Implantable Cardioverter Defibrillator:

Implantable Cardioverter Defibrillator. The Ventritex® Cadence® Model V-100 Tiered Therapy Defibrillator is a third generation antitachyarrhythmia device currently completing clinical trials in the United States. The implantable pulse generator is capable of high energy detibrillation, low energy cardioversion, as well as antitachycardia and bradycardia pacing. In addition, this microprocessor controlled device can deliver monophasic or biphasic defibrillation/cardioversion shocks, is noncommitted to deliver shock therapy after initiating charging for defibrillation or cardioversion therapy, and can store electrograms of spontaneous tachyarrhythmia episodes. These expanded device capabilities should improve therapy efficacy and patient management, and represent a major advance in the treatment of patients with ventricular tachyarrhythmias, ( J Cardiovasc Electrophysiol, Vol. 4, pp. 211–223, April 1993 )     

Potential proarrhythmic effects of implantable cardioverter-defibrillators

Implantable cardioverter-defibrillator (ICD) interventions have the potential to be proarrhythmogenic. New arrhythmias can occur in the setting of clinically appropriate therapies, as well as during a cardiac rhythm for which therapy is not intended. Cardioversion/defibrillation therapies, antitachycardia pacing, and antibradycardia pacing are potential triggers for the development of new arrhythmias. Newer ICDs allow better recognition and interpretation of the arrhythmias that are induced by delivered therapies. Two cases of ICD-induced proarrhythmias are described. Based on the course of these patients and review of previous reports, proarrhythmic effects of ICD interventions along with prevention and management strategies are discussed.     

Ventricular arrhythmias induced by appropriate antibradycardia pacing in patients with implantable defibrillators]

INTRODUCTION AND OBJECTIVES: The induction of ventricular arrhythmias by appropriate antibradycardia ventricular pacing in patients with implantable cardioverter defibrillators has been reported in only a few cases. The aim of this study was to assess the incidence, characteristics and management of these episodes. METHODS: The follow-up records of 180 patients with implantable cardioverter defibrillators with intracardiac electrogram storage were reviewed. Pacing induced episodes were defined as those occurring immediately after an appropriate paced stimulus in a patient with sporadic paced beats. We assessed the number and type of episodes, mode of onset, therapy administered and the efficacy of different prevention measures. RESULTS: Pacing induced episodes were found in 9 patients (5%). Seven received device administered therapy which was effective in all cases. One to 95 episodes were observed per patient, of which 138 were monomorphic ventricular tachycardias and 20 polymorphic ventricular tachycardia/ventricular fibrillation episodes. All were induced by a paced ventricular beat after a post-extrasystolic pause or after long RR intervals during atrial fibrillation. Pacing induced arrhythmias were prevented by changing the pacing rate or hysteresis in 3 out of 6 patients and by decreasing the stimulus energy in 3 out of 3. Antibradycardia pacing function was disabled in 4 patients. CONCLUSIONS: Ventricular arrhythmias induced by appropriate antibradycardia ventricular pacing are relatively common in patients with implantable cardioverter defibrillators. Effective prevention can be achieved in most cases by changing the pacing rate or the pacing stimulus energy, however in selected cases the antibradycardia function may be disabled.     

Progress in Interventional Cardiology

This issue of News & Views will review notable presentations from the 18th Annual Scientific Session of the North American Society of Pacing and Electrophysiology (NASPE), which took place in New Orleans, Louisiana, May 7-10, 1997. Highlights of the meeting included presentation of the results of clinical trials using implantable cardiac defibrillators (ICDs) in patients with life-threatening ventricular arrhythmias, and the application of interventional techniques for the treatment of atrial fibrillation (AF).     

Long-term reverse remodeling and clinical improvement by MultiPoint Pacing in a randomized,international, Middle Eastern heart failure study

Journal of Interventional Cardiac Electrophysiology - Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint? Pacing, MPP) has been shown to improve...     

Recent advances in pacemaker and implantable defibrillator therapy for young patients

PURPOSE OF REVIEW: This review is intended to highlight major clinical advances over the past year related to (1). biventricular pacing as a treatment for dilated myopathy, (2). growing clinical experience with implantable cardioverter defibrillators in pediatrics, (3). technical advances in standard antibradycardia pacing, and (4). an appraisal of the newly updated ACC/AHA/NASPE guidelines for device implant in children and adolescents. RECENT FINDINGS: Complex rhythm devices are being used more frequently in children. Biventricular pacing to improve ventricular contractility is a rapidly evolving technology that has now been applied to children and young adults with intraventricular conduction delay, such as bundle branch block after cardiac surgery. Implantable defibrillators are also being used for an expanding list of conditions, although lead dysfunction is seen as a fairly common complication in active young patients. Guidelines for device implantation have been developed, but the weight of evidence remains somewhat limited by the paucity of pediatric data in this field. SUMMARY: Thanks to refinements in lead design and generator technology, coupled with rapidly expanding clinical indications, pacemakers and implantable defibrillators have become increasingly important components of cardiac therapy for young patients. Expanded multicenter clinical studies will be needed to develop more objective guidelines for use of this advanced technology.     

Subcutaneous implantable defibrillator: State-of-the art 2013

The subcutaneous implantable cardioverter-defibrillator(S-ICD)has recently been approved for commercial use in Europe,New Zealand and the United States.It is comprised of a pulse generator,placed subcutaneously in a left lateral position,and a parasternal subcutaneous lead-electrode with two sensing electrodes separated by a shocking coil.Being an entirely subcutaneous system it avoids important periprocedural and long-term complications associated with transvenous implantable cardioverter-defibrillator(TV-ICD)systems as well as the need for fluoroscopy during implant surgery.Suitable candidates include pediatric patients with congenital heart disease that limits intracavitary lead placements,those with obstructed venous access,chronic indwelling catheters or high infection risk,as well as young patients with electrical heart disease(e.g.,Brugada Syndrome,long QT syndrome,and hypertrophic cardiomyopathy).Nevertheless,given the absence of intracavitary leads,the S-ICD is unable to offer pacing(apart from shortterm post-shock pacing).It is therefore not suitable in patients with an indication for antibradycardia pacing or cardiac resynchronization therapy,or with a history of repetitive monomorphic ventricular tachycardia that would benefit from antitachycardia pacing.Current data from initial clinical studies and post-commercialization"real-life"case series,including over 700 patients,have so far been promising and shown that the S-ICD successfully converts induced and spontaneous ventricular tachycardia/ventricular fibrillation episodes with associated complication and inappropriate shock rates similar to that of TV-ICDs.Furthermore,by using far-field electrograms better tachyarrhythmia discrimination when compared to TV-ICDs has been reported.Future results from ongoing clinical studies will determine the S-ICD system’s long-term performance,and better define suitable patient profiles.     

Implantable dual-chamber cardioverter-defibrillator-pacemaker

The fifth generation of implantable cardioverter-defibrillators offer enhanced modes of detection of atrial and ventricular arrhythmias, antitachycardia pacing and shocks, multiprogrammability, intracardiac electrogram storage, and all functions of antibradycardia dual-chamber pacing including rate responsiveness and mode switching. There is no consensus on the indications for dual-chamber pacemaker defibrillator systems. This review focuses on the four major options of newer devices that might benefit patients: 1) permanent dual-chamber pacing in ischemic coronary disease patients, 2) detection and management of atrial fibrillation or other atrial tachyarrhythmias, 3) some newer indications for pacing, and 4) the suppression of inappropriate interventions. On the basis of published data, newer indications for the dual-chamber systems, advantages and limitations, and future perspectives are discussed.     

Impact of the recommendations of the British Pacing and Electrophysiology Group on pacemaker prescription and on the immediate costs of pacing in the Northern Region.

BACKGROUND--The report from the Working Party of the British Pacing and Electrophysiology Group recommends the use of more sophisticated pacemakers in most patients. These proposals were initially circulated in September 1990 and are likely to have major cost implications. Their impact on pacing practice and the immediate costs of pacemaker hardware in the Northern Region were retrospectively audited. METHODS--The pacing records of 550 patients undergoing a first pacemaker insertion at the Freeman Hospital between March 1990 and August 1991 were reviewed. The patient's age, indication for pacing, pacing mode, and the cost of generator and lead(s) were recorded. The cost was compared with the costs of pacing with the optimal and alternative modes recommended by the Working Party. The costs were calculated from the actual mean cost of the recommended unit over the 18 month period of study multiplied by the number of patients who would have received that unit. RESULTS--96% of patients were paced for sinus node dysfunction, atrioventricular block, or atrioventricular block and atrial fibrillation. The mean (SD) ages of patients in each diagnostic group were: sinus node dysfunction 69.4 (14), sinus node disease and atrioventricular block 67.2 (17.6), atrioventricular block 73.9 (12.5), atrial fibrillation and atrioventricular block 74.0 (13.9), and carotid sinus hypersensitivity 74.6 (11.6) years. Over the 18 month audit period there was an increase in physiological pacing. AAI pacing in patients with sinus node dysfunction increased by 100% and DDD pacing in atrioventricular block increased by atrioventricular block increased by 56%. Over the whole 18 month period the adoption of the British Pacing and Electrophysiology Groups optimal recommendations would have increased expenditure on pacemaker hardware in the Northern Region by 94% and the use of the alternative mode would have increased it by 61%. For the last six months alone the excess would be 78% and 48%. CONCLUSIONS--The adoption of the recommendations of the British Pacing and Electrophysiology group in the Northern Region would greatly increase the cost of pacing hardware. The greater part of this increase would be attributable to the routine use of dual chamber pacing in patients with atrioventricular block and the increased use of rate responsive units. The benefits of sophisticated pacing in a predominantly elderly population need to outweigh the disadvantages of the increased cost and complexity of follow up.     

The role of cardiac pacing in atrial arrhythmia prevention

Pathophysiological considerations, animal data and acute clinical tests suggest some benefit of cardiac pacing in the prevention of paroxysmal atrial tachyarrhythmia. While early clinical studies confirm this notion, data of randomized prospective trials at least are mixed. The equivocal effects of using alternative atrial pacing sites and/or dedicated preventive pacing algorithms leaves the question of how to predict the beneficial effect of antitachycardia pacing strategies in the individual patient. Since the answer is lacking, the mere intention to prevent atrial arrhythmias is not a valid pacing indication. Pacing for the bradycardia tachycardia syndrome, however, may benefit from preventive techniques in individual cases.     

Pacemakers, defibrillators, and direct current cardioversion

Technology for pacemakers and automatic implantable defibrillators continues to evolve. Emphasis is placed not only on preventing cardiac death, but also on improving symptoms and quality of life. The basic antibradycardia function of pacemakers is complemented by highly sophisticated rate-responsive capabilities. The search for the perfect physiologic sensor has not ended; potential limitations of the systems currently available are considered in this review. Reports on outcome with pacing in different populations are also discussed. There have been two important advances in automatic implantable defibrillators. One is the introduction of the third generation defibrillator in clinical investigation. A tiered therapy (including antitachycardia pacing, cardioversion, and defibrillation) can now be programmed in the same device, with the protection of back-up antibradycardia pacing. The other remarkable innovation is the expanding use of nonthoracotomy techniques for implantable cardioverter-defibrillator placement. This approach permits the avoidance of a subcutaneous patch electrode in some cases, the system being entirely transvenous. Finally, recent insights on external cardioversion for atrial arrhythmias are briefly reviewed.     

Current topics (2005) in cardiac pacing

Currently, three areas of active development in cardiac pacing are of particular interest to clinical cardiologists. Biventricular pacing is now considered a type-I indication for adjuvant treatment in advanced and refractory heart failure. Consequently, some changes in everyday clinical practice will be seen when patients with end-stage heart failure start to receive resynchronization therapy. Secondly, the Cardiac Pacing Working Group of the Spanish Society of Cardiology has developed a national consensus document on sleep apnea and cardiac rhythm abnormalities. It appears that a novel way of tackling the current growing epidemic could be to use permanent cardiac pacing in an attempt to modify the cardiac rhythm alterations, mainly bradyarrhythmias, related to sleep apnea. Finally, promising developments are taking place in systems designed to reduce the unwanted right ventricular stimulation sometimes observed with antibradycardia pacing modalities. These new systems are expected to minimize significantly the well-known deleterious hemodynamic effects sometimes seen in our patients.     

Development of an entirely subcutaneous implantable cardioverter-defibrillator

The recent advent of an entirely subcutaneous implantable defibrillator (ICD) has provided a relevant contribution to the debate concerning the use of ICD therapy in patients at high risk for death. Although conventional transvenous ICDs have proven very effective during the past 23 years, they still appear to be limited by nontrivial acute and long-term complications. This study delineates some of the historical and current issues characterizing the advent of the subcutaneous ICD system in daily clinical practice. Subcutaneous ICDs have proven effective in more than 1100 patients worldwide and appear to be competitive with transvenous ICD in all clinical conditions not requiring antibradycardia, antitachycardia, or cardiac resynchronization pacing.     

心室起搏患者心肌缺血及梗死的心电图诊断

为探讨心室起搏患者并发急性心肌缺血和梗死的心电图诊断 ,笔者回顾分析了 30例右室起搏、3例冠状T波和 2 0例起搏后急性心肌缺血或梗死患者的心电图变化。结果 :①T波电张力调整性改变主要出现在Ⅱ、Ⅲ、aVF导联 ,也可影响胸前导联 ;②冠状T波者起搏后T波可转为低平 ;③任何部位急性心肌缺血和梗死 ,均可见ST段和T波的改变 ,有些部位梗死后的q(Q)波和R波的变化仍可显示出来 ,而有些部位将会被掩盖。自身心律时梗死图形与非起搏者基本相同。结论 :分析起搏患者并发心肌梗死的心电图时应结合临床症状、心电图动态变化、症状期前后的心电图对比、自身心律心电图及酶学变化进行综合判断     

Use of telemetry functions in the assessment of implanted antitachycardia device efficacy.

Twenty patients (aged 50 +/- 21 years and mean left ventricular ejection fraction 37 +/- 17%) with recurrent ventricular arrhythmias were treated with an investigational, implantable combined antitachycardia-pacing cardioverter defibrillator. The device's telemetry capabilities include both stored (1-second snapshots) and real-time display of endocardial and device-circuit signals. The device can store these before, during and after up to 50 tachycardia and antitachycardia pacing episodes. All stored events are indexed to a 24-hour internal clock. During 10.1 +/- 5.1 months of follow-up, the device was used in 11 of 20 patients. In the entire group, antitachycardia pacing was activated on 44 +/- 14 occasions per patient (total 874) and shock delivery occurred on 8 +/- 14 occasions per patient (total 156). Reconstruction by stored telemetry of all device-therapy episodes was possible. Twenty-six percent of all shocks delivered were not appropriate and were due to atrial arrhythmias in 2 patients and dysfunction of the sensing lead in 3. The absence of a relation between symptoms and appropriate shock delivery was documented in 1 patient. Antitachycardia pace acceleration occurred in 5.3% of cases; 7% of attempts at pacing were unsuccessful and needed shock therapy. It is concluded that the enhanced telemetry available in newer antitachycardia devices enables more accurate assessment of device use and enhances diagnosis of inappropriate therapy delivery.     

Atrial tachyarrhythmia prevention and treatment by means of special pacing algorithms.

Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results include an already high atrial pacing percentage in conventional DDDR, non-optimal atrial pacing site, deleterious effects of high percentages of apical ventricular pacing. Atrial antitachycardia pacing (ATP) therapies are effective in treating spontaneous atrial tachyarrhythmias, mainly when delivered early after arrhythmia onset and/or on slower tachycardias. Effective ATP therapies may reduce atrial fibrillation burden, but conflicting evidence does exist as regards this issue, probably because current clinical studies may be underpowered to detect such an efficacy. Wide application of atrial ATP may reduce the need for hospitalizations and electrical cardioversions and favorably impact on quality of life. Consistent monitoring of atrial and ventricular rhythm as well as that of ATP effectiveness may be extremely useful for optimizing device programming and pharmacological therapy.     

气囊电极床边紧急心脏临时起搏的临床观察

总结 36例经右颈内静脉、左锁骨下静脉及右股静脉三种不同的途径穿刺插管 ,行气囊电极床边紧急心脏临时起搏的经验。按Seldiger方法行静脉穿刺置管 ,按Swan Ganz球囊导管操作方法推送气囊电极导管 ,在无X线透视条件下 ,根据心腔内心电图、室性早搏出现或体表起搏心电图判断电极进入右室 ,行右室心内膜临时起搏。结果 :36例全获成功 ,其中右颈内静脉 (中位法 ) 16例、左锁骨下静脉 (下位法 ) 12例、右股静脉 8例。前两者开始穿刺至起搏成功时间为 3～ 10min ,后者为 10～ 2 5min。起搏效果肯定 ,起搏时间 2～ 2 0天。经股静脉插管者 2例误入下腔静脉分支 ,1例导管扭曲受阻 ,此 3例重新插管起搏成功。经左锁骨下静脉插管 1例误入左颈内静脉 ,改右颈内静脉起搏成功。全组除 11例腔内心电图和 5例边起搏边送管方法确定导管头位置外 ,余 2 0例在边送管边观察室性早搏出现的方法判断电极进入右室。术后胸片证实导管头位置与体表起搏图形定位的部位完全一致。除 3例电极移位和 2例短阵室性心动过速外 ,全部病例未发生心脏穿孔、气胸、血胸及感染等并发症 ,除 2例死于原发病外 ,余均痊愈出院。结论 :本法创伤小、方便快速、安全有效、无需X线引导 ,值得急救推广应用