The use of implanted pacemaker devices is increasing worldwide, owing to technological advances, new indications, and an aging population. Despite greater experience in implantation and improved device sophistication, patients continue to face complications associated with hardware implantation and device malfunction. This review summarizes current indications for permanent pacing, reviews epidemiologic data relevant to implant complications, and describes a clinical approach to the patient with potential pacing malfunction. The electrocardiographic diagnosis of hyperkalemia and acute myocardial infarction in paced rhythms is also discussed. Potential sources of electromagnetic interference and special considerations pertaining to the cardiac resuscitation of patients with implanted cardiac devices are reviewed. Finally, a basic approach to implanted cardioverter-defibrillator devices (which often accompany pacemaker devices) is presented.
An ill-appearing 74-year-old woman is brought in on a stretcher by EMS personnel who broke down her door to find her slumped on her couch. Her temperature is normal, her blood pressure is 86/40 mm Hg, and her heart rate is 42 beats/min. On the cardiac monitor, you see extremely wide QRS complexes following pacer artifacts and intermittent pauses where pacing artifacts appear alone. A prior ECG shows a paced rhythm and narrower QRS complexes. What are your critical actions?
A 38-year-old woman who fainted in the grocery store is wheeled into the last unoccupied room in your ED with a cardiac monitor. She has cardiac sarcoidosis and has a DDD pacemaker that was implanted 6 months ago. She tells you that this is the third time she has fainted in the past 24 hours. She is normotensive and her heart rate is 48 beats/min. The cardiac monitor shows pacing artifacts that are completely dissociated from QRS complexes. What steps will you take to diagnose the underlying cause of this patient’s recurrent syncopal episodes?
Cardiac pacemakers have evolved from singlechamber devices that deliver a fixed pacing rate to multichamber systems with programmable features that preserve and more closely mimic normal cardiac electrophysiology. Preservation of atrioventricular synchrony, physiologic heart rate, and interventricular synchrony are significant improvements that have been made possible with dual-chamber, rate-adaptive, and biventricular pacing systems. For patients, improved quality of life, increased exercise tolerance, and decreased disease progression are among the clinical outcomes driving new indications for pacemaker implantation and cardiac resynchronization therapy (CRT). At the same time, mortality benefits associated with implanted cardioverterdefibrillator devices (ICDs) in patients with heart failure have translated into an increasing number of biventricular pacing systems with integrated ICD technology. While pacemakers have become more complex and sophisticated, patients continue to present to the emergency department (ED) with symptoms related to device malfunctions. In addition, special considerations with regard to implanted pacemakers are relevant to the diagnostic workup of comorbid illnesses.
Implanted pacemakers are increasingly prevalent in the United States.1 Approximately 370,000 pacemakers are placed annually,2 the most common indication for which is sinus node disease.3 Regardless of the indication for pacing, dual-chamber pacemakers have been adopted as the technology of choice. However, since United States Food and Drug Administration (FDA) approval in 2001, CRT devices are being implanted more frequently.4 Most of these are combined with defibrillation technology, and CRT-defibrillator (CRT-D) devices have come to comprise approximately 40% of all pacemakers in the United States.5 Compared with the general population, patients receiving implanted devices are older (mean age of implantation of 75.6 years) and carry a higher burden of age-adjusted comorbid illness.1,6
PubMed and the Cochrane Database of Systematic Reviews were searched for English-language articles pertaining to the management of patients with implanted pacemakers and cardiac devices published between January 1, 1990 and February 21, 2014. Search terms included permanent pacemakers and the thematic topics of pacemaker complications, cardiac resynchronization therapy, pacemaker malfunction, and electromagnetic pacemaker interfer ence. The bibliographies of review articles were hand-searched and the level of evidence graded according to the guidelines from the American Heart Association Task Force on Practice Guidelines. (See Table 1.) Guidelines published by the American College of Cardiology Foundation/ American Heart Association (ACCF/AHA), the Heart Rhythm Society (HRS), the European Heart Rhythm Association (EHRA), and the European Society of Cardiology (ESC) were also reviewed.7-11
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study will be included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference.
Jennifer Martindale, MD; Ian S. deSouza, MD
September 2, 2014