Treatment of Cardiac Arrhythmias with Synchronized Electrical Counter-shock

Synchronized electrical countershock is an intriguing new method for the treatment of ectopic tachycardias. The authors applied this treatment to 20 patients with chronic atrial fibrillation and, in 17 patients, sinus rhythm was restored immediately. An additional four patients with atrial flutter were successfully converted to sinus rhythm. One patient developed a hemiplegia two weeks after cardioversion. No other untoward side effects were observed. In two patients with ventricular fibrillation electrical countershock terminated the arrhythmia. After successful cardioversion of atrial fibrillation, a maintenance dose of quinidine is given to help maintain sinus rhythm. In spite of this precaution, one-half of the patients reverted to atrial fibrillation within a month. The quinidine was administered for two to three days in advance of cardioversion; on this regimen, 10 of 34 patients reverted to sinus rhythm on quinidine alone and did not require countershock. The exact place of this treatment of cardiac arrhythmias has not yet been clearly defined.     

脂肪因子瘦素和内脂素与心房颤动关系的研究

摘要 目的：心房颤动（Atrial fibrillation,AF）是最常见的心律失常之一,其发生机制目前尚未完全阐明。多项研究表明脂肪因子（Adipokines）中的瘦素（leptin）、内脂素（Visfatin）与心血管疾病的关系密切,本研究拟探讨瘦素、内脂素与心房颤动的关系。方法：本研究通过收集检测AF组、窦性心律组外周血及心外膜脂肪组织,检测瘦素、内脂素分泌水平来探讨瘦素、内脂素与AF发生的相关性。结果：房颤组血清内脂素的平均浓度为15.95±10.44 ng/mL,窦性心律组为20.28±12.90 ng/mL（P=0.169）;房颤组血清瘦素的平均浓度为1.48 ng/mL,窦律组为2.56 ng/mL（P=0.0027）,窦性心律组血清瘦素水平明显高于心房颤动组;心外膜脂肪组织中,瘦素在房颤组中的表达量显著低于窦性心律组（P=0.032）,内脂素在两组中的表达无显著统计学差异（P=0.06）。结论：临床患者外周血血清及心外膜脂肪组织中高水平的瘦素可能降低房颤的发生率,然而,内脂素与房颤可能不具有相关性。     

Atrial fibrillation and stroke: prevalence in different types of stroke and influence on early and long term prognosis (Oxfordshire community stroke project)

OBJECTIVE--To determine in patients with first ever stroke whether atrial fibrillation influences clinical features, the need to perform computed tomography, and prognosis. DESIGN--Observational cohort study with maximum follow up of 6.5 years. SETTING--Primary care, based on 10 general practices in urban and rural Oxfordshire. SUBJECTS--Consecutive series of 675 patients with first ever stroke registered in the Oxfordshire community stroke project. MAIN OUTCOME MEASURES--Prevalence of atrial fibrillation by type of stroke; effect of atrial fibrillation on case fatality rate and risk of recurrent stroke, vascular death, and death from all causes. RESULTS--Prevalence of atrial fibrillation was 17% (95% confidence interval 14% to 20%) for all stroke types (115/675), 18% (15% to 21%) for cerebral infarction (97/545), 11% (4% to 11%) for primary intercerebral haemorrhage (7/66), and 0% (0 to 11%) for subarachnoid haemorrhage (0/33). For patients with cerebral infarction the 30 day case fatality rate was significantly higher with atrial fibrillation (23%) than with sinus rhythm (8%); the risk of early recurrent stroke (within 30 days) was 1% with atrial fibrillation and 4% with sinus rhythm. In patients who survived at least 30 days the average annual risk of recurrent stroke was 8.2% (5.9% to 10.9%) with sinus rhythm and 11% (6.0% to 17.3%) with atrial fibrillation. CONCLUSIONS--After a first stroke atrial fibrillation was not associated with a definite excess risk of recurrent stroke, either within 30 days or within the first few years. Survivors with and without atrial fibrillation had a clinically important absolute risk of further serious vascular events.     

慢性心力衰竭合并心房颤动发病的相关机制研究

目的:慢性心力衰竭(Chronic Heart Failure,CHF)是心血管系统常见的疾病,威胁患者的生存周期及生活质量。本研究针对慢性心力衰竭合并房颤的临床特征,进一步探讨其发病机制,为临床治疗提供依据。方法:将80例慢性心力衰竭患者平均分为两组,心律正常的为窦性心律组,伴有心房颤动的作为房颤组。观察并比较两组的左心室射血分数(LVEF)和二尖瓣口舒张期流速(E/A)等心脏功能指标。结果:房颤组左心室射血分数(LVEF)为(0.42±0.08);二尖瓣口舒张期流速(E/A)为(0.65±0.22);左心房内径(LAD)为(53.4±8.2)mm。窦律组左心室射血分数(LVEF)为(0.45±0.09);二尖瓣口舒张期流速(E/A)为(0.72±0.17);左心房内径(LAD)为(46.7±7.9)mm。房颤组患者的LVEF和E/A值均低于窦律组,而LAD则明显高于窦律组,差异具有统计学意义(P0.05)。房颤组醛固酮、血管紧张素(AngII)、脑钠肽(BNP)及超敏C反应蛋白(hs-CRP)均高于窦律组,差异具有统计学意义(P0.05)。结论:慢性心力衰竭合并房颤的发病与患者体内神经内分泌体液系统水平和心脏结构功能有关,具体发病机制需进一步深入研究。     

慢性心力衰竭合并心房颤动发病的相关机制研究

目的：慢性心力衰竭（Chronic Heart Failure,CHF）是心血管系统常见的疾病,威胁患者的生存周期及生活质量。本研究针对慢性心力衰竭合并房颤的临床特征,进一步探讨其发病机制,为临床治疗提供依据。方法：将80例慢性心力衰竭患者平均分为两组,心律正常的为窦性心律组,伴有心房颤动的作为房颤组。观察并比较两组的左心室射血分数（LVEF）和二尖瓣1：7舒张期流速（E／A）等心脏功能指标。结果：房颤组左心室射血分数（LVEF）为（0．42±0．08）;二尖瓣口舒张期流速（E／A）为（0．65±0．22）;左心房内径（LAD）为（53．4±8．2）min。窦律组左心室射血分数（LVEF）为（0．45±0．09）;二尖瓣口舒张期流速（E／A）为（0．72±0．17）;左心房内径（LAD）为（46．7±7．9）min。房颤组患者的LVEF和E／A值均低于窦律组,而LAD则明显高于窦律组,差异具有统计学意义（P〈0．05）。房颤组醛固酮、血管紧张素（AngII）、脑钠）]k（BNP）TZ超敏c反应蛋白（hs-CRP）均高于窦律组,差异具有统计学意义（P〈0．05）。结论：慢性心力衰竭合并房颤的发病与患者体内神经内分泌体液系统水平和心脏结构功能有关,具体发病机制需进一步深入研究。     

Exercise hyperventilation, dyspnea sensation, and ergoreflex activation in lone atrial fibrillation

Lone atrial fibrillation may be associated with daily life disability and exercise limitation. The extracardiac pathophysiology of these effects is poorly explored. In 35 subjects with lone atrial fibrillation (mean age 67 +/- 7 yr), we investigated pulmonary function, symptom-limited cardiopulmonary exercise performance, muscle ergoreflex (handgrip exercise) contribution to ventilation, and brachial artery flow-mediated dilation (as a measure of endothelial function) before and after (average interval 20 +/- 5 days) restoring sinus rhythm with external cardioversion. Respiratory volumes and lung diffusing capacity at rest were within normal limits during both atrial fibrillation and after restoring sinus rhythm. Cardioversion was associated with the following changes: a decrease of the slope of exercise ventilation vs. CO2 production (from 35 +/- 5 to 29 +/- 3; P <0.01) and of dyspnea sensation (Borg score from 4 to 2) and an increase of peak oxygen uptake (Vo2; from 16 +/- 4 to 20 +/- 5 ml.min(-1).kg(-1); P <0.01), Vo2 at anaerobic threshold (from 11 +/- 2 to 13 +/- 2 ml.min(-1).kg(-1); P <0.05), and O2 pulse (from 8 +/- 3 to 11 +/- 3 ml/beat; P <0.01). After cardioversion, the observed improvement in ventilatory efficiency was accompanied by a significant peak end-tidal CO2 increase (from 33 +/- 2 to 37 +/- 2 mmHg; P <0.01) and no changes in dead space-to-tidal volume ratio (from 0.23 +/- 0.03 to 0.23 +/- 0.02; P=not significant). In addition, the ergoreflex contribution to ventilation was remarkably attenuated, and the brachial artery flow-mediated dilatation was significantly augmented (from 0.32 +/- 0.07 to 0.42 +/- 0.08 mm; P <0.01). Ten patients had atrial fibrillation relapse and, compared with values after restoration of regular sinus rhythm, invariably showed worsening of endothelial function, exercise ventilatory efficiency, and muscle ergoreflex contribution to ventilation. In subjects with lone atrial fibrillation, an impairment in ventilatory efficiency appears to be involved in the pathophysiology of exercise limitation, and to be primarily related with a demodulated peripheral control of ventilation.     

Arterial embolism in thyrotoxicosis with atrial fibrillation.

In 262 patients with thyrotoxicosis and atrial fibrillation there were 26 episodes of arterial embolism (17 cerebral and nine elsewhere) in 21 patients. Twelve incidents occurred with active thyrotoxicosis, three on reversion to sinus rhythm, and 11 after the patients were euthyroid. This important complication is more common than is realised, and most patients should be put on prophylactic anticoagulants when first seen with atrial fibrillation.     

心力衰竭合并房颤患者血浆脑钠肽水平及相关因素分析

目的:探讨心力衰竭合并房颤患者血浆脑钠肽水平变化及相关因素,为心血管疾病的临床诊断提供理论依据。方法:选取我院2011年1月-2013年1月收治的心力衰竭患者94例,分为窦性心律组和心房颤动组。分别抽取两组患者的血液样本并检测血浆中的BNP浓度,比较不同NYHA分级患者血浆内的脑钠肽水平的变化情况,记录左心房和左心室舒张末内径及房颤持续时间等。结果:心力衰竭合并心房颤动组与窦性心律组血浆BNP水平比较,心房颤动组高于窦性心律组;差异有统计学意义(P0.05);两组NYHA不同分级相互比较,Ⅱ级、Ⅲ级和Ⅳ级间的BNP水平,心房颤动组BNP水平均高于窦性心律组;差异显著具有统计学意义(P0.05);血浆BNP水平与患者年龄、左心房大小、左心室大小、房颤持续时间因素呈正相关(r分别为0.0.801,0.748,0.854和0.703,P0.05),与左心室射血分数呈负相关(r=-0.41,P0.05)。结论:BNP血浆浓度与心功能状态密切相关,BNP浓度的检测有助于临床心血管疾病的诊断。     

Diagnostic value of thyrotrophin releasing hormone tests in elderly patients with atrial fibrillation.

A prospective study was carried out to compare clinical and biochemical thyroid states with responses of thyroid stimulating hormone (TSH) to thyrotrophin releasing hormone (TRH) in elderly patients with either atrial fibrillation (n = 75; mean age (SD) 79.3 (6.0) years) or sinus rhythm (n = 73; mean age 78.4 (5.6) years) admitted consecutively to the department of geriatric medicine. No patient in either group had symptoms or signs of hyperthyroidism. Overall, the TSH responses to TRH did not differ significantly between the two groups. Ten (13%) of the patients with atrial fibrillation (of whom four had raised thyroid hormone concentrations) and five (7%) of the patients with sinus rhythm showed no TSH response to TRH while 26% of each group (20 and 19 patients, respectively) showed a much reduced response. Only one of 13 patients with apparently isolated atrial fibrillation showed no TSH response to TRH, and none of these 13 patients was hyperthyroid. In particular, three patients (two with atrial fibrillation and one with sinus rhythm) who showed no TSH response to TRH at presentation exhibited a return of TSH response to TRH at follow up six weeks later. In conclusion, reduced or absent TSH responses to TRH are common in sick elderly patients whether they have atrial fibrillation or sinus rhythm and whether they are euthyroid or hyperthyroid biochemically. An absence of response is therefore an uncertain marker of hyperthyroidism in these groups of patients, and diagnosis and ablative treatment should be based at least on the presence of raised circulating free triiodothyronine or free thyroxine concentrations, or both.     

Characterizing left atrial appendage functions in sinus rhythm and atrial fibrillation using computational models

Clinical studies show that the left atrial appendage, a blind-ended structure that is attached to the left atrium, may be the cause of 90% of atrial thrombi in atrial fibrillation (abnormal heart rhythm), and it is much reduced in sinus (normal) rhythm. In this paper, the effects of blood flows in left atrium and left atrial appendage are studied to help characterize the atrial appendage functions in sinus rhythm and atrial fibrillation using mathematical models. Our results show that the left atrial appendage is not functional in sinus rhythm because the atrial transmitral velocities remained almost identical for atria with and without appendage, which agrees with the current clinical observations. However, in atrial fibrillation, a proper atrial contraction is absent, which causes the second emptying velocity (A-wave) to be missing in both transmitral velocity and appendage filling/emptying velocity. Without the proper emptying of the blood, vortices generated in the chamber remain high strengths and with longer durations. They induce ineffective emptying of the blood in the atrium and appendage, which then lead to blood stagnation and subsequent thrombus formation.     

Measuring blood pressure in the elderly: does atrial fibrillation increase observer variability?

OBJECTIVE--To compare the interobserver and intraobserver variability of blood pressure measurements in geriatric patients in atrial fibrillation and in sinus rhythm. DESIGN--Prospective assessment of blood pressure measurements carried out in random order in two groups of elderly patients by five doctors unaware of the aims of the study. SETTING--Acute assessment wards for geriatric medicine, Cardiff Royal Infirmary. PATIENTS--50 Elderly patients in sinus rhythm and 50 in atrial fibrillation. MAIN OUTCOME MEASURES--Interobserver and intraobserver variability of blood pressure measurements in the two groups expressed as the coefficient of variability and compared by the Mann-Whitney U test. RESULTS--Interobserver variability was significantly greater in the patients with atrial fibrillation for both systolic and diastolic pressures. Intraobserver variability was significantly greater in the atrial fibrillation group for diastolic pressures but the difference was not significant for systolic pressures. These differences were not related to pulse rate, age, or level of blood pressure. CONCLUSIONS--The findings suggest that in the presence of atrial fibrillation physicians'' interpretations of Korotkoff sounds are less uniform, which may have important clinical implications. Possibly a standardised methodology may overcome this problem.     

Maintenance digoxin after an episode of heart failure: placebo-controlled trial in outpatients.

The need for maintenance digoxin treatment was assessed in a double-blind, variable-dose, crossover comparison with placebo. Forty-six outpatients who had been prescribed the drug for heart failure were studied; 33 were in sinus rhythm and the remainder in atrial fibrillation. Mean serum digoxin concentrations in those with sinus rhythm averaged 1-33 nmol/l, but a lower concentration, averaging 0-97 nmol/l, was accepted in those with atrial fibrillation as six of them developed bradycardia. Sixteen of the 46 patients deteriorated on placebo, and eight completely recovered when digoxin was reintroduced; in the remainder additional diuretics were required temporarily. Spirometric values deteriorated on changing to placebo whether or not the patient showed clinical evidence of recurrence of heart failure. In a separate study of nine patients who showed no clinical evidence of deterioration on placebo, reintroduction of digoxin caused a shortening of left ventricular ejection time, which persisted for at least a month. This suggests that the inotropic response to digoxin is sustained during maintenance treatment.     

Atrial electrogram quality in single-pass defibrillator leads with floating atrial bipole in patients with permanent atrial fibrillation and cardiac resynchronization therapy

Many patients receiving cardiac resynchronization therapy (CRT) suffer from permanent atrial fibrillation (AF). Knowledge of the atrial rhythm is important to direct pharmacological or interventional treatment as well as maintaining AV-synchronous biventricular pacing if sinus rhythm can be restored. A single pass single-coil defibrillator lead with a floating atrial bipole has been shown to obtain reliable information about the atrial rhythm but has never been employed in a CRT-system. The purpose of this study was to assess the feasibility of implanting a single coil right ventricular ICD lead with a floating atrial bipole and the signal quality of atrial electrograms (AEGM) in CRT-defibrillator recipients with permanent AF.

Graves' disease and atrial fibrillation: the case for even higher doses of therapeutic iodine-131.

Seventy five consecutive patients with Graves'' disease complicated by atrial fibrillation were given a large single therapeutic dose of 600 MBq (16.2 mCi) iodine-131 in an effort to control their hyperthyroidism rapidly and thus restore sinus rhythm. Patients were initially followed up every three months after treatment and then at yearly intervals. The mean period of follow up was 3.1 years. A total of 44 of the patients became hypothyroid and 31 euthyroid, and 33 (75%) and 14 (45%) of these patients, respectively, reverted to sinus rhythm (p less than 0.01). Of the 33 who became hypothyroid and reverted to sinus rhythm, 30 had developed the hypothyroidism within six months after treatment. These results are a strong case for increasing the dose of radioiodine in patients with Graves'' disease complicated by atrial fibrillation in an effort to speed the onset of thyroid failure and thus maximise the rate of reversion to sinus rhythm.     

Aortic Stiffness in Lone Atrial Fibrillation: A Novel Risk Factor for Arrhythmia Recurrence

Background

Recent community-based research has linked aortic stiffness to the development of atrial fibrillation. We posit that aortic stiffness contributes to adverse atrial remodeling leading to the persistence of atrial fibrillation following catheter ablation in lone atrial fibrillation patients, despite the absence of apparent structural heart disease. Here, we aim to evaluate aortic stiffness in lone atrial fibrillation patients and determine its association with arrhythmia recurrence following radio-frequency catheter ablation.

Methods

We studied 68 consecutive lone atrial fibrillation patients who underwent catheter ablation procedure for atrial fibrillation and 50 healthy age- and sex-matched community controls. We performed radial artery applanation tonometry to obtain central measures of aortic stiffness: pulse pressure, augmentation pressure and augmentation index. Following ablation, arrhythmia recurrence was monitored at months 3, 6, 9, 12 and 6 monthly thereafter.

Results

Compared to healthy controls, lone atrial fibrillation patients had significantly elevated peripheral pulse pressure, central pulse pressure, augmentation pressure and larger left atrial dimensions (all P<0.05). During a mean follow-up of 2.9±1.4 years, 38 of the 68 lone atrial fibrillation patients had atrial fibrillation recurrence after initial catheter ablation procedure. Neither blood pressure nor aortic stiffness indices differed between patients with and without atrial fibrillation recurrence. However, patients with highest levels (≥75^th percentile) of peripheral pulse pressure, central pulse pressure and augmentation pressure had higher atrial fibrillation recurrence rates (all P<0.05). Only central aortic stiffness indices were associated with lower survival free from atrial fibrillation using Kaplan-Meier analysis.

Conclusion

Aortic stiffness is an important risk factor in patients with lone atrial fibrillation and contributes to higher atrial fibrillation recurrence following catheter ablation procedure.     

WNT signaling in atrial fibrillation

The Wnt signaling pathway regulates physiological processes such as cell proliferation and differentiation, cell fate decisions, and stem cell maintenance and, thus, plays essential roles in embryonic development, but also in adult tissue homeostasis and repair. The Wnt signaling pathway has been associated with heart development and repair and has been shown to be crucially involved in proliferation and differentiation of progenitor cells into cardiomyocytes. The investigation of the role of the Wnt signaling pathway and the regulation of its expression/activity in atrial fibrillation has only just begun. The present minireview (I) provides original data regarding the expression of Wnt signaling components in atrial tissue of patients with atrial fibrillation or sinus rhythm and (II) summarizes the current state of knowledge of the regulation of Wnt signaling components’ expression/activity and the contribution of the various levels of the Wnt signal transduction pathway to the processes of the development, maintenance, and progression of atrial fibrillation.     

Immediate Effects of Intravenous Verapamil in Cardiac Arrhythmias

Verapamil was administered by intravenous injection to 181 patients with various cardiac arrhythmias. The automaticity of the cardiac pacemaker was slowed in sinus, idionodal, and idioventricular tachycardia. In atrial fibrillation the drug usually slowed the ventricular response and often made it regular. In some cases atrial flutter was converted to sinus rhythm, the ventricular response being reduced in the remainder. Conversion of paroxysmal supraventricular tachycardia to sinus rhythm was consistently achieved. A favourable response occurred in four patients in whom arrhythmias were associated with pre-excitation syndromes. There were no adverse clinical side effects.     

Assessment of spatial organization in the atria during paroxysmal atrial fibrillation and adrenergic stimulation.

Non-linear parameters were computed to assess the extent of spatial organization in the atria in terms of coupling/synchronization between electrograms recorded in different atrial sites. Recordings of 9 patients suffering from paroxysmal atrial fibrillation were tested during four clinical experimental conditions: sinus rhythm and atrial fibrillation, both before and after isoproterenol infusion, a drug mimicking adrenergic activation. Two non-linear metrics were investigated: an index of non-linear association (NLA) and a synchronization (S) index based on the cross-conditional entropy. Results evidence the presence of reduced coupling after drug infusion in both sinus rhythm and atrial fibrillation. Moreover, passing from the NLA to the S index, the capability of the parameter to capture the subtle changes due to isoproterenol administration increased.     

Rate-control or rhythm-control: where do we stand?

Atrial fibrillation is the most common sustained rhythm disturbance and its prevalence is increasing worldwide due to the progressive aging of the population. Current guidelines clearly depict the gold standard management of acute symptomatic atrial fibrillation but the best-long term approach for first or recurrent atrial fibrillation is still debated with regard to quality of life, risk of new hospitalizations, and possible disabling complications, such as thromboembolic stroke, major bleeds and death. Some authors propose that regaining sinus rhythm in all cases, thus re-establishing a physiologic cardiac function not requiring a prolonged antithrombotic therapy, avoids the threat of intracranial or extracranial haemorrhages due to Vitamin K antagonists or aspirin. On the contrary, advocates of a rate control approach with an accurate antithrombotic prophylaxis propose that such a strategy may avoid the risk of cardiovascular and non cardiovascular side effects related to antiarrhythmic drugs. This review aims to explore the state of our knowledge in order to summarize evidences and issues that need to be furthermore clarified.