Permanent left atrial and left ventricular single-lead DDD pacing with a coronary sinus electrode

This report describes a patient with drug refractory severe chronic congestive heart failure, first-degree AV block, and wide QRS complexes of 175-ms duration with left bundle branch block who was successfully treated by a left-sided dual chamber pacemaker system using a single-lead coronary sinus electrode. Left atrial and ventricular signal amplitudes, left atrial and ventricular pacing thresholds were 2.5 mV, 13 mV, 1.8 V and 0.7 V (0.5 ms), respectively. Using DDD pacing with an optimal 120-ms AV delay the QRS duration decreased to 150 ms and the mitral filling pattern improved. Three months after implantation the patient's functional status improved from NYHA Class III-IV to Class II.     

心房纤颤心室率对心力衰竭患者血清NT-proBNP浓度的影响

目的 探讨心房纤颤(简称房颤)心室率对心力衰竭患者血清N-端脑利钠肽前体(NT-proBNP)浓度的影响.方法入选101例心力衰竭患者,按心电图诊断分为快速型房颤组(心室率大于100次/分,n=33)、普通型房颤组(心室率60～100次/分,n=32)和窦性心律组(n=36),再按纽约心脏病协会(NYHA)心功能分级标准分为心功能Ⅱ、Ⅲ和Ⅳ级3个亚组.采用胶体金法检测受试者血清NT-proBNP浓度并进行统计学分析.结果快速型房颤组、普通型房颤组及窦性心律组患者血清NT-proBNP浓度随NYHA心功能分级增加呈增高趋势,每组各亚组间比较差异有统计学意义(P＜0.05).窦性心律组、普通型房颤组、快速型房颤组患者血清NT-proBNP浓度在一定程度上呈增高趋势,但组间比较差异无统计学意义(P>0.05).在相同心功能分级亚组,快速型房颤组患者血清NT-proBNP浓度显著高于窦性心律组和普通型房颤组(P＜0.05),而普通型房颤组与窦性心律组比较,差异无统计学意义(P>0.05).结论 血清NT-proBNP浓度与心力衰竭严重程度相关;房颤对心力衰竭患者血清NT-proBNP浓度有一定影响,房颤心室率增快(超过100次/分)对血清NT-proBNP浓度影响越明显.     

Magnetic resonance imaging-based biventricular pacemaker upgrade

This report describes a patient with drug refractory severe chronic ischemic heart failure, atrial fibrillation with bradycardia, and left bundle branch block who had a failed implantation of a biventricular pacemaker because of a high left ventricular pacing threshold. VVI pacemaker implantation had not improved the patient's condition. MRI-guided biventricular pacemaker upgrade had been performed with a left ventricular epicardial lead at the lateral region where a 4-mm thickening during systole had been proven. After 6 months of effective resynchronization, the patient's functional class improved to NYHA II without further need of hospitalization.     

Permanent Overdrive Atrial Pacing in the Chronic Management of Recurrent Postoperative Atrial Reentrant Tachycardia in Patients with Complex Congenital Heart Disease

This study investigated the value of permanent atrial pacing as an adjunct to the current therapy in the chronic management of recurrent postoperative atrial reentrant tachycardia in patients with complex congenital heart disease. We studied the postpacing clinical course in 18 patients with recurrent atrial reentrant tachycardias unresponsive to conventional therapy who had an implanted atrial pacemaker. The pacemaker was programmed at a lower pacing rate 20% faster than the spontaneous mean daily rate previously determined with 24-hour Holter monitoring. Serial Holter recordings and pacemaker programming sessions were subsequently performed trying to mantain a paced atrial rhythm overdriving the spontaneous rhythm as long as possible. Twenty-four hour Holter monitoring documented a prevalent (> 80%) paced rhythm during the daily hours in all patients during the follow-up; all patients, however, required at least once a variation In programmed mode and pacing rate. Antiarrhythmic medications were discontinued after 6 months if the patient remained arrhythmia free while on pacing. Recurrences of atrial reentrant tachycardia occurred in five patients (29%) during the initial 6 months interval after the pacemaker implantation, while late recurrences occurred in only two patients (11 %). One patient died suddenly 10 months after the pacemaker implant. At the end of the follow-up, 15 patients (83%) were arrhythmia-free and only 2 of them were still on antiarrhythmic drugs. We conclude that permanent atrial overdrive pacing can be an important tool in the management of patients with atrial reentrant tachycardia following repair of congenital heart disease.     

起搏治疗对病窦综合征患者预后的影响

目的：观察不同起搏方式对病窦综合征预后的影响。方法：136例病窦综合征患者安装了永久人工心脏起搏器，其中VVI54例，DDD70例，AAI12例，分别随访了2～7．5年，观察房颤，充血性心力衰竭和起搏器综合征的发生率及病死率。结果：DDD，AAI与VVI起搏相比，房颤、充血性心力衰竭和起搏器综合征的发生率及病死率明显降低。结论：对病窦综合征患者起搏治疗应选择DDD和AAI起搏方式。     

A New Pacemaker for Paroxysmal Atrial Fibrillation Treated with Radiofrequency Ablation of the AV Junction

Atrial fibrillation is a relative contraindication to atrial synchronous pacing because of the risk of the tracking of rapid atrial rhythms by the pacemaker. In this study, we describe the clinical results of an AV synchronous rate responsive pacemaker with an original algorithm, which is able to sense pathological increments in atrial rate and automatically to switch into a non-AV synchronous mode of pacing. This pacemaker was implanted in 12 patients who had undergone radiofrequency ablation of the A V junction in order to cure severely symptomatic, drug refractory, paroxysmal atrial fibrillation. In an acute, intrapatient comparison between the standard AV synchronous mode and the automatic switching mode, ventricular tracking of atrial fibrillation occurred in 35% and 4% of total beats at rest and in 24% and 2% of total beats during exercise, respectively (P < 0.001). During 5 ± 4 months of follow-up, no further tachyarrhythmia related symptoms occurred. In conclusion, the standard DDDR mode is unable to eliminate ventricular tracking of atrial fibrillation, thus undermining the efficacy of AV junction ablation therapy. The automatic switching mode eliminates this adverse effect of dual chamber pacing.     

Magnet Application, a Cause of Persistent Arrhythmias in Physiological Pacemakers. Report of 2 Cases

Report of 2 cases. Magent application during routine pacemaker check-up induced persistent arrhythmias in two patients with physiological pacemakers. One patient had received an atrial synchronous ventricular demand pacemaker (VDD) because of alternating second-and third-degree atrio-ventricular block. During routine pacemaker follow-up, a magnet was applied over the pulse generator to measure the pacemaker rate. This converted the system to fixed rate ventricular pacing at a rate of 65 bpm which resulted in retrograde atrial activation. When the magnet was removed the retrograde conducted P-waves were sensed by the atrial amplifier and the ventricular output was triggered again, causing a re-entry pacemaker tachycardia with a rate of 175 bpm. The tachycardia could be suppressed by applying a magnet once more, but the pulse generator had to be programmed in the VVI-mode to prevent induction of the tachycardia again. A second patient had complete atrioventricular block and left heart failure. After three years of ventricular demand pacing, we decided to implant a DDD pacemaker because of persisting left heart failure and poor exercise tolerance. During a routine visit io the pacemaker clinic a magnet was applied over the pulse generator to measure the basic rate. The system was thus converted to fixed rate A-V-sequential pacing (DOO) which resulted in atrial flutter. When the magnet was removed and the pulse generator returned to its DDD mode, the atrial flutter was partially sensed by the atrial amplifier, resulting in a tachycardia with a variable rate up to 125 bpm. Fortunately we were able to terminate the atrial arrhythmia by applying the magnet again. In this patient fixed rate underdrive pacing stopped the atrial arrhythmia. (PACE, Vol. 5, September-October, 1982)     

Spontaneous Conversion of Permanent Atrial Fibrillation into Stable Sinus Rhythm After 17 Months of Biventricular Pacing

A 68-year-old woman with drug refractory congestive heart failure (NYHA Class III, ejection fraction 35%, moderate to severe mitral regurgitation) and permanent atrial fibrillation uninterrupted for >3 years, underwent implantation of a biventricular pacing system. Seventeen months later, atrial fibrillation spontaneously converted into sinus rhythm, which has been maintained for more than 6 months (to date). (PACE; 26[Pt. I]:1554–1555)     

Permanent Rapid Atrial Pacing to Control Supraventricular Tachycardia

A case is reported of a patient who had continuous supraventricular tachycardia with a ventricular rate of about 170. The arrhythmia was refractory to drugs and DC countershock, and did not convert with atrial pacing. Rapid atrial stimulation controlled the ventricular rate by simulating atrial fibrillation (pacing at 300-400/min), or by simulating a faster atrial tachycardia with 2:1 conduction (pacing at 205-210/min). This form of therapy was used on a permanent basis for more than five months.     

Atrial and Ventricular Vulnerability in a Patient with the Wolff-Parkinson-White Syndrome

An electrophysiologic study was carried out in a patient with the Wolff-Parkinson-White syndrome and a history of spontaneous atrial fibrillation but with no evidence of organic cardiac disease. A single induced premature ventricular depolarization resulted in ventricular tachycardia followed by ventricular fibrillation. Similarly, atrial pacing or premature atrial stimulation resulted in frequent episodes of atrial fibrillation or flutter, The atrial and ventricular effective refractory periods were 180 ms and < 160 ms, respectively, at a driven cycle length of 480 ms. Intravenous administration of procainamide resulted in lengthening of the refractory periods and failure to induce either atriaJ or ventricular arrhythmias with pacing. In most patients with enhanced atrioventricular nodal or accessory atrioventricular nodal bypass, the mechanism of ventricular tachycardia is related to an inordinately rapid ventricular response during supraventricular arrhythmias. In our patient, a unique mechanism was apparent: atrial and ventricular vulnerability to fibrillation was associated with extremely short myocardial effective refractory periods. The relationship of this finding to sudden cardiac death bears further study.     

Self-Conversion of Drug Resistant Ventricular Tachycardia by Rapid Atrial Pacing

A 52-year-old man with recurrent ventricular tachycardia two months post myocardial infarction is described. The tachycardia resulted in low output and heart failure af the lime of presentation. Following elcclrocardioversion of ventricular tachycardia, sinus rhythm would last for only a few seconds, and ventricular tachycardia could not be terminated or prevented by drugs, nor by overdrive pacing. Over a 20-hour period, asynchronous right ventricular pacing at 30/min resulted in repeated random interruption of successive paroxysms of ventricular tachycardia, resulting in maintenance of sinus rhythm about 60 to 70% of the time. This produced marked hemodynamic improvement and a decrease in the frequency of paroxysms of tachycardia which, however, continued to recur once every few days. Despite theirreduced frequency, these paroxysms continued to be resistant to drugs and had to be terminated by cardioversion. At this point it was discovered that rapid a trial pacing was able to terminate the patient's tachycardia reliably and reproducibly. A permanent right atrial externally activated radio frequency pacemaker device was inserted and over the ensuing eighteen-month period the patient self-terminated over fifty discrete episodes of ventricular tachycardia     

DDIR Versus VVIR Pacing in Patients with Paroxysmal Atrial Tachyarrhythmias

Patients with sinus node dysfunction (SND) in particular those with tachycardia-bradycardia syndrome and patients undergoing atrioventricular nodal ablation procedures for refractory paroxysmal atrial tachyarrhythmias (PAT), are candidates for single chamber (VVIR mode) or dual chamber rate responsive (DDIR mode) systems. To evaluate the benefits and disadvantages of each pacing mode we retrospectively analyzed 33 patients with a history of frequent PAT who received a VVIR (22 patients); or a DDDR pacemaker (11 patients) programmed to the DDIR mode. The mean follow-up time was 25 and 18 months, respectively. Preimplant left atrial diameter was significantly smaller in the DDIR group. Chronic atrial fibrillation developed in 54% of the VVIR patients and 27% of the DDIR group, but this difference was not significant. Complications of patients with VVIR pacemakers included new mitral and tricuspid insufficiency, stroke, pacemaker inlolerance and aggravated congestive heart failure. Patients with DDIR pacemakers had a lower incidence of symptoms and complications. However, this group received more antiarrhythmic medication, required a closer follow-up, and their pacemakers needed frequent reprogramming. Our findings suggest that VVIR is a poor choice for patients with SND, congestive heart failure, and PAT, and that DDIR may be an acceptable alternative.     

Benefits and Potential Risks of Atrial Antitachycardia Pacing After Repair of Congenital Heart Disease

Atrial reentry tachycardia is common after surgical repair of congenital heart disease. The arrhythmia is often difficult to treat and is occasionally life-threatening. This study reports experience with atrial antitachycardia (AAIT mode) pacing for the management of atrial reentry tachycardia, with emphasis on the risks and benefits of automatic pacing therapy. Eighteen patients (2–32 years of age) with a variety of congenital heart lesions underwent atrial antitachycardia pacemaker placement for recurrent atrial tachycardia that was amenable to pace termination prior to the implantation procedure. An appropriate antitachycardia program was determined by repeated induction and termination of atrial tachycardia using the noninvasive programmed stimulation mode of the pacemaker. Over 4–30 months of follow-up, 6 patients had 189 episodes of tachycardia successfully converted with AAI-T pacing, 4 patients had 8 episodes of tachycardia detected hut not successfully converted, and 8 patients had no episodes of tachycardia with antibradycardia pacing alone. The number of patients receiving pharmacological therapy other than digoxin or beta blockade fell from 12 to 6, Two subjects died suddenly, 1 while wearing a Holter monitor. In both, tachycardia was detected and pace cardioversion attempted. Conclusions: Atrial antitachyardia pacing is a useful tool in the management of patients with congenital heart disease and atrial arrhythmias; however, in selected cases, it may not prevent and may even exacerbate the lethal complications of the tachycardia. Antitachycardia function evaluation is recommended under varying levels of autonomic stress prior to institution of automatic therapy.     

Catheter Ablation versus Standard Conventional Treatment in Patients with Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE-AF) - Study Design

Background: Electrical isolation of the pulmonary veins by catheter ablation is an emerging treatment modality for the treatment of atrial fibrillation (AF) and is increasingly used in patients with heart failure.
Methods: The catheter ablation versus standard conventional treatment in patients with left ventricular dysfunction and atrial fibrillation trial (CASTLE-AF) is a randomized evaluation of ablative treatment of atrial fibrillation in patients with left ventricular dysfunction. The primary endpoint is the composite of all-cause mortality or worsening of heart failure requiring unplanned hospitalization using a time to first event analysis. Secondary endpoints are all-cause mortality, cardiovascular mortality, cerebrovascular accidents, worsening of heart failure requiring unplanned hospitalization, unplanned hospitalization due to cardiovascular reason, all-cause hospitalization, quality of life, number of therapies (shock and antitachycardia pacing) delivered by the implantable cardioverter-defibrillator (ICD), time to first ICD therapy, number of device-detected ventricular tachycardia and ventricular fibrillation episodes, AF burden, AF free interval, left ventricular function, exercise tolerance, and percentage of right ventricular pacing. CASTLE-AF will randomize 420 patients for a minimum of 3 years at 48 sites in the United States, Europe, Australia, and South America.     

The Potential Usage of Dual Chamber Pacing in Patients with Implantable Cardioverter Defibrillators

Bradycardia support by ICDs has been limited to fixed rate, ventricular pacing. Concomitant placement of a pacemaker and an ICD exposes a patient to potentially life-threatening device interactions. ICDs capable of dual chamber pacing have recently become available. The number of ICD recipients who stand to benefit from the addition of dual chamber pacing is debated, but no data have addressed this question. This retrospective study analyzed all patients who received nonthoractomy ICD system placement at the Mayo Clinic in Rochester, MN between March 1991 and October 1996 in order to determine the proportion of patients in whom a dual chamber pacing ICD may be indicated. Definitions: (1) Definitely indicated = pacemaker present at ICD implant or NASPE Class I pacing indication; (2) Probably indicated = NASPE Class II pacing indication, NYHA Functional Class III or IV, or history of systolic congestive heart failure; (3) Possibly indicated = history of paroxysmal atrial fibrillation or an ejection fraction ≤ 20%. The results were that nonthoracotomy ICDs were placed in 253 patients. A dual chamber ICD would have been definitely indicated in 11% of the study group, probably indicated in 28%, and possibly indicated in 14%. Chronic atrial fibrillation was present at ICD implant in 6.7% of patients and developed in 0.9%/yr during follow-up. The addition of dual chamber pacing to ICDs stands to potentially benefit approximately half (53%) of ICD recipients. These data do not address all patients who may benefit from dual chamber sensing.     

Pacemaker-mediated tachycardia in a biventricular pacing system

A 63-year-old man with chronic atrial fibrillation and heart failure had a biventricular pacing system implanted. The pulse generator was a standard DDDR pacemaker, using the atrial channel for the right ventricular lead and the ventricular channel for the left ventricular lead. During final adjustment of the pacing parameters, a pacemaker tachycardia triggered by T wave oversensing from the right ventricular lead was recorded.     

Four Chamber Pacing in Dilated Cardiomyopathy

A 54-year-old man received a four chamber pacing system for severe congestive heart failure (NYHA functional Class IV). His ECG showed a left bundle branch block (200-msec QHS duration) with 200-msec PR interval, normal QRS axis, and 90-msec interatrial interval. An acute hemodynamic study with insertion of four temporary leads was performed prior to the implant, which demonstrated a significant increase in cardiac output and decrease of pulmonary capillary wedge pressure. A permanent pacemaker was implanted based on the encouraging results of the acute study. The right chamber leads were introduced by cephalic and suhcla vian approaches. The left atrium was paced with a coronary sinus lead, Medtronic SP 2188–58 model. An epicardial Medtronic 5071 lead was placed on the LV free wall. The four leads were connected to a standard bipolar DDD pacemaker. Chorus 6234. The two atrial leads were connected via a Y-connector to the atrial channel of the pacemaker with a bipolar pacing configuration. The two ventricular leads were connected in a similar fashion to the ventricular channel of the device. The right chamber leads were connected to the distal poles. The left chamber leads were connected to the proximal poles of the pacemaker. Six weeks later, the patient's clinical status improved markedly with a weight loss of 17 kg and disappearance of peripheral edema. His functional class was reduced to NYHA II. Four chamber pacing is technically feasible. In patients with evidence of interventricular dyssynchrony, this original pacing mode probably provides a mechanical activation sequence closer to the natural one. We doubt that this technique will have an impact on long-term survival, but it could be of major importance to improve the patient's well-being and control heart failure.     

Safety of Transvenous Low Energy Cardioversion of Atrial Fibrillation in Patients with a History of Ventricular Tachycardia: Effects of Rate and Repolarization Time on Proarrhythmic Risk

The objective of this study was to assess the safety and efficacy of transvenous low energy cardioversion of atrial fibrillation in patients with ventricular tachycardia and atrial fibrillation and to study the mechanisms ofproarrhythmia. Previous studies have demonstrated that Cardioversion of atrial fibrillation using low energy, R wave synchronized, direct current shocks applied between catheters in the coronary sinus and right atrium is feasible. However, few data are available regarding the risk of ventricular proarrhythmia posed by internal atrial defibrillation shocks among patients with ventricular arrhythmias or structural heart disease. Atrial defibrillation was performed on 32 patients with monomorphic ventricular tachycardia and left ventricular dysfunction. Shocks were administered during atrial fibrillation (baseline shocks), isoproterenol infusion, ventricular pacing, ventricular tachycardia, and atrial pacing. Baseline shocks were also administered to 29 patients with a history of atrial fibrillation but no ventricular arrhythmias. A total of 932 baseline shocks were administered. No ventricular proarrhythmia was observed after well-synchronized baseline shocks, although rare inductions of ventricular fibrillation occurred after inappropriate T wave sensing. Shocks administered during wide-complex rhythms (ventricularpacing or ventricular tachycardia) frequently induced ventricular arrhythmias, but shocks administered during atrial pacing at identical ventricular rates did not cause proarrhythmia. The risk of ventricular proarrhythmia after well-synchronized atrial defibrillation shocks administered during narrow-complex rhythms is low, even in patients with a history of ventricular tachycardia. The mechanism of proarrhythmia during wide-complex rhythms appears not to be related to ventricular rate per se, but rather to the temporal relationship between shock delivery and the repolarization time of the previous QRS complex.     

Paroxysmal Atrial Fibrillation and High Degree AV Block: Use of Single-Lead VDDR Pacing with Mode Switching

Dual chamber rate responsive pacing incorporating a mode switching option is increasingly listed in patients with chronic paroxysmal atrial fibrillation and high degree AV block. Single-lead VDDR pacemakers have been rarely used for this indication. The purpose of this study was to determine thnir reliability of atrial sensing during atrial fibrillation, the percentage of at rial synchronous ventricular pacing, and the behavior of the sinus rate outside the phases of atrial fibrillation. We studied ten patients with a single-lead VDDR pacemaker implanted for this indication. Follow-up visits were performed at predischarge and after 1, 3, 6, 12. 18, and 24 months. During the mean follow-up period of 18.9 ± 6.9 months, the atrial sensing thresholds in sinus rhythm remained stable. Atrial synchronous ventricular stimulation was achieved in 68,7 ±31.2% (median 82.5%) of the whole follow-up time. All patients showed an adequate atrial rate response during sin us rhfthm. Atrial fibrillation was detected by the pacemakers in 24.0 ± 29.8% of time. In 3 of 10 patients the duration of atrial fibrillation showed a steady increase from visit to visit. The sensed amplitudes of atrial fibrillation ranged from 0.1–1.0 mV. A programmed atrial sensitivity of 0.1 mV was necessary to achieve complete sensing of atrial fibrillation. None of the patients experienced tachycardias with optimized pacemaker programming. Single-lead VDDR pacing incorporating a mode-switching option is useful in patients with high degree AV block and paroxysmal atrial fibrillation, since it provides atrial synchronous ventricular pacing in more than two-thirds of follow-up time. In a subgroup of patients, a progressive increase of the time during atrial fibrillation was demonstrated. A reliable detection of paroxysmal atrial fibrillation requires the programming of the atrial sensitivity to its most sensitive value.     

Indications for Pacing in Patients with Congenital Heart Disease

Background: Advances in pacing technology have increased indications for antibradycardia pacing and new indications have appeared for treatment of atrial tachycardia and cardiac failure in patients with congenital heart disease (CHD).
Methods and Results: Implantation of a pacemaker is mandatory for symptomatic children with complete atrio-ventricular block (CAVB). In asymptomatic neonates and infants, prophylactic pacing is indicated when the ventricular rhythm is <55 beats per minute (bpm) or 70 bpm in case of significant cardiac malformations. Beyond one year of age, PM implantation is recommended in children with an average heart rate <50 bpm or long pauses on 24-hour recordings. Post-operative block that persists 7 days after cardiac surgery is a class I indication for pacing. Postoperative heart block may also be transient, but patients with residual conduction abnormalities and a long HV interval have a high risk of late sudden death and should be paced. After cardiac surgery, atrial pacing may also be considered, in patients with severe sinus bradycardia and symptoms, or in those requiring antiarrhythmic drugs for tachy-bradycardia syndrome; in case of failure of antiarrhythmic drugs, antitachycardia atrial pacing now appears to be safe and efficacious. Finally, cardiac resynchronization therapy may apply to children with congenital heart block and cardiomyopathy, as well as to the population with CHD. Methods and results are described in the section dedicated to resynchronization.
Conclusion: Cardiac pacing indications have extended beyond prevention of sudden death and pacemaker implantation is now indicated to improve quality of life of patients with CHD and as a bridge to cardiac transplantation.