Vernakalant Hydrochloride: A NovelAtrial‐selective Agent for the Cardioversionof Recent‐onset Atrial Fibrillation in the Emergency Department

Objectives: Vernakalant is a relatively atrial‐selective antiarrhythmic agent that has been shown to successfully convert atrial fibrillation (AF) to normal sinus rhythm for some patients whose onset of dysrhythmia occurred less than 7 days previously. This study sought to evaluate the efficacy and safety of vernakalant for patients with recent‐onset AF. Methods: This was a post hoc analysis of patients with recent‐onset AF (> 3 to ≤ 48 hours) enrolled in the double‐blind, placebo‐controlled Atrial arrhythmia Conversion Trial (ACT) I and the open‐label ACT IV trials. The studies enrolled adults presenting with AF to 78 emergency departments (ED) and cardiac clinics in six countries. Patients received a 10‐minute intravenous infusion of vernakalant or placebo, followed by an additional infusion if necessary. Efficacy assessments included conversion to sinus rhythm within 90 minutes and median time to conversion. Safety evaluations included telemetry, Holter monitoring, and adverse events (AEs). Results: Of the 290 patients, 229 received vernakalant, 61 received placebo, and the overall mean age was 59 years. The vernakalant and placebo groups were similar. Of all patients given vernakalant, 136 (59.4%) converted to sinus rhythm within 90 minutes, compared with three (4.9%) placebo patients. The median time to conversion with vernakalant was 12 minutes (interquartile range = 7–24.5 minutes). Clinically significant bradycardia and hypotension were uncommon, and no cases of torsade de pointes or ventricular fibrillation occurred. Conclusions: Vernakalant rapidly converted recent‐onset AF to sinus rhythm in over half of patients, was well tolerated, and has the potential to offer an important therapeutic option for rhythm control of recent‐onset AF in the ED. ACADEMIC EMERGENCY MEDICINE 2010; 17:1175–1182 © 2010 by the Society for Academic Emergency Medicine     

Ibutilide for treatment of atrial fibrillation in the emergency department

The purpose of this study was to assess the efficacy and safety of ibutilide, a class III antiarrhythmic drug, for acute treatment of atrial fibrillation (AF) in the emergency department (ED) setting. A retrospective analysis was done reviewing all patients with AF who received ibutilide in the ED in a university hospital setting. A total of 22 patients received ibutilide. Another 24 patients who received rate control drugs only served as a control group. Of the 22 patients who received ibutilide, 14 (64%) converted to sinus rhythm. The mean (SD) rate of AF was 137 (24) bpm and the mean QTc interval immediately after conversion to sinus rhythm was 420 (28) ms. There were no complications. In the rate control group 7 patients (29%) converted to sinus rhythm (p<0.05, compared with ibutilide). The mean rate of AF was 126 (26) bpm (p = ns, compared with ibutilide) and the mean QTc interval in those who converted was 377 (28) ms (p<0.05, compared with ibutilide). One patient developed severe bradycardia. Ibutilide is effective for conversion of recent onset AF in patients presenting to the ED and there is a low rate of complications from ibutilide in this setting.     

Management of new-onset atrial fibrillation in the emergency department: is there any predictive factor for early successful cardioversion?

OBJECTIVES: The aim of this retrospective study was to assess the initial management of atrial fibrillation (AF) in the emergency department (ED) and to identify predictive factors of early conversion to sinus rhythm, which could justify a short stay in the ED observation unit (EDOU) instead of longer hospitalization. PATIENTS AND METHODS: All patients with acute AF, either of new onset or recurrent, admitted to our hospital during a 12-month period were included in the study. Hospital records were reviewed retrospectively. The success of conversion to sinus rhythm was recorded in association with a series of clinical and laboratory factors. RESULTS: Sixty-seven patients (39 men and 28 women), with a mean age of 63.6+/-12.2 years, were studied. The most frequent presenting symptom was palpitations (n=40, 59.7%). In forty-two patients (62.7%) the duration of symptoms was less than 48 h. Digoxine was the anti-arrhythmic agent most frequently administered (n=26, 38.8%), followed by amiodarone (n=17, 25.4%). Fifty patients (73.1%) converted to sinus rhythm and for 45 of them conversion took place during their stay in the ED or in the EDOU. Factors associated with early conversion to sinus rhythm were aged younger than 65 years (P=0.021) and symptom duration of less than 48 h (P=0.001). On the other hand, the presence of signs of heart failure was significantly associated with unsuccessful early cardioversion (P=0.001). CONCLUSIONS: The majority of patients admitted with AF of acute onset had early conversion to sinus rhythm. AF in young patients, with a duration of symptoms of less than 48 h and without signs of heart failure can be managed in the EDOU, thus avoiding a longer hospitalization.     

Intravenous amiodarone for acute pharmacological conversion of atrial fibrillation in the emergency department

Atrial fibrillation (AF) is the most common arrhythmia seen in patients presenting to the emergency department (ED). Pharmacological conversion of atrial fibrillation to normal sinus rhythm (NSR) may be a feasible management strategy in selected patients. Recent guidelines have recommended intravenous amiodarone, a class III antiarrhythmic agent, for the conversion of AF to NSR. The purpose of this review is to examine the published evidence for the efficacy of IV amiodarone for the acute conversion of AF to NSR in the ED. Currently available data from 11 randomized, controlled trials and 3 meta analyses do not support the use of conventional doses of IV amiodarone for acute conversion in the ED. High dose IV or combined IV and oral administration may be effective as early as 8 hours in patients with recent-onset AF of <48 hour duration in patients without contraindications to these high dose regimens. There are no data to support the use of IV amiodarone for acute conversion in patients with an ejection fraction of <40% or clinical heart failure, so its use in these scenarios should be limited to symptomatic patients who are refractory to electrical conversion. More well-designed studies are required to determine the role of IV amiodarone for the acute conversion of AF in the ED.     

Ibutilide to expedite ED therapy for recent-onset atrial fibrillation flutter

OBJECTIVE: Ibutilide is a type III antiarrhythmic agent approved for the pharmacologic conversion of atrial fibrillation (AF) and atrial flutter (AFl). Previous studies conducted outside the ED setting have demonstrated conversion rates of 60% to 80%. This response has been highest in patients with recent-onset AF-AFl. These observations and the 4-hour half-life of ibutilide suggest that it may be an excellent drug with which to treat AF-AFl in the ED. The purpose of the study was to examine the efficacy and safety of ibutilide in terminating AF-AFl in patients who present to the ED with symptoms of less than 3 days' duration, neither angina nor heart failure, and no comorbid conditions that require admission. METHODS: Among 36 enrolled patients, the admission electrocardiogram demonstrated AF in 26 and AFl in 10. Ibutilide 1 mg was administered intravenously for 10 minutes. If sinus rhythm was not present 10 minutes after the infusion concluded, a second infusion of 1 mg was given. Successful conversion was defined as restoration of sinus rhythm within 1 hour after the last dose of ibutilide. RESULTS: Sixteen (61.5%) of 26 patients with AF and 9 (90%) of 10 patients with AFl converted to sinus rhythm (overall conversion rate=69%). The mean time to arrhythmia termination was 19+/-9 minutes. The mean stay in the ED was 16.2 hours. No significant complications occurred. CONCLUSION: We conclude that ibutilide is an excellent therapy option for restoring sinus rhythm in the ED. Its use may obviate the need for admission, avoid the risks and inconveniences of general anesthesia to perform electrical cardioversion, and reduce the ED length of stay in selected patients with recent-onset atrial arrhythmias.     

Aminophylline Induced Atrial Fibrillation

Atrial fibrillation (AF) with a rapid ventricular response was induced by intravenous [W] aminophyJJine during treatment for symptomatic pulmonary disease in three patients who had no evidence of underlying heart disease or previous cardiac arrhythmia. Serum theophylline concentration was therapeutic in two patients and toxic in the third. Previous reports of AF related to aminophylline have underscored its association with toxic serum theophylline concentration. Conversion to sinus rhythm occurred at a time interval (9–14 hours] appropriate o t the serum decay of aminophylline, after its cessation. A shortened atrial refractory period and dispersed recovery of excitability consequent to aminophylline may engender multiple reentrant circuits and lead to AF, IV diltiazem was more effective than digoxin in the ventricular rate control of AF prior to conversion to sinus rhythm.     

Must antidysrhythmic agents be given to all patients with new-onset atrial fibrillation?

We investigated the spontaneous conversion rate of new-onset atrial fibrillation (AF) in emergency department patients and the recurrence rate of AF during a 1 month follow-up period. Sixty-six consecutive hemodynamically stable patients presenting to a university hospital emergency department with new-onset atrial fibrillation (less than 72 hours duration) comprised the study population. Patients were initially monitored for 8 hours and observed for spontaneous conversion of AF to sinus rhythm. If conversion did not occur in the first 8 hours, an oral loading dose (600 mg) of propafenone was given, and patients were observed for an additional 8 hours. All patients were reevaluated at 24 hours and at 1 month. The spontaneous conversion rate in patients presenting within 6 hours of AF onset during the initial 8-hour observation period was 71%. The spontaneous conversion rate for all patients during the initial observation period was 53%. The conversion rates between patients presenting "early" (less than 6 hours) and "late" (7-72 hours) were significantly different (P < 0.001). Many patients with new-onset AF, especially those with atrial fibrillation duration less than 6 hours, may need observation only, rather than immediate intervention, to treat their dysrhythmia.     

Termination of recent-onset atrial fibrillation/flutter in the emergency department: a sequential approach with intravenous ibutilide and external electrical cardioversion

Safety and effectiveness are the goals in treating patients with arrhythmias. In an open prospective study, we observed the efficacy and safety of up to 2 mg intravenous ibutilide, a new class III antiarrhythmic agent in haemodynamically stable patients presenting in the emergency department (ED) with symptoms of recent-onset (<48 h) atrial fibrillation/flutter. Arrhythmia termination within 90 min, haemodynamic parameters and proarrhythmic effects were assessed. Non-responders to the ibutilide infusion underwent external electrical cardioversion. We included 51 patients. In 31 patients therapeutic intervention with intravenous ibutilide was successful within 90 min (61%). In another seven patients conversion to sinus rhythm occurred after 90 min without any other intervention (14%). Blood pressure remained stable and no relevant proarrhythmic effects were observed. The 13 patients who did not respond to ibutilide treatment underwent successful external electrical cardioversion. The overall conversion rate was 100%. Forty-seven patients (92%) were discharged within a median of 9 h and managed as outpatients. In conclusion, in haemodynamically stable patients with recent-onset atrial fibrillation/flutter intravenous ibutilide and external electrical cardioversion for conversion to sinus rhythm turned out to be effective and safe. The short duration of admission makes this strategy attractive for use in the ED.     

Magnesium Sulfate versus Placebo for Paroxysmal Atrial Fibrillation: A Randomized Clinical Trial

Objectives: The objective was to investigate the efficacy of magnesium sulfate (MgSO₄) in decreasing the ventricular rate in emergency department (ED) patients presenting with new‐onset, rapid atrial fibrillation (AF). Methods: A double‐blinded, placebo‐controlled randomized clinical trial was conducted in an adult university hospital. Patients aged ≥18 years with AF onset of less than 48 hours and a sustained ventricular rate of >100 beats/min were randomized to either intravenous (IV) MgSO₄ 10 mmol or normal saline (NSal). Rhythm and instantaneous heart rate as measured by the monitor were recorded at baseline and every 15 minutes for 2 hours after starting the trial drug. Heart rate and rhythm were compared at 2 hours. A multilevel modeling analysis was performed to adjust for differences in baseline heart rate and any additional treatment and to examine changes in heart rate over time. Results: Twenty‐four patients were randomized to MgSO₄ and 24 to NSal. Baseline heart rate was lower in the MgSO₄ group (mean ± standard deviation [±SD] = 125 ± 24 vs. 140 ± 21 beats/min]. One and 3 patients in the MgSO₄ and NSal groups, respectively, were given another antiarrhythmic or were electrically cardioverted within 2 hours after starting the trial drug. Heart rate (mean ± SD) at 2 hours in both MgSO₄ (116 ± 30 beats/min) and NSal groups (114 ± 31 beats/min) decreased below their respective baseline levels. However, the rate of heart rate decrease across time did not differ between groups (p = 0.124). The proportion of patients who converted to sinus rhythm 2 hours post–trial drug did not differ (MgSO₄ 8.7% vs. NSal 25.0%, p = 0.25). Conclusions: This study was unable to demonstrate a difference between IV MgSO₄ 10 mmol and saline placebo for reducing heart rate or conversion to sinus rhythm at 2 hours posttreatment in ED patients with AF of less than 48 hours duration.     

Intravenous Propafenone for Converting Recent onset Atrial Fibrillation in Emergency Departments: A Randomized Placebo-Controlled Multicenter Trial

Atrial fibrillation (AF) is one of the most frequent dysrhythmias in patients coming to emergency departments (EDs), and pharmacological treatment is frequently performed. The aim of this randomized placebo-controlled multicenter trial was to compare propafenone (a class 1C antidysrhythmic agent), administered i.v. in the ED, with placebo in the treatment of recent-onset AF (<72 h). We randomly allocated 156 patients (88 males; 68 females) from 18 to 80 years old, with recent-onset AF, to receive i.v. propafenone (2 mg/kg for 10 min) or the matching placebo. The patients were followed for 2 h. Exclusion criteria were the presence of one of the following: lack of informed consent, clinical evidence of heart failure, clinical hyperthyroidism, recent acute myocardial infarction, atrioventricular block, cardiac valve dysfunction, a history of bronchial asthma, and current treatment with antidysrhythmic agents including digitalis. The two groups did not differ significantly in terms of sex, age, body weight, or estimated time elapsed since the beginning of atrial fibrillation. Conversion to sinus rhythm occurred in 13 of the 75 patients who received the placebo (17.3%) and in 57 of the 81 patients who were given propafenone (70.3%). In conclusion, intravenous propafenone administration in the ED can be considered a safe and effective approach for converting AF to sinus rhythm.     

快速型心房颤动患者静脉应用地尔硫卓和美托洛尔的疗效观察

目的 比较静脉注射地尔硫卓和美托洛尔控制心房颤动(简称房颤)患者快速心窒率的疗效.方法吉林人学第二医院2003年1月至2006年7月收治的48例心室率>120次/min 且收缩压≥100 mmHg的房颤患者分为地尔硫卓组(n=24)和美托洛尔组(n=24).地尔硫卓和美托洛尔的用法分别为10 nag和5 mg静脉注射.记录用药后5 min,10 min,15 min和30 min时的患者的心率和血压.治疗有效的定义为用药30 min后心室率下降至100次/min以下或较用药前的心率下降20%以上或转复为窦性心律.数据比较采用t检验、配对t检验及χ2检验.结果 和用药前比较,两种药物在上述各个时间点均能显著降低房颤时的快速心窒率(P<0.01),但除用药后30 min外,其它各时间点地尔硫卓组的心窒率显著低于美托洛尔组(P<0.05).在降低心室率的同时,这两种药物亦使血压有所降低,但两组之间的降压作用差异无统计学意义.两组均未见药物所敛的低血压者.用药后30min,地尔硫卓组和美托洛尔组的治疗有效率分别为91.7%和83.3%(P>0.05).结论 静脉注射地尔硫卓10 mg或荚托洛尔5 mg在30 min均能使房颤时的快速心室率显著降低,无以地而硫卓作用更强.     

A formula for the stratified selection of patients with paroxysmal atrial fibrillation in the emergency setting: a retrospective pilot study

Background: Amiodarone is a commonly used medication in the treatment of atrial fibrillation (AF) of recent onset. Study Objectives: The aim of the study was to identify a possible formula for selecting Emergency Department (ED) patients with paroxysmal AF who will spontaneously restore sinus rhythm (SR), successfully restore SR with the use of loading intravenous (i.v.) amiodarone, or require 24-h maintenance amiodarone infusion. Methods: This retrospective pilot study included 141 patients with recent-onset AF. Patients who did not restore SR spontaneously received i.v. amiodarone (5 mg/kg) within a period of 30 min. In case of no response, an additional dosage of 1000 mg of i.v. amiodarone was administered over a period of 24 h. Binary logistic regression models were used to determine the predictors of spontaneous conversion and the response to amiodarone administration. Results: The formula ([heart rate/systolic blood pressure] + 0.1 × number of past AF incidences) was chosen as the one with the highest combined sensitivity and specificity. This index identified the patients who spontaneously restored SR (cutoff point 1.31 with 78.6% sensitivity and 77.9% specificity), whereas for patients who responded to the loading i.v. amiodarone dose, the use of the index (cutoff point 1.24) exhibited 84.1% sensitivity and 75.3% specificity. Conclusions: This formula may be a useful and reliable bedside diagnostic tool to identify AF patients most likely to spontaneously convert, or respond to loading amiodarone administration in the emergency setting. The use of this index also can assist in patient risk stratification.     

Metoprolol vs. diltiazem in the acute management of atrial fibrillation in patients with heart failure with reduced ejection fraction

Objective

The objective of this study was to examine the effects of metoprolol versus diltiazem in the acute management of atrial fibrillation (AF) with rapid ventricular response (RVR) in patients with heart failure with reduced ejection fraction (HFrEF).

Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation

Objective: To compare the effectiveness of intravenous (IV) diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation (AF).

Methods: This prospective, randomised study was conducted in the Emergency Department of the Uludag University Medical Faculty Hospital, Bursa, Turkey. Forty AF patients with a ventricular rate 120/minute and systolic blood pressure 95 mm Hg were included and randomised to receive IV diltiazem 0.25 mg/kg (maximum 25 mg) or metoprolol 0.15 mg/kg (maximum 10 mg) over 2 minutes. Blood pressures and heart rate were measured at 2, 5, 10, 15, and 20 minutes. Successful treatment was defined as fall in ventricular rate to below 100/minute or decrease in ventricular rate by 20% or return to sinus rhythm.

Results: Between January 2000 and July 2002, 40 patients (18 men, 22 women) met the inclusion criteria. Of these 20 (8 men, 12 women; mean age 60.2 years, range 31–82) received diltiazem and 20 (10 men, 10 women; mean age 64.0 years, range 31–82) received metoprolol. The success rate at 20 minutes for diltiazem and metoprolol was 90% (n = 18) and 80% (n = 16), respectively. The success rate at 2 minutes was higher in the diltiazem group. The percentage decrease in ventricular rate was higher in the diltiazem group at each time interval. None of the patients had hypotension.

Conclusion: Both diltiazem and metoprolol were safe and effective for the management of rapid ventricular rate in AF. However, the rate control effect began earlier and the percentage decrease in ventricular rate was higher with diltiazem than with metoprolol.

     

Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation

Introduction

We compare the outcomes for patients who received esmolol to those who did not receive esmolol during refractory ventricular fibrillation (RVF) in the emergency department (ED).

Methods

A retrospective investigation in an urban academic ED of patients between January 2011 and January 2014 of patients with out-of-hospital or ED cardiac arrest (CA) with an initial rhythm of ventricular fibrillation (VF) or ventricular tachycardia (VT) who received at least three defibrillation attempts, 300 mg of amiodarone, and 3 mg of adrenaline, and who remained in CA upon ED arrival. Patients who received esmolol during CA were compared to those who did not.

Results

90 patients had CA with an initial rhythm of VF or VT; 65 patients were excluded, leaving 25 for analysis. Six patients received esmolol during cardiac arrest, and nineteen did not. All patients had ventricular dysrhythmias refractory to many defibrillation attempts, including defibrillation after administration of standard ACLS medications. Most received high doses of adrenaline, amiodarone, and sodium bicarbonate. Comparing the patients that received esmolol to those that did not: 67% and 42% had temporary return of spontaneous circulation (ROSC); 67% and 32% had sustained ROSC; 66% and 32% survived to intensive care unit admission; 50% and 16% survived to hospital discharge; and 50% and 11% survived to discharge with a favorable neurologic outcome, respectively.

Conclusion

Beta-blockade should be considered in patients with RVF in the ED prior to cessation of resuscitative efforts.     

Clinical management of atrial fibrillation: early interventions,observation, and structured follow-up reduce hospitalizations

Background

Novel facilities such as an intensive observation unit and an outpatient clinic could result in improving management of patients presenting with atrial fibrillation (AF).

Methods

This observational study enrolled 3475 patients. Group 1 (1120 patients; years 2004-2005) was managed with standard approach; group 2 (992 patients; years 2006-2007) was managed with additional intensive observation; group 3 (1363 patients; years 2008-2009) was managed with additional intensive observation and outpatient clinic. Primary end point was admission to hospital. Secondary end points included modalities of rhythm conversion and administration of class IC vs class III antiarrhythmic drugs in patients with AF lasting less than 48 hours.

Results

Lack of rhythm control, comorbidities, diabetes, and age were independent predictors of hospitalization. Admissions significantly decreased from group 1 (50%) to 2 (38%) and to 3 (24%) (P < .001). Interestingly, more than a quarter of patients in group 3 were referred to the outpatient clinic for short-term follow-up, eventually avoiding admission. Patients with AF lasting less than 48 hours (n = 2189) and without structural heart disease (n = 1685) achieved sinus rhythm in 89% of cases and were discharged. In these patients, early administration of antiarrhythmic drugs of class IC and III gained sinus rhythm in 80% and 20%, respectively (P < .001). Spontaneous conversion occurred in 26%; electrical, 17%; and pharmacological, 57%.

Conclusions

In patients with AF, beyond the standard approach, the novel organization with an additional intensive observation unit for early pharmacological interventions and an outpatient clinic for elective treatment and short-term follow-up significantly reduced admission irrespective of independent predictors of hospitalizations. Patients without structural heart disease treated with antiarrhythmic drugs achieved sinus rhythm in 89% of cases, mostly with class IC drugs.     

Atrial Lead Placement During Atrial Fibrillation. Is Restitution of Sinus Rhythm Required for Proper Lead Function? Feasibility and 12‐Month Functional Analysis

Unexpected atrial fibrillation (AF) during implantation of an atrial pacemaker lead is sometimes encountered. Intraoperative cardioversion may lengthen and complicate the implantation process. This study prospectively investigates the performance of atrial leads implanted during AF (group A) and compares atrial sensing and pacing properties to an age- and sex-matched control group in which sinus rhythm had been restored before atrial lead placement (group B). Patient groups consisted of 32 patients each. All patients received DDDR pacemakers and bipolar, steroid-eluting, active fixation atrial leads. In patients with AF at the time of implantation (group A), a minimal intracardiac fibrillatory amplitude of at least 1.0 mV was required for acceptable atrial lead placement. In patients with restored sinus rhythm (group B), a voltage threshold < 1.5 V at 0.5 ms and a minimal atrial potential amplitude > 1.5 mV was required. Patients of group A in whom spontaneous conversion to sinus rhythm did not occur within 4 weeks after implantation underwent electrical cardioversion to sinus rhythm. Pacemaker interrogations were performed 3, 6, and 12 months after implantation. In group A, implantation time was significantly shorter as compared to group B (58.7 +/- 8.6 minutes vs 73.0 +/- 17.3 minutes, P < 0.001). Mean atrial potential amplitude during AF was correlated with the telemetered atrial potential during sinus rhythm (r = 0.49, P < 0.001), but not with the atrial stimulation threshold. Twelve months after implantation, sensing thresholds (1.74 +/- 0.52 mV vs 1.78 +/- 0.69 mV, P = 0.98) and stimulation thresholds (1.09 +/- 0.42 V vs 1.01 +/- 0.31 V, P = 0.66) did not differ between groups A and B. However, in three patients of group A, chronic atrial sensing threshold was < or = 1 mV requiring atrial sensitivities of at least 0.35 mV to achieve reliable atrial sensing. Atrial lead placement during AF is feasible and reduces implantation time. However, bipolar atrial leads and the option to program high atrial sensitivities are required.     

Carotid Sinus Massage as a Diagnostic and Therapeutic Tool for Atrial Flutter-Fibrillation

Alterations in vagal tone can influence the atrial fibrillatory process by changing the atrial refractory period. We observed in a patient with paroxysmal atrial fibrillation (AF) that carotid sinus massage (CSM) changed a "coarse" type of fibrillation into a "fine" type, followed by termination of the arrhythmia. Although coincidental conversion of AF into sinus rhythm could not be excluded, we concluded that it is worthwhile to try CSM in every patient presenting with AF prior to other interventions to restore sinus rhythm.     

经食管超声心动图对心房颤动患者右心耳自发显影回声和血栓发生的研究

目的探讨经食管超声心动图(TEE)观察慢性心房颤动(房颤)时右心房、右心耳自发显影(SEC)和血栓发生情况。方法选取26例房颤患者和13例窦性心律患者，常规经胸超声心动图资料留取后，采用TEE充分清楚显示左、右心耳图像并采集血流流速曲线和其他相应指标。结果26例房颤患者左心耳内均可测及SEC，共测及血栓形成者10例；房颤患者右心耳内有SEC者共17例，共测及右心耳血栓形成者1例。结论房颤时右心耳内可有血栓发生，TEE检查在房颤抗凝治疗中和复律前后具有重要意义。     

Initial Clinical Experience with an Implantable Human Atrial Defibrillator

Low energy biatrial shock is an effective means of restoring sinus rhythm in patients with atril fibrillation (AF). Ventricular proarrhythmia is avoided provided that shocks are well synchronized to R waves that are not at closely coupled intervals or preceded by long-short cycles. Based on these principles, an implantable atrial defibrillator has been developed and was implanted in three patients with drug refractory paroxysmal AF. The device detects AF via an actively fixed right atrial and a self-retaining coronary sinus defibrillating leads, and delivers 3/3 ms biphasic shocks up to 300 V synchronized to the R wave. The mean implant threshold (ED50) was 195V (1.8 J), and minimum voltage at conversion during follow-up assessments at 1, 3, and 6 months were 260 V, 2.5 J, 250 V, 2.3 J, and 300 V, 3.0 J respectively. Detection of AF was 100% specific and shocks were 100% synchronized, although only a proportion of synchronized R waves were considered suitable for shock delivery primarily because of closely coupled cycles. Three patients had 9 spontaneous AF episodes. 8/9 (89%) successfully defibrillated by shocks of 260–300 V. Sedation was not used in 4 out of 9 (45%) episodes. Backup ventricular pacing was initiated by the device in 6 out of(67%) episodes. One patient had more frequent AF after lead placement, which subsided after a change of medication. There was no ventricular proarrhythmia. It is concluded that an implantable atrial defibrillator is a viable therapy for selected patients with paroxysmal AF. The device is capable of accurate AF detection, R wave synchronization and ventricular support pacing after successful defibrillation of AF.