The future of electrical defibrillators for the heart]

The aim of electric defibrillation of the heart is to salvage a greater percentage of victims of cardiac arrest in the future. An initial decisive pathway towards this goal is to get a defibrillator to the victim as quickly as possible and apply an electric shock. This has now been implemented on a large scale--by means of the widespread propagation of (semi-)automatic external defibrillators (AED) and their PAD (Public Access Defibrillator) variant for use by laypersons. This is an initial necessary prerequisite which, however, is not sufficient to have a real impact on saving lives. For experience has shown that, despite the early use of AEDs, an appreciable proportion of the victims cannot be saved. The intention is to improve this situation by increasing the efficacy and reducing the harmful downside of the defibrillation waveforms applied. The solution is optimally dimensioned biphasic waveforms with high efficacy at low energy levels. In this connection, it is shown that the efficacy of high-energy defibrillation shocks is exceeded by their injurious effects, thus thwarting life-saving defibrillation. Examples of new waveforms of particularly high efficacy are presented. It is shown how such impulses should be physiologically dimensioned, and clinical results of cardioversion (atrial defibrillation) and initial out-of-hospital results of emergency defibrillation are discussed. In addition, new approaches for future waveforms enabling pulsed pulse-pause-modulated biphasic shocks are described. In this way, waveforms with a physiologically optimal effect on the heart can be produced which were previously impossible with portable defibrillators. Waveforms that have already been tested or are still in the research stage, justify hopes that improved survival of cardiac arrest victims may be expected. These new waveforms may also be of benefit in other types of defibrillators (e.g. cardioversion or implanted defibrillators).     

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.     

Cardioversion and Risk of Adverse Events with Dabigatran versus Warfarin—A Nationwide Cohort Study

Aim

Cardioversion can rapidly and effectively restore sinus rhythm in patients with persistent atrial fibrillation. Since 2011 dabigatran has been available as an alternative to warfarin to prevent thromboembolic events in patients with non-valvular atrial fibrillation undergoing cardioversion. We studied time to cardioversion, risk of adverse events, and risk of readmission with atrial fibrillation after cardioversion according to anticoagulation therapy.

Methods and Results

Through the nationwide Danish registries we included 1,230 oral anticoagulation naïve patients with first time non-valvular atrial fibrillation and first time cardioversion from 2011 to 2012; 37% in the dabigatran group (n = 456), and 63% in the warfarin group (n = 774). Median time to cardioversion was 4.0 (interquartile range [IQR] 2.9 to 6.5) and 6.9 (IQR 3.9 to 12.1) weeks in the dabigatran and warfarin groups respectively, and the adjusted odds ratio of cardioversion within the first 4 weeks was 2.3 (95% confidence interval [CI] 1.7 to 3.1) in favor of dabigatran. The cumulative incidence of composite endpoint of stroke, bleeding or death were 2.0% and 1.0% at 30 weeks in the warfarin and dabigatran groups respectively, with an adjusted hazard ratio of 1.33 (95% CI 0.33 to 5.42). Cumulative incidence of readmission with atrial fibrillation after 30 weeks were 9% and 11% in the warfarin and dabigatran groups, respectively, and an adjusted hazard ratio of 0.66 (95% CI 0.41 to 1.08).

Conclusion

Anticoagulation treatment with dabigatran allows shorter time to cardioversion for atrial fibrillation than warfarin, and appears to be an effective and safe alternative treatment strategy to warfarin.     

左心房顿抑的影响因素和发生机制

心房顿 抑是 指与 复律 前 相比 ,心房 颤动 复律 后 心房 和 心耳 机械 功能 暂 时被 抑 制的 现象 .心房 颤动 复律 方式 、心房 颤 动持 续 的时 间、心 房的 大小 、潜在 的结 构 性心 脏 病是 影响 心房 顿 抑的 因 素 .目前 心 房顿 抑可 能的 机制 有 :单 纯 性心 房颤 动 引起 的心 房 细胞 结构 的 变化 ;心房 的心 肌 细胞 内钙 离 子的 变化 ;快速 房 性心 肌炎 和心 房纤 维 症 .这 里主 要讨 论 心房 颤动 复 律后 左心 房 和左 心耳 发 生的 顿抑 现 象 .     

NT-proBNP对胺碘酮用于急诊阵发房颤复律疗效的预测价值

目的:研究N末端B型利钠肽原(N-terminal pro B-type natriuretic peptide, NT-proBNP)对胺碘酮用于急诊阵发性非瓣膜病心房颤动疗效的预测价值。方法:收集2016-2017年于宣武医院急诊科诊断为阵发性非瓣膜病房颤(发病48h内)的患者共110例,记录所有患者人院时一般资料、既往病史、临床症状体征、实验室数据及测定肌钙蛋白I(Troponin-I, TnI)水平和基线NT-proBNP水平,均给予胺碘酮静脉转复治疗。按照胺碘酮转复情况分为成功组和失败组。结果:静脉应用胺碘酮成功转复91例(82.7%),平均转复时间8.15小时(SD10.16),转复失败者24 h内心室率均控制在100次/min以下,均无严重不良反应。成功组血浆基线NT-pro BNP水平显著低于失败组(P0.05);而两组患者性别、年龄、入室血压、心室率、胸痛、房颤持续时间、入室心电图ST段压低、Tn I水平、冠心病史、高血压、糖尿病、房颤史比较差异均无统计学意义(P0.05)。二元logistic回归分析显示NT-proBNP的自然对数,即In(NT-proBNP)为急诊房颤胺碘酮复律疗效的主要影响因素。结论:对于非瓣膜病房颤急性发作48 h的患者,胺碘酮转复是安全有效的;基线NT-proBNP水平是药物复律成功的重要预测因子,如基线NT-proBNP水平较高,则复律成功率低,为了避免药物的不良反应,可考虑控制心室率,而不是复律治疗。     

Treatment of nonvalvular atrial fibrillation.

Nonvalvular atrial fibrillation is an increasingly common condition. It may cause disabling symptoms and is an important risk factor for stroke. The goals of treatment include the relief and prevention of rate- and rhythm-related symptoms and the prevention of stroke and systemic emboli. Three principal treatments should be considered: pharmacologic rate control, cardioversion and antiarrhythmic therapy to restore and maintain sinus rhythm, and prophylactic anticoagulation or antiplatelet therapy to reduce the risk of stroke. The risks and benefits of each of these therapies have been reviewed. Symptoms, if present, can often be managed safely with rate-directed therapy alone. Until issues regarding safety and long-term efficacy are resolved, cardioversion and antiarrhythmic therapy should be limited to those patients whose symptoms cannot otherwise be controlled. The benefits of warfarin anticoagulation for the primary and secondary prevention of stroke in nonvalvular atrial fibrillation have been demonstrated convincingly by several randomized clinical trials. These benefits must be weighed against the real risk of major hemorrhage. For patients at low risk of stroke, the use of aspirin may be an acceptable alternative to warfarin sodium therapy.     

Digitalis Does not Improve Left Atrial Mechanical Dysfunction After Successful Electrical Cardioversion of Chronic Atrial Fibrillation

This study was designed to investigate whether administration of digitalis could improve mechanical function of left atrial appendage (LAA) and left atrium prospectively in patients with atrial stunning. Fifty-four consecutive patients in whom atrial stunning was observed immediately after cardioversion of chronic atrial fibrillation (AF) were randomized into digitalis or control group for 1 week following cardioversion. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were performed prior to, immediately following, 1 day after and 1 week after cardioversion to measure transmitral flow velocity and LAA flow velocity. Electrical cardioversion of AF elicited significantly slower left atrial appendage peak emptying velocity (LAA-PEV) and peak filling velocity (LAA-PFV) immediately following cardioversion in both groups. 1 day post cardioversion, there were no significant differences in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or left atrial appendage ejection fraction (LAA-EF) between digitalis and control groups. 1 week post cardioversion, no significant differences were found in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or LAA-EF between the two groups. The occurrence rates of spontaneous echo contrast were not significantly different between digitalis and control groups one day and one week post cardioversion. In conclusion, digitalis did not improve left atrial and appendage mechanical dysfunction following cardioversion of chronic AF. Digitalis did not prevent the development of spontaneous echo contrast in left atrial chamber and appendage. This may be due to the fact that digitalis aggravates intracellular calcium overload induced by chronic AF and has a negative effect on ventricular rate.     

N-terminal Pro-Brain Natriuretic Peptide And Atrial Fibrillation

NT-proBNP is produced from both atria and ventricles. The primary regulation of production is at the synthesis level. The plasma half-life of NT-proBNP is 60-120 min. Cutoff value of NT-proBNP for diagnosis of heart failure is 125 pg/ml in the age group below 75 years and 450 pg/ml in the age group above 75 years. It increases in atrial fibrillation and drops after successful cardioversion. High levels predict development of atrial fibrillation (AF) in healthy persons with sinus rhythm (SR). Some studies concluded that baseline level predicts maintenance of SR after cardioversion of AF while some others found that it did not. Many studies have proven that it is useful in monitoring rhythm stability after cardioversion of AF. Since it is increased in many other conditions, out of which some may also cause AF, care must be taken before ascribing changes in its level to AF alone.     

持续正压通气治疗阻塞性睡眠呼吸暂停综合征并发心房纤颤的临床研究

目的:研究持续正压通气治疗阻塞性睡眠呼吸暂停综合征(OSAHS)并发心房纤颤的临床疗效。方法:选取2013年1月到2014年1月我院收治的OSAHS并发心房纤颤患者60例,按照随机数字表法将患者分为实验组和对照组,每组30例。对照组给予常规治疗,实验组在对照组的基础上给予持续正压通气治疗,两组均治疗1年。分析治疗前、后两组心率(HR)、血氧饱和度(SPO2)、左心射血分数(LVEF)、脑钠肽(BNP),并比较两组心房纤颤转复率、复发率和不良反应。结果:治疗后实验组HR、SPO2、LVEF以及BNP显著优于对照组,两组比较差异具有统计学意义(P0.05);治疗后实验组心房纤颤转复率显著高于对照组,心房纤颤复发率显著低于对照组,两组比较差异具有统计学意义(P0.05);两组不良反应发生率比较无统计学意义(P0.05)。结论:持续正压通气治疗OSAHS并发心房纤颤具有较好的效果,有利于改善心功能,提高心房纤颤转复率降低房纤颤复发率。     

Clinical determinants of early spontaneous conversion to sinus rhythm in patients with atrial fibrillation

Netherlands Heart Journal - The current standard of care for acute atrial fibrillation (AF) focuses primarily on immediate restoration of sinus rhythm by cardioversion, although AF often terminates...     

Baseline NT-Pro-BNP Levels and Arrhythmia Recurrence in Outpatients Undergoing Elective Cardioversion of Persistent Atrial Fibrillation: A Survival Analysis

Background

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Elective electrical cardioversion is often performed in patients with persistent AF to attempt sinus rhythm (SR) restoration. However, AF recurrences are frequent after successful cardioversion and several predictors have been identified.

Aim of the study

The present study was designed to prospectively analyse the correlation between NT-pro-BNP levels and AF recurrence in consecutive patients referred for electrical cardioversion of persistent atrial fibrillation.

Results

Forty consecutive patients referred for elective cardioversion of AF were enrolled in the study. Cardioversion restored sinus rhythm in 34/40 patients but 2 of them presented an early recurrence of AF before discharge. Patients were then followed for 6 months to assess AF recurrence. Cox regression analysis was performed using the parameters found predictive on univariate survival analysis (NT-pro-BNP quartiles, beta-blockers). The only independent predictor of AF recurrence on Cox-regression analysis was a level of NT-pro-BNP in the fourth quartile (HR 3.21 95%CI 1.26-8.14, p=0.014). On receiver operating curve (ROC) analysis, NT-pro-BNP levels above 1707 pg/ml had a specificity of 92% (and a sensitivity of 36%) in predicting atrial fibrillation recurrence by 6 months.

Conclusions

Baseline NT-pro-BNP levels are an independent predictor of AF recurrence at 6 months follow-up in candidates for elective direct current cardioversion.     

不同剂量胺碘酮联合氯沙坦治疗阵发性房颤患者复律后的窦性心律维持效果

目的:研究不同剂量胺碘酮联合氯沙坦治疗阵发性房颤患者复律后的窦性心律维持效果。方法:选取2013年1月到2014年1月我院收治的阵发性房颤患者130例,按照随机数字表法将患者分为A组和B组,每组65例,两组均给予氯沙坦治疗,A组给予胺碘酮600 mg/d,1-2周后改用200 mg/d维持1年;B组给予胺碘酮600 mg/d,1-2周后改用200 mg/d,1个月后改为100mg/d维持1年,比较两组治疗前后转复维持有效率、心率、血压、左房内径(LAD)、左房舒张末期容积(LAEDV)、左房收缩末期容积(LAESV)、左心房射血分数(LAEF)以及不良反应。结果:两组转复维持有效率比较差异无统计学意义(P0.05);治疗后收缩压、舒张压、LAEDV和LAESV均优于治疗前(P0.05),但治疗后两组组间心率、收缩压、舒张压、LAD、LAEDV、LAESV、LAEF比较差异无统计学意义(P0.05);B组不良反应发生率显著低于A组,两组比较差异具有统计学意义(P0.05)。结论:小剂量胺碘酮联合氯沙坦与大剂量胺碘酮联合氯沙坦治疗阵发性房颤转复效果相当,但是不良反应较少。     

Should all patients receive dual chamber pacing ICDs? The rationale for the DAVID trial

All of the prospective multicenter trials that support the use of implantable defibrillators have used single chamber pacemakers/implantable cardiovertor defibrillators (ICDs). Despite the significantly increased cost of dual chamber pacemaker/ICD devices and the lack of outcome data, these devices accounted for approximately two-thirds of the ICDs implanted in the United States during the 12 months ending April 2001. Dual chamber pacemaker trials have not provided data that would support this trend, but the high incidence of atrial fibrillation, bradycardia, and congestive heart failure, as comorbid conditions, suggest that the situation could be different in the defibrillator patient population. The DAVID (Dual Chamber and VVI Implantable Defibrillator) trial is designed to measure the incremental benefit of dual chamber pacemaker/ICDs.     

Paradigm shifts in pathophysiology and management of atrial fibrillation—a tale of the RACE trials in the Netherlands

In the past 20 years the Netherlands-based RACE trials have investigated important concepts in clinical atrial fibrillation (AF). Their scope ranged from rhythm versus rate control to early or delayed cardioversion and also included early comprehensive management of AF in two trials, one focusing on early ‘upstream therapy’ and risk factor management and the other on integrated chronic nurse-led care. Studies were mostly triggered by simple clinical observations including futility of electrical cardioversion in persistent AF; many patients with permanent AF tolerating day-after-day ‘uncontrolled’ resting heart rates of up till 110 beats/min; patients being threatened more by vascular risks than AF itself; and insufficient guideline-based treatments for AF. Also the observation that recent-onset atrial fibrillation generally converts spontaneously, obviating cardioversion, triggered one of the studies. The RACE trials shifted a number of paradigms and by that could change the AF guidelines. The initial ‘shock-and-forget’ attitude made place for increased attention for anticoagulation, and in turn, broader vascular risks were recognised. In a nutshell, the adage eventually became: ‘look beyond the ECG, treat the patient’.

     

Atrial fibrillation precipitated by acute hypovolaemia.

Six patients with varying degrees of acute cardiorespiratory failure were seen. All patients deteriorated noticeably when rapid atrial fibrillation developed. In all patients intravenous digitalis failed to slow the ventricular response, and in three patients misguided attempts at electrical cardioversion failed. Haemodynamic monitoring showed a normal or low pulmonary artery occlusion pressure in all patients. Controlled expansion of plasma volume was associated with an immediate slowing of the heart rate in all patients, and the heart rate in all patients returned to sinus rhythm within 30 minutes of transfusion. It is suggested that hypovolaemia in critically ill patients may contribute to the development of atrial fibrillation.     

Increased inpatient mortality in patients hospitalized for atrial fibrillation and atrial flutter with concomitant amyloidosis: Insight from National Inpatient Sample (NIS) 2016-2017

PurposeUsing National Inpatient Database (NIS), comparison of clinical outcomes for patients primarily admitted for atrial fibrillation/flutter with and without a secondary diagnosis of amyloidosis was done. Inpatient mortality was the primary outcome and hospital length of stay (LOS), mean total hospital charges, odds of undergoing cardiac ablation, pharmacologic cardioversion, having a secondary discharge diagnosis of heart block, cardiogenic shock and cardiac arrest were secondary outcomes.MethodsNIS database of 2016, 2017 was used for only adult hospitalizations with atrial fibrillation/flutter as principal diagnosis with and without amyloidosis as secondary diagnosis using ICD-10 codes. Multivariate logistic with linear regression analysis was used to adjust for confounders.Results932,054 hospitalizations were for adult patients with a principal discharge diagnosis of atrial fibrillation/flutter. 830 (0.09%) of these hospitalizations had amyloidosis.Atrial fibrillation/flutter hospitalizations with co-existing amyloidosis have higher inpatient mortality (4.22% vs 0.88%, AOR: 3.92, 95% CI 1.81–8.51, p = 0.001) and likelihood of having a secondary discharge diagnosis of cardiac arrest (2.40% vs 0.51%, AOR: 4.80, 95% CI 1.89–12.20, p = 0.001) compared to those without amyloidosis.ConclusionsHospitalizations of atrial fibrillation/flutter with co-existing amyloidosis have higher inpatient mortality and odds of having a secondary discharge diagnosis of cardiac arrest compared to those without amyloidosis. However, LOS, total hospital charges, likelihood of undergoing cardiac ablation, pharmacologic cardioversion, having a secondary discharge diagnosis of heart block and cardiogenic shock were similar between both groups.     

Loss of atrial contractility is primary cause of atrial dilatation during first days of atrial fibrillation

Atrial fibrillation (AF) induces a progressive dilatation of the atria which in turn might promote the arrhythmia. The mechanism of atrial dilatation during AF is not known. To test the hypothesis that loss of atrial contractile function is a primary cause of atrial dilatation during the first days of AF, eight goats were chronically instrumented with epicardial electrodes, a pressure transducer in the right atrium, and piezoelectric crystals to measure right atrial diameter. AF was induced with the use of repetitive burst pacing. Atrial contractility was assessed during sinus rhythm, atrial pacing (160-, 300-, and 400-ms cycle length), and electrically induced AF. The compliance of the fibrillating right atrium was measured during unloading the atria with diuretics and loading with 1 liter of saline. All measurements were repeated after 6, 12, and 24 h of AF and then once a day during the first 5 days of AF. Recovery of the observed changes after spontaneous cardioversion was also studied. After 5 days of AF, atrial contractility during sinus rhythm or slow atrial pacing was greatly reduced. During rapid pacing (160 ms) or AF, the amplitude of the atrial pressure waves had declined to 20% of control. The compliance of the fibrillating atria increased twofold, whereas the right atrial pressure was unchanged. As a result, the mean right atrial diameter increased by approximately 12%. All changes were reversible within 3 days of sinus rhythm. We conclude that atrial dilatation during the first days of AF is due to an increase in atrial compliance caused by loss of atrial contractility during AF. Atrial compliance and size are restored when atrial contractility recovers after cardioversion of AF.     

Epicardial fat pad within the transverse sinus mimicking a left atrial appendage thrombus

The presence of left atrial thrombus is a contraindication to cardioversion or catheter ablation in patients with atrial fibrillation, due to the increased risk of systemic thromboembolism. Management of this situation includes changes in the anticoagulation regimen and repeat imaging tests. Accurate diagnosis of left atrial appendage thrombus is therefore essential but can sometimes be challenging. Multiple imaging modalities may sometimes be required in the setting of anatomical variations of the left atrial appendage and surrounding structures.We present the case of a patient awaiting ablation for atypical atrial flutter, who underwent a transthoracic echocardiogram that showed an echodense, mobile structure within the vicinity of the left atrial appendage, suggesting a possible thrombus. A cardiac CT demonstrated the image to correlate with an epicardial fat pad within the transverse sinus.     

Acute cardiovascular failure and its treatment--value of defibrillation in preclinical management]

Ventricular fibrillation is the most common cause of cardiac arrest. The only scientifically proved therapy that guarantees a long time survival is the early electrical defibrillation. As early as 200 years ago electricity was employed in trying to regain circulation in cases of unexpected death. In the field of emergency medicine almost all rescue services are equipped with defibrillators nowadays and the personnel is trained in using them. Since the application of electricity on the myocardium can lead to damage, there are devices with a varied defibrillation pulse available since recently. The advantage of the biphasic defibrillation is a less harmful impact on the myocardium at lower shock intensity. A further novelty which enables the application by groups other than the rescue services, is the automatic external defibrillator (AED). Extending the availability of defibrillators can contribute to an increase in the presently low success rates of resuscitation.