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PMID:Anti-arrhythmic drug therapy for atrial fibrillation: current anti-arrhythmic drugs, investigational agents, and innovative approaches. 1851 86

The prevalence of atrial fibrillation (AF) is forecast to rise to 2-5% of the general population by 2050. Of the two fundamental treatment strategies for AF management, rhythm control is the approach which is generally preferred for active, symptomatic, and/or younger patients, whereas rate control is all that is found necessary in the more elderly, sedentary, asymptomatic individual. In many cases, at neither extreme, there remains a genuine choice of therapy, and for those patients, antiarrhythmic strategies would be preferred if effective and safe antiarrhythmic medications were available. Many new antiarrhythmic agents exploiting new mechanisms of action or novel combinations of established antiarrhythmic activity are currently being investigated. Agents which selectively inhibit ion channels specifically involved in atrial repolarization, so-called atrial repolarization delaying agents, are widely acknowledged as potentially ideal antiarrhythmic treatments, as they will probably be both effective and safe, at the very least (free of pro-arrhythmic effects at the ventricular level). Modified analogues of traditional antiarrhythmic drugs with different combinations of ion channel and receptor blocking effects, novel mechanisms of action, and less complicated metabolic profiles are also under development. Completely innovative antiarrhythmic agents with new antiarrhythmic mechanisms, such as stretch receptor antagonism, sodium calcium exchanger blockade, late sodium channel inhibition, and gap junction modulation are also being explored. In addition, there is increasing evidence in support of the antiarrhythmic action of non-antiarrhythmic drugs. Treatments with statins, omega-3 fatty acids, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, and aldosterone antagonists are all potentially valuable, over and above any effect related to the treatment of underlying heart disease.
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PMID:New antiarrhythmic drugs for atrial fibrillation: focus on dronedarone and vernakalant. 1852 40

Brugada syndrome (BrS) is a primary electrical heart disease, which can lead to sudden cardiac death. In older patients with BrS, the disease may coexist with ischaemic heart disease (IHD) and recent studies support a synergistic proarrhythmic effect of the two disease entities. We report a case that illustrates this. The index patient was a middle-aged patient with BrS traits, IHD, and aborted sudden cardiac death. Mutation analysis discovered a novel mutation P468L in the Na(V)1.5 sodium channel. Surprisingly, voltage-clamp experiments on the wild-type and mutant Na(V)1.5 channels expressed in HEK cells revealed no functional effect of the mutation. In a patient like ours, the distinction between IHD and BrS as the cause of an aborted sudden cardiac death is hard to establish and mounting evidence shows that coexistence of the two may have a synergistic proarrhythmic effect.
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PMID:A Novel SCN5A Mutation in a Patient with Coexistence of Brugada Syndrome Traits and Ischaemic Heart Disease. 1982 66

The Brugada syndrome is an inherited cardiac disorder initially described in 1992 by Pedro and Josep Brugada, with variable electrocardiographic features characteristic of right bundle-branch block, persistent ST-segment elevation in the precordial leads (VI-V3) at rest and sudden cardiac death. The genetic abnormalities that cause Brugada syndrome have been linked to mutations in the ion channel gene SCN5A which encodes for the alpha-subunit of the cardiac sodium channel. A consensus conference report published in 2002 described the diagnostic criteria for the Brugada syndrome and described the three distinct types of Brugada syndrome. In 2005, a second consensus report was published which described the risk stratification and approaches to therapy. Two specific types of ST-segment elevation, coved and saddleback, are observed in the Brugada syndrome, the former of which is reported to relate to a higher incidence of ventricular tachycardial ventricular fibrillation (VTNF) and sudden cardiac death.The objective of this paper is to review the genetics and the molecular biology behind the Brugada syndrome, the diagnostic criteria, including clinical and electrocardiographic characteristics, and current management.
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PMID:The Brugada syndrome. 2012 57

Brugada syndrome is characterized by the electrocardiographic (ECG) pattern of right bundle-branch block (RBBB) with a high take-off, coved ST-segment elevation in the precordial leads V1 to V3, and the risk of sudden cardiac death. Typically, there is no evidence of structural heart disease. In many cases, Brugada syndrome has been linked to a mutation of the gene SCN5A, which encodes for the fast cardiac sodium channel. In patients with the Brugada syndrome, pharmacologic sodium channel blockade can increase the degree of ST-segment elevation. Interestingly, even in patients with a normal baseline ECG and no clinical suggestion of the Brugada syndrome, toxic doses of class I antiarrhythmic agents as well as toxicities with several nonantiarrhythmic drugs that possess sodium channel blocking properties can induce the Brugada ECG abnormality. Specifically, the beta-receptor blocker propranolol, at high doses, binds to the cardiac sodium channels and inhibits sodium uptake. In this report, we describe a case of severe propranolol toxicity, which resulted in the Brugada ECG pattern in an otherwise healthy individual who had no clinical or ECG suggestion of the genetically determined Brugada syndrome.
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PMID:Brugada-pattern electrocardiogram in propranolol intoxication. 2015 10

Current pharmacologic strategies for the management of Atrial fibrillation (AF) include use of 1) sodium channel blockers, which are contraindicated in patients with coronary artery or structural heart disease because of their potent effect to slow conduction in the ventricles, 2) potassium channel blockers, which predispose to acquired long QT and Torsade de Pointes arrhythmias because of their potent effect to prolong ventricular repolarization, and 3) mixed ion channel blockers such as amiodarone, which are associated with multi-organ toxicity. Accordingly, recent studies have focused on agents that selectively affect the atria but not the ventricles. Several Atrial-selective approaches have been proposed for the management of AF, including inhibition of the Atrial-specific ultra rapid delayed rectified potassium current (IKur), acetylcholine-regulated inward rectifying potassium current (IK-ACh), or connexin-40 (Cx40). All three are largely exclusive to atria. Recent studies have proposed that an Atrial-selective depression of sodium channel-dependent parameters with agents such as ranolazine may be an alternative approach capable of effectively suppressing AF without increasing susceptibility to ventricular arrhythmias. Clinical evidence for Cx40 modulation or IK-ACh inhibition are lacking at this time. The available data suggest that Atrial-selective approaches involving a combination of INa, IKur, IKr, and, perhaps, Ito block may be more effective in the management of AF than pure IKur or INa block. The anti-AF efficacy of the Atrial-selective/predominant agents appears to be similar to that of conventionally used anti-AF agents, with the major apparent difference being that the latter are associated with ventricular arrhythmogenesis and extra cardiac toxicity.
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PMID:How Do Atrial-Selective Drugs Differ From Antiarrhythmic Drugs Currently Used in the Treatment of Atrial Fibrillation? 2105 83

The long QT syndrome (LQTS) is an inherited cardiac arrhythmia that may lead to sudden death in the absence of structural heart disease. Mutations in the cardiac potassium and sodium channel genes can be found in approximately 70 percent of patients with a highly probable clinical diagnosis. In this study, we aimed to genotype and explore the yield of genetic testing of LQTS patients from Greece, for whom there are no collective published data available. We clinically evaluated and genetically screened 17 unrelated patients for mutations in the KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 cardiac ion channel genes. Genetic testing was positive in 6 out of 8 patients with a highly probable clinical diagnosis of LQTS and negative for all the other patients. Two patients carried KCNQ1 mutations (c.580G>C, c.1022C>T), while 4 patients carried KCNH2 mutations (c.202T>C, c.1714G>A, c.3103delC, c.3136C>T). To the best of our knowledge, the last mentioned mutation (c.3136C>T) is novel. Moreover, 27 single-nucleotide polymorphisms (SNPs) were detected, 5 of which are novel. Our preliminary data indicate a low genetic diversity of the Greek LQTS genetic pool, and are in accordance with international data that genetic testing of the major LQTS genes is efficient in genotyping the majority of patients with a strong clinical diagnosis. Therefore, the transition of an LQTS genetic screening program from research to the diagnostic setting within our ethnic background is feasible.
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PMID:Cardiac ion channel gene mutations in Greek long QT syndrome patients. 2106 70

Class I antiarrhythmic drugs are sodium channel inhibitors that act by slowing myocardial conduction and, thus, interrupting or preventing reentrant arrhythmia. Due to proarrhythmic effects and the risk of ventricular tachyarrhythmia, class I antiarrhythmics should not be administered in patients with structural heart disease. Nevertheless, there remains a broad spectrum of arrhythmias--among the most common being atrial fibrillation--that can successfully be treated with class I antiarrhythmic drugs. This review gives an overview on the classification, antiarrhythmic mechanisms, indications, side effects, and application modes of class I antiarrhythmic drugs.
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PMID:[Class I antiarrhythmic drugs: mechanisms, contraindications, and current indications]. 2111 5


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