Episode #63 Cardiovascular Implantable Electronic Devices Revisited

Hello and welcome back to the Anesthesia Patient Safety Podcast.  My name is Alli Bechtel and I am your host. Thank you for joining us for another show. Have you taken care of a patient with a cardiovascular implantable electronic device recently? What type of device was it? Who made the device? Was the patient dependent on the device? Did you need to reprogram the device or have any additional equipment available in the operating room? There are so many things to consider when providing anesthesia care for patient with cardiovascular implantable electronic devices.

Before we dive into today’s episode, we’d like to recognize Acacia Pharma, a major corporate supporter of APSF. Acacia Pharma has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Acacia Pharma- we wouldn’t be able to do all that we do without you!”

On the show today we are going to review safety consideration for patients with cardiovascular implantable electronic devices. We talked about this first on Episode 9 when we reviewed the article, “Managing Cardiovascular Implantable Electronic Devices During Perioperative Care” by Neelankavil, Thompson, and Mahajan from the Fall 2013 APSF Newsletter. On Episode 14, we introduced the 35^th anniversary APSF Newsletter which included an update to the original article. The article is called, “Change of Pace: An Update on the Perioperative Management of Cardiovascular Implantable Electronic Devices (CIEDs).” This is by the same authors of the 2013 article. Today, we are going to put this information together for an electrifying review for the safe management of patients with these devices.

First up, let’s head back to episode #9. In this episode, we review the recommendations from the 2011 Heart Rhythm Society and ASA expert consensus statement on the Perioperative Management of Patients with Implantable Defibrillators, Pacemakers, and Arrhythmia Monitors: Facilities and Patient Management. This statement was recently reaffirmed on June 16^th, 2021 and will be reassessed in 2026. I will include a link to this statement in the show notes. And now, episode 9…

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[Episode 9] “Cardiovascular implantable electronic devices include the following: Pacemakers indicated for bradyarrhythmia treatment, Implantable cardioverter defibrillators or ICDs for tachyarrhythmia management, and cardiac resynchronization therapy or CRT for patients with decreased systolic function combined with conduction delays.  You will likely come across patients with these devices for anesthesia care since the prevalence of cardiac arrhythmias is 14.4 million patients in the US and the indications for these devices continues to expand with favorable outcomes when compared to medical therapy alone. There is a call to action that anesthesia professionals understand the perioperative implications for patients with these devices especially since approximately 1 million patients around the world have a pacemaker or ICD placed each year.”

“Now let’s talk about the perioperative considerations and what better way to start then with the preoperative assessment. The consensus statement reports that the majority of patients do not need a new preoperative device evaluation by the device management team as long as this information is available from a recent device evaluation from clinic. Patients with these devices often have phone interrogations every few months and follow-up with their cardiologist yearly and these notes provide excellent information for the anesthesia team.

Before providing anesthesia care, you need to know what type of device the patient has since this offers information about the indication for the device and the perioperative considerations.  Let’s look at pacemakers first.  These devices are placed for bradyarrhythmia and are the only treatment for patients with symptomatic bradycardia from sinus node dysfunction such as sick sinus syndrome or from failed impulse propagation such as complete heart block. The next question to ask is, “Is the patient dependent on the device?” Device dependence refers to lack of a perfusing rhythm in the absence of pacing.  Patients who are dependent on their pacemaker will need to have a secondary method for pacing in case the implanted pacemaker fails and these options include transesophageal pacing, transcutaneous pacing, and transvenous pacing. The authors remind us that it is vital to have a backup plan as well as the necessary equipment and support before starting anesthesia care. The next step is to consider any additional pacemaker functions such as rate responsiveness which provides increased pacing to patients during physical exertion and decreased pacing rates during rest periods. For the most part, rate responsiveness will likely need to be disabled during anesthesia and surgery.

Let’s turn our attention now to ICDs. These devices have 4 functions including sensing atrial or ventricular electrical activity, classifying the electrical activity depending on programmed “heart rate zones,” providing electrical therapy to terminate ventricular tachycardia or fibrillation, and providing backup pacing in case of bradycardia. It is important to recognize when a patient has an ICD since depending on the patient’s device and the surgery, the tachyarrhythmia therapy may need to be disabled in order to prevent inappropriate pacing or shocks from electromagnetic interference. There is an important corresponding step since once the patient’s ICD is disabled, you will need to monitor the patient carefully for a tachyarrhythmia and have an external defibrillator immediately available.  Patients with ICDs will often need continuous electrocardiogram monitoring and defibrillator pads in place to monitor and defibrillate if needed. For patients with combined pacemaker and ICD devices, make sure that you evaluate the pacemaker as well.

What about patients with biventricular ICDS or cardiac resynchronization devices? These devices help to optimize ejection function and this therapy has several important benefits including decreased myocardial oxygen consumption and improved stroke volume in patients with reduced EF, significant intraventricular conduction delay, or interventricular dyssynchrony. These patients often require continuous pacing intraoperatively to take advantage of these benefits and have improved hemodynamic stability.

Remember, that for patients with these implanted devices, the team approach with anesthesia professionals, the surgeon, and the device team is vital to provide appropriate and individualized management. From the consensus statement, we see that there is not just one recommended approach for these patients. Communication between the team members is important so that the device team is knows the type of procedure and risk for electromagnetic interference and on the flip side, the device team can then communicate with the anesthesia and surgery teams about options for reprogramming the device…or not…during the perioperative time period. The anesthesia and surgery teams will also need to communicate about options for monitoring and external therapy, such as location of the defibrillator pads.

I mentioned electromagnetic interference or EMI already, but let’s take a closer look at this.  EMI in the operating room may lead to malfunction of pacemakers and defibrillators including failure to pace or inappropriate shock therapy or even damage to the pulse generator. Perioperative EMI has been described due to TENS units and electroconvulsive therapy, but the most common cause is monopolar electrocautery and the closer to the pulse generator, especially within 6 inches, the more likely there is to be interference. What about bipolar electrocautery? When bipolar is used the current is small and energy travels only the distance between the poles of the pen or stylus.  Unfortunately, bipolar is not the most common electrocautery used since it can only be used for coagulation rather than coagulation and dissection which monopolar is able to accomplish. Surgeons often use bipolar for microsurgery including eye surgery and neurosurgery. One of the complications with EMI is oversensing. This can occur with a pacemaker or an ICD. When oversensing occurs with a pacemaker, the pacemaker interprets the EMI falsely as intrinsic cardiac activity so that pacing from the device is inhibited even when a patient really needs to be paced. When oversensing occurs with an ICD, the ICD interprets the EMI falsely as a tachyarrhythmia leading to the ICD providing inappropriate pacing or shock therapy even when the patient does not need it. The risk of inappropriate defibrillation is causing a real ventricular arrhythmia or patient movement during the surgery. The implantable devices are better than ever at minimizing inappropriate therapy or failed therapy, but it is still important to understand the effect of EMI on devices during the perioperative time period. Recommendations for monopolar cautery including using in short bursts for several seconds at a time. Using monopolar in shorts bursts minimizes the risk for inappropriate ICD therapy since the ICD requires several second to detect the tachyarrhythmia before providing therapy. Another benefit is shorter periods of interrupted pacing and improved hemodynamic stability for patients who are dependent on their pacemaker. Make sure that the cautery dispersion pad is placed in a location that the EMI path does not cross the pulse generator.

The location of the surgery is an important consideration.  For surgery below the level of the umbilicus, the consensus statement recommends that it is likely not necessary to reprogram the device or use a magnet because there is a low risk of oversensing and damage to the generator or leads.

What about magnets for perioperative management of patients with implantable devices. In the past, magnets were placed over the device in order to reprogram the device to an asynchronous pacing mode and disable anti-tachycardia therapy. But it is important to keep in mind that the magnet mode will vary depending on the type of device and the manufacturer. The magnet mode was originally developed to enable device interrogation and battery life outside of the operating room. When a magnet is placed over a pacemaker, the response can be programmed by the device team so this is a good question to ask the device team during a preoperative interrogation. “What will happen if I place a magnet over the pacemaker?” The pacing rate is also variable in magnet mode and often depends on the manufacturer and the remaining battery life of the generator. If the generator has a low battery level, the magnet mode pacing rate may be too low depending on the patient and the surgical procedure.  The magnet mode for an ICD is to disable anti-tachycardia defibrillation without changing the ICD pacing function. Thus, if you place a magnet over a patient’s ICD, the underlying pacemaker function will not change to asynchronous.  Patients who are dependent on their pacemaker and have an ICD will likely require a perioperative evaluation and reprogramming with the device team. Keep in mind there is some variability in the magnet mode for ICDs so once again this is a good question to ask the device team when you are evaluating a patient’s device. What will happen to the patient’s device if I place a magnet over their ICD during the surgery?

An important patient safety consideration is perioperative device failure including failure to sense, failure to pace, or generator damage.  You will want to ensure that the perceived pacemaker failure is not due to rate adaptive features that were left on during the procedure. Another rare event to be aware of is electrical reset. This can happen if EMI directly contacts the pulse generator and can cause device failure. This is most likely to occur during therapeutic radiation and it is much less likely to occur with monopolar electrocautery or cardioversion. In case of an electrical reset, the device should default to a particular setting depending on the device type and the manufacturer. This helps to ensure that the device will continue to function, but keep in mind that the device will need to be interrogated as soon as possible and possibly reprogrammed back to the patient’s original settings or even replaced. It is important to keep the path of the EMI away from the pulse generator since this may damage the generator as well. Failure of the device to sense or pace during the procedure may also be due to lead damage or damage to the tissue-lead interface from EMI.

Let’s talk about an approach for patients with an implantable device who are coming to the OR for non-emergent surgery. The authors remind us that pacemakers should be interrogated at least every 12 months and ICDs every 6 months. The device team should know the procedure type, patient position, type of EMI, anticipated cardioversion, and post-op destination in order to make appropriate recommendations. The anesthesia team will need to know the type of device, indication for device placement, battery life at greater than 3 months, the programming mode, pacemaker dependence, and underlying rhythm and finally what is the magnet mode for the device. It is a lot of information to gather preoperatively, but it is so important for patient safety. The location of the surgery is also an important consideration since with the procedure is below the umbilicus, there is usually not a need for device reprogramming and you may be able to just keep a magnet on hand…as long as you know what the magnet mode is for the device. When the procedure is above the umbilicus, you will likely need to disable tachycardiac therapy for an ICD and rate responsiveness for a pacemaker.  Patients who have a biventricular ICD for resynchronization therapy may benefit from an asynchronous pacemaker mode to ensures pacing throughout the procedure in order to maintain hemodynamic stability. Check out the show notes for a list of crucial information for the device team and anesthesia team.

What about when we have a patient with a device who comes to the OR for emergency surgery? The device team may not be able to weigh in on device management prior to heading back to the OR.  If this is the case, the anesthesia team should try to identify what type of device is in place from the medical records and any patient information cards. A CXR can provide additional information as well since pacemaker leads have a uniform texture and thickness and ICDs have a shock coil located near the distal end of the lead that is brighter and thicker while patients with biventricular ICDs will have an additional lead in the coronary sinus that you can see on Chest X-ray. If the emergent surgery is above the umbilicus, using a pre-op EKG or rhythm strip can provide information about if the patient is being paced. Patients with frequent pacer spikes are likely dependent on their device. Patients without visible pacer spikes are likely not dependent on their device and you can go back to the OR with a magnet available.  Communication with the surgical team about short bursts of monopolar electrocautery whenever possible is also helpful to prevent pacemaker oversensing and bradycardia in patients who are dependent on their pacemakers. Patients with ICDs in place will require a magnet over the device for emergency surgery above the umbilicus and a method for external defibrillation. For emergent procedures, it is important to reach out to the device team as soon as possible because they can still offer intraoperative recommendations and postoperative interrogation.

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Next, let’s return to the October 2020 APSF Newsletter article for the update on perioperative management of cardiovascular implantable electronic devices. Here we go…

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[Episode 14] “The past 7 years has brought us newer types of pacemakers and ICDs. For example, the Medtronic Micra device is a leadless pacemaker with a self-contained generator and electrode in a single chamber device that is implanted in the right ventricle by way of the femoral vein.  This is a pacemaker only and cannot perform defibrillation. For perioperative care, it is important to know that there is no magnet sensor (the device is very small after all) and it is recommended that the device be reprogrammed to an asynchronous ventricular pacing mode to decrease the risk for oversensing.

Another newer device is the Boston Scientific subcutaneous ICD for patients. This extra thoracic device includes a pulse generator that you will find between the anterior and midaxillary lines in the 6th intercostal space and a single subcutaneous lead that is tunneled medially to the xiphoid process and then superiorly along the left parasternal border. This device is capable of defibrillation as well as pacing at 50 beats per minute for 30 seconds if needed following defibrillation. There is a magnet mode for this device that will turn off the anti-tachycardia therapies while the magnet is applied to the device, and you will know that the device is in magnet mode because the device will emit a beeping sound. Removal of the magnet will return the device to the prior programming. It is important to evaluate the patient and the positioning for surgery when deciding on using a magnet versus reprogramming the device.

Another important update for 2020 is that the ASA published an updated practice advisory for device management that highlights obtaining a preoperative device interrogation and figuring out the risk from EMI before entering the operating room. The updated advisory also provides information on what to do for emergency cardioversion or defibrillation for a patient with a device. Here are the steps to take: Stop all EMI, remove the magnet, watch the patient and monitors for appropriate anti-tachycardia therapy. If removing the magnet fails to re-activate the anti-tachycardia therapy or the anti-tachycardia therapy was programmed to OFF for the procedure, you have 2 options, either immediately re-program the device or perform emergent external cardioversion or defibrillation. There is also guidance about devices that are safe for MRIs and further emphasis on not putting a magnet on every device in the OR. It is very important to know what the magnet mode is for your patient’s device before you place a magnet. The authors leave us with the final thought that in 2020 and beyond, anesthesia professionals will have the ability to create thoughtful individualized plans for all patients with cardiac implantable electronic devices. Thank you Neelankavil, Thompson, and Mahajan for this wonderful update.”

Stay vigialnt the next time your patient has one of these devices so that you will be prepared to keep your patient safe throughout the perioperative time period.

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Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

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