Electrophysiology FOLLOW UP AND OPTIMISATION OF CARDIAC PACING. Heart 2005; 91: doi: /hrt

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1 Take the online multiple hoie questions assoiated with this artile (see page 1245) Correspondene to: Dr Paul R Roberts, Southampton University Hospital, Tremona Road, Southampton. SO16 6YD, UK; Paul.Roberts@suht.swest.nhs. uk Eletrophysiology FOLLOW UP AND OPTIMISATION OF CARDIAC PACING PACEMAKER P Paul R Roberts Heart 2005; 91: doi: /hrt aemaker implantation is only the initial phase in the lifelong management of the patient with a paemaker. The hallenge of this treatment lies in the omprehensive follow up of the devie. As the number of implanted devies inreases so does the burden of follow up. This is ompounded by inreasing data provided by devies and inreasing sophistiation in programming therapy and detetion algorithms. There are some general guidelines on paemaker follow up provided by national organisations, but very little provided in the way of detail. 1 2 This is refleted in the immense variation in the manner of paemaker follow up both nationally and internationally. Like most medial interventions paemaker follow up has to be tailored to the individual. The fundamental priniples of paemaker follow up are listed in table 1. CLINIC RESOURCES In order to follow up patients with implanted devies adequately there has to be a basi resoure provision in terms of real estate, equipment, and appropriately trained personnel. A dediated area for paemaker follow up should be provided whih enables the patient to have their appointment performed in privay and safety. Full resusitation failities should be immediately available, though reourse to resusitation failities as a diret onsequene of a paemaker follow up is extremely rare. Relevant paemaker programmers and appropriate tehnial information for all followed paemakers should be available. A omprehensive list of basi required equipment is desribed in table 2. Paemaker follow up is inreasingly performed by non-medial staff suh as ardia physiologists (tehniians) and nursing staff. The faility should exist in these irumstanes for the patients to have aess to medial input in the event of an emergeny or problemati follow up. There should be a basi ompeteny level of those staff performing follow up. This level is often defined at a national level but should ertainly be defined loally. PACEMAKER FOLLOW UP PROCEDURE The frequeny of paemaker follow up varies from entre to entre. Follow up an be divided into three phases: early surveillane, maintenane period, and intensified monitoring period. In most ases a first follow up after disharge from hospital should be within four to six weeks (early surveillane). Thereafter follow up will be generally every six or 12 months (maintenane period). In the paediatri population this should be at least every six months. More intense follow up will be neessary as the devie approahes the end of its battery life (for example, 75% of battery apaity onsumed intensified monitoring period). A history should be taken from all patients to identify whether there are likely to be any paemaker related problems or linial problems that may be aided by alternate devie programming. Speifially, hange in symptoms suh as presynope, synope, dyspnoea, lethargy, palpitations, and hest pain should be defined. A full mediation review should be onsidered as part of the follow up proess. The devie should be interrogated using the appropriate programmer and software. Table 3 defines those parameters that should be evaluated and reorded and onsidered as minimum essential data for follow up. In the first instane analysis of endoardial eletrograms will be performed followed by paing lead integrity. In the majority of ases this will be in the form of a alulated impedane value. Providing this is satisfatory paing and sensing parameters should be reorded. An important aspet of this will be omparison with previous reorded values and analysis of trends in order that potential problems may be predited. Most devies reord further information that an be invaluable in patient are. This may be in the form of rate histograms, reorded eletrograms, ativity levels, mode swithes, et. The next setion will onentrate on the more advaned features of urrent paemaker tehnology that need to be managed and optimised at the time of paemaker follow up. AUTOMATIC CAPTURE MEASUREMENT Many devies have the ability to determine the paing threshold and adjust the output of the devie to just above this threshold. This ompares to setting the output at a fixed level usually 1229

2 1230 Table 1 Fundamental priniples of paemaker follow up Evaluation of orret devie funtion and patient safety (to national standards) Optimisation of system funtion and maximisation of devie longevity Aim to omprehensively troubleshoot paemaker problems/ ompliations Provision of patient/family support and eduation Appropriate storage of data Sheduling of next visit or devie replaement twie the threshold of the last paing hek. The first paemaker to be suessfully introdued with automati apture was in Algorithms to hek threshold usually require the delivery of a paing pulse at derementing outputs and the evaluation of a sensed evoked response following this pulse. If no evoked response is reorded a paing pulse at a fixed high output is delivered to ensure apture. Often this testing is programmed to our at night time so as to avoid symptoms. Key requirements to suh a system are the determination of the evoked response and ability to distinguish from the polarisation signal (that is, paing spike ). Evoked response may take a period of weeks/months to stabilise in terms of onsisteny of amplitude and may vary with hanges in the patients physiology and pharmaotherapy. A requirement of suh a system is a bipolar lead. Generally, the evoked response in the atrium is of inadequate amplitude to make suh a faility reliable for atrial paing. Some devies examine the period following a test pulse looking not for an evoked response but for a sensed intrinsi atrial eletrogram indiating failure to apture and thus intrinsi ativity. Capture management algorithms are urrently well established in ventriular paing and are beginning to evolve in atrial paing. This automati faility has potentially a number of benefits. By reduing the output there will be less drain on the battery and potentially inreased devie longevity. This has been demonstrated to inrease devie longevity by up to 65%. 3 More importantly the devie has the ability to adjust to alterations in threshold and thus has an important safety mehanism. It is possible for the threshold of the lead to inrease for a number of reasons, inluding devie related problems suh as miro displaement, or hanges in physiology suh as eletrolyte abnormalities, or alteration in pharmaology suh as antiarrhythmi drugs. These hanges will be very apparent when the threshold trend data are reviewed. EVENT COUNTERS Counter information provides data regarding the total number or perentage of paed and sensed events in both the atrium and the ventriles sine the ounters were reset. Counters are usually reset at the ompletion of the last paemaker hek. It will also indiate the number of atrial and ventriular extrasystoles, atrial/ventriular tahyardias, and will also indiate the number of times ertain algorithms are ativated for example, mode swith, rate drop response, et. With the knowledge of the patient s underlying ardia status and rhythm this information an be used to program the devie optimally. It is important that the amount of paing that a patient reeives from their devie is arefully evaluated eah time. The general prinipal should be to Table 2 up Basi resoures required for paemaker follow Tehnial information on devies and previous follow up data ECG monitor/12 lead reorder Appropriate paemaker programmer Full resusitation equipment Medial grade paemaker magnets Aess to database for data olletion and retrieval Failities to admit patients in the event of an emergeny enourage as muh intrinsi ativity as is possible and physiologially appropriate. This ensures more physiologial ardia performane, has less drain on the battery life, and may make the individual less paing dependant. This has to be balaned with the patient s degree of eletrial ondution abnormality and potential hronotropi insuffiieny. Enouraging intrinsi ativity is usually possible by altering parameters suh as the atrioventriular (AV) delay or lower rate limit. A number of algorithms have dynami AV delays that aim to maximise intrinsi ondution. ELECTROGRAM STORAGE Most paemakers have the ability to reord eletrograms along with annotated markers when predefined events our. Marker annotation allows an understanding of devie behaviour but an provide inaurate information in a number of different irumstanes suh as over/undersensing, ross talk, interferene and far-field sensing. The real value is in the analysis of the reorded endoardial eletrograms. 4 Experiene of endoardial eletrograms is extensive from implantable ardioverter-defibrillators (ICDs) that doument therapy events. Stored eletrograms have provided the liniian with an invaluable tool in aiding linial follow up of arrhythmias and potential trouble shooting of devie related programming issues or hardware problems suh as lead frature or displaement (fig 1). 5 Most devies now will allow a number or pre-programmed events to be reorded, varying from a few seonds to several minutes. Eah event may also inlude two setions: an onset reording, and post trigger period that is, after detetion riteria made. Reording the onset setion greatly enhanes arrhythmia diagnosis. 6 Ativating the faility to reord eletrograms redues battery longevity by only a small amount for example, two days in a year. The reorded eletrograms allow analysis of potentially non-symptomati events, although the time of reording is made and subsequently an be orrelated with symptom history. Myopotential interferene is now less of a problem as many paemaker systems have bipolar leads. However, some patients have unipolar leads that have been in plae for many years and are funtioning appropriately. Oasionally Table 3 Essential minimum information to be reorded at the time of paemaker follow up Paing lead impedane Sensed P/R wave amplitude Paing threshold Battery voltage and impedane

3 A B C Ventriular paing impedane At implant Last 624 ohms >3000 ohms Highest Lowest >3000 ohms 464 ohms 10/19/04 Last 80 weeks (min/max per week) 12/28/04 03/08/05 03/21/05 Last 14 days > <200 Figure 1 Paemaker ompliations observed at follow up. (A) Mirodisplaement of atrial lead in patient with sik sinus syndrome leading to intermittent failure to aurately atrial sense. This results in atrial paing spikes wandering through the QRS omplex. This patient required lead repositioning. (B) Inorret ventriular sensitivity setting resulting in failure to sense intrinsi ventriular eletrograms. This leads to failure of next impulse to apture (arrow) as falling within refratory period of previous omplex. Adjustment of ventriular sensitivity orreted this problem. (C) Reurrene of patient s symptoms four months after paemaker was implanted. Histogram demonstrates a sudden rise in ventriular lead impedane and a hest x ray onfirmed sublavian lead rush. insulation ompliations an warrant programming of leads from bipolar to unipolar. Inappropriate sensing of myopotential ativity in these irumstanes may lead to inhibition of paing and potentially synope. Having the ability to orrelate ounters with the eletrograms makes the diagnosis of this issue relatively straightforward. Patient triggered diagnostis may be reorded by ativating a devie held by the patient or in the ase of some devies ativation using a Ohms magnet. Stored eletrograms at the time of symptoms will establish whether the ause is an arrhythmia or devie related problem. This allows the devie to be used and the linial data applied in a similar manner to an implanted loop reorder. 7 Additional asymptomati stored eletrograms may inlude prognostially signifiant ventriular arrhythmias or asymptomati atrial arrhythmias that may indiate the need for formal antioagulation. A limitation of stored eletrograms is the ompression of the data in order to reord adequate eletrogram sequenes. This an produe less lear endoardial reordings in some ases. RATE RESPONSE Rate response (adaptive) paing allows an inrease in heart rate with level of physial ativity. 8 A number of ativity sensors have been developed using different algorithms suh as QT interval, minute ventilation, stroke volume, and aelerometers. Some devies have ombined or so alled blended sensors. The rate response is programmable with an upper limit and sensitivity. These parameters have the potential to signifiantly impat on an individual s performane and thus effort should be spent in tailoring the settings of rate response to an individual. Careful analysis of the ounters should enable an assessment of the appropriateness of the urrent rate sensor settings. Fators to be onsidered should inlude the age of the patient, the relative ativity of the individual, additional health issues, and pharmaologial treatment. The inreased use of b blokers in the management of heart disease an also aount for an inadequate inrease in heart rate with ativity and thus should be taken into aount when adjusting the devie settings. An inadequate sensitivity or upper limit may produe symptoms of lethargy, dyspnoea, palpitations, or presynope on exertion. MODE SWITCHING AND ATRIAL ARRHYTHMIA ALGORITHMS/TREATMENTS The ventriular rate of DDD paemakers is dependant on the atrial rate. Therefore, there is the potential for very fast ventriular rates to be traked by the paemaker should the patient develop an atrial tahyardia. This is not an unusual ourrene in paed patients. A signifiant number of patients with sinus node disease have tahyardia bradyardia syndrome and there is also an inreasing inidene of atrial fibrillation with inreasing age. It has been demonstrated that the inidene of atrial fibrillation in paed patients is as high as 13% with an overall risk of 2 3% per year developing atrial fibrillation. 9 The most ommon reason (38%) for reprogramming a paemaker at the time of follow up is for an arrhythmia and the most frequent programming hange is the stimulation mode (81%). 10 Fast traking of atrial tahyarrhythmias is usually prevented by algorithms known as automati mode swithing (AMS) The detetion of the atrial arrhythmia will depend on the algorithm but usually involves the detetion of sudden onset of a fast atrial rate. This will then produe a hange in the programmed mode swithing from DDD to DDI, VDI or VVI mode. The devie will revert bak to dual hamber mode when sinus rhythm is restored. The number of mode swithing events is reorded providing an aurate assessment of the number of episodes of atrial arrhythmias. This provides invaluable information that may allow the liniian to alter the patient s medial management or onsider more interventional approahes suh as atheter ablation. It also provides a 1231

4 1232 Figure 2 This ECG was reorded at a patient s first follow up visit following implantation. While the patient was asymptomati the ECG demonstrates that the first paing pulse (blak arrow) stimulates the ventrile and the seond pulse (grey arrow) falls within the QRS omplex. A plain hest x ray onfirmed that the atrial lead had displaed into the right ventrile. mehanism for assessing the response to suh an intervention. If the patient has retrograde ondution through the atrioventriular node then there exists the potential mehanism for a paemaker mediated tahyardia (PMT) to develop with ventriular traking of the retrograde atrial ondution. Most devies ontain algorithms to prevent this and these should be onsidered if retrograde ventriular atrial ondution has been demonstrated. A number of triggers of atrial arrhythmias and speifially atrial fibrillation have been demonstrated. These inlude atrial premature beats (APB), pauses after APBs, and inreased vagal tone. Many urrently available devies have algorithms that may be ativated in order to redue the number of episodes of atrial arrhythmias by suppressing APB ativity or reduing the short long sequene seen with an APB. Algorithms aim to dynamially overdrive pae the atrium by paing at a rate just above the intrinsi rate or smooth the atrial rate by paing after APBs, thus preventing short long yle lengths. In those patients who have vagally mediated atrial fibrillation the prevention of a sudden redution in atrial rate an be eliminated by atrial paing. Typially this may our after vigorous physial exerise. The early reurrene of atrial fibrillation (ERAF) has also been addressed by some algorithms by high rate atrial paing immediately after the termination of atrial arrhythmia. 13 Some devies have the ability to treat atrial arrhythmias using anti-tahyardia paing in a manner similar to ICD therapy for ventriular tahyardia. BATTERY STATUS Interrogation of the paemaker will give an assessment of the urrent status of the battery. This information, ombined with the patient s history that is, per ent paing enables a predition of the life expetany of the devie to be displayed. Battery measurements are usually assessed several times eah day. Battery status allows for planning of the next paemaker follow up and ultimately pulse generator replaement. In most situations plaing a magnet over the devie will default to a fixed paing mode at a rate determined by the battery status. For example, a fixed rate of 100/min may indiate satisfatory battery measurements with a redution to 85/min for eletive replaement time and, 85/min for end of life. These figures will vary from devie to devie but should be readily available at the time of paemaker follow up. TROUBLESHOOTING At routine follow up it should be possible to identify any problems with the paemaker system performane. System problems may relate to the hardware in terms of the pulse generator and leads or there may be a software issue in terms of devie programming. An important aspet of paemaker follow up is the management and systems employed to reat to devie alerts or realls. Pulse generator failures are extremely unusual but do our. This may present in a number of manners ranging from omplete system failure and inability to ommuniate with the devie to premature battery depletion or malfuntion of one or more omponents of the devie. Lead related problems are more ommonplae and should be identified at a paemaker follow up visit (fig 2). Lead failure may our for many reasons suh as lead frature, displaement, exit blok, drug treatment, et. Lead failure may be seen at paemaker follow up by a hange in sensed eletrogram (size or interferene), paing threshold, or impedane. 14 Most of these data are presented at follow up in trend graphs (fig 1C). If a lead related problem is suspeted then radiologial imaging will be required (fig 3). In the first instane this is

5 likely to be a plain hest radiograph, but more areful assessment may be required with high intensity fluorosopi sreening. 15 If a lead failure is suspeted then failities to admit the patient for further imaging or devie revision should be available. Oasionally patients will report deterioration in their symptoms or onset of new symptoms. It should be possible by appropriate use of the diagnosti information presented by the devie to determine whether this is a paemaker related issue or not. The psyhologial impat of paemaker therapy should not be underestimated. The dependene on devie therapy an have devastating onsequenes in some patients. It is important to be able to offer the appropriate support and ounselling to patients in these irumstanes. Table 4 Potential soures of eletromagneti interferene of paemaker systems Environmental interation Potential interation Advie Figure 3 This patient reported reurrent synope four months after a routine pulse generator hange. A repeat hest film demonstrated a lear frature (arrow) in the paing lead ompared to the film taken before the generator hange (top). This required replaement of the ventriular lead. ENVIRONMENTAL INTERACTIONS The paemaker industry has onentrated signifiant resoures into the prevention of environmental interation with paemaker systems. However, inreasing environmental soures of eletromagneti radiation makes this hallenging. Eletromagneti interferene has the potential to ause a paemaker to respond in a number of ways: inappropriate inhibition or triggering of paemaker output, asynhronous paing, reprogramming to bakup mode, or even irreversible damage to paemaker omponents (table 4). 16 DEVICE ADVISORIES AND RECALLS There is a ertain inevitability that as paemaker tehnology progresses there will be some devie failures. When these are Eletroni antitheft surveillane devies Paemaker inhibition, undersensing or oversensing Patient advised to move through devies quikly Cellular telephones Temporary asynhronous paing or inhibition (only if Use of ontralateral ear to devie or use hands free devie devie plaed diretly over generator) High voltage generators or ar welding Inhibition of paing Work environment assessed to quantify any possible interferene Magneti resonane imaging (MRI) Inhibition or asynhronous paing, irreversible devie Avoid malfuntion, or lead displaement Eletroautery devies and diathermy Inhibition of paing and irreversible devie malfuntion. Inreased paing threshold Use of bipolar diathermy, programming of devie to fixed rate paing before surgery if surgial field in proximity to pulse generator. Full assessment of devie postoperatively Therapeuti irradiation Problems very rare but theoretially ould ause Shielding of devie if lose to irradiation field irreversible malfuntion Diagnosti radiology No interation Defibrillation Potential irreversible devie malfuntion Maintain defibrillation paddles as far from pulse generator as possible. Consider anteroposterior paddle positions 1233

6 1234 Paemaker follow up: key points Should only be performed with appropriate infrastruture and trained staff Main aim should be to ensure appropriate safe devie funtion tailored to the individual and to meet national standards Personnel performing follow up should have a omprehensive knowledge of the advaned features of individual devies Care pathways should be in plae to manage paemaker related problems and devie advisories/realls identified advisories are issued by national regulatory authorities suh as the Food and Drug Administration (FDA) in the USA and the Mediines and Healthare Regulatory Ageny (MHRA) in the UK. In the last deade advisories in the USA affeted paemakers and ICDs. Every entre performing paemaker follow up should have in plae an established poliy on dealing with devie related advisories and a mehanism of disseminating information to the appropriate personnel. Usually reommendations are made by the paemaker manufaturer. This may involve software/programming hanges, inreased follow up or in some ases devie extration/replaement. In most situations these deisions will be made on linial grounds with a shared deision with the patient. The mehanism and pathway to making these deisions need to be defined. It is lear that different entres and physiians manage advisories in different ways. 17 All entres should have in plae loal proedures to failitate the timely reporting of adverse inidents involving paemakers to the appropriate authority. In the UK this is done by means of an online reporting system to the MHRA whih results in a rapid turn around and investigation of potential problems. REMOTE DEVICE FOLLOW UP The faility for transtelephoni monitoring (TTM) of paemakers has been in plae for many years. Its uptake has varied between healthare systems. As the sophistiation of paemaker devies inreases the mode of follow up will inevitably hange. The vast amount of data that an now be retrieved from a paemaker is likely to ontinue to inrease and so the manner of follow up has to adapt. With wireless tehnology and transtelephoni/internet ommuniation the need for a patient to ome to the lini or hospital and have a wand plaed over their devie is likely to beome obsolete. It is likely that patients will have their devies interrogated eah night by a unit in their home that ommuniates the interrogated information transtelephonially to a seure server where the data are available to the patient s physiian. Most paemaker manufaturers now have in plae systems to allow remote paemaker follow up. The real advantage of this system is the ability for more regular but less intrusive follow up and the potential to troubleshoot in a more expeditious manner. Programming of devies in a remote fashion arries a number of regulatory issues and onerns with safety and so it is likely that interrogation may only be possible remotely. THE FUTURE OF PACEMAKER FOLLOW UP There have been dramati hanges in paemaker tehnology over a relatively small timesale. Paemaker follow up has mirrored this in terms of its omplexity and level of expertise required to keep up with these tehnologial advanes. It is likely that the next phase in development of the tehnology might be in advanes in physiologial data obtained from devies. Inreasingly ICD tehnology provides us with biomedial data suh as heart rate variability, transthorai impedane, et. As sensors are developed to assess ardia output and blood pressure it is likely that paemaker follow up will involve more linial interpretation of these types of data rather than the mostly tehnial data that are presented at the moment. In response to this there is a trend to inreasing the automati management of suh tehnial aspets of devie funtion. With remote data management strategies we are likely to see a more holisti and omprehensive approah to patient follow up. Competing interest: Paul Roberts is in reeipt of researh funding, oasional onsultany fees and support for onferene attendane from paemaker manufaturers (Guidant, Medtroni, St Jude, Sorin-ELA). In ompliane with EBAC/EACCME guidelines, all authors partiipating in Eduation in Heart have dislosed potential onflits of interest that might ause a bias in the artile REFERENCES 1 Fraser JD, Gillis AM, Irwin ME, et al. Guidelines for paemaker follow-up in Canada: a onsensus statement of the Canadian working group on ardia paing. Can J Cardiol 2000;16: National Canadian guidelines on paemaker follow up providing omprehensive details on minimum requirements. 2 Hayes DL, Naarelli GV, Furman S, et al. NASPE training requirements for ardia implantable eletroni devies: seletion, implantation and follow-up. Pae Clin Eletrophysiol 2003;26: Erdinler I, Akyol A, Okmen E, et al. Long term follow-up of paemakers with and autoapture paing system. Jpn Heart J 2003;43: Nowak B. 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Permanent paemaker seletion and subsequent survival in elderly Mediare paemaker reipients. Cirulation 1995;91: Martinelli M, de Arruda Melo S, Nishioka SAD, et al. Atrioventriular paemaker. Inidene and auses of reprogramming in long-term follow-up. Arq Bras Cardiol 2001;76: Lau CP, Leung SK, Tse HF, et al. Automati mode swithing of implantable paemakers: I. Priniples of instrumentation, linial and hemodynami onsiderations. Paing Clin Eletrophysiol 2002;25: Lau CP, Leung SK, Tse HF, et al. Automati mode swithing of implantable paemakers: II. Clinial performane of urrent algorithms and their programming. Paing Clin Eletrophysiol 2002;25: These two review artiles examine all aspets of mode swith and urrently available algorithms in eah of the major devie ompanies systems. 13 Mithell ARJ, Sulke N. How do atrial paing algorithms prevent atrial arrhythmias? Europae 2004;6: Review artile examining the different algorithms employed to prevent atrial fibrillation by ounterating proposed trigger mehanisms. 14 Sharif MN, Wyse DG, Rothshild, et al. Changes in paing lead impedane over time predit lead failure. Am J Cardiol 1998;82: Burney K, Burhard F, Papouhado M, et al. Cardia paing systems and implantable ardia defibrillators (ICDs): a radiologial perspetive of equipment, anatomy and ompliations. Clin Radiol 2004;59: Review of all aspets of radiologial paemaker follow up and paemaker related ompliations. 16 Shah PM, Ellenbogen KA. Life after paemaker implantation: management of ommon problems and environmental interations. Cardiol Review 2001;9: Review of all possible paemaker interations, their potential effet, and reommended management strategies. 17 Maisel WH. Physiian management of paemaker and implantable ardioverter defibrillator advisories. Paing Clin Eletrophysiol 2004;27: