-
Cardiology Journal 2008Despite the advancements in pharmacological and non-pharmacological management of atrial fibrillation (AF) observed during last decades, available treatment modalities... (Review)
Review
Despite the advancements in pharmacological and non-pharmacological management of atrial fibrillation (AF) observed during last decades, available treatment modalities and predictors of their success are still far from optimal. Understanding of pathophysiological mechanisms underlying AF and assessment of atrial electrophysiological properties using easily available non-invasive diagnostic tools such as surface ECG are essential for further improvement of patient-tailored treatment strategies. P-wave duration is generally accepted as the most reliable non-invasive marker of atrial conduction and its prolongation has been associated with history of AF. However, patients with paroxysmal AF without structural heart disease may not have any impressive P-wave prolongation thus suggesting that the global conduction slowing is not an obligatory requirement for development of AF. In these settings, the morphology of P-wave becomes an important source of information concerning propagation of atrial activation. One of the most common morphologies, i.e. biphasic configuration of P-waves in right precordial leads has been considered a marker of left atrial enlargement but, seen in patients with structurally normal hearts, appears to be linked to an interatrial conduction defect. Recent advances in endocardial mapping technologies have linked certain P-wave morphologies with interatrial conduction patterns that may have clinical implications for invasive treatment of AF patients. The value of P-wave morphology extends beyond cardiac arrhythmias associated with atrial conduction delay and can be used for prediction of clinical outcome of wide range of cardiovascular disorders such as survival after myocardial infarction or the risk of stroke.
Topics: Atrial Fibrillation; Electrocardiography; Heart Atria; Heart Conduction System; Humans
PubMed: 18810714
DOI: No ID Found -
Journal of the American College of... Feb 2008Atrial fibrillation (AF) is the most common arrhythmia in the clinical setting, and traditional pharmacological approaches have proved to have important weaknesses.... (Review)
Review
Atrial fibrillation (AF) is the most common arrhythmia in the clinical setting, and traditional pharmacological approaches have proved to have important weaknesses. Structural remodeling has been observed in both clinical and experimental AF paradigms, and is an important feature of the AF substrate, producing fibrosis that alters atrial tissue composition and function. The precise mechanisms underlying atrial fibrosis are not fully elucidated, but recent experimental studies and clinical investigations have provided valuable insights. A variety of signaling systems, particularly involving angiotensin II and related mediators, seem to be centrally involved in the promotion of fibrosis. This paper reviews the current understanding of how atrial fibrosis creates a substrate for AF, summarizes what is known about the mechanisms underlying fibrosis and its progression, and highlights emerging therapeutic approaches aimed at attenuating structural remodeling to prevent AF.
Topics: Animals; Anti-Arrhythmia Agents; Atrial Fibrillation; Fibrosis; Heart Atria; Humans
PubMed: 18294563
DOI: 10.1016/j.jacc.2007.09.064 -
European Heart Journal. Cardiovascular... Dec 2021Atrial arrhythmias, including atrial fibrillation and atrial flutter, may be treated through catheter ablation. The process of atrial arrhythmia catheter ablation, which... (Review)
Review
Atrial arrhythmias, including atrial fibrillation and atrial flutter, may be treated through catheter ablation. The process of atrial arrhythmia catheter ablation, which includes patient selection, pre-procedural planning, intra-procedural guidance, and post-procedural assessment, is typically characterized by the use of several imaging modalities to sequentially inform key clinical decisions. Increasingly, advanced imaging modalities are processed via specialized image analysis techniques and combined with intra-procedural electrical measurements to inform treatment approaches. Here, we review the use of multimodality imaging for left atrial ablation procedures. The article first outlines how imaging modalities are routinely used in the peri-ablation period. We then describe how advanced imaging techniques may inform patient selection for ablation and ablation targets themselves. Ongoing research directions for improving catheter ablation outcomes by using imaging combined with advanced analyses for personalization of ablation targets are discussed, together with approaches for their integration in the standard clinical environment. Finally, we describe future research areas with the potential to improve catheter ablation outcomes.
Topics: Atrial Fibrillation; Atrial Flutter; Catheter Ablation; Heart Atria; Humans; Multimodal Imaging; Treatment Outcome
PubMed: 34747450
DOI: 10.1093/ehjci/jeab205 -
Cardiovascular Diabetology Nov 2020Metformin has been shown to have various cardiovascular benefits beyond its antihyperglycemic effects, including a reduction in stroke, heart failure, myocardial... (Review)
Review
Metformin has been shown to have various cardiovascular benefits beyond its antihyperglycemic effects, including a reduction in stroke, heart failure, myocardial infarction, cardiovascular death, and all-cause mortality. However, the roles of metformin in cardiac arrhythmias are still unclear. It has been shown that metformin was associated with decreased incidence of atrial fibrillation in diabetic patients with and without myocardial infarction. This could be due to the effects of metformin on preventing the structural and electrical remodeling of left atrium via attenuating intracellular reactive oxygen species, activating 5' adenosine monophosphate-activated protein kinase, improving calcium homeostasis, attenuating inflammation, increasing connexin-43 gap junction expression, and restoring small conductance calcium-activated potassium channels current. For ventricular arrhythmias, in vivo reports demonstrated that activation of 5' adenosine monophosphate-activated protein kinase and phosphorylated connexin-43 by metformin played a key role in ischemic ventricular arrhythmias reduction. However, metformin failed to show anti-ventricular arrhythmia benefits in clinical trials. In this review, in vitro and in vivo reports regarding the effects of metformin on both atrial arrhythmias and ventricular arrhythmias are comprehensively summarized and presented. Consistent and controversial findings from clinical trials are also summarized and discussed. Due to limited numbers of reports, further studies are needed to elucidate the mechanisms and effects of metformin on cardiac arrhythmias. Furthermore, randomized controlled trials are needed to clarify effects of metformin on cardiac arrhythmias in human.
Topics: Action Potentials; Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Heart Atria; Heart Rate; Heart Ventricles; Humans; Hypoglycemic Agents; Metformin; Myocytes, Cardiac
PubMed: 33234131
DOI: 10.1186/s12933-020-01176-4 -
Current Cardiology Reviews 2015Atrial tachycardias are common after open heart surgery. Most commonly these are macro-reentrant including cavotricuspid isthmus dependent atrial flutter, incisional... (Review)
Review
Atrial tachycardias are common after open heart surgery. Most commonly these are macro-reentrant including cavotricuspid isthmus dependent atrial flutter, incisional right atrial flutter and left atrial flutter. Focal atrial tachycardias occur less frequently. The specific type of atrial tachycardia highly depends on the type of surgical incision. Catheter ablation can be very effective, however requires a thorough understanding of anatomy and surgical technique.
Topics: Arrhythmias, Cardiac; Atrial Flutter; Cardiac Surgical Procedures; Catheter Ablation; Heart Atria; Humans; Postoperative Complications
PubMed: 25308810
DOI: 10.2174/1573403x10666141013122021 -
The Journal of Physiology Jun 2017Atrial fibrillation (AF) is a common arrhythmia. Better prevention and treatment of AF are needed to reduce AF-associated morbidity and mortality. There are several... (Review)
Review
Atrial fibrillation (AF) is a common arrhythmia. Better prevention and treatment of AF are needed to reduce AF-associated morbidity and mortality. There are several major mechanisms that cause AF in patients, including a genetic predisposition to develop AF. Genome-wide association studies have identified genetic variants associated with AF populations, with the strongest hits clustering on chromosome 4q25, close to the gene for the homeobox transcription factor PITX2. The effect of these common gene variants on cardiac PITX2 mRNA is currently under study. PITX2 protein regulates right-left differentiation of the embryonic heart, thorax and aorta. PITX2 is expressed in the adult left atrium, but much less so in other heart chambers. Pitx2 deficiency results in electrical and structural remodelling, and impaired repair of the heart in murine models, all of which may influence AF through divergent mechanisms. PITX2 levels and single nucleotide polymorphisms on chromosome 4q25 may also be a predictor of the effectiveness of anti-arrhythmic drug therapy.
Topics: Animals; Arrhythmias, Cardiac; Atrial Fibrillation; Chromosomes, Human, Pair 4; Gene Expression Regulation; Genetic Predisposition to Disease; Genome-Wide Association Study; Heart Atria; Homeodomain Proteins; Humans; Polymorphism, Single Nucleotide; Transcription Factors; Homeobox Protein PITX2
PubMed: 28217939
DOI: 10.1113/JP273123 -
Annals of Noninvasive Electrocardiology... Jul 2012Increasing awareness of atrial fibrillation (AF) and its impact on public health revives interest in identification of noninvasive markers of predisposition to AF and... (Comparative Study)
Comparative Study Review
Increasing awareness of atrial fibrillation (AF) and its impact on public health revives interest in identification of noninvasive markers of predisposition to AF and ECG-based risk stratification. P-wave duration is generally accepted as the most reliable noninvasive marker of atrial conduction, and its prolongation has been associated with history of AF. However, patients with paroxysmal AF without structural heart disease may not have any impressive P-wave prolongation, thus suggesting that global conduction slowing is not an obligatory requirement for development of AF. P-wave morphology is therefore drawing increasing attention as it reflects the three-dimensional course of atrial depolarization propagation and detects local conduction disturbances. The factors that determine P-wave appearance include (1) the origin of the sinus rhythm that defines right atrial depolarization vector, (2) localization of left atrial breakthrough that defines left atrial depolarization vector, and (3) the shape and size of atrial chambers. However, it is often difficult to distinguish whether P-wave abnormalities are caused by atrial enlargement or interatrial conduction delay. Recent advances in endocardial mapping technologies have linked certain P-wave morphologies with interatrial conduction patterns and the function of major interatrial conduction routes. The value of P-wave morphology extends beyond cardiac arrhythmias associated with atrial conduction delay and can be used for prediction of clinical outcome of a wide range of cardiovascular disorders, including ischemic heart disease and congestive heart failure.
Topics: Atrial Fibrillation; Coronary Artery Disease; Electrocardiography; Female; Heart Atria; Heart Conduction System; Heart Failure; Humans; Male; Myocardial Ischemia; Predictive Value of Tests; Prognosis; Risk Assessment; Severity of Illness Index
PubMed: 22816534
DOI: 10.1111/j.1542-474X.2012.00534.x -
Medicina (Kaunas, Lithuania) 2017Atrial fibrillation is the most common sustained arrhythmia and its prevalence is rapidly rising with the aging of the population. Cardiac alternans, defined as cyclic... (Review)
Review
Atrial fibrillation is the most common sustained arrhythmia and its prevalence is rapidly rising with the aging of the population. Cardiac alternans, defined as cyclic beat-to-beat alternations in contraction force, action potential (AP) duration and intracellular Ca release at constant stimulation rate, has been associated with the development of ventricular arrhythmias. Recent clinical data also provide strong evidence that alternans plays a central role in arrhythmogenesis in atria. The aim of this article is to review the mechanisms that are responsible for repolarization alternans and contribute to the transition from spatially concordant alternans to the more arrhythmogenic spatially discordant alternans in atria.
Topics: Action Potentials; Arrhythmias, Cardiac; Atrial Fibrillation; Heart Atria; Humans; Myocytes, Cardiac
PubMed: 28666575
DOI: 10.1016/j.medici.2017.04.004 -
JCI Insight Sep 2020Atrial fibrillation (AF) is the most common cardiac arrhythmia, yet the molecular signature of the vulnerable atrial substrate is not well understood. Here, we...
Atrial fibrillation (AF) is the most common cardiac arrhythmia, yet the molecular signature of the vulnerable atrial substrate is not well understood. Here, we delineated a distinct transcriptional signature in right versus left atrial cardiomyocytes (CMs) at baseline and identified chamber-specific gene expression changes in patients with a history of AF in the setting of end-stage heart failure (AF+HF) that are not present in heart failure alone (HF). We observed that human left atrial (LA) CMs exhibited Notch pathway activation and increased ploidy in AF+HF but not in HF alone. Transient activation of Notch signaling within adult CMs in a murine genetic model is sufficient to increase ploidy in both atrial chambers. Notch activation within LA CMs generated a transcriptomic fingerprint resembling AF, with dysregulation of transcription factor and ion channel genes, including Pitx2, Tbx5, Kcnh2, Kcnq1, and Kcnip2. Notch activation also produced distinct cellular electrophysiologic responses in LA versus right atrial CMs, prolonging the action potential duration (APD) without altering the upstroke velocity in the left atrium and reducing the maximal upstroke velocity without altering the APD in the right atrium. Our results support a shared human/murine model of increased Notch pathway activity predisposing to AF.
Topics: Action Potentials; Animals; Atrial Fibrillation; Biomarkers; Gene Expression Regulation; Heart Atria; Heart Failure; Humans; Mice; Myocytes, Cardiac; Receptors, Notch; Transcriptome
PubMed: 32841220
DOI: 10.1172/jci.insight.135319 -
JACC. Clinical Electrophysiology Jan 2023Atrial standstill (AS) is a rare condition characterized by absence of electrical activity within the atria. Studies to date have been limited.
BACKGROUND
Atrial standstill (AS) is a rare condition characterized by absence of electrical activity within the atria. Studies to date have been limited.
OBJECTIVES
The authors sought to describe the clinical characteristics, genetics, and outcomes of patients with AS.
METHODS
This was a retrospective multicenter study of patients <18 years at AS diagnosis, defined as absence of atrial activity documented during an electrophysiology study, device placement, or noninvasive rhythm tracings and confirmed by echocardiogram. Patients with acquired disorders were excluded. Clinical details and genetic variants were recorded and analyzed.
RESULTS
Twenty patients were diagnosed at a median age of 6.6 years (IQR: 2.9-10.8 years). Arrhythmias included 16 (80%) with atrial/supraventricular arrhythmias and 8 (40%) with ventricular tachycardia, including 4 with cardiac arrests. A type 1 Brugada pattern was documented in 4. Pacemakers were implanted in 18 (90%). Although atrial leads were attempted in 15, only 4 achieved pacing at implantation. During a median follow-up of 6.9 years (IQR: 1.2-13.3 years), 7 (35%) had thromboembolic events. Of these, none had atrial pacing, 6 were not on anticoagulation, and 1 was on aspirin. Genetic testing identified SCN5A variants in 13 patients (65%). Analyses suggest SCN5A loss-of-function may be one mechanism driving AS. Ventricular arrhythmias and cardiac arrest were more commonly seen in patients with biallelic SCN5A variants.
CONCLUSIONS
AS may be associated with loss-of-function SCN5A variants. Patients demonstrate atrial and ventricular arrhythmias, and may present challenges during device placement. Patients without the capacity for atrial pacing are at risk for thromboembolic events and warrant anticoagulation.
Topics: Humans; Child; Child, Preschool; Atrial Fibrillation; Heart Atria; Heart Block; Heart Arrest; Anticoagulants
PubMed: 36435694
DOI: 10.1016/j.jacep.2022.08.022