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Biomedical subjects

N M van Hemel

Publications and source records attributed to N M van Hemel.

At least 19 recordsLinked to original sources

FOLLOWPACE study: a prospective study on the cost-effectiveness of routine follow-up visits in patients with a pacemaker.

AIMS: This communication describes the design of the FOLLOWPACE study. The overall aim of FOLLOWPACE is to quantify the cost-effectiveness of routine follow-up visits in patients with a pacemaker (PM). Specific aims are (i) to quantify the incidence of complications and the quality of life 1 year after PM implantation; (ii) to quantify which baseline characteristics measured during implantation are predictors of the occurrence of complications and quality of life after 1 year; (iii) to determine the added predictive value of follow-up measurements to improve the efficiency of follow-up and to demonstrate which follow-up measurements are redundant. METHODS AND RESULTS: FOLLOWPACE is a prospective, observational, prognostic cohort study. About 40 PM centres in the Netherlands will participate to include about 2,500 patients. Each patient aged >or=18 receiving a PM for the first time is eligible. At baseline, i.e. time of implantation, all potential predictors of complications and quality of life after 1 year are documented. After implantation, follow-up visits will be carried out conforming with routine care, usually three in the first year. At these visits, other potential prognostic predictors will be documented. Primary outcome is the incidence of PM- or cardiac complications at 1 year. Secondary outcome parameters are quality of life and costs after 1 year. CONCLUSION: This study will lead to definition of a more efficient routine follow-up schedule for patients with a PM, aiming to reduce time and energy while preserving the safety of pacing therapy and the prognosis of the patient. The study will ultimately provide evidence-based guidelines for PM follow-up including knowledge of the responsibilities of cardiologists, technicians, and representatives of PM manufacturers.

Appointments and Schedules↗

Hospital discharge diagnoses of ventricular arrhythmias and cardiac arrest were useful for epidemiologic research.

OBJECTIVE: We investigated the validity of hospital discharge diagnosis regarding ventricular arrhythmias and cardiac arrest. METHODS: We identified patients whose record in the PHARMO record linkage system database showed a code for ventricular or unspecified cardiac arrhythmias according to codes of the International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM). The validity of ICD codes for ventricular arrhythmias and cardiac arrest (427.1, 427.4, 427.41, 427.42, 427.5, 427.69) and ICD codes for unspecified cardiac arrhythmias (427.2, 427.60, 427.8, 427.89, 427.9) was ascertained through manual review of hospital clinical records. The positive predictive value (PPV) was calculated, and differences between characteristics of true and false positives were evaluated. RESULTS: The PPV of ICD codes for ventricular arrhythmias and cardiac arrest was 82% (95% confidence interval CI = 72-92). True positive results were associated with male gender (P = .09) and younger age (P = .05). Of the unspecified cardiac arrhythmias 10% (95% CI = 2-18) were identified as ventricular arrhythmias or cardiac arrest. CONCLUSION: Hospitalizations for ventricular cardiac arrhythmias and cardiac arrest (coded according to ICD-9-CM as paroxysmal ventricular tachycardia, ventricular fibrillation, ventricular flutter, ventricular premature beats, or cardiac arrest) have a high PPV and are useful for selecting events in epidemiological studies on drug-induced arrhythmias.

Data Collection↗

The maze operation as a surgical treatment of atrial fibrillation.

In this study we reviewed the history of the surgical treatment of atrial fibrillation (AF). Of the various types, the maze operation has become nowadays the most successful surgical treatment of AF with or without concomitant cardiac surgery. We report on our 10-year experience with conventional maze III surgery: 203 patients were operated on without in-hospital mortality and acceptable morbidity. Success defined as the freedom of AF and other supraventricular arrhythmias was 80.1% for the patients with lone AF and 64.5% for the patients with concomitant AF after a mean of 4 years after surgery. We conclude that despite the complexity of the maze III operation this approach remains the golden standard from which future surgical and other ablative treatments of AF will be derived.

Atrial Fibrillation↗

Ten year follow-up after radiofrequency catheter ablation for atrioventricular nodal reentrant tachycardia in the early days forever cured, or a source for new arrhythmias?

BACKGROUND: Radiofrequency (RF) catheter ablation is highly effective with a low complication rate. However, lesions created by RF energy are irreversible, inhomogeneous, and therefore potentially proarrhythmic. OBJECTIVES: The aim of this study was to examine the magnitude and importance of long-term proarrhythmic effects of RF energy. METHODS AND RESULTS: Between 1991 and 1995, 120 patients underwent RF ablation for atrioventricular nodal reentrant tachycardia (AVNRT). Patient data were collected by contacting patients and/or filling out a questionnaire, and medical files were screened for recurrent, documented arrhythmias, pharmacological treatment, and repeated EP study. Referring cardiologists were asked about recurrences of tachyarrhythmias. Fourteen patients (11%) were lost to follow-up. During a mean follow-up of 10 years, six patients died. Recurrences of AVNRT were not any more observed after 3 years after ablation. A total of 29 patients (24%) suffered from new arrhythmias, 6 from type 1 atrial flutter, 6 from atrial tachycardia, 9 from atrial fibrillation, and finally 16 from symptomatic premature atrial contractions (PACs), needing medical treatment or a combination of these arrhythmias. Nine patients underwent pacemaker implantation, 4 after developing procedural atrioventricular (AV) conduction disturbances, 2 after His ablation for permanent atrial fibrillation, 1 patient for sick sinus syndrome, and another 2 patients after developing late AV block, respectively, 7 and 9 years after ablation. CONCLUSION: During long-term follow-up after RF ablation for AVNRT, no AVNRT recurrences were observed, but 29 patients (24%) suffered from new arrhythmias or late AV block. This potential proarrhythmic effect of RF energy promotes the application of alternative energy sources for ablative therapies for cardiac arrhythmias.

Adult↗

[Dyspnoea in pregnant female immigrants due to unexpected mitral valve stenosis].

Three female patients, a 22-year-old Moroccan woman, a 25-year-old Turkish woman and a 35-year-old Iraqi woman, became increasingly dyspnoeic during their pregnancy; this was a symptom of congestive heart failure due to mitral valve stenosis. Since all patients were refractory to medical treatment, they underwent invasive therapy by percutaneous transvenous mitral balloon valvotomy (PTMV). In two patients this therapy was successful, but in one patient a closed mitral valvotomy was needed. All three women delivered healthy infants, two immediately following the PTMV; at follow-up 2-4 years later, the women and infants were all doing well. The prevalence of mitral valve stenosis in the western world is increasing because of changing immigration patterns. When pregnant patients start complaining about dyspnoea, especially if they are immigrants, one should be aware of the possibility of mitral valve stenosis. PTMV is a safe and successful treatment for these patients and is preferred above surgical therapy because of its low morbidity and mortality for both mother and foetus. PTMV must be performed in a thoracic surgery centre by an experienced team and the X-ray exposure should be minimised.

Adult↗

Myocardial adaptation in different endurance sports: an echocardiographic study.

OBJECTIVE: Of this study was to investigate three groups of highly trained competitive endurance athletes consisting of marathon runners, triathletes and cyclists for differences in left ventricular adaptation. METHODS: 25 marathon athletes, 21 triathlon athletes and 38 cyclists underwent a standard echocardiographic and Doppler study. RESULTS: The left ventricular internal diameter in diastole divided by body surface area was significantly larger in cyclists than in marathon runners (31.6+/-3.0 vs. 30.0+/-2.0 mm/ m2, p < 0.05) but did not differ of that of triathletes. Left ventricular mass was significantly different between marathon runners and triathletes (253.6+/-63.7 vs. 322.0+/-62.1 g, p < 0.005) and between marathon runners and cyclists (253.6+/-63.7 vs. 314.2+/-79.2 g, p < 0.005). Systolic wall stress was significantly different between the marathon runners and the triathletes (88.4+/-11.7 vs. 78.9+/-11.0 g/cm2 p < 0.05). Only a minority of the endurance athletes showed concentric remodeling (7%), whereas a majority showed eccentric remodeling (65%) of the left ventricle. The prevalence of eccentric remodeling was more apparent in cyclists. There were some specific differences in left ventricular diastolic function between the three different endurance sports, but no left ventricular diastolic dysfunction could be detected. CONCLUSION: There is a sport-specific left ventricular adaptation in endurance athletes. The triathlon heart and the heart of a cyclist differ significantly from a marathon heart.

Adaptation, Physiological↗

Right atrial modification of maze surgery does not affect refractoriness and conduction patterns of human lone atrial fibrillation.

BACKGROUND: Tissue mass and structure are relevant for initiation and persistence of fibrillation. Modification of the right atrium during maze surgery may change the arrhythmogenic substrate of atrial fibrillation (AF). METHODS AND RESULTS: Epicardial mapping was performed in 9 patients undergoing unmodified maze III surgery for lone paroxysmal AF. Simultaneous recording of AF on the right and left atrium was carried out with two spoon-electrodes each harbouring 64 terminals. Activation maps of AF were made to study AF wavelet organization. The recording position on right and left atria was outside the surgical field and remained unchanged before and after surgery. Before surgery, mean right and left fibrillatory intervals were 174+/-23 ms, and 175+/-26 ms, respectively, and did not differ. After completed right atrial surgery, these fibrillary intervals remained unchanged. Mean right and left atrial dispersion of refractoriness (expressed as the coefficient of variation) were 4.2+/-0.8 and 5.2+/-3.8 ms. Only right atrial dispersion of refractoriness increased significantly after right-sided surgery. Prior to surgery, activation patterns of the left atrium were more complex than that of the right atrium. The left activation patterns became less complex afterwards; the right atrial activation patterns did not change. CONCLUSION: The right atrial modification of maze III surgery neither affects atrial refractoriness during human lone AF nor changes AF wavelet organization. Thus, right atrial surgery does not modify the arrhythmogenic substrate of AF. These findings may imply that maze surgery can be restricted to the left atrium.

Atrial Fibrillation↗

Long-term follow-up of cardiac rhythm after percutaneous mitral balloon valvotomy. Does atrial fibrillation persist?

AIMS: Little information is available about short-term and none about long-term follow-up of cardiac rhythm after percutaneous mitral balloon valvotomy (PTMV). METHODS AND RESULTS: We studied the long-term course of the supraventricular rhythm in 137 consecutive patients with severe mitral stenosis, who underwent PTMV. The rhythm before PTMV was sinus rhythm (SR) in 55% and chronic AF in 45% of patients. The mean follow-up time was 3.7+/-2.5 years (n=126). In patients with SR before PTMV, SR persisted in 91% of patients at the end of follow-up. In patients with chronic AF before PTMV, 84% of these patients were still in chronic AF at the end of follow-up, spontaneous conversion to SR did not occur. In 12 of 14 patients (85%), selected for cardioversion, SR was achieved, by DC cardioversion (n=11) or by drugs alone (n=1). After 2 years this outcome persisted, but after 4 years only 38% remained in SR. CONCLUSION: Pre-procedural SR will persist following PTMV. However in patients with chronic AF PTMV is not associated with reversion to SR, suggesting that measures should be undertaken to restore sinus rhythm.

Atrial Fibrillation↗

A randomized study of combining maze surgery for atrial fibrillation with mitral valve surgery.

AIM: Mitral valve surgery seldom suppresses atrial fibrillation (AF), present prior to surgery. Maze III surgery eliminates AF in >80% of cases, the reason why combining this procedure with mitral valve surgery in patients with AF seems worthwhile. We prospectively studied the outcome of combining the Maze III procedure with mitral valve surgery. METHODS: Thirty-five patients with AF and a mean age of 64 years undergoing mitral valve surgery were prospectively randomized according to a 2.5:1 ratio to surgery with (n=25), or without (n=10) maze III and followed for at least 1 year. RESULTS: At discharge and after 12 months freedom from AF was 56% and 92%, respectively, in the maze group, and 0% and 20%, respectively, in patients without maze (group differences at discharge p=0.002, after 12 months p=0.0007). Sinus node incompetence was seen in 1 of 25 maze patients requiring pacing. No in-hospital or late death occurred; stroke was observed in 1 patient (without maze). Quality of life markedly improved after surgery, but did not differ between patients with or without maze surgery. CONCLUSIONS: This first prospective randomized study shows that combining maze III with mitral valve surgery resulted in a significantly better elimination of preoperative AF than mitral valve surgery alone. As the quality of life did not differ between patients with, or without maze surgery, additional maze surgery is primarily recommended in patients in whom anticoagulation therapy can be avoided after surgery, specifically in patients with scheduled mitral valve plasty.

Anti-Arrhythmia Agents↗

[Chronic simultaneous stimulation of both ventricles, a new treatment option for severe congestive heart failure].

Dilated congestive heart failure due to systolic left ventricle dysfunction frequently leads to intraventricular conduction disturbances with a prolonged QRS complex (> 120 ms). The prolonged conduction time in the ventricles causes electrical asynchrony of the ventricles and contributes to a further reduction of systolic function, changes of filling and relaxation intervals, and promotes mitral valve insufficiency. Chronic simultaneous stimulation of both the right and left ventricle in patients with severe heart failure improves functional status, quality of life, and exertion tolerance. At present the implantation of a biventricular pacemaker is time consuming because the positioning of the lead in a left ventricular epicardial vein is difficult. As congestive heart failure is frequently associated with an increased risk of ventricular fibrillation, the combined implantation of a biventricular stimulator and an implantable automatic defibrillator is sometimes necessary. Preliminary calculations show that about 750 patients per year with severe congestive heart failure are eligible for a biventricular stimulator.

Cardiac Pacing, Artificial↗

[Implanted pacemakers in the Netherlands, 1984-1997; number, types and patient characteristics].

OBJECTIVE: To carry out a survey of the numbers of patients in the Netherlands who received a pacemaker in 1984-1997 and the types of pacemaker. DESIGN: Retrospective, descriptive. METHOD: Information on pacemaker patients and pacemakers in the Netherlands during the years 1984-1997 was obtained from the Dutch Pacemaker Patient Registration organisation and those in 15 other West-European countries from the European Working Group on Cardiac Pacing. Both organisations use the European Pacemaker Identification Card. Demographic information was collected via Statistics Netherlands. RESULTS: In the Netherlands, 23 and 28 primo-implantations/100,000 inhabitants were carried out in 1984 and 1997 respectively. The increase was primarily due to a higher number of implants in people > 65 years of age. The 1997 implant figures were lower than the average in Western Europe (34/100,000). In 1997 there was no difference in gender, mean age at the time of first implant, indications and aetiology between the Netherlands and Western Europe. With respect to the choice of type of pacemaker implanted--VVI(R) or DDD(R)-in Western Europe, the Netherlands lay in the middle. Between 1984 and 1997, the number of Dutch centres with 1-25 implants/year decreased while the number with 51-130 implants/year increased. CONCLUSION: In 1997 the number of primo-implantations at Dutch centres increased in comparison with 1984, but less than the West European average. Implants were increasingly performed in high-volume centres.

Age Factors↗

Psychometric properties of Aquarel. a disease-specific quality of life questionnaire for pacemaker patients.

In cardiac pacing current clinical practice permits the use of ventricular or atrioventricular-synchronous pacemakers. However, it is not known which type of pacemaker results in superior clinical and patient outcomes. To date, there is no feasible and validated disease-specific questionnaire for pacemaker patients to assess quality of life (QoL) available. The Aquarel questionnaire was developed as a disease-specific extension to the Short-Form-36 (SF-36). A cross-sectional study was carried out in 74 pacemaker patients to evaluate validity and reliability of this instrument. Items were selected and scales constructed based on factorial analysis. Internal consistency, content validity and test-retest reliability were moderate to excellent. Correlations with the SF-36 scales, pacing mode and functional tests were as hypothesized, demonstrating the individual value and distinctiveness of the Aquarel subscales. The results support the feasibility and usefulness of evaluating QoL in pacemaker patients when using Aquarel as an extension to the SF-36.

Activities of Daily Living↗

Changes in quality-of-life after pacemaker implantation: responsiveness of the Aquarel questionnaire.

Before being introduced for widespread use, health status instruments should be evaluated for reliability, validity, and responsiveness to relevant clinical changes. In a previous study the validity and reliability of Aquarel, a disease-specific quality-of-life (QOL) questionnaire for pacemaker patients, were tested and found satisfactory. The purpose of this study was to assess the sensitivity to change in health of Aquarel. A cohort of 51 patients was assessed at baseline and at 4-6 weeks after pacemaker implantation. We compared the sensitivity to change over time on the Aquarel scores to the scores on the SF-36 using various techniques (t-test value, effect size, standard error of measurement). Using the 1-standard error of measurement (SEM) criterion for clinically relevant change, Aquarel seemed to provide better classification of patients compared to the SF-36 alone. This study supports the value of Aquarel as a disease-specific measure of QOL in pacemaker patients.

Aged↗

Pace mapping of postinfarction scar to detect ventricular tachycardia exit sites and zones of slow conduction.

INTRODUCTION: The exit site and central common pathway of slow conduction are preferred sites to guide radiofrequency ablation of postinfarction ventricular tachycardia (VT). Both require inducibility of VT. In addition, their low amplitude hampers direct recording of potentials generated by activation in pathways of slow conduction. We hypothesized that pace mapping during sinus rhythm would help to detect the VT exit site and potentials generated by activation in pathways of slow activation. METHODS AND RESULTS: In 13 patients suffering from VT late after anterior (n = 10) or inferior (n = 3) myocardial infarction, stimulation was performed in scarred endocardium at 23.5 (range 13 to 36) sites per patient during arrhythmia surgery. Multielectrode recordings (64 sites) during stimulation at a fixed cycle length of 500 msec were obtained. Endocardial breakthrough sites distant (>2 cm) from the pacing site were found at 4.3 (range 3 to 19) pacing sites per patient. Low-amplitude discrete potentials (LADPs) could be detected between the pacing site and the breakthrough site in 2.3 (range 0 to 13) of 4.3 stimulation sequences. In these patients, 19 VTs were induced and the exit site determined. In 6 patients, the distant pacing breakthrough site was identical to the VT exit site; in 7 patients, no similar exit sites were found. LADPs during VT were found at a median 2.0 (range 0 to 14) sites per patient. CONCLUSION: Pace mapping of the postinfarction endocardial scar during sinus rhythm revealed 50% of the endocardial exit sites of VT and the same number of LADPs observed during VT.

Cardiac Pacing, Artificial↗

Relation between body surface mapping and endocardial spread of ventricular activation in postinfarction heart.

INTRODUCTION: Body surface mapping (BSM) can be used to identify the site of earliest endocardial activation of ventricular tachycardias (VTs). The multielectrode QRS morphology during VT is determined by both the site of earliest activation and the subsequent spread of electrical activation through the ventricles. This study investigated the relationship between the site of earliest endocardial activation, endocardial spread of activation, and the morphology of the multielectrode surface map in patients with remote myocardial infarction. METHODS AND RESULTS: In 14 patients with VT late (8.2+/-5.2 years) after myocardial infarction, BSM and simultaneous left ventricular 64-site basket endocardial mapping was performed during a total of 17 monomorphic VTs. In addition, multisite pacing by sequential use of the 64 basket electrodes was performed in 9 patients. BSM and basket mapping revealed the same endocardial breakthrough sites in 8 (47%) of 17 VTs and 189 (59%) of 322 pacing sites; adjacent sites were found in 2 (12%) of 17 VTs and 36 (11%) of 322 pacing sites. Large zones of conduction block explained the mismatch in localization in 2 (12%) of 17 VTs and 52 (16%) of 322 pacing sites. Regional differences in endocardial electrogram amplitudes were found as a cause for dissimilarity in 3 (18%) of 17 VTs and 73 (23%) of 322 pacing sites. Multiple endocardial breakthrough sites were found in 1 (6%) of 17 VTs and 8 (2%) of 322 pacing sites Finally, an epicardial exit site was suggested in 3 (18%) of 17 VTs as an explanation for mismatch, as no early endocardial activity could be recorded. CONCLUSION: Zones of conduction block, regional differences in signal amplitude, and multiple endocardial breakthrough sites are frequent causes for mismatch between BSM and basket catheter activation mapping.

Aged↗

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.

Adult↗

Mitral valve surgery and atrial fibrillation: is atrial fibrillation surgery also needed?

OBJECTIVE: Atrial fibrillation (AF) persisting after mitral valve surgery reduces survival due to heart failure and thrombo-embolisms, and impairs quality of life. Arrhythmia surgery for AF shows today very satisfying results and therefore mitral valve surgery with AF surgery appears appealing. This study explores whether combined surgery in view of today's results of mitral valve surgery is indicated. METHODS AND RESULTS: An outcome analysis of the arrhythmia outcome of patients undergoing exclusive mitral valve surgery with or without tricuspid repair was done. Preoperative baseline characteristics including arrhythmia pattern, surgical methods and follow-up findings were reviewed. Postoperative management of AF was not protocolized. Between 1990 and 1993, 162 consecutive patients underwent mitral valve surgery; follow-up was a mean of 3.3+/-1.9 years. In-hospital and late mortality were 1 and 9%, respectively. Sinus rhythm was preserved in 40 of 57 (70%) patients with preoperative sinus rhythm whereas AF persisted in 58 of 68 (85%) of patients with preoperative chronic AF (>1 year present). Sinus rhythm without AF was observed in 10 of 29 (34%) patients with preoperative paroxysmal AF. The 4-year Kaplan-Meier survival did not differ between patients with preoperative sinus rhythm (95.2%), paroxysmal AF (89.2%) and chronic AF (82.9%) but AF persisting after surgery tended to determine survival (P=0.05). Gender, age and right ventricular pressure and tricuspid valve repair were risk factors for postoperative recurrence of AF in patients with sinus rhythm at discharge, relative risk 0.35, 1.06, 1. 04 and 2.9, respectively. CONCLUSION: Current mitral valve surgery with or without tricuspid valve repair does not eliminate preoperative paroxysmal or chronic AF. Secondly, because preoperative AF did not determine survival after mitral valve surgery, whereas postoperatively persisting AF was weakly associated with survival, atrial arrhythmia surgery primarily aims to reduce morbidity due to AF. Some characteristics can identify patients with increased propensity for persisting AF after surgery. Randomized studies of AF surgery are needed to identify suitable candidates for combined surgery.

Adult↗

Temporary pacing after His bundle ablation for drug-refractory atrial fibrillation: a risky enterprise?

AIM: In patients with and without a permanent pacemaker His bundle ablation was performed for symptomatic drug-refractory atrial fibrillation. This study was performed to examine the complications of temporary pacing in patients without an already implanted pacemaker. METHODS AND RESULTS: Between January 1996 and December 1998, 152 consecutive patients, both referred and our own (non-referred), underwent His bundle ablation for drug-refractory atrial fibrillation. Primary end-point complications were temporary lead dislodgement requiring immediate repositioning (1), severe arrhythmia (2), death (3) and persistent damage to an already implanted pacing system (4). Secondary end-points were malsensing and malpacing of the temporary lead, and blood vessel problems. Lead dislodgement of the temporary pacemaker occurred in three patients (2.9%), all of whom were in the referred group. Severe arrhythmia and death did not occur. Persistent damage of the already implanted pacing system was not observed. Secondary end-points occurred in 15.8%) of the patients and were successfully managed by a conservative approach. CONCLUSION: Permanent pacemaker implantation is recommended prior to His bundle ablation in order to avoid haemodynamic deterioration due to dislocation of the temporary pacemaker lead. RF current used for His bundle ablation caused no permanent damage to permanent pacing systems.

Atrial Fibrillation↗