Chronic Rapid Atrial Pacing to Maintain Atrial Fibrillation: Use to Permit Control of Ventricular Rate in Order to Treat Tachycardia Induced Cardiomyopathy

LR was a patient, followed over a 16-year period, who presented with an atrial tachycardia which was initially intermittent, but became incessant. Neither the atrial tachycardia nor the associated rapid ventricular response rate could be treated successfully with available drug therapy, resulting in a dilated cardiomyopathy and New York Heart Association (NYHA) class III-IV congestive heart failure. Acute induction of atrial fibrillation with rapid atrial pacing demonstrated that the associated ventricular rate could be satisfactorily slowed with digitalis therapy. Initially, short bursts from an implanted, radiofrequency controlled, patient activated pacemaker programmed to a rate of 600 bpm and connected to a permanent endocardial atrial J lead successfully interrupted the tachycardia and precipitated atrial fibrillation. Over a period of 3 months, this therapy changed the patient's heart failure to NYHA class II status. Subsequently, precipitation of atrial fibrillation with this technique failed, resulting in return to NYHA class III-IV congestive heart failure. Therefore, a custom-designed, high rate, rate-programmable pacemaker was implanted to pace the atria rapidly and continuously to maintain atrial fibrillation. A pacing rate of 375 bpm plus digoxin slowed the ventricular rate to 70-80 bpm, with stabilization of the congestive heart failure to NYHA class II. The pacemaker generator was replaced 6 months later, and after another 5 months, pacing was discontinued. The patient's subsequent rhythm remained stable atrial fibrillation with clinically successful control of both the ventricular rate and heart failure (NYHA class II) until the patient's death 72 months later. This unique case demonstrates another form of chronic therapy which, in selected cases, can be used for the long term control of rapid ventricular response rates to supraventricular arrhythmia.     

Atrial Fibrillation: Maintaining Stability of Sinus Rbythm or Ventricular Rate Control? The Need for Prospective Data: The PIAF Trial

Atrial fibrillation is one of the most commonly encountered clinical arrhythmias. Different treatment options for this rhythm disorder exist with the electrical and/or pharmacological cardioversion to sinus rhythm with subsequent antiarrhythmic drug therapy to prevent recurrences being one of the primary therapeutic goals. Another alternative, however, is represented by the control of the ventricular rate in patients with persistent atrial fibrillation. The question of which of these two strategies should be preferred in the majority of patients with atrial fibrillation has not been studied in a prospective way. Given the background of conflicting data with respect to the prognostic impact of atrial fibrillation and of the increasing evidence concerning the risks of antiarrhythmic drug treatment in atrial fibrillation, a prospective multicenter trial has been initiated to compare these two therapeutic alternatives prospectively. Patients will be randomly assigned to cardioversion with subsequent antiarrhythmic drug therapy to prevent recurrent atrial fibrillation or to a therapy aiming exclusively at control of the ventricular rate during persistent atrial fibrillation. All patients will receive anticoagulation by means of warfarin (target INR 2.5-3.5) to prevent thromboembolic complications. The rationale and the design of the PIAF trial (Pharmacological Intervention in Atrial Fibrillation) are discussed below. The pilot phase of this study has begun patient enrollment in the spring of 1995.     

Management of common arrhythmias: Part I. Supraventricular arrhythmias

Family physicians frequently encounter patients with symptoms that could be related to cardiac arrhythmias, most commonly atrial fibrillation or supraventricular tachycardias. The initial management of atrial fibrillation includes ventricular rate control to provide adequate cardiac output. In patients with severely depressed cardiac output and recent-onset atrial fibrillation, immediate electrical cardioversion is the treatment of choice. Hemodynamically stable patients with atrial fibrillation for more than two days or for an unknown period should be assessed for the presence of atrial thrombi. If thrombi are detected on transesophageal echocardiography, anticoagulation with warfarin for a minimum of 21 days is recommended before electrical cardioversion is attempted. Patients with other supraventricular arrhythmias may be treated with adenosine, a calcium channel blocker, or a short-acting beta blocker to disrupt reentrant pathways. When initial medications are ineffective, radiofrequency ablation of ectopic sites is an increasingly popular treatment option.     

Rhythm or rate control in atrial fibrillation: insights from the randomized controlled trials

Pharmacologic treatment remains the mainstay of therapy in patients with atrial fibrillation for the maintenance of normal sinus rhythm. Initial therapy of atrial fibrillation is often directed toward the maintenance of sinus rhythm by means of cardioversion and the use of antiarrhythmic drugs. Heart rate control is often only pursued when rhythm control fails. Four randomized controlled trials have carefully evaluated the yield of these two treatment strategies as the initial approach to patients with paroxysmal or persistent atrial fibrillation. In essence, all four trials demonstrated that an initial strategy of rate control is equally effective compared to the rhythm control approach in terms of clinically important outcome measures including mortality, stroke prevention, or quality of life. Accordingly, rate control can be considered as an initial approach to therapy in patients with paroxysmal or persistent atrial fibrillation. The four randomized trials clearly demonstrate that continuous anticoagulation is mandatory in all patients with atrial fibrillation and risk factors for stroke, irrespective of the initial therapeutic approach of rhythm or rate control.     

Enhancement of myocardial vulnerability by atrial fibrillation

Certain groups are known to have an increased risk for sudden cardiac death. Epidemiologic studies have suggested that patients with atrial fibrillation may be at higher risk. The authors hypothesize that atrial fibrillation may increase myocardial vulnerability. To test this hypothesis, 37 dogs were studied using programmed electrical stimulation techniques to determine myocardial vulnerability as assessed by the ability to provoke ventricular tachycardia. Prior to atrial fibrillation, programmed electrical stimulation did not induce ventricular tachycardia. Aconitine was then topically applied to the right atrial appendage with care taken not to make contact with the ventricle. Application of aconitine caused atrial fibrillation with an increase in ventricular rate, but did not affect arterial blood pressure. Ventricular tachycardia was induced by programmed electrical stimulation studies in 25 of 26 dogs in atrial fibrillation. The enhanced vulnerability was noted following atrial fibrillation, not after aconitine application to the great veins, which did not cause atrial fibrillation. To further exclude the possibility that aconitine application may cause changes in ventricular threshold, atrial fibrillation was induced by pacing techniques in five dogs. Prior to atrial fibrillation induction, programmed electrical stimulation did not induce ventricular tachycardia. Following atrial fibrillation, ventricular tachycardia could be repeatedly induced. Mean heart rate following atrial fibrillation increased, while pacing animals at this increment in rate did not change the noninducibility of dogs in sinus rhythm. Six patients with a history of atrial fibrillation and ventricular tachycardia were studied to determine if AF lowered myocardial threshold to VT induction. Ventricular tachycardia could only be induced by PES techniques in four of five patients when the patients' rhythm was AF (P < 0.05). This study suggests that atrial fibrillation lowers myocardial threshold for ventricular tachycardia induction and thus enhances myocardial vulnerability. The association of AF with a higher incidence of sudden death may be due to an enhanced electrical instability.     

A review of carvedilol arrhythmia data in clinical trials

beta-Blockers are currently being evaluated more intensively to define their role in clinical use as antiarrhythmic agents. beta-Adrenergic blockade has been studied in relation to atrial fibrillation, ventricular arrhythmias, and sudden death; however, it is apparent from a number of studies that not all beta-blockers are equally effective. Randomized clinical trial data, both in heart failure and post-myocardial infarction (MI) patients, have shown differences in mortality benefits in addition to a variable effect on arrhythmias and sudden death. Carvedilol, a third-generation beta-blocker with proven clinical benefit in the management of heart failure and post-MI patients, has properties that may make it an effective antiarrhythmic agent. This paper reviews the current clinical arrhythmia data available for carvedilol from large-scale clinical trials and small studies. The trial evidence demonstrates that carvedilol therapy can be an effective adjunctive rate-control therapy in patients with atrial fibrillation, prevent mortality in patients with heart failure or post-MI with left ventricular dysfunction, with or without atrial fibrillation, and reduce its onset and the incidence of ventricular arrhythmia and sudden death.     

Atrial fibrillation: diagnosis and treatment

Atrial fibrillation is the most common cardiac arrhythmia. It impairs cardiac function and increases the risk of stroke. The incidence of atrial fibrillation increases with age. Key treatment issues include deciding when to restore normal sinus rhythm, when to control rate only, and how to prevent thromboembolism. Rate control is the preferred management option in most patients. Rhythm control is an option for patients in whom rate control cannot be achieved or who have persistent symptoms despite rate control. The current recommendation for strict rate control is a resting heart rate of less than 80 beats per minute. However, one study has shown that more lenient rate control of less than 110 beats per minute while at rest was not inferior to strict rate control in preventing cardiac death, heart failure, stroke, and life-threatening arrhythmias. Anticoagulation therapy is needed with rate control and rhythm control to prevent stroke. Warfarin is superior to aspirin and clopidogrel in preventing stroke despite its narrow therapeutic range and increased risk of bleeding. Tools that predict the risk of stroke (e.g., CHADS2) and the risk of bleeding (e.g., Outpatient Bleeding Risk Index) are helpful in making decisions about anticoagulation therapy. Surgical options for atrial fibrillation include disruption of abnormal conduction pathways in the atria, and obliteration of the left atrial appendage. Catheter ablation is an option for restoring normal sinus rhythm in patients with paroxysmal atrial fibrillation and normal left atrial size. Referral to a cardiologist is warranted in patients who have complex cardiac disease; who are symptomatic on or unable to tolerate pharmacologic rate control; or who may be candidates for ablation or surgical interventions.     

The Value of Rate Regularity and Multiplicity Measures to Detect Ventricular Tachycardia in the Presence of Atrial Fibrillation or Flutter

The predominant cause of inappropriate therapy by implantable antitachycardia devices with pacing and nonpacing cardioverter defibrillators, is mistaking a fast ventricular response during atrial fibrillation or flutter with true ventricular tachycardia (VT). The distinction between these arrhythmias is an important consideration in addressing the problem of reducing false-positives in detection mechanisms for implantable devices. Dual chamber analysis that examines atrial and ventricular event ratios has been proposed as a solution to this problem, but would still fail in distinguishing paroxysmal VT requiring treatment from a fast but otherwise benign ventricular response during atrial fibrillation or flutter. In this study, two methods for discriminating these tachyarrhythmias were evaluated. Method 1 examined ventricular rate and rate regularity as a method for VT detection. Method 2 combined rate and regularity as well as an additional multiplicity criterion for recognition of atrial flutter with a fast ventricular response. In 20 patients. Method 1 had 100% sensitivity of VT detection and 80% specificity for detection of atrial fibrillation or flutter. Method 2 had 90% sensitivity and 90% specificity. These results suggest that use of these algorithms in future implantable devices would result in a decrease in false-positive device therapies.     

Acute therapy of maternal and fetal arrhythmias during pregnancy

Atrial premature beats are frequently diagnosed during pregnancy. Supraventricular tachycardia (atrial tachycardia, atrioventricular nodal reentrant tachycardia, circus movement tachycardia) is diagnosed less frequently. For acute therapy, electrical cardioversion with 50 to 100 J is indicated in all unstable patients. In stable supraventricular tachycardia, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during pregnancy and are benign in most patients; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia, ventricular flutter, or ventricular fibrillation) may occur. Electrical cardioversion is necessary in all patients who are hemodynamically unstable with life-threatening ventricular tachyarrhythmias. In hemodynamically stable patients, initial therapy with ajmaline, procainamide, or lidocaine is indicated. In patients with syncopal ventricular tachycardia, ventricular fibrillation, ventricular flutter, or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In patients with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of pregnancy. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered.     

Overview of management of atrial fibrillation in symptomatic elderly patients: pharmacologic therapy versus AV node ablation

Atrial fibrillation is an abnormal heart rhythm affecting the upper chambers of the heart in which uncoordinated electrical depolarizations lead to ineffective contractions. Approximately five million patients in the US have atrial fibrillation, and this number is expected to double to 10 million over the next 30 years. Advancing age is a major risk factor for the development of atrial fibrillation; new cases of atrial fibrillation are diagnosed in men over age 80 at the rate of 2% per year. Although several drugs are available for management of atrial fibrillation, the efficacy of these drugs may be limited in elderly patients. In this review, we provide an overview of management of atrial fibrillation, with special emphasis on pharmacologic therapy versus arteriovenous (AV) node ablation in symptomatic elderly patients.     

急性心肌梗死并发心房颤动33例临床分析

目的 探讨急性心肌梗死并发心房颤动的临床特点及治疗。方法 对３３例急性心肌梗死并发心房颤动的临床资料进行了回顾性分析。结果 急性心肌梗死并发心房颤动的发生率为１４．４％,梗死部位以广泛前壁乡见。结论 急性心肌梗死并发心房颤动多见于梗死后左心功能不全或窦房结功能低下所致,当。心室率＞１２０／分时应给予紧急措施控制心室率．若心房颤动持续不能转复则预后不良。     

Ventricular Fibrillation Following Successful DC Cardioversion for Atrial Fibrillation

Cardioversion remains an important therapy in the management of atrial fibrillation. Here, we report a case where direct current cardioversion resulted in a sudden dramatic change of heart rate that was associated with multiple ventricular fibrillation arrests in a manner akin to that previously observed post-atrioventricular node ablation. (PACE 2012;35:e361-e364).     

琥珀酸美托洛尔缓释片对慢性心房颤动伴慢性充血性心力衰竭患者心室率及心功能的影响

目的观察琥珀酸美托洛尔缓释片对慢性心房颤动（AF）伴慢性充血性心力衰竭（CHF）患者心室率及心功能的影响。方法慢性AF合并CHF患者共69例,随机分为治疗组（35例）和对照组（34例）,两组均常规使用地高辛、利尿剂、血管紧张素转换酶抑制剂（ACEI）或血管紧张索Ⅱ受体拮抗剂（ARB）、抗凝剂。治疗组在常规治疗的基础上给与琥珀酸美托洛尔缓释片。治疗6个月,观察两组治疗前后静息心室率、运动后心室率、左室舒张末期内径（LVEDD）、左室收缩末期内径（LVESD）、左室射血分数（LVEF）及6min步行试验。观察治疗后6个月时的临床症状变化。结果①两组患者的静息心室率治疗后比治疗前均明显降低（P〈0．01）;运动后心室率治疗组治疗后比治疗前明显减低（P〈0．01）,对照组治疗前后变化不显著（P〉0．05）,治疗后运动后心室率治疗组比对照组明显减低（P〈0．01）;②治疗6个月后两组左室舒张末内径（LVEDD）、左室收缩末内径（LVESD）、左室射血分数（LVEF）、6min步行试验都有明显改善（P〈0．01～0．05）,但治疗组明显优于对照组,差异有统计学意义（P〈0．05）;③治疗组临床症状改善,总有效率为93．8％,明显高于对照组的77．4％（P〈0．05）。结论在使用强心、利尿、ACEI或ARB基础上,琥珀酸美托洛尔缓释片能有效控制慢性AF伴CHF患者心室率,显著改善心功能,改善心室重塑。     

Broad complex atrial fibrillation

The management of broad complex atrial fibrillation is complex and may be a source of morbidity and mortality if not correctly recognized and treated appropriately. We present a case series of 3 patients who were managed in our emergency department after complaints of palpitations. They presented with varying forms of rapid atrial fibrillation that had broad complexes on the 12-lead electrocardiogram. The first 2 patients were treated with calcium channel blockers for rate control, and treatment was complicated by rapid arrhythmia that required cardioversion. The final patient was correctly treated with intravenous procainamide. The diagnosis of Wolff-Parkinson-White syndrome was eventually made in all these patients. Broad complex atrial fibrillation must be treated with respect. Cases with rapid ventricular rate can decompensate from mismanagement due to poor ability to recognize the possibility of Wolff-Parkinson-White syndrome in such patients. Procainamide forms the cornerstone of treatment in hemodynamically stable rapid broad complex atrial fibrillation of unknown origin.     

Ablating the Imperceptible: A Novel Application of Para‐Hisian Pacing

In some elderly patients with atrial fibrillation, especially in combination with heart failure, a rate control strategy may be preferred. When pharmacological therapy is ineffective or not tolerated, it is reasonable to perform atrioventricular (AV) node ablation with ventricular pacing. We describe a case in which this approach was necessary for management. However, the presence of periprocedural, drug‐induced AV block just before ablation provided a unique and challenging circumstance. We discuss the steps taken to ensure a successful procedure.     

A review of the literature on atrial fibrillation: rate reversion or control?

Aims. The aim of this paper is to review the current literature describing the aetiology of atrial fibrillation and to examine the evidence for rate reversion and rate control. Background. Atrial fibrillation is the most commonly seen arrhythmia within the clinical setting. Treatment depends on severity of symptoms, which are predominantly palpitations and shortness of breath. The primary complications from atrial fibrillation are thrombo‐embolic events (such as a pulmonary embolus or stroke). Objectives and methods. A comprehensive literature review on atrial fibrillation, rate reversion and rate control was undertaken to examine the incidence of atrial fibrillation, to review research on management of atrial fibrillation and to determine if rate reversion was superior to rate control in the treatment of atrial fibrillation. Results. Many studies have been carried out to determine the best treatment for this condition. The choices are currently pharmacological and electrical cardioversion in conjunction with anticoagulant therapy. Drug therapies are not without their problems, especially toxicity and the need for close clinical monitoring. Transaesophageal echocardiography has been used to establish the presence of left atrial thrombi and aims to reduce the anticoagulation time and reduce the risk of thrombo‐embolic events. A randomized comparative study of transaesophageal echocardiography and conventional anticoagulation therapy prior to cardioversion demonstrated statistically significant reduction in haemorrhagic events and a shorter time to cardioversion in those in the transaesophageal echocardiography group compared with the conventional group. For those with persistent atrial fibrillation, surgery is an option with valve repair or replacement carried out in conjunction with a bi‐atrial surgical ablation. Conclusions. The management of atrial fibrillation is dependent on many factors and to date there are no proven clinical rationale for rate control or reversion. Relevance to clinical practice. Atrial fibrillation requires immediate attention in order to avoid thrombo‐embolic complications and the use of transaesophageal echocardiography and conventional anticoagulation therapy can significantly reduce these complications.     

206例心房颤动临床分析

目的 分析心房颤动的流行病学及其治疗现状。方法对206例心房颤动患者的临床资料进行回顾性分析。结果206例心房颤动的最常见的病因依次为冠心病、高血压和风湿性心脏病；心房颤动患者合并心力衰竭的发生率较高，约占49．0％；阵友性心房颤动药物复律约占50．O％。持续性或永久性心房颤动以洋地黄类及胺碘酮等控制心室率为主(58．5％)；应用抗凝治疗患者占44．1％。结论 206例心房颤动的主要病因为冠心病和高血压．合并心力衰竭的患者心房颤动的发生率较高；持续性和永久性心厉颤动药物控制心室率的效果亦佳。     

Efficacy of radiofrequency catheter ablation in treatment of elderly patients with supraventricular tachyarrhythmias and ventricular tachycardia

Radiofrequency catheter ablation was performed in 100 men and 81 women, mean age 78 +/- 5 years, referred for ablation of atrial flutter, supraventricular tachycardia, and ventricular tachycardia, and for ablation of the atrioventricular junction with permanent pacemaker implantation in patients with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy. A hematoma in 1 of 182 ablation procedures (<1%) was the only complication. Radiofrequency catheter ablation was successful in treating 63 of 70 patients (90%) with atrial flutter, in treating 60 of 66 patients (91%) with supraventricular tachycardia, in treating 2 of 2 patients (100%) with ventricular tachycardia, and in ablating the atrioventricular junction in 43 of 44 patients (98%) with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy.     

Near Doubling of Heart Rate After Intravenous Verapamil for Treatment of Atrial Fibrillation Without Preexcitation

Initial treatment of atrial fibrillation often involves pharmacological therapy to control ventricular response. While verapamil is usually safe and effective when used for this purpose, we report a proarrhythmic response. In this report a 30-year-old female presented with paipitations associated with atrial fibrillation and a ventricular response of 145 beats/min. Soon after she was given 5 mg of intravenous verapamil her ECG documented a regular wide QRS tachycardia at 290 beats/min. After 7 seconds the rhythm returned to an irregularly irregular narrow QRS tachycardia at 125–150 beats/min. At a later electropliysiology study there was neither evidence of preexcitation norinducible supraventricular or ventricular tachycardia. These data suggest that verapamil may have been associated with acceleration of the heart rate. The mechanism of proarrhythmia may be reiated to an aiteration in the atrial rhythm from atriaL fibrillation to atrial flutter, with additional factors as well.     

孤立性房颤与心脏结构功能相关性研究

目的:探讨孤立性房颤(LAF)患者心脏结构功能的特点。方法:依据ACC/AHA/ESC 2006房颤指南孤立性房颤诊断标准(LAF标准)分为LAF组(LAF组)49例,对照组(Normal组)49例均为同期健康体检者。观察超声心动图检测的各腔室容积、收缩功能和左室质量。结果:LAF组左室质量、左室质量指数、左房容积、右房容积明显大于对照组(P<0.05)。在房颤组中可看到左房容积与左室质量指数存在正相关(r=0.335,P<0.05)。结论:即使无器质性心脏病,孤立性房颤患者的双房、左室质量也已增大;心房容积、左室质量有可能成为孤立性房颤新的预测因子。