Dual-chamber pacing

Dual-chamber pacing has been available since the early 1980s, yet it is a topic with which critical care nurses consistently have difficulty. New advances in pacemaker technology have built on the principles inherent in dual-chamber pacing, making it imperative that practitioners have a basic understanding of dual-chamber pacemaker function. With dwindling clinical resources, the responsibility of the bedside nurse to evaluate appropriate pacemaker function and identify the patient's response to pacemaker therapy has increased.     

Clinical Experience with a Bradycardia Indicating Pacemaker

The beneficial effect of permanenl pacing is controversial in certain patient groups. Once pacing has been instituted it isseldom terminated and an evaluation of pacemaker depen'dence is therefore not possible. An implantable puise generator, detecting bradycardia beiow 30 bpm has beendeveiopedin order tobroaden ourknowledgeabout the natural history of bradyarrhythmias treated by permanent pacing. This pacemaker has been implanted in 30 patients who did not have clear-cut indications for permanent pacing. They have been followed for a mean of 13 months. Bradycardia was detected in 33 patients 1 to 21 months (4.6 mean) affer implantation. Twenty-one patients did not have a defected bradycardia for Jong periods (months-years). Minor symptoms of lightheadedness a dributable to bradycardia were reported by 15 patients during periods when the pacemaker had been activated. Holter monitoring for at least 24 hours was carried out in all patienls and electronic analysis of explanted generalors was performed in eieven cases. No tecnnical failure relaled to the bradycardia-detecting facility was observed. The combination of diagnostic and therapeutic properties in the bradycardia-indicating pacemaker provides means for safe evaluation of pacemaker dependency over long time periods in patienl groups with controversial indications for permanent pacing.     

The Frequency of New Permanent Pacemaker Implantations in 1975, 1980 and 1990 A Model Study Taking into Account the Dependence of Age and Sex

Statistics of the number of new, permanent pacemaker systems per year have been obtained for various countries since the end of the 1960's. These figures have been expressed mostly as the number of new paced patients per million inhabitants. There is a progressive increase in the need of a pacemaker with increasing age. Demographic data show considerable differences in the number of elderly in the various countries. More pacemakers have been implanted in males than in females, The predicted number of new permanent pacemaker systems in 1960 and 1990 has been calculated for eleven countries and has been estimated to be 200 per million inhabitants of the total population (age and sex distributions in the populations have been taken into account). Considerable differences appear.     

体外充电植入式人工心脏起搏器的设计

背景：人工心脏起搏器长期植入人体,使用寿命至关重要,目前尚没有可充电的植入式人工心脏起搏器问世。目的：探讨植入式人工心脏起搏器体外充电技术,以期降低人工心脏起搏器寿命对电池能量的依赖。方法：利用某种对人体无创、无害的介质,把体外能量隔离传输给植入体内的接收转换装置,进而对人工心脏起搏器可充电电池的能量给予补充,以延长使用寿命。结果与结论：试制了可充电人工心脏起搏器实验样机,完成了一期动物实验,同时以超声波为能量传输载体进行了隔离无刨充电试验,对相关技术做了探讨。     

Health-related quality of life in pacemaker patients: a single and multidimensional self-rated health comparison study.

Since implantation of the first permanent pacemaker in 1958, significant advances have been made in pacemaker technology. To date, however, health-related quality of life (HRQoL) in a large pacemaker population has not been investigated. With dwindling clinical resources, it is important to study HRQoL in a pacemaker population in a reliable and straightforward manner. This study aimed to determine and compare single and multidimensional self-rated health (SRH) in a pacemaker population in terms of sociodemographic characteristics, pacemaker mode and symptoms. The findings showed that irrespective of whether the perspective was single or multidimensional, this Swedish pacemaker population (n=697) with a mean age of 76 years had an acceptable HRQoL. Men, aged 65-84 years, persons who were cohabiting, who had their own dwelling, who had a DDD or who had a pacemaker for 相似文献   

体外充电植入式人工心脏起搏器的设计

背景:人工心脏起搏器长期植入人体,使用寿命至关重要,目前尚没有可充电的植入式人工心脏起搏器问世.目的:探讨植入式人工心脏起搏器体外充电技术,以期降低人工心脏起搏器寿命对电池能量的依赖.方法:利用某种对人体无创、无害的介质,把体外能量隔离传输给植入体内的接收转换装置,进而对人工心脏起搏器可充电电池的能量给予补充,以延长使用寿命.结果与结论:试制了可充电人工心脏起搏器实验样机,完成了一期动物实验,同时以超声波为能量传输载体进行了隔离无创充电试验,对相关技术做了探讨.     

Electrical Alternans of Pacemaker Spike Amplitude: an Unusual Manifestation of Permanent Pacemaker Generator Malfunction

A case of electrical alternans of pacemaker stimulus amplitude is presented, with constant alternation of large and small amplitude pacemaker spikes without loss of ventricular capture, due to a defect in the oscillator hybrid of a rate programmable Medtronic unit. This represents an unusual electrocardiographic manifestation of pacemaker generator malfunction which, to our knowledge, has not been reported previously.     

Echocardiography-guided biventricular pacemaker optimization: role of echo Doppler in hemodynamic assessment and improvement

In spite of improvements in heart failure management and increasing utilization of cardiac resynchronization therapy (CRT), approximately 30–40% of CRT patients remain nonresponders and 50% or more are echocardiographic nonresponders (defined as less than 15% reduction in left ventricular end systolic volume post-CRT). Optimization guided by echocardiography has been studied as one of the methods to improve the nonresponder rate to CRT. Echo-guided biventricular (Biv) pacemaker optimization has been associated with improvement in acute cardiac hemodynamics and improvement in functional class. In this review, the authors discuss various methods to optimize Biv pacemaker by echocardiography, recent advances in pacemaker optimization and the limitations of echocardiography. The authors also demonstrate complex hemodynamic derangements in heart failure via multiple case examples highlighting the role of comprehensive echo Doppler in elucidating cardiac hemodynamics encountered in CRT nonresponders, as well as tailoring of Biv pacemaker optimization to the underlying physiologic derangement.     

Pacemaker diagnostics to determine treatment and outcome in sick sinus syndrome with paroxysmal atrial fibrillation

Sequential analysis of pacemaker diagnostics has been used to help manage the treatment and pacemaker program in patients who have sick sinus syndrome with documented paroxysmal atrial fibrillation. One hundred consecutive patients were followed for an average of 18 months. Knowledge of the atrial fibrillation burden led to major changes in medical management for half of the patients and changes to pacemaker programming for all. At the end of the study, 48 patients were free of arrhythmia with pacing although 14 required antiarrhythmic medication. We advocate using pacemaker diagnostics to improve patient management.     

Pacemakers of the 1980s. An overview

Methods and devices for permanent cardiac pacing remained relatively stable for over two decades with use of the single-chamber ventricular demand (VVI) pacemaker. However, changes have occurred in the 1980s and are expected to continue with the availability of more advanced technology and with increasing knowledge about cardiac pacing. The physiologic benefit of the newer dual-chamber atrial synchronous (VDD) and fully automatic, universal (DDD) pacemakers over the VVI pacemaker in patients with permanent complete heart block and normal sinus node function has been established. These newer units not only reestablish atrioventricular synchrony but also are physiologically rate-responsive. The VDD pacemaker is expected to be phased out in favor of the DDD pacemaker. When the atrial rate or interval is lower than the lower rate limit, the VDD pacemaker functions as a VVI, whereas the DDD pacemaker functions as an atrioventricular sequential (DVI) pacemaker to maintain continuous atrioventricular synchrony. Contrary to general belief, patients with complete heart block and normal sinus node function may gain very little physiologic benefit, if any, from DVI pacing. The sinus node will compete with the pacemaker's atrial stimulation when the sinus rate is faster than the DVI pacemaker rate (which usually occurs during activity). Also, the ventricular pacing rate will not vary with physiologic change. The DVI and atrial demand (AAI) pacemakers have been used in some patients with sinus node dysfunction. Increasing exercise tolerance should not be expected in the majority of patients because they are not pacemaker-dependent during activity, ie, their heart rate is higher than the pacemaker rate. However, these pacemakers appear to help in eliminating pacemaker syndrome, which does not infrequently occur with VVI pacemakers. Patients with sinus node dysfunction but without atrioventricular block do not gain more physiologic benefit with a DDD than with a DVI pacemaker. Whether these patients have severe sinus node dysfunction all the time or adequate sinus node function most of the time during follow-up, the DDD pacemaker will function as a noncommitted DVI with atrial sensing (DDI). The early report of DVI pacemaker-induced atrial fibrillation during follow-up has been refuted by more recent works. If the DDD pacemaker is significantly more expensive than the DVI pacemaker, the latter type may be a good alternative for this condition.     

Pacemaker Dependence in Transient High-grade Atrioventricular Block

In a prospective study 16 patients who had been given a pacemaker because of symptomatic high-grade atrioventricular block and whose conduction had been recovered were checked for their dependence on the pacemaker. During a follow-up time ranging from 32 to 158 months (median 62 months) six patients proved to be dependent on the device owing to the development of recurrent stable high-grade atrioventricular block. The subsequent return of atrioventricular block was evidently not associated with etiology, age, sex, ECG-pattern or length of follow-up period. Five additional patients equipped with a bradycardia-indicating pacemaker all proved to be pacemaker-dependent after a follow-up time ranging from 1-20 months (median 7 months), even though atrioventricular conduction had recovered and its presence had been confirmed at regular outpatient checks. It is thus evident that the conventional clinical methods are of limited value for examining the course of conduction defect and assessing the prognosis for patients whose spontaneous cardiac activity has returned after periods of symptomatic high-grade atrioventricular block. When a bradycardia-indicating pacemaker was furnished, pacemaker dependence was demonstrated in most of the patients whose atrioventricular conduction had recovered. This confirms that pacing introduced because of symptomatic high-grade atrioventricular block should not be discontinued even if a conducted heart rhythm has been established and maintained for long periods.     

Interpretation of Dual Chamber Pacemaker Electrocardiograms

A diagramming system has been developed to assist in interpreting dual chamber pacemaker electrocardiograms. The system is based on the ladder diagram principle but uses two separate ladders, one for the ECG allowing proper representation of atrial A-V and ventricular activation, and a second ladder diagram below it for pacemaker events. The system is applicable to all current single and dual chamber pacing modes and is easy to draw. The ladder diagram allows the logical sequence of timing events to be easily illustrated, and pacemaker malfunction becomes clearly recognizable as a conflict between the ECG events ladder and the pacemaker timing ladder. The system is easy to apply and may eventually prove suitable for automatic generation by computer utilizing sophisticated pacemaker telemetry.     

Reticulated telangiectatic erythema of the pacemaker

Reticulated telangiectatic erythema is a rare entity; it has been reported to occur following the placement of implanted cardiac devices and drug delivery systems. Histologically, reticulated telangiectatic erythema of the pacemaker is characterized by slight spongiosis and increased dermal telangiectasias. We describe a patient that developed reticulated telangiectatic nonpruritic patches on the left chest after the placement of a pacemaker. The patient responded favorably to the removal of the pacemaker.     

Echocardiography-guided biventricular pacemaker optimization: role of echo Doppler in hemodynamic assessment and improvement

In spite of improvements in heart failure management and increasing utilization of cardiac resynchronization therapy (CRT), approximately 30-40% of CRT patients remain nonresponders and 50% or more are echocardiographic nonresponders (defined as less than 15% reduction in left ventricular end systolic volume post-CRT). Optimization guided by echocardiography has been studied as one of the methods to improve the nonresponder rate to CRT. Echo-guided biventricular (Biv) pacemaker optimization has been associated with improvement in acute cardiac hemodynamics and improvement in functional class. In this review, the authors discuss various methods to optimize Biv pacemaker by echocardiography, recent advances in pacemaker optimization and the limitations of echocardiography. The authors also demonstrate complex hemodynamic derangements in heart failure via multiple case examples highlighting the role of comprehensive echo Doppler in elucidating cardiac hemodynamics encountered in CRT nonresponders, as well as tailoring of Biv pacemaker optimization to the underlying physiologic derangement.     

Testing of Work Environments for Electromagnetic Interference

A challenge for pacemaker therapists is whether a patient working in an environment with the potential for electromagnetic interference (EMI) can return to their work after a pacemaker has been implanted. Common practice has been to prohibit pacemaker patients from using electric welding machines. Twelve work environments and a new method for monitoring the pacemaker rhythm in the presence of EMI were tested. The new method uses a special memory called the event record found in several Siemens Pacesetter pacemaker models. Surface ECGs with a marking system, intracardiac electrograms, and a digital monitor were used to verify the results with event records. The results from several sources of EMI are reported. Twenty-one in vivo and in vitro tests were performed in the work environments of 12 patients. Event records were useful and accurate both in vivo and in vitro. Electric arc welding machines up to 225 A did not affect these pacemakers. Arc welding machines using 1,000 A or more inhibited the in vitro test system within 1 or 2 meters of the weld or power generator. Electric welding machines with high frequency voltage superimposed on the welding current affected the pacemaker when it was within 2 meters of the power unit and 1 meter of the weld. Very large industrial degaussing coils affected pacemakers within 2 meters. The test method using event records was found to be an effective addition to monitoring the pacemaker. These results are specific for the pacemaker models tested. Such testing allows the physician to make a knowledgeable decision regarding return to work for the pacemaker patient in a high EMI environment.     

Pacemaker dysfunction in the clinical practice

Lead dysfunction is still the predominant cause of pacemaker dysfunction. Beyond lead dysfunction clinicians might encounter problems resulting from the surgical procedure of pacemaker implantation, from specific programmable pacemaker functions (e.g. undersensing of premature ventricular complexes when autosensing is activated) and from interference with electromagnetic fields. Electromagnetic interference between pacemakers and mobile phones has been demonstrated both in vitro and in vivo, but in daily life pacemaker patients can readily use mobile phones when certain security measures are taken into account. Electromagnetic interference between anti-theft devices and pacemakers can arise from situations where the pacemaker is in close proximity to the anti-theft device, but in daily life these interferences are rare. The electromagnetic fields generated during magnetic resonance imaging (MRI) are considerably stronger than those generated by mobile phones or anti-theft devices, therefore permanent pacemakers are still considered a contraindication for MRI, although several case reports have recently been published that reported on uneventful MRI procedures in pacemaker patients. The present review summarizes the current knowledge on the most frequent pacemaker dysfunctions and electromagnetic interferences that might be relevant in clinical practice.     

Intermittent Pacemaker Syndrome: Revision of VVI Pacemaker to a New Cardiac Pacing Mode for Tachy-Brady Syndrome

A patient with tachy-brady syndrome manifested by paroxysmal atrial fibrillation and symptomatic sinus bradycardia and treated by VVI pacing developed pacemaker syndrome during episodes of ventricular pacing. His cardiac pacemaker was revised to a dual chamber system utilizing the new AV sequential DDI pacing mode which eliminated pacemaker-related tachycardias and totally abolished the pacemaker syndrome symptoms. There have been no further episodes of atrial fibrillation, possibly due to elimination of temporal dispersion of refractory periods during bradycardia. The propensity for atrial fibrillation has also been minimized by excluding competitive atrial stimulation during DVI pacing. The DDI mode provides the clinician increased utility and flexibility in the use of AV sequential pacing therapy.     

Retrograde (Ventriculoatrial) Conduction in Congenital Complete Heart Block

Retrograde ventriculoatrial (VA) conduction is documented at the time of dual chamber pacemaker implantation in a 36-year-old patient with congenital complete atrioventricular (AV) block. Programmed ventricular stimulation with stimuli of increasing prematurity demonstrated a lack of decremental conduction via a unidirectional retrograde pathway. Because retrograde VA conduction has been associated with pacemaker mediated endless loop tachycardia, the status of retrograde conduction should be assessed in all patients undergoing dual chamber pacemaker implantation, including those with congenital complete AV block who have previously been considered to have no conductive tissue between atria and ventricles.     

Delayed Pulse Generator Malfunction after D.C. Countershock

Immediate pacemaker malfunction following defibrillation or cardioversion has been reported. In this paper we report one patient whose pacemaker appeared to be functioning normally after D. C. countershock but malfunctioned 13 days later manifested by changing from an R-wave inhibited to an R-wave synchronous mode.     

Pacemaker Surveillance "a la Franchise": An Attempt to Detect Faulty Series of Permanent Pacemakers at an Early Stage

Until the present, implantable pacemakers have not been subject to government regulation in France, as it had been feared that unreasonable controls would interfere with the development of this new form of therapy. Physicians were left to choose what seemed the most reliable device, and patients benefitted immediately from every manufacturing and technological advance. Despite advantages, the absence of restriction and regulation had a serious drawback--there was no governmental agency to ensure that manufacturers would inform physicians of an unreliable pacemaker, and once a manufacturer recognized a problem, it could inform the physician at the most commercially opportune time rather than the earliest, safest time for the patient. For this reason, several physicians decided to share their experiences with pacemaker function. The number gradually increased until they were able to set up a system of pacemaker suveillance and reporting which has had the capability of detecting defective pacemaker models at an early date. The center of this pacemaker group is at Hopital Fernand-Widal in Paris and is sponsored by the A.R.E.C. (Association de Recherche et d'Entraide Cardiologiques) and by the pacemaker group of the French Society of Cardiology.