Practice Advisory for the Perioperative Management of Patients with Cardiac Rhythm Management Devices: Pacemakers and Implantable Cardioverter–Defibrillators

Abstract

Developed by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Cardiac Rhythm Management Devices: James R. Zaidan, M.D., M.B.A. (Chair), Atlanta, Georgia; John L. Atlee, M.D., Milwaukee, Wisconsin; Peter Belott, M.D., El Cajon, California; Kurt S. Briesacher, M.D., Atlanta, Georgia; Richard T. Connis, Ph.D., Woodinville, Washington; John D. Gallagher, M.D., Lebanon, New Hampshire; David Hayes, M.D., Rochester, Minnesota; Jane E. Hershey, M.D., Highland, Maryland; Neal Kay, M.D., Birmingham, Alabama; David G. Nickinovich, Ph.D., Bellevue, Washington; Marc A. Rozner, Ph.D., M.D., Houston, Texas; Mark F. Trankina, M.D., Birmingham, Alabama.Click on the links below to access all the ArticlePlus for this article.Please note that ArticlePlus files may launch a viewer application outside of your web browser.PRACTICE advisories are systematically developed reports that are intended to assist decision making in areas of patient care. Advisories provide a synthesis and analysis of expert opinion, clinical feasibility data, open forum commentary, and consensus surveys. Advisories are not intended as standards, guidelines, or absolute requirements. They may be adopted, modified, or rejected according to clinical needs and constraints.The use of practice advisories cannot guarantee any specific outcome. Practice advisories summarize the state of the literature and report opinions derived from a synthesis of task force members, expert consultants, open forums, and public commentary. Practice advisories are not supported by scientific literature to the same degree as standards or guidelines because of the lack of sufficient numbers of adequately controlled studies. Practice advisories are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice.For this Advisory, a cardiac rhythm management device (CRMD) refers to any permanently implanted cardiac pacemaker or any implantable cardioverter–defibrillator (ICD). The term CRMD also refers to any cardiac resynchronization device. The term CRT refers to a CRMD that provides cardiac resynchronization therapy using biventricular pacing techniques. Generic pacemaker and defibrillator codes are provided in appendix 1. Note that every ICD includes both pacing and shock therapies for the management of bradyarrhythmias and tachyarrhythmias.The purposes of this Advisory are to (1) facilitate safe and effective perioperative management of the patient with a CRMD and (2) reduce the incidence of adverse outcomes. Perioperative management refers to the preoperative, intraoperative, postoperative or recovery period in any setting where an anesthesia provider delivers anesthesia care. Adverse outcomes associated with a CRMD include (but are not limited to) damage to the device, inability of the device to deliver pacing or shocks, lead–tissue interface damage, changes in pacing behavior, electrical reset to the backup pacing mode, or inappropriate ICD therapies.*Adverse clinical outcomes include (but are not limited to) hypotension, tachyarrhythmia or bradyarrhythmia, myocardial tissue damage, and myocardial ischemia or infarction. Other related outcomes may include extended hospital stay, delay or cancellation of surgery, readmission to manage device malfunction, or additional hospital resource utilization and cost.This Advisory focuses on the perioperative management of patients who have a preexisting, permanently implanted CRMD for treatment of bradyarrhythmia, tachyarrhythmia, or heart failure. Both inpatient and outpatient procedures are addressed by this Advisory. This Advisory does not address the perioperative management of any patient undergoing CRMD implantation or revision. It is not applicable to any patient (1) without a permanently implanted pacemaker or ICD, (2) with a temporary CRMD, (3) with a noncardiac implantable device (e.g. , neurologic or spinal cord stimulator), or (4) with an implantable mechanical cardiac assist device (e.g. , ventricular assist device). This Advisory does not address any procedure where there are no known perioperative CRMD concerns, such as diagnostic radiation (e.g. , x-ray studies, fluoroscopy, or mammograms), computed tomography scans, or ultrasound.This Advisory is intended for use by anesthesiologists and all other individuals who deliver or who are responsible for anesthesia care. The Advisory may also serve as a resource for other physicians and healthcare professionals who treat patients with CRMDs.The American Society of Anesthesiologists (ASA) appointed a Task Force of 12 members to (1) review and assess currently available scientific literature, (2) obtain expert consensus and public opinion, and (3) develop a practice advisory. The Task Force members consisted of anesthesiologists and cardiologists in private and academic practices from various geographic areas of the United States and two methodologists from the ASA Committee on Practice Parameters.The Task Force used a six-step process. First, they reached consensus on the criteria for evidence of effective perioperative management of cardiac rhythm management devices. Second, original published articles from peer-reviewed journals relevant to these issues were evaluated. Third, consultants who had expertise or interest in CRMDs and who practiced or worked in various settings (e.g. , academic and private practice) were asked to (1) participate in opinion surveys on the effectiveness of various perioperative management strategies and (2) review and comment on a draft of the Advisory developed by the Task Force. Fourth, additional opinions were solicited from random samples of active members of both the ASA and the Heart Rhythm Society (HRS).†Fifth, the Task Force held an open forum at a national anesthesia meeting and at a major cardiology meeting to solicit input on the key concepts of this Advisory. Sixth, all available information was used to build consensus within the Task Force on the Advisory.The draft document was made available for review on the ASA Web site, and input was invited via e-mail announcement to all ASA members. All submitted comments were considered by the Task Force in preparing the final draft.Practice advisories are developed by a protocol similar to that of an ASA evidence-based practice guideline, including a systematic search and evaluation of the literature. However, practice advisories lack the support of a sufficient number of adequately controlled studies to permit aggregate analyses of data with rigorous statistical techniques such as meta-analysis. Nonetheless, literature-based evidence from case reports and other descriptive studies is reported. This literature often permits the identification of recurring patterns of clinical practice.As with a practice guideline, formal survey information was collected from Consultants and members of the ASA. For this Advisory, surveys were also sent to members of the HRS. Additional information was obtained from open forum presentations and other invited and public sources. The advisory statements contained in this document represent a consensus of the current spectrum of clinical opinion and literature-based findings.‡Perioperative treatment of CRMD patients is a common occurrence. It has been reported that more than 500,000 individuals in the United States have permanently implanted pacemakers or ICDs with 115,000 new devices implanted each year.1Perioperative management of CRMD patients typically begins with a focused preoperative evaluation consisting of (1) establishing whether a patient has a CRMD, (2) defining the type of device, (3) determining whether a patient is CRMD dependent for antibradycardia pacing function, and (4) determining device function.Although no controlled trials of the clinical impact of performing a focused preoperative evaluation for CRMD patients were found, case reports suggest that incomplete preoperative examination of patients with CRMDs may lead to adverse outcomes (e.g. , inhibited CRMD function, asystole).2–4The majority of Consultants and random samples from the ASA and HRS memberships agree that the above four preoperative evaluation activities should be conducted.§The consensus of the Task Force is that a focused preoperative evaluation should include establishing whether a patient has a CRMD, defining the type of device, determining whether a patient is CRMD dependent for pacemaking function, and determining CRMD function.Determining whether a patient has a CRMD should be based on (1) a focused history including but not limited to the patient interview, medical records review, review of available chest x-ray films, electrocardiogram, or any available monitor or rhythm strip information and (2) a focused physical examination (checking for scars, palpating for device).Defining the type of device is accomplished by (1) obtaining the manufacturer’s identification card from the patient or other source, (2) ordering chest x-ray studies if no other data are available,∥or (3) referring to supplemental resources (e.g. , manufacturer’s databases, pacemaker clinic records, consultation with a cardiologist).Cardiac rhythm management device dependency for pacemaking function may be determined by one or more of the following: (1) a verbal history or an indication in the medical record that the patient has experienced a bradyarrhythmia that has caused syncope or other symptoms requiring CRMD implantation, (2) a history of successful atrioventricular nodal ablation that resulted in CRMD placement, or (3) a CRMD evaluation that shows no evidence of spontaneous ventricular activity when the pacemaking function of the CRMD is programmed to VVI pacing mode at the lowest programmable rate.Cardiac rhythm management device function is ideally assessed by a comprehensive evaluation of the device.5If a comprehensive evaluation is not possible, then, at a minimum , confirm whether pacing impulses are present and create a paced beat. Consultation with a cardiologist or CRMD service may be necessary. Contacting the manufacturer for perioperative recommendations may be a consideration.Preparation for patient safety and proper maintenance of the device during a procedure includes (1) determining whether electromagnetic interference (EMI) is likely to occur during the planned procedure; (2) determining whether reprogramming the CRMD pacemaking function to an asynchronous pacing mode or disabling any special algorithms, including rate adaptive functions, is needed; (3) suspending antitachyarrhythmia functions if present; (4) advising the individual performing the procedure to consider use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel to minimize potential adverse effects of EMI on the pulse generator or leads; (5) assuring the availability of temporary pacing and defibrillation equipment; and (6) evaluating the possible effects of anes-thetic techniques on CRMD function and patient–CRMD interactions.Numerous descriptive studies and case reports suggest that the following procedures are likely to be associated with EMI: (1) electrocautery,6–11(2) radio frequency ablation,12–20(3) magnetic resonance imaging (MRI),21–31and (4) radiation therapy.32–34No studies were found that reported EMI during electroconvulsive therapy (ECT). Some descriptive studies report the occurrence of EMI during lithotripsy,35,36whereas other descriptive studies and case reports indicate no apparent EMI effects.37–39No controlled trials of the clinical impact of programming the pacemaking function to an asynchronous mode for a procedure were found. Although some case reports suggest that such reprogramming is beneficial during electrocautery,40–42other reports indicate that EMI may continue to affect reprogrammed pacemakers.43,44The literature lacks sufficient guidance regarding the potential perioperative impact of anesthetic techniques on CRMD function. The majority of Consultants as well as the samples of ASA and HRS members agree that it should be determined whether EMI is likely to occur before a planned procedure. The majority of Consultants agree that a CRMD’s rate-adaptive therapy should be turned off before a procedure, whereas the ASA and HRS members are equivocal. The majority of Consultants and HRS members disagree that all patients’ CRMDs should be programmed to an asynchronous mode before surgery, whereas the ASA members are equivocal. In addition, the majority of Consultants and HRS members agree that pacemaker-dependent patients’ CRMDs should be programmed to an asynchronous mode before surgery, whereas the ASA members are again equivocal. The majority of Consultants and ASA and HRS members agree that (1) suspending antitachyarrhythmia functions if present, (2) advising the individual performing the procedure to consider use of a bipolar electrocautery system to minimize potential adverse effects of EMI on the pulse generator or leads, (3) assuring the availability of temporary pacing and defibrillation equipment, and (4) evaluating the possible effects of anesthetic techniques on CRMD function and patient–CRMD interactions are important steps in promoting patient safety and successfully treating patients with CRMDs. The Consultants and ASA members agree and the HRS members are equivocal regarding the consideration of using an ultrasonic scalpel.The Task Force agrees that planned procedures should include a determination as to whether EMI is likely to occur for either conventional pacemakers or ICDs.If EMI is likely to occur, the conventional pacing function of a CRMD should be altered by changing to an asynchronous pacing mode#in pacemaker-dependent patients and suspending special algorithms, including rate-adaptive functions. These alterations may be accomplished by programming or applying a magnet when applicable.**However, the Task Force cautions against the use of the magnet over an ICD.††In addition, an ICD’s antitachyarrhythmia functions should be suspended, if present. For ICD patients who depend on pacing function for control of bradyarrhythmia, these functions should be altered by programming as noted above. Consultation with a cardiologist or pacemaker–ICD service may be necessary.For all CRMDs, consider advising the individual performing the procedure to use a bipolar electrocautery system or an ultrasonic scalpel when applicable. Temporary pacing and defibrillation equipment should be immediately available before, during, and after a procedure.Finally, the Task Force believes that anesthetic techniques do not influence CRMD function. However, anesthetic-induced physiologic changes (i.e. , cardiac rate, rhythm, or ischemia) in the patient may induce unexpected CRMD responses or adversely affect the CRMD–patient interaction.The primary activities associated with intraoperative management of a CRMD include (1) monitoring the operation of the device; (2) preventing potential CRMD dysfunction; and (3) performing emergency defibrillation, cardioversion, or heart rate support.Intraoperative monitoring includes continuous electrocardiography as well as monitoring of the peripheral pulse (e.g. , palpation of the pulse, auscultation of heart sounds, monitoring of a tracing of intraarterial pressure, ultrasound peripheral pulse monitoring, or pulse plethysmography or oximetry).45Although no controlled trials were found that examine the clinical impact of electrocardiography or peripheral pulse monitoring for CRMD patients, case reports note the importance of intraoperative electrocardiographic monitoring in the detection of pacemaker or cardiac dysfunction for these patients.4,46–50The majority of Consultants and ASA and HRS members agree that (1) continuous electrocardiographic monitoring should be done for all CRMD patients and (2) continuous peripheral pulse monitoring should be conducted.Electrocardiography and peripheral pulse monitoring are important components of perioperative treatment of patients with CRMDs. The Task Force agrees that a patient’s electrocardiogram should be continuously displayed, as required by ASA standards, from the beginning of anesthesia until the patient is transferred out of the anesthetizing location, with additional electrocardiographic monitoring in the postoperative period as indicated by the patient’s medical condition.45,51The Task Force believes that these standards should apply to all CRMD patients receiving general or regional anesthesia, sedation, or monitored anesthesia care. Continuous peripheral pulse monitoring should be performed for all CRMD patients receiving general or regional anesthesia, sedation, or monitored anesthesia care. If unanticipated device interactions are found, consider discontinuation of the procedure until the source of interference can be eliminated or managed.Procedures using electrocautery, radiofrequency ablation, lithotripsy, MRI, or radiation therapy may damage CRMDs or interfere with CRMD function, potentially resulting in severe adverse outcomes. Sources of EMI are often unique to specific procedures, and the management of each of these potential EMI sources is reported separately below.Management of potential sources of EMI associated with electrocautery includes (1) assuring that the cautery tool and current return pad‡‡are positioned so that the current pathway does not pass through or near the CRMD pulse generator and leads; (2) avoiding proximity of the cautery’s electrical field to the pulse generator or leads; (3) using short, intermittent, and irregular bursts at the lowest feasible energy levels; and (4) using a bipolar electrocautery system or an ultrasonic (harmonic) scalpel, if possible.Two case reports52,53and one observational study54suggest that EMI may occur despite positioning the current return pad as far as possible away from the generator and leads. However, the majority of Consultants and ASA and HRS members agree that the current return pad should be positioned so that the electrosurgical current pathway does not pass through or near the CRMD pulse generator or leads.One case report suggested that application of unipolar electrocautery on the sternum resulted in complete pacemaker inhibition.55Although some manufacturers suggest substituting bipolar for monopolar electrocautery to minimize CRMD interactions, no clinical literature was found to support this recommendation. The majority of Consultants and ASA and HRS members agree that direct contact between the electrocautery system and the CRMD pulse generator or its leads should be avoided.Although no recent studies were found examining the benefit of using short, intermittent bursts at the lowest feasible energy levels, earlier literature§§suggests that short, intermittent bursts may be useful in completing procedures without notable EMI interference.56–60The majority of Consultants and ASA and HRS members agree that short, intermittent bursts should be performed.Finally, case reports suggest that surgery for pacemaker patients may proceed uneventfully when bipolar electrocautery systems42,43,46or harmonic scalpels61,62are used. The majority of Consultants and ASA and HRS members agree that bipolar electrocautery systems should be used when possible. The majority of Consultants and ASA members agree that harmonic scalpels should be used when possible, and HRS members are equivocal.Management of potential sources of EMI associated with radiofrequency ablation primarily involves keeping the radiofrequency current path (electrode tip to current return pad) as far away from the pulse generator and lead system as possible. One observational study reports 3 of 12 cases that resulted in a significant decrease in resistance on the pacemaker leads when radiofrequency ablation was used in proximity to the leads.63One case report suggests that positioning of the radiofrequency ablation cluster electrode no closer than 5 cm from the pacer leads allowed the procedure to continue uneventfully.40The majority of Consultants and ASA and HRS members agree that the individual performing the procedure should avoid direct contact between the ablation catheter and the CRMD and leads and should keep the radiofrequency ablation current path as far away from the pulse generator and lead system as possible.Management of potential sources of EMI associated with lithotripsy includes (1) avoiding focus of the lithotripsy beam near the pulse generator and (2) disabling atrial pacing if the lithotripsy system triggers on the R wave. The literature is silent regarding the benefits of focusing the lithotripsy beam away from the pulse generator as well as the benefits of disabling atrial pacing during lithotripsy. The majority of Consultants and ASA and HRS members agree that focusing the lithotripsy beam near the pulse generator should be avoided, and all three groups are equivocal regarding whether atrial pacing should be disabled before a procedure if the lithotripsy system triggers on the R wave.The literature is not sufficiently rigorous to examine the effects of specific management activities related to CRMD patients receiving MRI. Some descriptive studies and case reports suggest that MRI may be completed without notable EMI under specific circumstances and with appropriate patient qualification and monitoring.30,31,64–71However, other literature generally suggests that MRI is contraindicated.21–29The majority of Consultants and ASA and HRS members generally agree that MRI is contraindicated for all CRMD patients.The literature does not provide sufficient guidance regarding specific management activities related to CRMD patients undergoing radiation therapy. However, none of the Consultants or HRS members and only 10% of the ASA members agree that radiation therapy is contraindicated for all CRMD patients. Fifty-seven percent of the Consultants, 59% of the HRS members, and 37% of the ASA members agree that radiation therapy is contraindicated for some but not all CRMD patients, whereas 43% of the Consultants, 41% of the HRS members, and 53% of the ASA members agree that radiation therapy is not contraindicated for any CRMD patient.No clinical studies were found that report EMI effects or permanent CRMD malfunction associated with ECT. One study reports two cases where patients’ ICDs were turned off before ECT but does not report the effect of the therapy on ICD function.72However, the author indicates that treatment with ECT might be associated with significant cardiac risks. Transient electrocardiographic changes (e.g. , increased P-wave amplitude, altered QRS shape, T-wave and ST-T abnormalities) may result from ECT, and additional cardiac complications (e.g. , arrhythmia or ischemia) may occur in patients with preexisting cardiac disease. Finally, physiologic stresses after ECT, such as a period of bradycardia and reduced blood pressure, followed by tachycardia and an increase in blood pressure, may account for cardiac failure in the extended postoperative period (i.e. , several hours or days after ECT) among patients with marginal cardiac function.The Task Force believes that EMI could be minimized during certain procedures using a variety of intraoperative management techniques.The Task Force agrees that the risk of intraoperative interference from electrocautery systems may be minimized by (1) positioning the cautery tool and current return pad so that the current pathway does not pass through or near the CRMD system∥∥; (2) avoiding proximity of the cautery’s electrical field to the pulse generator and leads, including avoidance of waving the activated electrode over the generator##; (3) using short, intermittent, and irregular bursts at the lowest feasible energy levels; and (4) using bipolar electrocautery systems or ultrasonic (harmonic) scalpels if possible. Advising or reminding the individual performing the procedure to implement these management techniques should be considered.Risk of interference from radiofrequency ablation may be reduced by avoiding direct contact between the ablation catheter and the pulse generator and leads and by keeping the radiofrequency’s current path (electrode tip to current return pad) as far away from the pulse generator and leads as possible. During all radiofrequency ablative procedures, consider discussing with the individual performing the procedure any concerns regarding the proximity of the ablation catheter to the CRMD leads.During lithotripsy, the lithotripsy beam should not be focused near the pulse generator. If the lithotripsy system triggers on the R wave, atrial pacing might need to be disabled before the procedure.The Task Force believes that MRI is generally contraindicated for CRMD patients. If MRI must be performed, consult with the ordering physician, the patient’s pacemaker specialist or cardiologist, the diagnostic radiologist, and the CRMD manufacturer.The Task Force believes that radiation therapy can be safely performed for CRMD patients.***The device must be outside the field of radiation. Therefore, some pulse generators will require surgical relocation before commencing radiation. Most manufacturers recommend verification of pulse generator function during and at the completion of radiation. Problems may include pacemaker failure and runaway pacemaker.†††Although transient or long-term myocardial and nervous system effects may be associated with ECT, the Task Force believes that such therapies may be administered to CRMD patients without significant damage to a disabled CRMD. If ECT must be performed, consult with the ordering physician and the patient’s cardiologist to plan for the first and subsequent ECTs. All CRMDs should undergo a comprehensive interrogation before the procedure(s). ICD functions should be disabled for shock therapy during ECT; however, be prepared to treat ventricular arrhythmias that occur secondary to the hemodynamic effects of ECT. CRMD-dependent patients may require a temporary pacing system to preserve cardiac rate and rhythm during shock therapy. Also, the CRMD may require programming to asynchronous activity to avoid myopotential inhibition of the device in pacemaker-dependent patients.During the perioperative period, emergency defibrillation or cardioversion may become necessary for a CRMD patient. In this case, the primary concern is to minimize the current flowing through the pulse generator and lead system. Recent and earlier case reports suggest that optimal positioning of the defibrillation or cardioversion pads or paddles may be an important factor in the prevention of adverse CRMD-related outcomes.73–77The majority of Consultants and ASA and HRS members agree that the defibrillation or cardioversion pads should be positioned as far as possible from the pulse generator. The majority of Consultants and ASA and HRS members also agree that the anterior–posterior position should be used and that a clinically appropriate energy output should be used regardless of the type of CRMD.The Task Force believes that before attempting emergency defibrillation or cardioversion of a patient with an ICD and magnet-disabled therapies, all sources of EMI should be terminated, and the magnet should be removed to reenable antitachycardia therapies. The patient should then be observed for appropriate CRMD therapy. For patients with an ICD and antiarrhythmic therapies that have been disabled by programming, consider reenabling therapies through programming. If the above activities do not restore ICD function, proceed with emergency external defibrillation or cardioversion.Overriding the above discussion is the need to follow existing Advanced Cardiac Life Support and emergency guidelines78to provide rapid cardioversion or defibrillation, and attention should be turned to providing this therapy as quickly as possible.If a life-threatening arrhythmia occurs, follow Advanced Cardiac Life Support guidelines for energy level and for paddle placement. If possible, attempt to minimize the current flowing through the pulse generator and lead system by (1) positioning the defibrillation or cardioversion pads or paddles as far as possible from the pulse generator and (2) positioning defibrillation or cardioversion pads or paddles perpendicular to the major axis of the CRMD pulse generator and leads to the extent possible by placing them in an anterior–posterior location. A clinically appropriate energy output should always be used regardless of the presence of a CRMD, and the paddles should be positioned as best as can be done in an emergency.Postoperative treatment of CRMD patients primarily consists of interrogating and restoring CRMD function. Although no recent studies were found examining outcomes associated with interrogating or restoring CRMD function, an earlier case report indicates that postoperative evaluation resulted in the discovery and correction of a pacemaker problem.79The majority of Consultants and ASA and HRS members agree that postoperative patient treatment should include interrogating and restoring CRMD function in the postanesthesia care unit or intensive care unit.The Task Force believes that cardiac rate and rhythm should be continuously monitored throughout the immediate postoperative period. Backup pacing capability and cardioversion–defibrillation equipment should be immediately available at all times.Postoperative interrogation and restoration of CRMD function are basic elements of postoperative management. The CRMD first should be interrogated to assess postoperative device functions. If interrogation determines that CRMD settings are inappropriate, the device should be reprogrammed to appropriate settings. For an ICD, all antitachyarrhythmic therapies should be restored. Consultation with a cardiologist or pacemaker–ICD service may be necessary.The generic pacemaker and defibrillator codes were developed as joint projects by the North American Society of Pacing and Electrophysiology (NASPE)‡‡‡and the British Pacing and Electrophysiology Group (BPEG).80,81The five positions refer to the order of the programmed settings on the CRMD (tables 1 and 2).For this Advisory, a literature review was used in combination with opinions obtained from experts and other sources (e.g. , professional society members, open forums, Web-based postings) to provide guidance to practitioners regarding the perioperative treatment of patients with CRMDs. Both the literature review and opinion data were based on evidence linkages , consisting of directional statements about relations between specific perioperative management activities and CRMD function or clinical outcomes.A study or report that appears in the published literature is included in the development of an advisory if the study (1) is related to one of the specified linkage statements, (2) reports a finding or set of findings that can be tallied or measured (e.g. , articles that contain only opinion are not included), and (3) is the product of an original investigation or report (i.e. , review articles or follow-up studies that summarize previous findings are not included). Because CRMDs represent a rapidly changing technology, earlier literature (i.e. , literature published before 1990) was rarely included in the evaluation of evidence for this Practice Advisory.Although evidence linkages are designed to assess causality, few of the reviewed studies exhibited sufficiently acceptable quantitative methods and analyses to provide a clear indication of causality. Therefore, the published literature could not be used as a source of quantitative support (required for the development of practice guidelines). However, many published studies were evaluated that provided the Task Force with important noncausal evidence. For example, descriptive literature (i.e. , reports of frequency or incidence) is often useful in providing an indication of the scope of a problem. Information regarding whether a particular adverse outcome is common or rare may have considerable bearing on the practicality of an advisory. Case reports are typically used as a forum for reporting and recognizing unusual or adverse outcomes and may suggest caution when devising an advisory.For the literature review, potentially relevant studies were identified via electronic and manual searches of the literature. The electronic search covered a 39-yr period from 1966 through 2004. The manual search covered a 45-yr period from 1961 through 2005. More than 1,500 citations were initially identified, yielding a total of 411 nonoverlapping articles that addressed topics related to the evidence linkages. After review of the articles, 283 studies did not provide direct evidence and were subsequently eliminated. A total of 128 articles (from 39 journals) contained direct linkage-related evidence. No evidence linkage contained enough studies with well-defined experimental designs and statistical information to conduct a quantitative analysis (i.e. , meta-analysis).Interobserver agreement among Task Force members and two methodologists was established by interrater reliability testing. Agreement levels using a κ statistic for two-rater agreement pairs were as follows: (1) type of study design, κ= 0.72–0.90; (2) type of analysis, κ= 0.80–0.90; (3) evidence linkage assignment, κ= 0.84–1.00; and (4) literature inclusion for database, κ= 0.70–1.00. Three-rater chance-corrected agreement values were (1) study design, Sav = 0.81, Var (Sav) = 0.010; (2) type of analysis, Sav = 0.86, Var (Sav) = 0.009; (3) linkage assignment, Sav = 0.82, Var (Sav) = 0.005; and (4) literature database inclusion, Sav = 0.78, Var (Sav) = 0.031. These values represent moderate to high levels of agreement.Future studies should focus on prospective methodologies, when possible, that use traditional hypothesis testing techniques. Use of the following methodologic procedures for assessing the impact of perioperative management of CRMDs is recommended: (1) comparison studies (i.e. , one technique vs. another) when clinically feasible; (2) randomization; and (3) full reporting of sample size, effect size estimates, test scores, measures of variability, and P values.Consensus was obtained from multiple sources, including (1) survey opinion from Consultants who were selected based on their knowledge or expertise in perioperative management of CRMDs, (2) survey opinions from randomly selected samples of active members of the American Society of Anesthesiologists and active members of the HRS, (3) testimony from attendees of two publicly held open forums at a national anesthesia meeting and at a major cardiology meeting,§§§(4) Internet commentary, and (5) Task Force opinion and interpretation. The survey rate of return was 56% (n = 23 of 41) for Consultants, 15% (n = 89 of 600) for the ASA membership, and 15% (n = 44 of 300) for the HRS membership. Survey results are presented in the text of the document and in table 4.The ASA Consultants were also asked to indicate which, if any, of the evidence linkages would change their clinical practices if the Advisory was instituted. The rate of return was 39% (n = 16 of 41). The percent of responding Consultants expecting no change associated with each linkage were as follows: preoperative evaluation—67%; preoperative patient preparation—67%; intraoperative monitoring of CRMDs—67%; emergency defibrillation or cardioversion—87%; postoperative monitoring of CRMDs—73%; postoperative interrogation and restoration of CRMD function—60%; intraoperative management of EMI during: electrocautery—73%, radiofrequency ablation—73%, lithotripsy—80%, MRI—80%, radiation therapy—80%, and electroconvulsive therapy—73%. Forty percent of the respondents indicated that the Advisory would have no effect on the amount of time spent on a typical case. Nine respondents (60%) indicated that there would be an increase in the amount of time they would spend on a typical case with the implementation of this Advisory. The amount of increased time anticipated by these respondents ranged from 5 to 30 min.