Pradnicka 80, Krakow, Poland. Corresponding author. Tel: 44 ; fax: 44 E-mail address : jmajewski interia. Oxford Academic. Jacek Lelakowski. Select Format Select format. Permissions Icon Permissions. Conflict of interest: none declared. Google Scholar Crossref.
Search ADS. Google Scholar PubMed. Published on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals. APS-II features 28 pacing functions and thousands of programming combinations to accommodate diverse lifestyles. Microprocessor unit also records and stores pertinent patient data up to a year. Pacemaker dependency after transcatheter aortic valve implantation with the self-expanding Medtronic CoreValve System.
To determine pacemaker PM dependency at follow-up visit in patients who underwent new permanent pacemaker implantation PPI following transcatheter aortic valve implantation TAVI. Long term follow-up was complete for all patients and ranged from 1 to 40 months median IQR : Overall, 20 out of the 36 patients Partial and even complete resolution of peri-operative AV conduction abnormalities after MCS valve implantation occurred in more than half of the patients.
Neuromodulators, such as Substance P SubP play an important role in modulating many rhythmic activities driven by central pattern generators e. However, the mechanism by which SubP enhances breathing regularity has not been determined.
Moreover, SubP enhancement of network regularity is accomplished via selective enhancement of ICAN- dependent intrinsic bursting properties. Neuromodulators, such as substance P SubP , play an important role in modulating many rhythmic activities driven by central pattern generators e.
Moreover, SubP enhancement of network regularity is accomplished via selective enhancement of ICAN inward non-specific cation current - dependent intrinsic bursting properties. Case study thoracic radiotherapy in an elderly patient with pacemaker : The issue of pacing leads. To assess clinical outcome of patients with pacemaker treated with thoracic radiation therapy for T8-T9 paravertebral chloroma. A year-old male patient with chloroma presenting as paravertebral painful and compressive T8-T9 mass was referred for radiotherapy in the Department of Radiation Oncology, Institut Curie.
The patient presented with cardiac dysfunction and a permanent pacemaker that had been implanted prior. The decision of Multidisciplinary Meeting was to deliver 30 Gy in 10 fractions for reducing the symptoms and controlling the tumor growth. The patient received a total dose of 30 Gy in 10 fractions using 4-field conformal radiotherapy with MV photons. Themore » dose to pacemaker was 0. The patient was treated the first time in the presence of his radiation oncologist and an intensive care unit doctor.
Moreover, the function of his pacemaker was monitored during the entire radiotherapy course. No change in pacemaker function was observed during any of the radiotherapy fractions.
The radiotherapy was very well tolerated without any side effects. The function of the pacemaker was checked before and after the radiotherapy treatment by the cardiologist and no pacemaker dysfunction was observed. Although updated guidelines are needed with acceptable dose criteria for implantable cardiac devices, it is possible to treat patients with these devices and parts encroaching on the radiation field.
This case report shows we were able to safely treat our patient through a multidisciplinary approach, monitoring the patient during each step of the treatment. Background: Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. Methods: This study was conducted on patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar to Mar Conclusion: The variables predicting mortality in all-cause model were completely different from those in cause-specific model.
Measuring pacemaker dose: a clinical perspective. A simple phantom was used to quantify the angular and energy dependence of each dosimeter. If a discrepancy is observed between the measured and expected dose especially when the pacemaker to field edge is Electrical interference in non-competitive pacemakers. Patients with 41 implanted non-competitive pacemakers were investigated.
A variety of domestic electrical equipment, a motor-car, and a physiotherapy diathermy apparatus were each operated in turn at various ranges from the patient. Interference effects on pacemaker function were assessed on the electrocardiograph.
Medtronic demand pacemakers were stopped by diathermy while Cordis Ectocor pacemakers developed a fast discharge rate. Cordis triggered pacemakers both Atricor and Ectocor were sensitive to interference from many items of domestic equipment and the motor car. The Elema EM ran at an increased rate when an electric razor was running close to the pacemaker. The Devices demand and the Medtronic demand were not affected by the domestic equipment tested.
The significance of interference effects is discussed in relation to pacemaker design. Images PMID The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker -mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers , and runaway pacemakers , have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker.
Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker , patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral.
Purpose: To investigate the effect of proton beam therapy PBT on implanted cardiac pacemaker function. Methods and Materials: After a phantom study confirmed the safety of PBT in patients with cardiac pacemakers , we treated 8 patients with implanted pacemakers using PBT to a total tumor dose of gray equivalents GyE in dose fractions of 2.
The combined total number of PBT sessions was Although all pulse generators remained outside the treatment field, 4 patients had pacing leads in the radiation field.
All patients were monitored by means of electrocardiogram during treatment, and pacemakers were routinely examined beforemore » and after PBT. Results: The phantom study showed no effect of neutron scatter on pacemaker generators. In the study, changes in heart rate occurred three times 2. However, these patients remained completely asymptomatic throughout the PBT course.
Conclusions: PBT can result in pacemaker malfunctions that manifest as changes in pulse rate and pulse patterns. Therefore, patients with cardiac pacemakers should be monitored by means of electrocardiogram during PBT.
The new system incorporates the company's PDx diagnostic and programming software and a powerful microprocessor that allows more functions to be fully automatic and gives more detailed information on the patient 's health and the performance of the pacing systems.
The pacemaker incorporates bidirectional telemetry used for space communications for noninvasive communication with the implanted pacemaker , smaller implantable pulse generators from space microminiaturization, and longer-life batteries from technology for spacecraft electrical power systems. The purpose of this study was to assess the burden borne by and the costs to informal caregivers of patients with remotely monitored RM pacemakers.
The PONIENTE study was a controlled, non-randomised clinical trial, with data collected from informal caregivers, 12 months after implantation of pacemakers. The survey on disabilities, personal autonomy, and dependency situations was used to gather information on demographic and social characteristics, levels of professionalism, time and types of care, difficulties in providing care, health status, professional aspects, economic and family or leisure impacts due to informal caregiving for patients with pacemakers.
Of which, 26 were included in the RM group and 50 in the hospital-monitored group HM. The mean ages were The majority The costs related to care provided by the informal caregivers were The PONIENTE study shows a significant impact of informal care on relatives and friends of patients with pacemakers in terms of their well-being and costs. 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. Retrospective analysis of reasons for failure of DDD pacemaker implantation in patients operated on between and The purpose of the study was to analyse retrospectively the reasons for DDD pacemaker failure in patients operated on between and We reviewed retrospectively all implantation data from to to identify patients with primary failure of DDD pacemaker implantation.
We implanted pacemakers , including The mean age of the patients was DDD pacing was unsuccessful in 1. The mean age of these patients was Between and venous anomalies and a high pacing threshold were the main causes of failure. Currently the main difficulties encountered during pacemaker implantation are venous anomalies and a high pacing threshold. We analyzed the incidence of bradycardia and the safety of patients with severely calcified coronary lesions who underwent orbital atherectomy without the insertion of a temporary pacemaker.
The presence of severely calcified coronary lesions can increase the complexity of percutaneous coronary intervention due to the difficulty in advancing and optimally expanding the stent.
High-pressure inflations to predilate calcified lesions may cause angiographic complications like perforation and dissection. Suboptimal stent expansion is associated with stent thrombosis and restenosis. Orbital atherectomy safely and effectively modifies calcified plaque to facilitate optimal stent expansion. The incidence of bradycardia in orbital atherectomy is unknown. Fifty consecutive patients underwent orbital atherectomy from February to September at our institution, none of whom underwent insertion of a temporary pacemaker.
The final analysis included 47 patients in this retrospective study as 3 patients were excluded because of permanent pacemaker implantation.
The primary endpoint was significant bradycardia, defined as bradycardia requiring emergent pacemaker placement or a heart rate patients , all driven by patients who experienced a heart rate decreasing to patient experienced target-vessel revascularization, stroke, or stent thrombosis. Significant bradycardia was uncommon during orbital atherectomy. Performing orbital atherectomy without a temporary pacemaker appears to be safe. This article aims at clarifying the effects of a clinical magnet on pacemakers and Implantable Cardioverter Defibrillators.
The effects of electromagnetic interferences on such devices, including interferences linked to electrosurgery and magnetic resonance imaging are also discussed. In general, a magnet provokes a distinctive effect on a pacemaker by converting it into an asynchronous mode of pacing, and on an Implantable Cardioverter Defibrillator by suspending its own antitachyarythmia therapies without affecting the pacing.
In the operating room, the magnet has to be used cautiously with precisely defined protocols which respect the type of the device used, the type of intervention planned, the presence or absence of EMI and the pacing- dependency of the patient. The Programalith is an advanced cardiac pacing system which permits a physician to reprogram a patient 's implanted pacemaker without surgery. System consists of a pacemaker , together with a physician's console containing the programmer and a data printer.
Signals are transmitted by wireless telemetry. Two-way communications, originating from spacecraft electrical power systems technology, allows physician to interrogate the pacemaker as to the status of the heart, then to fine tune the device to best suit the patient 's needs. Aspergillus fumigatus endocarditis is one of the rarest and severest complications in cardiological patients.
We describe a patient with an intracardial pacemaker who was diagnosed as having Aspergillus fumigatus endocarditis. Postmortem examination showed a large, Aspergillus-infected thrombus encased in the right ventricle, pulmonary trunk and main pulmonary branches. Effects of high-intensity power-frequency electric fields on implanted modern multiprogrammable cardiac pacemakers.
The effect on an implanted, multiprogrammable pacemaker of power-frequency 50 Hz electric fields up to an intensity unperturbed value measured at 1. Radiotelemetric monitoring of the electrocardiogram allowed supervision of the electrocardiogram throughout exposure to the alternating electric field.
None of the pacemakers was inhibited, triggered or reverted to fixed rate operation during the exposure. The programmable functions, programmability or output characteristics were not affected. Small changes in cardiac rate and rhythm elicited the correct pacemaker responses. Electromagnetic interference with pacemakers caused by portable media players. Electromagnetic fields generated by electrical devices may cause interference with permanent pacemakers.
Media players are becoming a common mode of portable entertainment. The most common media players used worldwide are iPods. These devices are often carried in a shirt chest pocket, which may place the devices close to an implanted pacemaker. The purpose of this study was to determine if iPods cause interference with pacemakers. In this prospective, single-blinded study, patients who had cardiac pacemakers were tested with four types of iPods to assess for interference.
Patients were monitored by a single-channel ECG monitor as well as the respective pacemaker programmer via the telemetry wand. To simulate actual use, standard-issue headphones were plugged into the iPods. To maintain consistency, the volume was turned up maximally, and the equalizer was turned off. A subset of 25 patients underwent testing on 2 separate days to assess for reproducibility of interference. Pacemaker interference was categorized as type I or type II telemetry interference. Type II interference did not affect pacemaker rate counters.
Electromagnetic emissions from the four iPods also were evaluated in a Faraday cage to determine the mechanism of the observed interference.
One hundred patients 63 men and 37 women; mean age Reproducibility testing confirmed that interference occurred regardless of pacing configuration unipolar or bipolar , pacing mode AAI, VVI, or DDD , and from one day to the next. Electromagnetic emissions. The number of patients undergoing transcatheter aortic valve replacement TAVR worldwide is increasing steadily. Atrioventricular conduction disturbances, with or without the need for permanent pacemaker PPM implantation, are one of the most common adverse events after TAVR.
Depending on the reported data referred to, historical data showed that up to one-third of the patients required implantation of a PPM following TAVR. Current data support the hypothesis that conduction abnormalities leading to pacemaker dependency result from mechanical compression of the conduction system by the prosthesis stent frame and individual predisposing conduction defects such as right bundle-branch block RBBB. With several large randomised trials and registry studies having been published recently and second generation THV having been introduced, the debate about predictors for pacemaker implantation and their impact on outcome after TAVR is still ongoing.
Pacemaker failure associated with therapeutic radiation. A year-old white man with a multiprogrammable Intramedics pacemaker was treated for inoperable lung cancer with a course of cobalt radiotherapy total rad. Several weeks subsequent to his last radiation treatment, the patient presented to the emergency department with chest and abdominal pain, shortness of breath, hypotension, and tachycardia. A paced tachycardia was noted, and application of a magnet over the pacemaker completely inhibited its function, allowing a normal sinus rhythm to ensue and the patient 's symptoms to be relieved.
Pacemaker failure probably was a complication of radiotherapy. Frequency of pacemaker malfunction associated with monopolar electrosurgery during pulse generator replacement or upgrade surgery. The aim of this study is to investigate the frequency of electrosurgery-related pacemaker malfunction.
A retrospective study was conducted to investigate electrosurgery-related pacemaker malfunction in consecutive patients undergoing pulse generator PG replacement or upgrade from two large hospitals in Minneapolis, MN between January and January The occurrence of this pacemaker malfunction was then studied by using MAUDE database for all four major device vendors. A total of consecutive patients from 2 large tertiary referral centers in Minneapolis, MN undergoing PG replacement or upgrade surgery were retrospectively studied.
Four patients 0. During the same period, cases of pacemaker malfunctions were reported on the same models in MAUDE database, 37 of which 3. The distribution of adverse events was loss of pacing The majority of these No electrosurgery-related malfunction was found in MAUDE database on pacemaker malfunction cases during the same period from other vendors.
Electrosurgery during PG replacement or upgrade surgery can trigger output failure or inappropriate low pacing rate in certain models of modern pacemakers. Cautions should be taken for pacemaker-dependent patients. Black US residents experience higher rates of ischemic stroke than white residents but have lower rates of clinically apparent atrial fibrillation AF , a strong risk factor for stroke. It is unclear whether black persons truly have less AF or simply more undiagnosed AF.
We obtained administrative claims data from state health agencies regarding all emergency department visits and hospitalizations in California, Florida, and New York. We identified a cohort of patients with pacemakers , the regular interrogation of which reduces the likelihood of undiagnosed AF. We compared rates of documented AF or atrial flutter at follow-up visits using Kaplan-Meier survival statistics and Cox proportional hazards models adjusted for demographic characteristics and vascular risk factors.
We identified 10 black and 91 white patients without documented AF or atrial flutter before or at the index visit for pacemaker implantation. During 3. After adjustment for demographic characteristics and comorbidities, black patients had a lower hazard of AF hazard ratio 0. In a population-based sample of patients with pacemakers , black patients had a lower rate of AF compared with white patients. These findings indicate that the persistent racial disparities in rates of ischemic stroke are likely to be related to factors other than undiagnosed AF.
Published on behalf of the American Heart Association, Inc. MRI-conditional pacemakers : current perspectives. Use of both magnetic resonance imaging MRI and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radio frequency energy used in MRI.
Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety.
The resulting MRI-conditional pacemakers were first introduced in and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness.
In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models.
Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field. Aggregatibacter aphrophilus pacemaker endocarditis: a case report.
Aggregatibacter bacteria are a rare cause of endocarditis in adults. Among these organisms, several Haemophilus species have been reclassified under the genus Aggregatibacter.
Very few cases of Aggregatibacter endocarditis in patients with pacemaker devices have been reported. We present here what we believe to be the first case of Aggregatibacter aphrophilus pacemaker endocarditis. A year-old African American male with a medical history significant for dual-chamber pacemaker placement in for complete heart block with subsequent lead manipulation in , presented to his primary care doctor with fever, chills, night sweats, fatigue, and ten-pound weight loss over a four-month period.
Physical examination revealed a new murmur and jugular venous distension which prompted initiation of antibiotics for suspicion of endocarditis. Both sets of initial blood cultures were positive for A. Transesophageal echocardiogram revealed vegetations on the tricuspid valve and the right ventricular pacemaker lead Figure 1. This case highlights the importance of identifying rare causes of endocarditis and recognizing that treatment may not differ from the standard treatment for typical presentations.
The patient received intravenous ceftriaxone for his endocarditis for a total of six weeks. Upon device removal, temporary jugular venous pacing wires were placed.
After two weeks of antibiotic treatment and no clinical deterioration, a new permanent pacemaker was placed and the patient was discharged home. This is the first case of A. Our patient had no obvious risk factors other than poor dentition and a history of repeated pacemaker lead manipulation. This suggests that valvulopathies secondary to repeated lead manipulation can be clinically significant factors in morbidity. High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia, and a domestically developed pacemaker will help lower the burden.
This study aimed to evaluate the safety and efficacy of Qinming DR Qinming Medical, Baoji, China , the first domestically developed dual-chamber pacemaker of China, compared with a commercially available pacemaker Talos DR Biotronik, Berlin, Germany in Chinese patients.
A prospective randomized trial was conducted at 14 centers in China. Parameters of the pacing systems were collected immediately after device implantation and during follow-ups. The effective pacing rate at 6-month follow-up was recorded as the primary end point. Electrical properties, magnet response, single- and double-pole polarity conversion, rate response function, and adverse events of the pacing system were analyzed.
The Cochran-Mantel-Haenszel Chi-square test, paired t-test, and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data. They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity. Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set In both data sets, noninferiority of the trial group was above the predefined noninferiority limit The safety and efficacy of Qinming DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.
Influence of digital and analogue cellular telephones on implanted pacemakers. The aim of this study was to find out whether digital and analogue cellular 'phones affect patients with pacemakers.
The study comprised continuous ECG monitoring of pacemaker patients. During the monitoring certain conditions caused by interference created by the telephone were looked for: temporary or prolonged pacemaker inhibition; a shift to asynchronous mode caused by electromagnetic interference; an increase in ventricular pacing in dual chamber pacemakers , up to the programmed upper rate.
The Global System for Mobile Communications system interfered with pacing 97 times in 43 patients During tests on Total Access of Communication System telephones, there were 60 cases of pacing interference in 35 patients Cellular 'phones may be dangerous for pacemaker patients. It possesses pacing and sensing capabilities in both the atrium and the ventricle, and it is the most commonly used pacing mode.
This mode is most appropriate for patients with combined sinus node dysfunction and AV nodal dysfunction. It is also appropriate for patients with sinus node dysfunction and normal AV node conduction, normal sinus node function with AV nodal conduction abnormalities, and carotid hypersensitivity with symptomatic cardio-inhibitory response.
The use of DDD R pacing mode in conjunction with an algorithm that minimizes ventricular pacing is preferred. Asynchronous modes, VOO or DOO: These are asynchronous pacing modes in which the pulse generator delivers a pacing stimulus at a fixed rate, without any sensing capabilities. These modes are rarely used for extended periods of time. They are typically used when a pacemaker dependent patient is undergoing a surgical procedure that uses electrocautery that could be sensed by the pacemaker as native electrical conduction, which would inhibit pacemaker output and subsequently the patient could have profound bradycardia or even asystole.
There is a small possibility that pacing in an asynchronous mode could induce a pacing stimulus in the vulnerable period on the T wave , which could potentially induce a lethal ventricular tachyarrhythmia. While there are no absolute contraindications to pacemaker implantation, there are several factors that must be considered prior to implantation and which may alter the timing or approach to implant.
These include vascular access difficulties, concurrent infection, bleeding diatheses, or need for future MRI. If access cannot be obtained percutaneously due to vascular thrombosis or occlusion, a surgical epicardial approach may be considered or rarely venous angioplasty.
Pacemaker implantation is generally not performed when the patient has a concurrent infection, and is typically deferred until the active infection is appropriately treated. In some instances, active bleeding diatheses will preclude implantation until the bleeding is controlled. Pacemakers, however, are often implanted in patients with therapeutic international normalized ratio INR and who are concurrently taking one or more antiplatelet medications.
Thoughtful consideration should also be given to the patient who will require multiple MRIs in the future. MRIs are considered contraindicated in patients with implanted pacemakers, although there is reported experience that in selected cases off-label MRIs can be performed with reasonable safety.
The FDA has recently approved a pacemaker generator and lead model with which the safety of some types of MRI studies have been formally documented, and on-label MRIs can be performed in patients whose pacing system is comprised of these components. Procedures to implant transvenous pacemakers are considered low-risk. In adults, implantation is nearly always performed with intravenous conscious sedation and local anesthesia in an electrophysiology EP laboratory or an operating room.
General anesthesia is often used in children and others thought to be poor candidates for conscious sedation. In the vast majority of instances, a pacemaker can be implanted in the upper pectoral region via a transvenous approach.
Subcutaneous lidocaine is administered and a 4 to 5 cm infraclavicular incision is created. Electrocautery dissection is carried down to the level of the prepectoral fascia and a pocket large enough to accommodate the pacemaker is also created. Venous access is obtained either with subclavian vein puncture, axillary vein puncture, or cephalic vein cutdown.
Guided by fluoroscopy, leads are then advanced to the appropriate chambers and secured to the endocardium. Pacing impedance, sensing, and capture thresholds are measured; if not acceptable then repositioning of the lead is required. Once a lead is placed, it is sutured to the prepectoral fascia near the venous entry site using a suture sleeve for stability.
Typically, the pocket is then irrigated using an antibiotic solution. The pocket is finally closed using two or three layers of suture. The incision is then covered with an occlusive dressing.
Device parameters are programmed at the end of the procedure prior to the patient departing from the lab. Following the procedure, a chest x-ray should be obtained to assess for lead position and any perioperative complications such as pneumothorax. The patient is typically observed in-hospital overnight. Device function is rechecked the morning after the procedure to ensure appropriate sensing, capture thresholds, and lead impedances. In the vast majority of patients, pacemakers are implanted because of symptomatic bradycardia.
Implantation of a pacemaker is very effective in alleviating the symptoms of bradycardia. Elective generator change. Although elective generator change of EPDs is considered a routine procedure for experienced implanters, the presence of pacemaker dependency makes the process more challenging and demanding.
There are no reported recommendations about the mode of generator change in these patients. Some physicians prefer to do the replacement of the generator quickly without having a temporary pacemaker as a back-up. In this instance, programming of bipolar sensing in both the old and the new device is recommended. The major advantage of this option is that there is reduced risk of infection, given that generator change operations carry almost a double risk for infection compared with initial implantations, whereas the use of a temporary wire increases the infection risk significantly.
Selection of pacing mode. The mode of pacing may have particular impact in pacemaker-dependent patients. The CTOPP trial showed that the yearly event rate of cardiovascular death or stroke steadily increased with decreasing unpaced heart rate assessed at the first follow-up visit in the ventricular pacing group, but it remained constant in the physiological pacing group.
It was therefore concluded that pacemaker-dependent patients with low unpaced heart rate probably are paced frequently and will likely benefit from physiological pacing.
The incidence of pacemaker dependency is variable and depends on the definition and testing technique. As mentioned before, there are differences in the protocols in terms of the lower basic pacing rate during the test, the gradual or not reduction of the rate of ventricular pacing, the duration of the test, and the evaluation of symptoms apart from the presence or absence of an escape rhythm. Of note, current protocols do not usually apply a complete cessation of back-up pacing for some time period.
The latter process was very common in the past when external programmability by telemetry was unavailable. Moreover, the particular practice of each country regarding EPD implantation indications significantly affects the incidence of pacemaker dependency.
For example, in poor countries with very poor resources and no cover of the costs by a national insurance, the pacemaker dependency incidence would be very high since only very symptomatic patients with advanced bradyarrhythmic disorders would have been implanted a PPM. The incidence of long-term pacemaker dependency depends mainly on the underlying bradyarrhythmic abnormality. It is well known that patients with high-grade AV block become pacemaker-dependent more frequently than those with SND.
Nagatomo et al. After a mean follow-up of 3. Several factors have been associated with the development of pacemaker dependency after permanent pacing for standard bradycardic indications. The data regarding the underlying mechanisms of pacemaker dependency and how this phenomenon can be modulated are scarce.
An episode of prolonged ventricular asystole cardiac standstill in the setting of pacemaker dependency may have catastrophic consequences due to haemodynamic collapse, especially in patients who have significant underlying heart disease. On the other hand, in some patients with structural heart disease, the depressed idioventricular automaticity and the consequent exaggeration of overdrive suppression lead to a prolonged ventricular arrest.
The mechanisms that contribute to depressed intrinsic pacemaker activity of subsidiary infranodal centres include insufficient blood supply, electrolyte disturbances, anoxia, administration of antiarrhythmic or anaesthetic drugs, alterations of sympathetic activity, ageing-related abnormalities, and others.
It has been consistently demonstrated in patients with PPMs that the magnitude of subsidiary infranodal pacemaker activity is affected by the rate and duration of overdrive pacing. Specifically, it was shown that up to 60 s of overdrive incremental stimulation exerts an additional influence on impulse depression, whereas beyond this critical duration, the intrinsic impulse suppression is dependent only on the rate of incremental pacing.
Despite the aforementioned data, several issues remain obscure and remain to be elucidated. The exact mechanisms implicated in the long-term pacemaker dependency are not known. Although previous studies indicate a role of short-term overdrive suppression, the relative effect of long-term continuous pacing or frequent brief episodes of pacing have not been examined.
Specifically, data on the critical burden of ventricular pacing and the particular values of variables that may affect dependency number and duration of ventricular pacing periods, mean rate of pacing, mode of pacing, rate-responsive pacing, and other parameters in each individual are lacking. Furthermore, the exact effect of underlying medical conditions, drugs, and other potentially modifiable risk factors on pacemaker dependency is unknown.
Also, there are no reported specific data for pacemaker dependency in ICD patients who do not have standard indications for pacing. Pacemaker dependency is observed in an appreciable number of paced patients after implantation of EPDs and may have dangerous consequences. Although there is no standard definition or consensus regarding the mode of testing, it is generally accepted that pacemaker dependency has a significant impact on the management of patients in various clinical settings.
Several prognostic factors have been reported in the literature but the most important is the presence of AV block before the implantation. Further studies are needed to elucidate the underlying mechanisms implicated in this phenomenon. The putative merit of interventions in particular pacing parameters, or risk factors, as well as the modulation of specific molecular or electrophysiological targets, constitutes a subject of future research.
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