A block in the heart’s electrical conduction system or a malfunction of the heart’s natural pacemaker (the SA node) can cause a heart dysrhythmia. The primary purpose of the pacemaker is to sustain an adequate heart rate that will maintain sufficient blood pressure and perfuse all organs adequately.
In some patients, artificial pacemakers are used externally to address a temporary need, and in other patients with permanent conditions, pacemakers are implanted surgically.
Whether temporary or permanent, a pacemaker provides an electrical stimulus traveling through lead wires to stimulate the myocardium (heart muscle) to depolarize and contract.
The parts of a pacemaker include the battery/brains, known as the pulse generator, and lead wires that have electrodes on the ends.
The pulse generator houses the pacemaker’s energy source and controls. The nurse should verify that the rate prescribed matches the rate set on the pulse generator.
The mode of pacing can be set on demand or asynchronous. Demand pacing senses the heart’s impulses and paces only when the patient needs it. Asynchronous pacing mode sets the pacemaker to fire at a fixed rate regardless of the heart’s ability to generate impulses.
Temporary pacing is necessary for short-term management of dysrhythmias until the patient’s rhythm is stabilized or a permanent pacemaker can be inserted.
Normally, all types of temporary pacing are by demand, in which the pacemaker delivers electrical current only when the heart’s rate falls below the preset rate. They are typically used for less than three days.
Types of temporary pacing include:
Transcutaneous external pacing is primarily for unstable rhythms in emergency situations, requiring two electrodes on the chest, either in the anterior/lateral position or the anterior/posterior position.
With a transvenous pacemaker, the pacer wire is inserted through a large vein into the right ventricle, with the leads attached to an external pulse generator box.
Epicardial pacing is most commonly used with cardiac surgery patients undergoing an open thoracotomy. Temporary lead wires are sutured loosely to the outermost layer of the heart, exposed through the skin, and connected to an external pulse generator similar to transvenous pacing.
Transesophageal pacing involves placing an electrode in the esophagus through the nose or by a pill-electrode that is swallowed. The electrode connects to an external pulse generator by a wire. This type of pacing is commonly used only for atrial pacing in sinus bradycardia, supraventricular tachycardia, or for diagnostic studies.
When caring for a patient with a temporary pacemaker, there are several guidelines to follow for safe practice:
Assess the patient’s tolerance of the heart rhythm – This is done by continuous ECG monitoring, and assessing the patient’s mental status, blood pressure, pulse, heart sounds, lung sounds, skin color, warmth, and urinary output.
Check the system for proper functioning – secure all connections, secure generator box to the patient, check the pacing threshold every 12 hours, replace the battery generator or connecting cable for failure to pace, and adjust sensitivity for undersensing or oversensing (and notify the physician).
Maintain electrical safety – Verify that wires are connected and secured to the correct connector ports, keep the insulation cover over the uninsulated ends, wear rubber gloves when handling exposed terminals, do not touch the patient and electrical equipment at the same time, keep ungrounded electrical equipment from contact with the patient, and prevent liquids from coming in contact with the generator, cables, or insertion site.
Monitor for complications at insertion site – assess the site daily for infection, change dressing every 48 hours using central line dressing sterile technique.
Assess patient safety and comfort – Explain the purpose of the pacemaker to decrease anxiety, position patient comfortably to avoid tension on the external wires and generator, provide pain medication or sedation as needed, and provide diversional activities when mobility is limited.
Permanent pacemakers are used to treat various bradycardic arrhythmias and are implanted during a short surgical procedure, usually under local anesthesia.
The electronic control center of the pacemaker is called the pulse generator, which is encased in titanium with a lithium iodide battery inside that lasts 5-12 years. The pulse generator is attached to one or more lead wires that are threaded through large blood vessels in the upper chest into the heart.
Small electrodes at the ends of the leads attach to the inner surface of the heart and pick up the heart’s natural electrical signals and deliver the pacing pulse from the generator. The pulse generator is usually placed under the skin below the collarbone.
Most implanted pacemakers are dual-chambered pacemakers, in which an electrode is placed in the right atrium and one in the right ventricle.
If necessary, a third lead can be placed in the left ventricle with a biventricular device.
When caring for a patient with a permanent pacemaker, teach the patient before surgery about:
- The reasons for the pacemaker
- Potential complications
- Pretests, including baseline 12-lead ECG and bleeding function bloodwork
- The need for IV access for fluids, sedation, and emergencymedications
- They are to have nothing by mouth for 8 hours before procedure
Preop, Op, and Postop
The nurse will:
- Assess baseline VS, peripheral pulses, and heart and lung sounds.
- Assess the patient’s anxiety level – actively listen, reassure, educate, and give sedation as needed.
- Shave and scrub the access site where the generator will be implanted.
- Maintain a sterile field.
- Keep a cardiac monitor on at all times during the procedure.
Following the procedure:
- Monitor for complications of insertion such as:
◦ Pneumothorax (collapsed lung)
◦ Hemothorax (collection of blood in the pleural cavity)
◦ Perforation from the pacemaker lead
◦ Cardiac tamponade (pressure on the heart caused by fluid build-up around the heart)
*These complications are seen as shortness of breath, low blood pressure, chest pain, or a rapid heart rate.
- Monitor for lead dislodgement, seen as ECG changes or hiccups if diaphragm is being paced.
- Monitor ECG for loss of sensing, loss of capture, or failure to pace.
- Provide pain medications and interventions as needed.
- Assess insertion site for bleeding and infection.
- Apply ice pack to minimize pain and swelling for first 6 hours.
- Maintain bedrest for 12 hours.
- Restrict movement of the affected arm for 12-24 hours. After 24 hours, assist with gentle ROM exercises 3 times daily, to restore normal movement and prevent stiffness.
- Do not give aspirin or heparin for 48 hours.
- If defibrillation is necessary, avoid the area surrounding generator site.
Discharge instructions to teach the patient:
- Placement of the pacemaker generator and leads, how it works,and the rate at which it is set.
- Monitor site for bleeding and infection for the first week. Bruising may be present.
- Avoid immersing the site in water for 3 days.
- Minimize arm and shoulder activity of affected arm and wear loose covering over incision for 1-2 weeks, to prevent dislodgement of new leads.
- Avoid contact sports and heavy lifting for 2 months after surgery.
- Contact physician with fatigue, palpitations, or recurrence of symptoms (may indicate pacemaker malfunction or battery depletion).
- Take radial pulse daily before arising and notify physician for rates outside those programmed (may indicate pacemaker malfunction or battery depletion).
- Carry pacemaker information at all times and wear a MedicAlert bracelet (pacemaker will trigger some airport security alarms).
- Discuss any possible procedures with cardiologist (some procedures – MRI, electrocautery – may affect the pacemaker).
- Household appliances such as microwave ovens, radios, and gardening tools will not affect the pacemaker. Cell phones currently don’t appear to affect pacemakers.
Modern pacemakers have built-in features to protect them from most types of interference produced by other electrical devices; however, the patient must always be aware of their surroundings and the devices that may interfere.
Devices with possible risk include:
- Anti-theft systems
- Strong metal detectors
- MP3 player headphones (keep at least 3cm away from pacemaker)
- Shock-wave lithotripsy (non-invasive treatment for kidney stones)
- Power-generating equipment
- Arc welding equipment
- Powerful magnets
- Therapeutic radiation (cancer treatment)
- TENS units for pain relief
Avoid high-voltage or radar machinery or working over large running motors. If interference with the pacemaker is suspected, move away from the electrical device or turn off the equipment.
Signs of pacemaker malfunction include:
- Chest pain
Maintain follow-up care with the physician as recommended. Between office visits, the doctor can keep track of the pacemaker’s operation through transtelephonic monitoring. Pacemaker malfunctions should be reported to the physician, and include loss of sensing, failure to capture, and failure to pace.
Loss of sensing: Pacemaker is either “oversensing” and senses an external signal as an impulse and does not pace or it is “undersensing” the heart’s own impulse and it paces the heart unnecessarily. (As you can see in the example of undersensing, the first 2 beats are paced, then several intrinsic beats occur, but the pacemaker fails to sense these beats, resulting in competition between paced beats and the heart’s intrinsic rhythm.) The nurse should check for electromagnetic interference and proper grounding of equipment. In undersensing, increase the sensitivity of the pacer. In oversensing, decrease the sensitivity of the pacer.
Failure to capture: Pacemaker fires but does not depolarize the ventricle. The nurse should turn patient to left side (to bring lead in better contact with endocardium), check all connections, and increase the energy delivered. (In the example, atrial pacing and capture occur after pacer spikes 1,3,5, and 7. The remaining pacer spikes fail to capture, resulting in no conduction to the ventricles, and no arterial waveform).
Failure to pace: Electrical impulse is never initiated, so there are no pacer spikes shown on the ECG strip. The nurse should keep an external or temporary pacemaker at the bedside, assessing the patient until the cause of the failure is determined and corrected.
Implanted Cardioverter-Defibrillators (ICDs)
Many pacemakers have the added function of an implanted cardioverter-defibrillator (ICD), which is for patients at risk for dysrhythmias that do not respond to antidysrhythmic therapy. The ICD continuously monitors heart activity and can automatically deliver a countershock to correct a perceived dysrhythmia.
The teaching required for the patient with ICD insertion is similar to a permanent pacemaker insertion. However, the shock from an ICD is generally painful and patients should be advised of this in advance. Others in physical contact with the patient will experience a mild sensation with the shock delivery, but no harm is done. Most doctors recommend that patients be shock-free for 6 months before resuming driving. Emotional support is critical for patients and family, as there is often anxiety, depression, fear, and anger associated with ICD placement.
Patients may choose to decline a pacemaker with ICD functionality, as they may interfere with the natural process of dying by continuing to function and deliver shocks. As a patient approaches the end of life, healthcare providers should discuss the options with the patient and family.
Remember, when caring for a pacemaker patient in the hospital, the ECG will continue to show pacing spikes and possible electrical activity even without a pulse. The healthcare team may choose to monitor the patient remotely, so as to avoid confusion in family members at the bedside.
Pacemaker technology is changing constantly, but the goal of therapy remains the same: to sustain an adequate heart rate that will maintain sufficient blood pressure and perfuse all organs adequately.