Nonpharmacological therapy is being evaluated for the prevention of atrial fibrillation (AF). Pacing has been proposed as a one of the option to prevent AF. In patients with bradycardia and requiring pacemaker, physio...
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Nonpharmacological therapy is being evaluated for the prevention of atrial fibrillation (AF). Pacing has been proposed as a one of the option to prevent AF. In patients with bradycardia and requiring pacemaker, physiological pacing such as dual chamber pacing or atrial pacing has an advantage against ventricular pacing in prevention AF. Pacing from novel site like the dual-site atrium, biatrial, Bachman, and low sepatl pacing may reduce AF burden and new anti-AF pacemakers with atrial prevention algorithm may decrease AF further. However, selecting the appropriate patients and adopting tailored-therapy for individual patient is likely to remain one of the difficulties in achieving an advantage. This review discusses the current status of pacing therapy for the prevention of AF. It also discusses the some of merits and limitations of pacing therapy for the treatment of AF.
The case of a 17-year-old female who had been implanted a dual-chamber DDD pacemaker because of third-degree atrioventricular block is reported. There is a history of continued dizziness and even occasional syncopes. ...
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The case of a 17-year-old female who had been implanted a dual-chamber DDD pacemaker because of third-degree atrioventricular block is reported. There is a history of continued dizziness and even occasional syncopes. At heart rates of 111/min to 124/min, 24-h Holter electrocardiography revealed isolated missing ventricular beats in an otherwise continuous atrially sensed and triggered, ventricularly paced rhythm. Differential diagnoses of a putative pacemaker dysfunction are presented, comprising 2:1-block at maximum programmed heart rate, intermittent lead fracture, anti-pacemaker-mediated tachycardia algorithm, ventricular oversensing, P wave signal undersensing, and atrial oversensing.
Atrial Preventive Pacing. Introduction: Pacing has been proposed as a nonpharmacologic treatment option to prevent atrial tachyarrhythmias (ATs) in drug-refractory patients. This article reviews the current state of p...
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Atrial Preventive Pacing. Introduction: Pacing has been proposed as a nonpharmacologic treatment option to prevent atrial tachyarrhythmias (ATs) in drug-refractory patients. This article reviews the current state of pacing to prevent ATs. Methods and Results: Different pacing modalities have been assessed with regard to their ability to prevent AT: conventional DDDR pacing with elevated lower rate limit, biatrial pacing, dual-site right atrial pacing, atrial septal pacing, and pacing with the use of dedicated pacing algorithms. Small studies suggest a benefit of conventional pacing for AT prevention in patients with bradycardia, but a randomized trial did not reveal any AT reduction by conventional pacing in patients without bradycardia. AT prevention by biatrial or dual-site right atrial pacing has been reported in small studies, but randomized trials did not show a clear benefit of these pacing techniques. Small studies showed a reduced AT recurrence rate in patients with septal pacing at the triangle of Koch or at Bachmann's bundle. Two large randomized trials with preventive pacing algorithms showed a significant AT reduction compared to conventional pacing, but this was not confirmed in four trials. Conclusion: Pacing seems to be able to suppress ATs in minority of patients;however, prospective identification of responders to different pacing modalities does not appear to be feasible at the present time.
Dual chamber systems are currently implanted in an increasing number of patients with a pacing indication and paroxysmal atrial tachyarrhythmias (ATAs). To avoid tracking of high atrial rates during ATA while providin...
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Dual chamber systems are currently implanted in an increasing number of patients with a pacing indication and paroxysmal atrial tachyarrhythmias (ATAs). To avoid tracking of high atrial rates during ATA while providing AV synchronous pacing during sinus rhythm and AV block, automatic mode switching (MS) to a nontracking mode has been developed. Several concepts of MS algorithms have been introduced differing in sensitivity and specificity of ATA detection, delay between ATA onset and MS, pacing mode during MS, rapidity of MS termination upon detection of sinus rhythm, and special algorithms pertinent to MS. This review classifies and analyzes algorithms that are integrated into MS concepts and outlines considerations on optimal MS performance. Based on simulations and clinical studies, fast MS concepts avoiding high paced ventricular rates seem preferable but require special functions to avoid loss of ACT synchrony by inappropriate MS. Similarly, fast return to tracking mode after ATA cessation seems preferable but requires algorithms to prevent mode oscillations. Sudden ventricular rate changes have to be avoided by rate smoothing functions, and an appropriate ventricular rate during nontracking mode has to be provided by rate responsive pacing. Programming of the device includes individual optimization of atrial sensitivity, atrial blanking times, and tachycardia detection rates. In addition, a high signal-to-noise ratio by careful atrial lead implantation, narrowly spaced bipolar atrial leads and a good sensing amplifier, together with special algorithms for atrial sensing adjustment improve the performance of MS algorithms.
Background: Automatic mode switching is defined as the ability of a pacemaker to reprogram itself from tracking to nontracking mode in response to atrial tachyarrhythmias, and to regain tracking mode as soon as the ta...
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Background: Automatic mode switching is defined as the ability of a pacemaker to reprogram itself from tracking to nontracking mode in response to atrial tachyarrhythmias, and to regain tracking mode as soon as the tachyarrhythmia terminates. In contrast to upper rate behavior, mode switching does not only limit atrial tracking at a certain rate but actively drives the ventricular pacing rate back to lower rate or sensor rate as long as the atrial tachyarrhythmia persists. In contrast to DDD with mode switch, AV synchrony may be lost in DDIR mode if the sinus rate exceeds the sensor rate. DDD pacing with mode switching represents a valuable option in patients with AV block and paroxysmal atrial tachyarrhythmias. It may prevent the transition from paroxysmal to permanent atrial fibrillation after AV node ablation to a higher extent than VVI(R) pacing. On the other hand, patients with sinus node disease and normal AV conduction may benefit from DDIR mode with long AV interval. Mode switching should provide a rapid, sensitive a nd specific detection of atrial tachyarrhythmias, fa st switch to non-tracking mode without ventricular pacing at the upper rate limit, adequate ventricular rate during the atrial tachyarrhythmia, rapid, sensitive and specific detection of conversion to sinus rhythm and fast switch back to tracking mode. In addition, oscillations between DDD and DDI mode with sudden ventricular rate changes should be avoided. Mode-Switching algorithms: To achieve these aims, different mode-switching algorithms have been developed which all show specific disadvantages: reliable but slow response to atrial tachyarrhythmias, fast but unspecific switch to nontracking mode, mode oscillations, inclination to inadequate mode-switching due to ventricular far-field sensing, failure to perform modeswitching during atrial flutter or intermittent atrial undersensing. Some of these problems can be avoided by careful atrial lead implantation providing atrial signals above 2 m
Constant rapid pacing may suppress arrhythmias, but it is usually poorly tolerated in the long term. We report a pilot study of a new pacing algorithm for overdrive suppression of atrial premature Complexes (APCs) and...
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Constant rapid pacing may suppress arrhythmias, but it is usually poorly tolerated in the long term. We report a pilot study of a new pacing algorithm for overdrive suppression of atrial premature Complexes (APCs) and atrial fibrillation (AF), which prevents postextrasystolic pauses and varies the pacing rate in response to the frequency of APCs. The algorithm was tested in a multiple crossover study for 24 hours in dual chamber pacemakers implanted in 70 patients. Comparison was made on ambulatory recordings between the number of atrial arrhythmias commencing with the algorithm active and inactive. In all cases, the algorithm functioned as designed. No patient was aware of its operation, and no malignant arrhythmias were induced. The 36 recordings that showed atrial arrhythmia were included for analysis. The effects of the algorithm were: APCs (estimated from pacemaker statistics) reduced in 18 patients, increased in 8 (P = 0.02);atrial salves reduced in 12, increased in 4 (P = 0.041);and AF reduced in 11, increased in 8 (P = NS). In all patients with frequent AF (> 5 episodes in total), fewer episodes occurred when the algorithm wets active. We conclude that the algorithm is safe and well tolerated, reduces atrial ectopic activity, and may reduce the frequency of sustained atrial fibrillation.
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