How Should We Prepare the Patient With a Pacemaker/Implantable Cardioverter-Defibrillator?

INTRODUCTION

Battery-operated pacemakers (PMs) revolutionized the treatment of fatal electrical conduction abnormalities in 1958, just a few years after the invention of the transistor. With the maturation of this technology, PMs were designed to also provide atrioventricular synchronization, improve the quality of life for the chronotropically incompetent patient, and prevent and treat atrial fibrillation. The development of implantable cardioverter-defibrillators (ICDs), capable of antitachycardia pacing (ATP) and high-energy shock, extended this technology to patients who are at risk for or experience ventricular tachyarrhythmias. After the first successful human implant in 1980, ICDs received United States (U.S.) Food and Drug Administration (FDA) approval in 1985. In addition to delivering high-energy therapy for ventricular arrhythmias, every conventional (i.e., transvenous) ICD now provides the entire functional set of pacing capabilities found in a conventional PM.

Today, cardiac implantable electronic devices (CIEDs) are not only confined to keeping the heart beating between a minimum rate (i.e., pacing function) and a maximum rate (i.e., ICD functions); they are also employed as therapy to improve the failing heart by reducing ventricular contractile dyssynchrony in the presence of cardiomyopathy (i.e., biventricular [BiV] pacing, also called cardiac resynchronization therapy [CRT]). Other relatively recent major technological advances include the leadless PM and subcutaneous ICD (S-ICD).

Since CIEDs were first introduced, the number of patients receiving them has steadily increased because of population aging, new indications for their use, and continued technological enhancements. Today, in the U.S alone, more than 3 million people have a PM, more than 300,000 have an ICD, and approximately 500,000 CIEDs are implanted annually. Although the incidence of patients with a CIED undergoing surgery is unknown, this number is surely substantial, given the high prevalence of these devices and because more than 80 million surgical procedures are performed annually in the U.S.

Safe and efficient perioperative management of patients with a CIED depends on a basic understanding of how these devices function, the indications for their use, and the needs they create. Unfortunately, the increasing specialization, proprietary nature of hardware and software, and device complexity limit generalizations about perioperative CIED management. Additionally, the paucity of published trials and the logistical and technical challenges involved in appropriately evaluating CIEDs perioperatively add to the difficulties in properly managing these patients. Moreover, a mounting number of published reports suggest that adverse outcomes occur when CIED patients receive suboptimal perioperative care.

These issues led the American Society of Anesthesiologists (ASA) to publish a Practice Advisory for these patients in 2005, which was most recently updated in 2020. In addition, in 2011 the Heart Rhythm Society (HRS) and ASA, in collaboration with the American Heart Association (AHA) and the Society of Thoracic Surgeons (STS), published an Expert Consensus Statement. Other societies have published recommendations as well. ^,

OPTIONS/THERAPIES

Information contained herein applies to the perioperative management of patients with CIEDs (i.e., PMs and ICDs). It does not address the management of patients for whom these therapies might become necessary or are no longer needed.

EVIDENCE

Indications for PM, ICD, and CRT implantation are shown in Boxes 10.1A , 10.1B , and 10.1C .

<B Type A>

<B Type A>

<B Type A>

For patients with ventricular tachycardia (VT) or ventricular fibrillation, ICDs reduce death and are superior to antiarrhythmic drug therapy. Further studies evaluating prophylactic ICD placement in patients without a history of tachyarrhythmias (Multicenter Automatic Defibrillator Implantation Trial–II [MADIT-II], which studied patients with ischemic cardiomyopathy and an ejection fraction less than or equal to 30%, and Sudden Cardiac Death–Heart Failure Trial [SCD-HeFT], which studied patients with ischemic and nonischemic cardiomyopathy and ejection fraction less than or equal to 35%) have significantly increased the number of patients for whom ICD therapy is indicated.

Although ICDs save lives, both appropriate and inappropriate defibrillator shocks are associated with adverse effects including pain and posttraumatic stress disorder, myocardial ischemia, and even increased mortality. For example, in the aforementioned MADIT-II and SCD-HeFT trials, ICD shocks were associated with a two- to fivefold increased risk for death. Subsequently, the Multicenter Automatic Defibrillator Implantation Trial–Reduce Inappropriate Therapy (MADIT-RIT) prospectively tested a longer detection time and separately higher heart rate to trigger ICD therapy in patients with primary prevention ICDs. These strategies reduced the risk of inappropriate ICD therapy by more than 70% and in secondary analysis reduced overall mortality by about 50%. Although the frequency of inappropriate ICD therapy during surgical procedures remains unknown, mounting evidence suggests that these events occur more frequently than might be appreciated and that this issue constitutes an important and largely preventable patient safety concern. ^,

Another potential concern is device malfunction or outright failure. Although PMs and ICDs are very reliable, some devices fail prematurely. Maisel and colleagues searched the FDA database for the years 1990 to 2002; they found that 4.6 PMs and 20.7 ICDs per 1000 implants had been explanted for failures other than battery depletion. For the study period, 2.25 million PMs and 415,780 ICDs were implanted, and 30 PM and 31 ICD patients died as a direct result of device malfunction. Safety notices, advisories, and recalls continue to occur periodically. Prior alerts for premature ICD lead failure, which can result in inappropriate shock or failure of shock, and for silent, premature battery failure have been announced. In addition, one entire Guidant (now Boston Scientific) product line of ICDs had their magnet mode permanently disabled because of a switch malfunction.

Whether the presence of a CIED indicates increased independent risk for perioperative morbidity or mortality is a question that remains ripe for investigation. There are a dearth of prospective studies; however, observational reports suggest that these patients might be at increased perioperative risk. Levine and colleagues reported increases in pacing thresholds (i.e., the amount of energy required to depolarize the myocardium) in some thoracic operations. In 1995, Badrinath and colleagues retrospectively reviewed ophthalmic surgery cases in one hospital in Madras, India, from 1979 through 1988 (14,787 cases) and found that the presence of a PM significantly increased the probability of a mortal event within 6 weeks postoperatively, regardless of the anesthetic technique. Pili-Floury and colleagues reported that 2 of 65 PM patients (3.1%) undergoing significant noncardiac surgery died postoperatively of cardiac causes over a 30-month study period. They also reported that 12% of patients required preoperative and 7.8% required postoperative modification of PM programming. In abstract form, Rozner and colleagues reported a 2-year retrospective review of 172 PM patients evaluated at a preoperative anesthesia clinic, showing that 27 of 172 (16%) needed a preoperative intervention (9 of 27 were pulse generator replacement for battery depletion). Additionally, follow-up of the 149 patients who underwent an open surgical procedure showed five ventricular pacing threshold increases, one atrial pacing threshold increase, and one PM electrical reset, all of which took place in patients undergoing nonthoracic surgery. All of these cases involved electromagnetic interference (EMI) from a monopolar electrosurgical unit (ESU), and one large ventricular pacing threshold was observed after a significant fluid and blood resuscitation after the loss of 2500 mL of blood in a 45-year-old woman. Cheng et al. prospectively evaluated 57 patients with ICDs (17% not evaluated in the past 3 months) and 35 with PMs (23% not evaluated in the past 6 months) for a variety of cases. There was no change in pacing or sensing thresholds but significantly decreased lead impedance in all chambers. One ICD reported an elective reset because of battery depletion during the case. At postoperative evaluation, several devices reported EMI but no ICDs delivered therapy. More recently, a prospective cohort study found that that the use of monopolar ESU caused clinically meaningful EMI (defined as EMI that would have resulted in inappropriate antitachycardia therapy had the ICD not been reprogrammed) in 20% (5/70) of patients during noncardiac surgery above the umbilicus, in 29% of patients during cardiac surgery, and in no patients during below the umbilicus surgery (0/40).