A pacemaker is a small, implanted medical device that uses electrical pulses to regulate a person’s heart rhythm when it is too slow or irregular. The device is powered by a sealed battery contained within the pulse generator. Battery depletion is normal, with a lifespan typically ranging from five to 15 years. The entire pulse generator, including the battery, is replaced in a scheduled procedure before it fully runs out of power.
Physical Symptoms of Battery Depletion
When the pacemaker battery nears the end of its life, the device may not deliver the necessary electrical energy consistently, causing a return of the original heart rhythm issues. A primary warning sign is the reappearance of symptoms the pacemaker was implanted to prevent. Patients may notice a sudden sense of exhaustion or lethargy not relieved by rest. This fatigue occurs because the heart is no longer pumping blood efficiently enough to meet the body’s metabolic demands.
Many individuals experience lightheadedness, dizziness, or near-fainting episodes (syncope) due to an insufficient heart rate. A low battery can also lead to shortness of breath, particularly during mild exertion, as the heart struggles to circulate oxygenated blood. Other signs include the sensation of a slow, fluttering, or irregular pulse. These symptoms indicate that the pacemaker is failing to maintain the programmed rhythm.
How Pacemaker Function Changes
Long before complete battery failure, the pacemaker alters its operation in a pre-programmed way to conserve energy and signal the need for replacement. This state is called the Elective Replacement Indicator (ERI) mode, triggered when the battery voltage drops to a specific level. A common technical change is a programmed drop in the base pacing rate. This slight reduction in heart rate is an energy-saving measure and can cause patient symptoms like fatigue and shortness of breath.
During the ERI phase, some dual-chamber devices may simplify their operational mode, such as switching to a single-chamber mode. This mode change, along with the loss of features like rate response, can increase symptoms for some patients. The device’s ability to deliver maximum output, characterized by the pulse width and amplitude of the electrical signal, may also decrease. These programmed changes reduce the device’s energy draw, sacrificing optimal performance to create a window for replacement.
Clinical Monitoring and Planned Replacement
Pacemaker battery replacement is almost always a scheduled, preventative procedure, not an emergency reaction. The battery lifespan, typically between 5 and 15 years, is influenced by the device model and the amount of time the heart requires pacing. Regular in-office device checks, often scheduled every three to six months, are the primary method for monitoring battery health. During these visits, a technician uses a specialized programmer to wirelessly interrogate the device and measure the battery’s voltage and internal resistance.
Remote monitoring, or telemetry, has enhanced this proactive approach by allowing the care team to track battery status daily from a distance. The ERI is a programmed threshold indicating that replacement should be scheduled. This typically provides a “replacement window” of three to six months before the battery is fully depleted. This window ensures the procedure can be planned before the battery reaches its End of Service (EOS) state, the point of imminent failure.
Immediate Action Steps
If a patient experiences a return of symptoms like lightheadedness, severe fatigue, or an irregular pulse, they should contact their cardiology clinic immediately. These symptoms, even if mild, indicate that the pacemaker’s reduced function may be compromising heart performance. Patients should not wait for their next scheduled follow-up appointment or dismiss the symptoms.
The medical team will likely request an urgent, unscheduled device check to confirm the battery status and determine the cause of the symptoms. If symptoms are severe, such as sudden fainting, chest pain, or profound shortness of breath, the individual should seek emergency medical attention. This involves calling emergency services or going to the nearest emergency room.