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Jan.28.2021

Implantable Cardioverter-Defibrillator: Emergency Management - CE

ALERT

Strong magnetic fields, such as from magnetic resonance imaging (MRI), diathermy, electrocautery, electrolysis and thermolysis, lithotripsy, radiation treatment for cancer, and use of transcutaneous electrical nerve stimulation (TENS), may lead to malfunction of, or damage to, the implantable cardioverter-defibrillator (ICD). Although risk mitigation strategies are possible, a cardiologist who is familiar with the device must be consulted.undefined#ref1">1,4

With the defibrillation function turned off, no defibrillation shocks are delivered if the patient goes into ventricular fibrillation (VF) or ventricular tachycardia (VT). Ensure that an external monitor or defibrillator is present during emergency management of an ICD.

OVERVIEW

Implantable cardiac defibrillators are sometimes called automatic implantable cardioverter-defibrillators (AICDs). First brought into service in 1980, these devices have become a standard of care for patients who are at high risk for sudden cardiac arrest and sustained VT. ICDs currently available have the capabilities to treat:

  • Atrial arrhythmias (through defibrillation functions)
  • Ventricular arrhythmias (through defibrillation functions)
  • Bradycardia (through pacing functions)
  • Tachycardias (with overdrive pacing capabilities)

Some devices are connected to cardiac lead wires and are continually monitored by an electrocardiogram (ECG). Other devices may be placed subcutaneously outside the thoracic cavity where they sense the rhythm and deliver the shock without invasive leads threaded through the central vasculature. The amount of energy delivered with each shock is determined at the time of implantation, based on the amount of energy needed to convert the patient’s rhythm. The settings can only be altered by a cardiologist or an ICD specialist. Because the device is implanted, much lower energy levels are needed with an ICD than with external cardioversion or defibrillation.

Patients who have an ICD may require emergency care under these circumstances:

  • The patient was in cardiac arrest before arrival but was successfully resuscitated by defibrillating shocks from the ICD and arrives with a perfusing rhythm. This patient should be treated the same as any patient who has undergone successful resuscitation after cardiac arrest. In addition, the cardiology department should be notified so the ICD can be interrogated and the event recorded, printed, and preserved. If the patient is conscious, information should be solicited about the number of shocks delivered, any symptoms preceding the defibrillation, and the patient’s activity around the event.
  • The patient arrives in cardiac arrest, despite the fact that the ICD functioned properly. If a patient arrives in cardiac arrest and the ICD continues to function (as evidenced by muscular movement synchronous with firing of the ICD), the remaining resuscitation interventions should be performed.3 If the patient arrives in cardiac arrest and the ICD has stopped its defibrillation (ICDs shut down the defibrillation function after a set number of defibrillations according to a preprogrammed algorithm), manual defibrillation should be initiated. Ideally, the defibrillation pads or electrodes should be placed at least 10 cm (4 inches) away from the ICD.3 Alternate positions for the defibrillator pads or paddles, such as the anterolateral or anteroposterior positions, may be required to avoid delivering a shock directly over the ICD device; however, alternate positioning should not delay defibrillation.3
  • The patient was successfully converted from a tachycardic rhythm by the ICD before arrival. This patient should be treated as any patient who has been converted from a tachycardic rhythm. The cardiology department should be notified for device interrogation.
  • The patient has a tachycardic rhythm that was shocked by the ICD but the rhythm did not correct. This patient should be treated per advanced cardiac life support (ACLS) guidelines for any patient with tachycardia.
  • The patient has a tachycardic rhythm and the ICD does not fire. The underlying tachycardic rate may fall out of the range to which the ICD is programmed to respond. This patient should be treated per ACLS guidelines for any patient with tachycardia.
  • The patient arrives at the emergency department complaining of inadvertent firing of the defibrillator. Frequent causes of inadvertent firing include supraventricular tachycardias such as atrial tachycardia and sinus tachycardia; lead fractures; T-wave sensing; and electromagnetic interference. The Assessment and Preparation section below has guidelines on caring for this patient.
  • The patient presents with another problem not related to the ICD, for which the patient may undergo procedures that may damage or disrupt the device. The Education section below has a list of medical equipment that may disrupt or damage an ICD.

Depending on the situation, the patient’s ICD may or may not need to be deactivated. The nurse’s role in deactivating an ICD is described in the Procedure section below.

EDUCATION

  • Instruct the patient to contact his or her cardiologist for any concerns regarding the ICD.
  • Provide information about which devices the patient should avoid or devices around which caution is recommended.
    • Explain to the patient with an ICD that most medical equipment is safe for use. This includes most radiographic studies (x-rays, fluoroscopy, computed tomography [CT], mammography, and ultrasound) as well as ultrasonic dental cleaners.
    • Instruct the patient to avoid procedures such as an MRI, electrical nerve and muscle stimulators (TENS units), diathermy, lithotripsy, electrolysis and thermolysis, and electrocautery until his or her cardiologist is consulted.
    • Instruct the patient on the use of electronic and battery-powered devices, tools, equipment, and magnets.
      • Keep cell phones and portable multimedia players at least 15 cm (6 inches) from the device.1 Avoid carrying a phone in a breast pocket and avoid hooking it to the belt if doing so places the phone too close to the ICD.
      • Hold a cell phone against the ear on the opposite side of the body from the device.
      • Avoid putting magnets or products containing magnets close to the ICD.
      • Use caution when working with tools or appliances in situations in which injury may occur if the patient becomes dizzy or receives a therapeutic shock from the ICD.
    • Instruct the patient to move away from the vicinity of electronic equipment if feelings of light-headedness occur, beeping tones are heard, or a defibrillation shock is experienced. The patient should call his or her cardiologist to report the episode.
    • Instruct the patient about going through a security screening system.
      • Walk through the screening areas at a normal pace; do not linger in these areas.
      • Request that the screener avoid the ICD if using a hand wand to search the patient.
      • Move away from the screening devices if dizziness or weakness occurs.
    • Caution the patient about equipment in industrial areas.
      • Many types of large industrial equipment, such as generators, electric motors, and arc welders, generate strong electromagnetic fields that may interfere with an ICD.
      • The patient should make sure that equipment is properly grounded before working near it.
  • Encourage a patient who comes to the emergency department with a history of ICD implantation to discuss end-of-life requests with his or her cardiologist and family. Implantation of an ICD may be appropriate for a patient with do-not-resuscitate orders who experiences arrhythmias from a primary cardiac condition. At some point, however, continued shocks may be uncomfortable and inconsistent with comfort care.
  • Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

  1. Perform hand hygiene before patient contact and don gloves if needed.
  2. If time permits, verify the correct patient using two identifiers.
  3. Assess the patient for a history of acute myocardial infarction (AMI).
  4. Assess for signs and symptoms of hemodynamic instability.2
    1. Dizziness
    2. Exertional symptoms
    3. Weakness
    4. Hypotension
    5. Abnormal heart rate (tachycardia or bradycardia)
  5. If time permits, facilitate interrogation of the ICD by a member of the cardiology department.
    Rationale: Interrogation is performed to determine whether the ICD is activated or inactivated.
  6. Identify the type of ICD (check to see if the patient is wearing a medical information bracelet or necklace or carrying an identification card with information about the ICD).

Preparation

  1. Connect the patient to a cardiac monitor and have an external defibrillator readily available.
  2. Obtain a standard 12-lead ECG if the patient’s condition permits.
  3. Establish IV access in case IV medications are necessary.
  4. Remove gloves (if donned) and perform hand hygiene.
    Rationale: Gloves are not needed for deactivation of an ICD.

PROCEDURE

  1. Perform hand hygiene.
  2. If time permits, verify the correct patient using two identifiers.
  3. Collaborate with the practitioner to determine whether the ICD should be deactivated. Indications for deactivation include:
    1. The ICD is providing inappropriate shocks. Any number of factors may contribute to inadvertent firing, including supraventricular tachycardias such as atrial tachycardia and sinus tachycardia; lead fractures; T-wave sensing; and electromagnetic interference.
    2. The ICD is not converting the underlying rhythm. A patient may experience cardiac arrest due to a lethal arrhythmia or have a nonlethal tachycardic rhythm and the ICD continues to fire but does not convert the underlying rhythm. In these cases, deactivation of the ICD may be desired so that manual defibrillation can be attempted as an alternative to the ICD device.3
    3. The patient will be undergoing a procedure that may cause inadvertent firing of the ICD. During such procedures (e.g., TENS, electrocautery), temporary deactivation may be considered.
    4. In the postresuscitation period, the ICD is inadvertently firing secondary to ventricular arrhythmias caused by epinephrine administered during resuscitation, as well as ventricular irritability secondary to myocardial ischemia. In this case, temporary deactivation may be appropriate.3
    5. In a patient receiving end-of-life care, the firing of the ICD is causing anxiety and discomfort and prolonging life. Sometimes, a patient and his or her family prefer to have the device deactivated as part of the dying process.
  4. Determine how the patient’s ICD responds to a magnet by reviewing the manufacturer’s information or consulting with the cardiologist to clarify how to deactivate the device.
    1. For some devices, the application of a magnet deactivates the defibrillation function while the magnet is in place; the defibrillation function returns when the magnet is removed.
    2. For other devices, the magnet is removed and the defibrillation function is inactivated until the magnet is reapplied to reactivate the device.
    3. If the type of device is unknown, observe the ICD’s response to the magnet on the cardiac monitor to determine how to proceed.
  5. To deactivate the ICD, place a doughnut-shaped magnet on top of the ICD pulse generator. The placement of a magnet over an ICD causes the cardioversion and defibrillation functions to immediately cease but allows the pacemaker function of the ICD to continue.4
    Different ICDs respond to magnets differently, depending on the manufacturer and model of the device, as well as the mode setting. When a magnet is placed over an ICD, notify a cardiologist, who is familiar with the device, or the manufacturer of the action to ensure that the ICD will work properly after the magnet is removed.
  6. Remove the magnet and obtain a 12-lead ECG.
    Rationale: A 12-lead ECG is performed to record the current state of the device.
  7. Discard supplies and perform hand hygiene.
  8. Document the procedure in the patient’s record.

MONITORING AND CARE

  1. Assess, treat, and reassess pain.
  2. If the patient is to be discharged home, instruct him or her to follow up with a cardiologist.
    Rationale: A follow-up is required to check the functionality of the device.
  3. If the device is deactivated and there is a delay in admission or the patient requires transfer to another facility for admission, place external defibrillation pads on the patient and keep a defibrillator near him or her.
    Rationale: If the device is deactivated, the patient will likely be admitted to a monitored bed.

EXPECTED OUTCOMES

  • Stable cardiac rhythm
  • Hemodynamic stability

UNEXPECTED OUTCOMES

  • VF or tachycardia
  • Asystole

DOCUMENTATION

  • Indication for deactivating the ICD
  • Time at which the ICD was inactivated
  • Either an ECG or a rhythm strip (or both) before and after deactivation
  • Unexpected outcomes and related interventions
  • Education

REFERENCES

  1. Pfaff, J.A., Gerhardt, R.T. (2019). Chapter 13: Assessment of implantable devices. In J.R. Roberts and others (Eds.), Roberts and Hedges’ clinical procedures in emergency medicine and acute care (7th ed., pp. 258-274). Philadelphia: Elsevier.
  2. Samii, S.M. (2015). Indications for pacemakers, implantable cardioverter-defibrillator and cardiac resynchronization devices. Medical Clinics of North America, 99(4), 795-804. doi:10.1016/j.mcna.2015.02.008
  3. Squire, B., Niemann, J.T. (2018). Chapter 70: Implantable cardiac devices. In R.M. Walls, R.S. Hockberger, M. Gausche-Hill (Eds.), Rosen’s emergency medicine: Concepts and clinical practice (9th ed., pp. 959-970). Philadelphia: Elsevier.
  4. Swerdlow, C.D., Wang, P.J., Zipes, D.P. (2019). Chapter 41: Pacemakers and implantable cardiovertor-defibrillators. In D.P. Zipes and others (Eds.), Braunwald’s heart disease: A textbook of cardiovascular medicine (11th ed., pp. 780-806). Philadelphia: Elsevier.
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