If the extent of your education about pacemakers and defibrillators was a pacer spike or two during an EKG course you are not alone! To many experienced advanced practitioners, pacemakers and defibrillators are mysterious metal boxes inside a few elderly patients surrounded with uncertainty. Here are some clinical pearls that will help you to better care for patients with implanted cardiac devices.
So, what’s the difference anyway?
Both pacemakers and defibrillators are small metal devices implanted under the skin usually placed under the left clavicle allowing for vein access to thread wires (leads) into indicated chambers of the heart. A pacemaker is utilized in patients with heart block or bradycardia. Pacemaker wires are usually implanted in the right atria and ventricle to provide pacing support should the heart’s intrinsic conduction system not create or appropriately conduct an impulse within a set timeframe. Defibrillators at their most basic function are a “shock box” providing defibrillation of a life-threatening arrhythmia. When educating patients, I often describe a defibrillator’s function to that of a parachute. On a daily basis the device will not affect how they feel or their heart’s function; however, on the day they have a life-threatening arrhythmia, the defibrillator will provide a shock in an attempt to terminate the arrhythmia. Defibrillators are indicated in patients with profoundly low ejections fractions or cardiomyopathies putting them at high risk for sudden cardiac death. While the majority of patients you will encounter will have one of the devices described above, with dramatic technological advancements there are an increasing variety of implanted cardiac devices. In recent years, there are much more advanced devices including leadless pacemakers, subcutaneous defibrillators, implanted loop recorders for long-term rhythm monitoring, and advanced defibrillators that provide cardiac resynchronization for patients with advanced heart failure.
What should you do if a problem is suspected?
If you suspect your patient with an implanted cardiac device is having a problem related to the device, the first thing that should be done is to have the device checked. The vast majority of patients have home monitors that allow them to send a transmission to their cardiologist’s office for review. If they do not have a home monitor, the device can be checked in the cardiologist’s office or if there seems to be a more emergent situation, the emergency department. This “device check” can provide important information about the battery life and function of the device as well as information about the patient’s heart rhythm. It is important to remember that while malfunctions are possible, devices in general are incredibly reliable and programmed with a myriad of safeguards and back up functions. It is also important to remember that the device interrogation report will not provide any information about blood pressure, coronary perfusion, valve functions, or ejection fraction.
What if your patient has an infection?
If a vegetation forms on a lead or the device implant site (pocket) becomes infected, the entire system will likely need to be removed. While putting in a pacemaker or defibrillator is a relatively low risk procedure, taking them out is another story. The morbidity and mortality for device explant is high and is typically performed at large centers by experienced electrophysiologists. If your patient with an implanted device presents with an infection, it is important to treat appropriately. If you have questions or concerns about which antibiotic is best, or the duration of therapy do not hesitate to discuss the case with an infectious disease specialist or the implanting cardiologist. Early consultation of wound care teams can also be of great benefit in affected patients.
What about an MRI?
Historically, patients with implanted cardiac devices have not been candidates for MRIs. There are now some pacemakers and defibrillators that are MRI compatible. Patients should only have MRIs performed if their device has been deemed MRI compatible by the implanting cardiologist and the imaging center has a protocol for and support personnel to manage the device during the study.
What if your patient gets a shock?
If your patient comes to or calls your office reporting a shock from their defibrillator, they need to be seen for clinical evaluation and have their device checked. Remember that defibrillators are programmed to shock patients for dangerous tachyarrhythmias such as ventricular tachycardia (VT) or ventricular fibrillation (VF). If a patient has had one of these rhythms, it is important to get a laboratory evaluation with special attention to their potassium and magnesium levels as well as a review of the patient’s medications. Many times, prior to a shock, a patient will lose consciousness due to cerebral hypoperfusion secondary to the VT/VF. Other patients might feel poorly but may have relatively few symptoms in the time surrounding their arrhythmia and subsequent shock. Even if they appear to be clinically stable proper labs and a device check should be performed quickly and communicated with the cardiology team.
If you want to learn more about implanted cardiac devices, Heart Rhythm Society is a great place to get more reliable information for yourself and your patients about heart rhythm disorders and implanted cardiac devices. Additionally, ThriveAP’s post-graduate training and education program, ThriveAP covers clinical topics such as these in our Cardiology and Internal Medicine Block. For more information, contact firstname.lastname@example.org.
Corrie Morris has been a nurse practitioner for over ten years. She has experience in internal medicine and electrophysiology, and is a frequent speaker for our ThriveAP curriculum. She has a passion for patient care, advocacy, and education especially regarding patients with pacemakers, defibrillators, and other implanted cardiac devices.