Trends in replacement of pacemaker leads in the Netherlands: A long-term nationwide follow-up study.

BACKGROUND: Our objective was to investigate trends over time in longevity and reasons for replacement with or without extraction of pacemaker leads after first implantation. METHODS: Data collected between 1984 and 2006 in the national Dutch pacemaker registry were used. This registry covered 84% of sold leads. First lead replacement with or without extraction of one or more leads implanted with a first pacemaker generator was the endpoint of interest. The time interval of and reason for first replacement were analyzed. A 7-year follow-up interval after first implantation was used to analyze changes over time. RESULTS: During 22 years of data collection, 138,225 leads were implanted with a first pacemaker generator. Within a mean 5.5 (SD 4.4) years for 7,377 patients one or more leads were extracted for the first time. In total, 8,849 leads (6.4%) were replaced or extracted. The main reasons for first replacement of leads with or without extraction were insulation failures (14.6%), infection (8.8%), displacement (7.6%), or for elective reasons (10.0%). The number of insulation failures peaked during 1991-1995. CONCLUSIONS: Despite improvements in pacing techniques and experience with cardiac devices, we found that insulation and conductor failures, and complications such as infections, did not diminish over the 20 years of the registry. Continuing attention in clinical practice for the evaluation of these adverse outcomes and maintaining quality registries is warranted, whereas manufacturers should use this information to further improve their devices.

Trends in service time of pacemakers in the Netherlands: a long-term nationwide follow-up study.

AIMS: After decades of experience and strongly improved technology, service time of pacemaker generators is expected to increase. To test this hypothesis, we conducted a retrospective review of a large cohort of patients with a pacemaker. METHODS: We reviewed data collected between 1984 and 2006 in the first national Dutch pacemaker registry. This registry covered 96% of all generators implanted. We analysed the time of and reason for explantation of pacemaker generators. A 7-year follow-up interval after first implantation and following replacements was used to analyse changes over time. RESULTS: During 22 years of data collection, nearly 97,000 first pacemaker generators were implanted. A total of 27,937 (22.4%) generators were explanted within a mean of 6.3 (standard deviation 3.3) years. Reasons for approximately 60% of these explantations were 'end of life' of the pacemaker generator or elective system change. Complications or failures such as infections and recalls accounted for approximately 20% of the explantations. For the remaining 20%, the reasons for explantation had not been registered. CONCLUSION: Despite progress in technology, a substantial proportion of pacemaker generators is explanted before its expected service time, with one in five generators being replaced due to technical failures, infections or other complications. Furthermore, the time interval between pacemaker implantation and explantation due to normal 'end of life' (battery EOL) decreased. Infections continue to rank highly as a cause for pacing system replacement, despite all current preventive measures.

Utilisation of cardiac pacemakers over a 20-year period: Results from a nationwide pacemaker registry.

The implantation of cardiac pacemakers has become a well-established therapy for conduction disorders and sinus node dysfunction. In many countries pacemaker registries have been initiated in order to collect information on patient characteristics, trends in numbers and the types of pacemakers used, to identify problematic devices, and for safety monitoring. For this utilisation study the Central Pacemaker Patients Registration (CPPR) from the Netherlands Pacemaker Registry Foundation (CPPR-SPRN) containing data collected for more than 20 years was used. During this period nearly 97,000 first pacemakers were implanted. Analyses show an increase in the rate of implanted devices. The change in pacemaker type from VVI to DDD, followed by biventricular stimulation, is reflected by the number of simultaneously implanted leads, which is partly a consequence of cardiac resynchronisation therapy. Our data demonstrate that indications for implantation and type of pacemaker are comparable with other European countries.

Quality of care: not hospital but operator volume of pacemaker implantations counts.

Literature about pacemaker (PM) implantations shows that several clinical and technical factors determine the short- and long-term complications after the intervention. Annual hospital volume, however, does not negatively affect complications in contrast with the cumulative experience of the operator. In view of this observation, the current required number of 20 to 30 first PM implantations for cardiology training does not match standards for quality of care. In addition, concentration of implants and replacement of pacemakers to a limited number of operators per hospital to comply with the increasing demands of patients and other parties has to be seriously considered.

Patients with left bundle branch block pattern and high cardiac risk myocardial SPECT: does the current management suffice?

INTRODUCTION: Myocardial perfusion SPECT (MPS) is frequently used for cardiovascular risk stratification. The significance of MPS in patients with abnormal electrical ventricular activation is often questionable. This review assesses the value of MPS for risk stratification of patients with intrinsic left bundle branch block or that due to right ventricular apical pacing. METHODS: We reviewed the literature by a search of the MEDLINE database (January 1980 to September 2010). The terms prognosis or prognostic value were combined with SPECT and LBBB or pacing or pacemakers. MPS was categorised as low and high risk according to the original definitions. RESULTS: We identified 11 studies suitable for review. A low-risk MPS is associated with a low risk of cardiac events whereas high-risk MPS carries a 4.8-fold increased risk, 95% CI [3.2 - 7.2] (p < 0.0001). Despite secondary prevention and an improved medical and interventional care, these figures have hardly changed over time. CONCLUSION AND CLINICAL IMPLICATIONS: A low-risk MPS permits a policy of watchful waiting whereas a high-risk MPS requires further analysis and treatment. The persistent high cardiac death and acute myocardial infarction rate after a high-risk MPS suggest that the current management of these patients does not suffice and needs reconsideration.

Clinical application of pacemakers in atrial tachyarrhythmias.

The diagnostic programmes of modern pacemakers have increased our knowledge of atrial tachyarrhythmias (ATAs) in chronically paced patients. These programmes also support the evaluation of the effects of pharmacological treatment of ATAs. The success of interruption and/or prevention of ATAs with pacemakers depends strongly on the diagnostic accuracy and the properties of the pacing algorithms, their individual programming and the site and configuration of the pacing leads. Atrial septum pacing can be beneficial in patients with paroxysmal atrial fibrillation and prolonged P wave duration. Recent large-scale studies on preventive and interruptive atrial pacing of ATAs show modestly positive or no results. Therefore, atrial pacing therapy for ATAs should be considered cautiously, serving as an adjuvant to pharmacological treatment rather than as a primary intervention. This also applies for pacing interventions for ATAs in cardiac resynchronisation therapy. The pacemaker algorithms for the detection of ATAs and atrial lead configuration are crucial for the success of pacemaker-mediated prevention or interruption of ATAs. The success of these interventions is dependant on future improvements of pacemaker technology. (Neth Heart J 2008;16(Suppl1):S20-S24.).

Diagnostic tools for atrial tachyarrhythmias in implantable pacemakers: a review of technical options and pitfalls.

BACKGROUND: Correct pacemaker (PM) diagnosis of paroxysmal atrial tachyarrhythmias is crucial for their prevention and intervention with specific atrial pacing programmes. The PM mode switch to only ventricular pacing after detection of atrial tachyarrhythmias is often used as the parameter to quantify the 'burden' of atrial tachyarrhythmias. OBJECTIVES: This review addresses potential errors in the detection and diagnosis of atrial tachyarrhythmias, sometimes resulting in incorrect mode switches. The interpretation of PM-stored data of patients with atrial tachyarrhythmias and the results of trials of pace prevention and intervention can be better appreciated with more insight into the technical options and pitfalls. RESULTS: Literature and clinical experience demonstrate that the correctness of PM-derived diagnosis of atrial tachyarrhythmias depends on 1) the sensitivity setting to detect the onset and perpetuation of atrial tachyarrhythmias frequently characterised by variable and low-voltage signals, 2) the rejection of far-field R wave sensing by the atrial sense amplifier, 3) the facility for verification of mode switches by a high-quality intracardiac registration of the nonmodified atrial electrogram. The configuration of the atrial lead also contributes to the diagnostic performance of the PM. CONCLUSION: Not only pacing algorithms and diverse technical PM features but also the atrial lead configuration are currently the limiting factors to the fully reliable, automated detection and diagnosis of atrial tachyarrhythmias. If these technical shortcomings can be improved, better signal processing will result. Then atrial pacing to prevent or suppress atrial tachyarrhythmias will be more justified. (Neth Heart J 2008;16:201-10.).

A review of factors contributing to health related quality of life achieved with cardiac resynchronization therapy for heart failure.

UNLABELLED: Electrical cardiac resynchronization therapy (CRT) with biventricular pacing improves the impaired left ventricular function in selected patients and reduces mortality, morbidity and the number of hospitalizations for heart failure. Reversed left ventricular remodelling following CRT has been documented by various imaging METHODS: Application of CRT involves many factors as selection, implantation procedure, pacing site, programming of the atrioventricular and interventricular pacing intervals, optimal medical and anti-arrhythmic treatment and counselling of the patient with congestive heart failure (CHF). The contribution of various components of CRT to the hemodynamic response and to the left and right ventricular function has been extensively documented. Large prospective studies also demonstrated improvement of health related quality of life (QoL) compared to control patients. The cost-effectiveness of CRT and CRT/implantable cardioverter defibrillators (ICD) in terms of quality adjusted life year appears satisfying provided life expectancy of the recipient is enlarged. However, the follow up of most studies is rather short and QoL is always compared with the baseline condition. Furthermore, the clinical relevance of the reported numerical improvement of QoL and its persistence are fully unknown. The individual improvement of QoL of the CRT recipient cannot be predicted from clinical variables. Literature shows that the contribution of the various CRT factors to the hemodynamic response and to the left and right ventricular function and clinical benefit are extensively studied but not their contribution to health related QoL. For this purpose the contribution to QoL of all factors that are related to CRT response, was stepwise reviewed. Literature showed for several reasons no clear association with any individual CRT component and QoL. It can be concluded that prospective serial QoL studies of CRT patients in conjunction with studies of the cardiac function are requested to identify not only the contribution of CRT factors to QoL but also (sub)groups that benefit most. In these trials the methods and relevance of regular re-examination of the left ventricular function and of reprogramming of the device parameters to obtain a sustained positive CRT responsiveness, need to be established. Finally, because CRT has become a multidisciplinary therapy for chronic heart failure, the professional influence on QoL of the CRT recipient has to be studied.

Health-related quality of life relative to clinical outcomes in patients with atrial fibrillation treated with ventricular rate stabilisation pacing.

AIMS: It is uncertain whether patient perception of atrial fibrillation (AF) is based on the fast ventricular rate as such or the irregularity of the ventricular responses. This trial was designed to confirm the effectiveness of a ventricular rate stabilisation (VRS) algorithm in reducing ventricular irregularity during permanent pacing in patients with AF and to assess the patient preference and effect on quality of life (QoL). METHODS: In this multicentre single-blind randomised crossover trial, 184 patients with drug-refractory permanent (n=91) or paroxysmal (n=93) AF received a VVI(R) or DDD(R) pacemaker respectively and were paced in a randomised sequence with VRS on or off for two months. Clinical assessments (QoL, New York Heart Association (NYHA) classification, echocardiography, six-minute walk test and Holter recording) were carried out at baseline, at randomisation and after each crossover period. QoL assessment was performed using Aquarel, a new disease-specific QoL questionnaire for pacemaker patients, the Short Form 36 survey (SF-36), the Duke Activity Status Index (DASI) and the Symptom Checklist frequency and severity scores. At the end of the study patients preferences for VRS-on or VRS-off were recorded. RESULTS: VRS pacing reduced ventricular irregularity without increasing the mean ventricular rate. VRS-on was preferred by 65.8% of patients with paroxysmal AF; patients with permanent AF had no preference. QoL did not show improvement during VRS pacing on any of the instruments. CONCLUSION: VRS pacing is effective in reducing ventricular rhythm irregularity. QoL does not improve during VRS pacing but preference for VRS pacing appears particularly outspoken for patients with paroxysmal AF.

Results of maze surgery for lone paroxysmal atrial fibrillation.

BACKGROUND: If drug refractoriness to paroxysmal atrial fibrillation (PAF) occurs, arrhythmia surgery that involves channelling and the exclusion of specific atrial areas can abolish atrial fibrillation. The purpose of this study was to establish the effectiveness and safety of maze III surgery to abolish PAF. METHODS AND RESULTS: Surgery was performed in 41 selected patients who had long-standing, symptomatic, drug-refractory, lone PAF. At discharge, 35 patients (85%) were arrhythmia free, and 6 patients (15%) showed PAF and paroxysmal atrial tachycardia. Death or stroke did not occur during a mean follow-up of 31+/-16 months. At the end of follow-up, 39 patients (95%) had no PAF; however, in 2 patients (5%), PAF persisted and eventually required His bundle ablation and pacing. Three months after surgery, nodal escape rhythm was observed in only 1 patient, whereas sick-sinus syndrome emerged late after surgery in 2 patients. Antiarrhythmic drugs were used in 20% of patients during follow-up. The quality of life improved markedly after surgery and remained unchanged afterward. Echocardiographic findings did not alter, but exercise capacity increased. CONCLUSIONS: This pilot study demonstrates the effectiveness and safety of maze III surgery for lone PAF. In patients without sick-sinus syndrome, this intervention offers a sensible alternative to His bundle ablation and lifelong pacemaker dependency.

Slow potentials in the atrioventricular junctional area of patients operated on for atrioventricular node tachycardias and in isolated porcine hearts.

OBJECTIVES: The purpose of this study was to 1) investigate extracellular electrograms in the atrioventricular (AV) junctional area of patients with AV node reentrant tachycardia, 2) compare them with recordings made in isolated porcine hearts, and 3) study their origin. BACKGROUND: Electrograms with slow components have been used to target the delivery of radiofrequency energy for the cure of AV node reentrant tachycardia. The origin of these electrograms is unknown. METHODS: In 12 human and 19 porcine hearts, extracellular recordings were made simultaneously from 64 sites. In five other porcine hearts, intracellular recordings were made at sites at which extracellular electrograms revealed slow potentials. Histologic investigations were carried out in four of these hearts. RESULTS: Electrograms with slow components were recorded in five human and eight porcine hearts. These signals were found at sites up to 12 mm from the His bundle. Characteristics of the electrograms did not differ significantly among human and porcine hearts. Electrophysiologic evidence for multiple pathways was present in four hearts. Superficial impalements with microelectrodes at sites with slow potentials showed action potentials with AV node characteristics. In the majority of these recordings, the upstroke coincided with the downstroke of slow potentials. Histologic investigations of the sites of impalement revealed transitional cells directly underneath the endocardium. CONCLUSIONS: Slow potentials were recorded in both human and porcine hearts in similar measure. They arise from transitional cells and have action potentials similar to N cells.

Increased dispersion of "refractoriness" in patients with idiopathic paroxysmal atrial fibrillation.

The average interval between local depolarizations during atrial fibrillation, the so-called atrial fibrillation interval, was used as an index for local "refractoriness." This was based on the assumption that during fibrillation, cells are reexcited as soon as their refractory period ends. A very good correlation was found between refractory periods determined with the extrastimulus technique at a basic cycle length of 400 ms and atrial fibrillation intervals measured at the same epicardial sites of the right atrium. This new technique was used to assess dispersion in atrial fibrillation intervals in 10 patients with idiopathic paroxysmal atrial fibrillation and in a control group of 6 patients who were undergoing cardiac surgery. After a routine median sternotomy a multiterminal grid with up to 40 electrodes was placed over the right atrium, and atrial fibrillation was induced by premature stimulation. The average fibrillation interval in the test group, recorded at 247 sites, was 152 +/- 3 ms and that in the control group, recorded at 118 sites, was 176 +/- 8.1 ms (p less than 0.05). Dispersion in atrial fibrillation intervals, defined as the variance of the fibrillation intervals at all the recording sites, was three times larger in the group with paroxysmal atrial fibrillation than in the control group. This study suggests that both a shorter refractory period and a larger dispersion in refractoriness are responsible for the recurrence of atrial fibrillation.

Value of body surface mapping in localizing the site of origin of ventricular tachycardia in patients with previous myocardial infarction.

OBJECTIVES: This study examined the performance of the 62-lead body surface electrocardiogram (ECG) in identifying the site of origin of ventricular tachycardia in patients with a previous myocardial infarction. BACKGROUND: Because the accuracy of ECG localization of ventricular tachycardia using standard 12-lead recordings is restricted to the identification of rather large ventricular areas, application of multiple torso lead recordings may augment the resolving power of the surface ECG and result in more discrete localization of arrhythmogenic foci. METHODS: Thirty-two patients were selected for electrophysiologically guided ablative therapy for drug-resistant postinfarction ventricular tachycardia. In these patients, QRS integral maps of distinct monomorphic ventricular tachycardia configurations were correlated with a previously generated infarct-specific reference data base of paced QRS integral maps. Each paced pattern in the data base corresponded with ectopic endocardial impulse formation at 1 of 18 or 22 discrete segments of the left ventricle with a previous anterior or inferior myocardial infarction, respectively. Electrocardiographic localization was compared with the results obtained during intraoperative or catheter endocardial activation sequence mapping. RESULTS: Body surface mapping was performed during 101 distinct ventricular tachycardia configurations. Compared with the activation mapping data that were acquired in 64 of 101 ventricular tachycardias, body surface mapping identified the correct segment of origin in 40 (62%) of 64 tachycardias, a segment adjacent to the segment where the arrhythmia actually originated in 19 (30%) of 64 tachycardias and a segment disparate from the actual segment of origin in 5 (8%) of 64 tachycardias. With respect to infarct location, the segment of origin was correctly identified in 28 (60%) of 47 ventricular tachycardias in patients with anterior, 7 (70%) of 10 tachycardias in patients with inferior and 5 (71%) of 7 tachycardias in patients with combined anterior and inferior myocardial infarction. CONCLUSIONS: This study shows that body surface mapping enables precise localization of the origin of postinfarction ventricular tachycardia in 62% and regional approximation in 30% of tachycardias. The multiple-lead ECG may be used to guide and shorten catheter-based mapping procedures during ventricular tachycardia and to provide relevant information on the origin of tachycardias that cannot be mapped with conventional single-site mapping techniques because of unfavorable characteristics.

The value of class IC antiarrhythmic drugs for acute conversion of paroxysmal atrial fibrillation or flutter to sinus rhythm.

In a single-blind randomized study, the efficacy and safety of intravenous propafenone (2 mg/kg body weight per 10 min) versus flecainide (2 mg/kg per 10 min) were assessed in 50 patients with atrial fibrillation or flutter. Treatment was considered successful if sinus rhythm occurred within 1 h. Conversion to sinus was achieved in 11 (55%) of 20 patients with atrial fibrillation treated with propafenone and in 18 (90%) of 20 with atrial fibrillation treated with flecainide (p less than 0.02). If atrial fibrillation was present less than or equal to 24 h, conversion to sinus rhythm was achieved in 8 (57%) of 14 patients in the propafenone group and 13 (93%) of 14 in the flecainide group (p less than 0.05). Atrial flutter was converted in two (40%) of five patients treated with propafenone and in one (20%) of five with flecainide (p = NS). Mean time to conversion was 16 +/- 10 min in the propafenone group versus 18 +/- 13 min in the flecainide group (p = NS). QRS lengthening (83 +/- 15 to 99 +/- 20 ms) was observed only in the patients treated with flecainide (p less than 0.001). Patients successfully treated with propafenone showed significantly higher plasma levels than those whose arrhythmia did not convert to sinus rhythm. Transient adverse effects were more frequent in the flecainide group (40%) than in the propafenone group (8%) (p less than 0.01). In conclusion, at a dose of 2 mg/kg in 10 min, flecainide is more effective than propafenone for conversion of paroxysmal atrial fibrillation to sinus rhythm. However, considering the propafenone plasma levels and very few adverse effects, the dose or infusion rate, or both, used in the propafenone group may not have been sufficient to achieve an optimal effect. Neither drug seems very effective in patients with atrial flutter.