How does a pacemaker work and what happens if it fails?

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1. 1

   Pacemaker (Wikipedia)

   WikipediaPublished Oct 15, 2026Checked Oct 17, 2026

   “A pacemaker, also known as an artificial cardiac pacemaker, is an implanted medical device that generates electrical pulses delivered by electrodes to one or more of the chambers of the heart. Each pulse causes the targeted chamber(s) to contract and pump blood, thus regulating the function of the electrical conduction system of the heart. The primary purpose of a pacemaker is to maintain an even heart rate, either because the heart's natural cardiac pacemaker provides an inadequate or irregular heartbeat, or because there is a block in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow a cardiologist to select the optimal pacing modes for individual patients. Most pacemakers are on demand, in which the stimulation of the heart is based on the dynamic demand of the circulatory system. Others send out a fixed rate of impulses. A specific type of pacemaker, called an implantable cardioverter-defibrillator, combines pacemaker and defibrillator functions in a single implantable device.”

2. 2

   When the Pacemaker Goes Rogue: Pacemaker-Induced Tachycardia, Syncope, and Car Crash.

   Case reports in cardiology (Grogg et al.)Published May 26, 2026Checked Oct 17, 2026

   “However, atrial threshold testing promptly provoked a PMT. The induced PMT led to a tachycardia of 130 bpm, causing severe symptomatic hypotension with a mean blood pressure falling below 50 mmHg. This could be easily reproduced several times. Given the patient's severe left ventricular systolic dysfunction and the absence of any overt alternative explanation, the PMT likely triggered the syncope preceding the car accident. Management focused on reprogramming the DR ICD. The most critical adaptation was a mode switch from DDD to DDIR to prevent atrial tracking, effectively terminating PMT episodes. A prolongation of the postventricular atrial refractory period (PVARP) was not possible due to the very slow VA conduction. The follow-up revealed no other episodes of PMT and the patient no longer experiences episodes of presyncope or syncope. This report highlights the potential for PMTs to induce severe hemodynamic instability and syncope, underscoring the importance of meticulous device evaluation.”

3. 3

   Pacing cessation just before generator replacement - A life-threatening consequence of pacemaker battery depletion: A case report.

   Journal of cardiology cases (Mitsumizo et al.)Published May 7, 2026Checked Oct 17, 2026

   “This lack of surveillance resulted in a critical reduction of the pacing rate to 14 ppm, culminating in the complete cessation of pacing immediately before generator replacement. Despite the Abbott device's specified End-of-Life (EOL) safety mechanism, pacing function failed entirely-a rare but life-threatening complication. Uniquely, this case provides serial electrocardiographic documentation capturing the full progression of severe battery depletion. These findings underscore that continuous follow-up and remote monitoring, as emphasized in recent guidelines, are pivotal for preventing such critical outcomes.Learning objectiveThis case highlights the potential for profound pacemaker rate reduction and complete pacing cessation beyond manufacturer-defined End-of-Life settings in the setting of extreme battery depletion. It emphasizes the importance of regular device follow-up, timely generator replacement, and the use of remote monitoring to detect critical battery status changes and prevent life-threatening complications during pacemaker management.”

4. 4

   When Pacing Fails After Generator Replacement: A Stepwise Diagnostic Approach to a Reversible Lead-Header Interface Problem.

   Reports (MDPI) (Cacciapuoti et al.)Published Apr 29, 2026Checked Oct 17, 2026

   “The electrocardiogram showed absence of effective ventricular pacing with a slow escape rhythm. Device interrogation revealed loss of ventricular capture in bipolar configuration associated with markedly elevated impedance, initially raising concern for lead malfunction. However, switching to unipolar pacing restored effective capture with normal electrical parameters, suggesting preserved lead integrity and prompting reconsideration of the underlying mechanism. Further diagnostic evaluation, including imaging and intraoperative assessment, was therefore undertaken to clarify the cause and guide management; Conclusions: Early pacing failure should not automatically be equated with lead damage. Beyond documenting a reversible lead-header interface problem, this case highlights the diagnostic value of a stepwise approach integrating pacing configuration behavior, targeted imaging, and intraoperative header-independent testing. Such an approach may facilitate rapid localization of reversible defects and help avoid unnecessary lead revision.”

5. 5

   Expert Consensus Statement: Committee on Implantable Devices and Committee on Social Issues, Japanese Heart Rhythm Society (JHRS) Statement on Remote Monitoring of Cardiac Implantable Electronic Devices.

   Journal of arrhythmia (Watanabe et al.)Published Sep 1, 2026Checked Oct 17, 2026

   “Remote monitoring (RM) has been established as a standard tool for the management of patients with cardiac implantable electronic devices (CIEDs), offering advantages such as early event detection, fewer routine outpatient visits, and reduced mortality. As RM becomes more common, its appropriate implementation and the need for safe, efficient management have become increasingly important. This statement of the Japanese Heart Rhythm Society (JHRS) provides comprehensive guidance for medical professionals and device manufacturers involved in RM. Specifically, it outlines recommendations on personnel placement, workflow optimization, patient and caregiver education, alert notification settings, physiological parameter monitoring, and insurance claims. It also addresses the responsibilities of device manufacturers, the use of third-party resources, and strategies for reducing workload based on alert notifications. Recommendation classes and evidence levels were determined by the consensus of the writing team, and the proposed recommendations were reviewed and peer-reviewed by the JHRS' Committee on Implantable Devices.”

6. 6

   In Vitro Assessment of 3T MRI Effects on Non-3T-Compatible Cardiac Implantable Electronic Devices.

   Journal of cardiovascular electrophysiology (Fukuoka et al.)Published Jun 7, 2026Checked Oct 17, 2026

   “However, among pacemakers, telemetry failure or parameter reset occurred in 6 non-MRI-conditional and 3 1.5-T MRI-conditional devices, including some devices with MRI mode ON. Reset or telemetry failure was more frequent in devices with low battery status (≤ 30% to ERI) than in those with higher status (6/11 [55%] vs. 3/22 [14%], p= 0.013). With MRI mode OFF, magnet mode was activated in 11 3T and 7 non-MRI-conditional pacemakers; activation frequency did not differ between asynchronous and demand pacing (16/31 [52%] vs. 18/31 [58%], p= 0.610). In some pacemakers and ICDs, demand pacing led to atrial mode switch or pacing inhibition, but no reset or telemetry failure occurred in ICDs.ConclusionsIn direct in vitro 3T MRI exposure experiments involving non-3T MRI CIEDs, some pacemakers approaching ERI demonstrated an increased risk of telemetry failure or reset, and those with MRI mode turned off showed non-negligible mode switching. However, the majority of devices did not exhibit severe electrical malfunctions necessitating replacement in a clinical setting, and no instances of device reset or telemetry failure were observed in ICDs.”