心房颤动、结构重构与肾素-血管紧张素-醛固酮系统关系

心房颤动是临床上最常见的心律失常之一,有较高的发病率、致残率,严重影响患者的生活质量。但是关于心房颤动的发病机制至今并未完全明确,目前对其结构重构的发生机制研究较多,包括钙离子超载、心肌局部肾素-血管紧张素系统激活、基质金属蛋白酶改变、缝隙连接蛋白改变等。同时,针对导致心房颤动结构重构的可能机制,出现了一些新的预防和治疗心房颤动策略。现就心房颤动结构重构的发病机制研究及相应治疗进展做一综述。     

Discrimination of Sinus Rhythm, Atrial Flutter, and Atrial Fibrillation Using Bipolar Endocardial Signals

Discrimination of NSR, AFL, and AF. Introduction : Analysis of endocardial signals obtained from an electrode located in the right atrium as realized in newly designed dual chamber, implantable cardioverter defibrillators might be used to provide additional therapeutic options, such as overdrive pacing or low-energy atrial cardioversion for the treatment of concomitant atrial flutter (AFL) or atrial fibrillation (AF). Therefore, we developed a computer algorithm for discrimination of normal sinus rhythm (NSR), AFL, and AF that may lead to adequate differential therapy of atrial tachyarrhythmias in an automated mode.
Methods and Results : During an electrophysiologic study, bipolar endocardial signals from the high right atrium were obtained in 28 patients during sustained AFL or AF and after restoration of NSR. A total of 286 data segments of 5-second duration were recorded (NSR: 96, AFL: 86, AF: 104). Mean atrial cycle length (MCL), standard deviation of mean atrial cycle length (SDCK), and index of irregularity (IR). defined as the ratio between MCL and SDCL, were calculated for each data segment. A cutoff of 315 msec for MCL allowed discrimination of NSR from atrial tachyarrhythmias with 100% sensitivity and specificity. For discrimination of AF from AFI- by using SDCL, a cutoff value of 11.5 msec led to a sensitivity of 99% and a specificity of 90%. Best discrimination of AF from AFL was found for the criterion IR ≥ 7.5%, resulting in a sensitivity of 100% with a specificity of 95% for AF detection.
Conclusion : The investigated algorithm provides discrimination of NSR, AFL, and AF with high sensitivity and specificity. Incorporation of this algorithm in an implantable automated antitachycardia device may lead to adequate differential therapy in patients suffering from spontaneous episodes of AF and AFL.     

Atrial fibrillation,stroke, and anticoagulation

Journal of General Internal Medicine -     

Atrial remodeling, systemic hypertension, stroke

Atrial remodeling has been demonstrated to be associated with rapid atrial pacing or with hemodynamic overload. It may refer to changes in electrophysiological properties and/or in structure and function. Hemodynamic overload of the atria has been found to be an important pathogenic factor of atrial fibrosis, providing a morphological substrate for atrial fibrillation. This finding could partly account for the high risk of stroke in hypertensive patients. In this respect, a strong involvement of the renin angiotensin system has been suggested by experimental, clinical and epidemiological data. Thus, prevention or even partial regression of atrial remodeling could be reasonably expected from ACE-inhibitors and angiotensin 2-blockers.     

Prediction of Stroke Risk in Atrial Fibrillation,Prevention of Stroke in Atrial Fibrillation,and the Impact of Long-Term Monitoring for Detecting Atrial Fibrillation

Atrial fibrillation (AF) is a large public health problem that affects about 1% of the population in the United States. It confers an increased risk for stroke and thromboembolism, but the stroke risk is not equal in all patients. Further refinement in stratifying stroke risk in patients with AF will help in properly directing therapy for AF patients while minimizing adverse events. Warfarin is the first-line treatment for stroke reduction in patients with AF, but many new drugs are on the horizon that will significantly change practice. New and improved cardiac monitoring techniques and devices will help with detection of AF in those at risk for stroke and will assist in assessing which patients will most benefit from anticoagulation.     

Atrial fibrillation,cancer and anticancer drugs

Active cancer is associated with an increased risk of atrial fibrillation (AF), which varies depending on the pre-existing substrate (particularly in older patients), the cancer type and stage, and the anticancer therapeutics being taken. To date, studies have not been able to identify the individual contribution of each factor. During anticancer drug therapy, AF may occur with a frequency of ≈ 15–20% according to several factors, including the patient's baseline cardiovascular toxicity risk and the AF-detection strategies used. Many anticancer drugs have been associated with AF or AF reporting, both in terms of incident and recurrent AF, but robust data are lacking. Only bruton tyrosine kinase inhibitor associated AF (mainly ibrutinib) has a high level of evidence, with a ≈ 3–4-fold higher risk of AF. AF in patients with active cancer is associated with a twofold higher risk of systemic thromboembolism or stroke, and the “TBIP” (Thromboembolic risk, Bleeding risk, drug–drug Interactions, Patient preferences) structured approach must be used to evaluate the need for anticoagulation therapy. AF in patients with active cancer is also associated with a sixfold higher risk of heart failure, and optimal symptom control must be targeted, usually with rate-control drugs (beta-blockers), but a rhythm-control strategy may be proposed in patients remaining symptomatic despite optimal rate-control. AF is generally manageable, with the continuation of anticancer drugs (including ibrutinib); interruption of cancer drugs must be avoided whenever possible and weighed against the risk of cancer progression.     

Lone,Mobile Left Atrial Hydatid Cyst

Echinococcosis is endemic in various regions of Turkey. Cardiac involvement in echinococcosis is rare, and lone cardiac hydatid cysts are even more unusual. Because cardiac hydatid disease can be fatal, even asymptomatic patients are optimally referred for surgical treatment. We present a rare case of a lone, primary, mobile hydatid cyst in the left atrium of a 62-year-old woman. The cyst caused dyspnea from left ventricular inflow obstruction. In addition to reporting the patient''s fatal case, we discuss cardiac hydatid cysts in terms of the scant medical literature.     

炎症、氧化应激与心房颤动

许多证据表明心房颤动中存在炎症和氧化应激,炎症和氧化应激可导致心房重构,包括电重构和结构重构,提示炎症和氧化应激可能在心房颤动的发生和维持中起着一定作用。抗炎和抗氧化治疗可减少心房颤动的发生和复发,这为干预心房颤动的发生和复发提供了新思路。     

Atrial fibrillation: epidemiology, mechanisms, and management

The incidence of AF, the most common sustained arrhythmia in clinical practice, increases with age, and coronary artery disease, hypertension, and valvular heart disease are common underlying substrates. Occasionally, however, AF may occur without any underlying heart disease. The most widely accepted theory of its mechanism is Moe's multiple wavelet hypothesis, although recent studies are helping to shed light on other mechanisms, including the focal origin of AF in some patients. Most patients experience palpitations, but fatigue, dyspnea, and dizziness may also occur.Therapy includes prevention of thromboembolism, control of rate, and restoration and maintenance of sinus rhythm. The risks and benefits of each treatment modality need to be assessed according to each patient's circumstances. Unlike other arrhythmias, there is still no highly successful therapy for treating AF. However, significant advances are being made using nonpharmacologic approaches to either prevent or cure this troublesome arrhythmia.     

Atrial Tachycardias Following Atrial Fibrillation Ablation

One of the most important proarrhythmic complications after left atrial (LA) ablation is regular atrial tachycardia (AT) or flutter. Those tachycardias that occur after atrial fibrillation (AF) ablation can cause even more severe symptoms than those from the original arrhythmia prior to the index ablation procedure since they are often incessant and associated with rapid ventricular response. Depending on the method and extent of LA ablation and on the electrophysiological properties of underlying LA substrate, the reported incidence of late ATs is variable. To establish the exact mechanism of these tachycardias can be difficult and controversial but correlates with the ablation technique and in the vast majority of cases the mechanism is reentry related to gaps in prior ablation lines. When tachycardias occur, conservative therapy usually is not effective, radiofrequency ablation procedure is mostly successful, but can be challenging, and requires a complex approach.     

Atrial fibrillation, arrhythmia burden and thrombogenesis

Atrial fibrillation (AF) is the most common cardiac arrhythmia, which is associated with substantial risk of stroke and thromboembolism. The epidemiology and health care burden associated with AF have increased significantly, and will continue to rise. Until recently, the concept and/or quantification of disease burden in AF tended to be ignored nor its consequences recognised. However, AF burden can now be assessed more accurately and reliably with the aid of cardiac rhythm management devices. There is a lot of interest on the issue of 'how much AF is needed to cause thromboembolism?' and this article summarises the available literature on this topic, with the aim of providing a better understanding of the clinical importance of device-detected atrial high-rate episodes and an overview of arrhythmia burden on thrombogenesis and clinical thromboembolism.