Pacemakers are among the most reliable implanted medical devices, but living with one does come with a real list of potential side effects ranging from surgical-site soreness and occasional device-related infections to subtler long-term issues like changes in heart-pumping efficiency and psychological adjustment. Most people do well, and serious complications are uncommon on any individual visit to the cardiologist. Still, the side effects are worth understanding because they span everything from the first week after surgery to years down the road when the battery runs low and the generator needs replacing.
Complications in the First Days and Weeks
The implant procedure itself carries risks similar to other minor surgeries involving the chest. The device generator, roughly the size of a small matchbox, is placed in a pocket just under the skin below the collarbone. Wires called leads are threaded through a vein into the heart. Two complications that tend to show up early are pocket hematoma and pneumothorax.
A pocket hematoma is a collection of blood around the generator site. It is more than a cosmetic nuisance. A study following patients who developed a significant hematoma found that those patients had roughly a seven-fold higher risk of device-related infection over the following year compared to patients without one.1Journal of the American College of Cardiology. Clinically Significant Pocket Hematoma Increases Long-Term Risk of Device Infection: BRUISE CONTROL INFECTION Study Infection at the device site is one of the more feared early complications because it can sometimes require complete removal of the pacemaker system.
Pneumothorax, a partial collapse of the lung, happens because the leads are typically inserted through a vein near the top of the chest. A puncture that nicks the lung lining can let air leak into the space around it. One series found pneumothorax occurred in about 2.6% of patients who had leads placed via subclavian puncture, with most cases being partial and manageable without surgery.2PubMed Central. Pneumothorax resulting from subclavian puncture: a complication of permanent pacemaker lead implantation Complete lung collapse requiring a chest tube is rarer but possible.
Lead Displacement and Perforation
Once the leads are anchored inside the heart, they are expected to stay put for years. In practice, though, leads occasionally shift out of position. Long-term displacement rates reported in the literature range from under 2% to as high as 8%, depending on the study and how broadly displacement is defined.3PubMed Central. An Unusual Cause of Pacemaker Lead Displacement: ‘Reverse Ratchet’ Syndrome A large product surveillance registry covering tens of thousands of implanted leads found a displacement rate of about 1.7% of patients over the study period.4PubMed. Short- and Long-Term Risk of Lead Dislodgement Events: Real-World Experience From Product Surveillance Registry A displaced lead may not cause obvious symptoms right away. It is often caught at a routine check-up when the device’s pacing thresholds look off.
More concerning, though much less common, is lead perforation, where the tip of the wire pushes through the heart wall. Reported rates range from about 0.1% to 6%, a wide spread that reflects differences in how aggressively clinicians look for it and which imaging methods they use.5PubMed Central. Identification and management of right ventricular perforation using pacemaker and cardioverter-defibrillator leads: A case series and mini review A five-year study from a high-volume center in India found an incidence of about 0.4% and noted that pericardial effusion, a buildup of fluid around the heart, developed in the vast majority of those cases.6PubMed Central. Pacemaker lead perforations: a five-year study from a high-volume center in India Symptoms can include sharp chest pain and shortness of breath, but many perforations are asymptomatic and discovered incidentally. In a small fraction of cases, fluid accumulation around the heart becomes severe enough to cause cardiac tamponade, which is a medical emergency requiring drainage.7EP Europace. Diagnosis and management of iatrogenic cardiac perforation caused by pacemaker and defibrillator leads
Vein Narrowing and Blood Clots
The leads that run from the generator into the heart sit inside veins, and over time those veins can narrow or become obstructed. This is especially relevant for people who might eventually need additional leads placed for a device upgrade. Obstruction of the subclavian, brachiocephalic, or superior vena cava veins is recognized as an important complication that can cause arm swelling and limit future device options.8Journal of the American College of Cardiology. Lead-Related Venous Obstruction in Patients With Implanted Cardiac Devices: JACC Review Topic of the Week Upper-extremity deep vein thrombosis, meaning a blood clot in the arm or shoulder veins, is another recognized risk. A case series of 20 patients with pacemaker-related upper-extremity clots found both partial and complete vein occlusion, with no single factor clearly predicting who would get a complete blockage versus a partial one.9PubMed. Permanent pacemaker-related upper extremity deep vein thrombosis: a series of 20 cases You might notice swelling, discomfort, or a feeling of heaviness in the arm on the pacemaker side if this occurs.
Pacemaker Syndrome
Not all side effects are mechanical. Pacemaker syndrome is a term for a cluster of symptoms that can develop when the pacemaker’s pacing style puts the heart’s upper and lower chambers out of sync. Older single-chamber pacemakers that only stimulate the ventricle are the classic culprit. When the atria and ventricles are not contracting in their normal coordinated sequence, the result can feel lousy: fatigue, dizziness, low blood pressure, shortness of breath, and sometimes a pulsing sensation in the neck.10PubMed. Pacemaker Syndrome: A Narrative Review Symptoms range from mild tiredness to full-on fainting.11PubMed. Pacemaker syndrome: definition and evaluation The fix typically involves reprogramming the device or upgrading to a dual-chamber system that paces both the atrium and the ventricle.
Pacing-Induced Cardiomyopathy
One of the more insidious long-term side effects is pacing-induced cardiomyopathy, a gradual weakening of the heart’s pumping ability caused by chronic right ventricular pacing. When a pacemaker stimulates the right ventricle, the electrical signal spreads through the heart muscle in an abnormal pattern rather than the normal conduction system. Over months or years, this unnatural activation can remodel the heart and reduce its efficiency.12PubMed Central. Pacemaker Induced Cardiomyopathy: An Overview of Current Literature A systematic review and meta-analysis of nearly 58,000 patients found a pooled prevalence of about 12%, meaning roughly one in eight patients with chronic right ventricular pacing develops this problem.13Heart Rhythm. Definition, prevalence, risk factors, and management of pacing-induced cardiomyopathy: A systematic review and meta-analysis Risk factors include a higher percentage of paced beats, lower baseline heart function, and wider paced electrical signals.
The clinical consequences are real. Abnormal ventricular activation from right ventricular pacing has been associated with heart failure hospitalizations, the development of atrial arrhythmias, and increased mortality.14PubMed. Pacing induced cardiomyopathy: recognition and management This is one reason cardiologists try to program devices to minimize how often they actually pace the ventricle, and why newer pacing strategies targeting the heart’s natural conduction system have generated so much excitement.
Electrical Quirks and Device Oddities
A pacemaker is a small computer attached to wires sitting inside a beating heart, so it is not surprising that it occasionally misbehaves in strange ways. Phrenic nerve stimulation is one such quirk. The phrenic nerve, which controls the diaphragm, runs near the heart. If a lead sits close to it or shifts position, the pacemaker’s electrical pulses can stimulate the nerve, causing involuntary diaphragm contractions. In one reported case, a man developed persistent hiccups and chest-muscle twitching a week after his pacemaker was implanted, traced to an atrial lead that had dislodged and was stimulating his phrenic nerve.15PubMed Central. Phrenic Nerve Stimulation-Induced Persistent Singultus: A Case of Atrial Lead Dislodgement After Dual-Chamber Pacemaker Implant
Twiddler’s syndrome is another unusual but well-documented problem. It occurs when a patient, sometimes unconsciously, manipulates the device through the skin, causing the generator to rotate inside its pocket. That rotation winds the leads around the device like thread on a spool, retracting them from the heart. A case series found that it occurred most often in older women and caused symptomatic device failure within weeks of implantation.16Hearts. Twiddler’s Syndrome: Predictors, Prevention, and Outcomes in a Case Series
Dual-chamber pacemakers can also develop pacemaker-mediated tachycardia, a circuit where the device tracks its own signals in a feedback loop and drives the heart rate inappropriately fast. Placing a magnet over the device typically breaks the loop, and reprogramming prevents recurrence.17JAMA Internal Medicine. Tachycardia in a Patient With a Dual-Chamber Pacemaker—Discussion
Electromagnetic Interference and MRI
Living with a pacemaker means being aware that certain electromagnetic fields can interfere with the device. A systematic review found that cardiac implants are susceptible to malfunction from electromagnetic fields in the intermediate-frequency range, with anti-theft security systems and induction cooktops among the most relevant household or commercial sources.18Oxford Academic. Electromagnetic interference in cardiac electronic implants caused by novel electrical appliances emitting electromagnetic fields in the intermediate frequency range: a systematic review In practice, brief passage through a store security gate is typically fine, but lingering near one is not recommended. Strong industrial magnets, welding equipment, and certain medical devices also pose risks.
MRI scanning has historically been the biggest headache. Older pacemakers were considered incompatible with MRI because the scanner’s powerful magnetic field could heat the leads, move the device, or reset its programming. MRI-conditional pacemakers, designed with materials and circuitry that tolerate the scanner environment, were introduced in 2008 and have accumulated a solid safety record under specific conditions.19PubMed Central. MRI-conditional pacemakers: current perspectives Even patients with older, non-MRI-conditional devices have undergone MRI safely in some settings. A large prospective study found no long-term clinically significant adverse events across more than 1,500 MRI examinations in patients with both legacy and newer devices, though in a small fraction of scans the device transiently reset to a backup mode.20PubMed Central. Safety of Magnetic Resonance Imaging in Patients with Cardiac Devices Another study comparing MRI-conditional and older pacing systems directly found no differences in device parameter changes afterward, though some shifts approached thresholds that warranted monitoring.21European Journal of Radiology. MRI with cardiac pacing devices – Safety in clinical practice The bottom line is that MRI is increasingly feasible for pacemaker patients but still requires careful coordination with the pacemaker team.
Psychological and Emotional Effects
The side effects of a pacemaker are not exclusively physical. Having a device implanted in your chest that your heart depends on can weigh on you mentally. A study of permanent pacemaker patients found that about one in five met criteria for a psychiatric diagnosis, most commonly adjustment disorder and major depression.22PubMed. Psychiatric morbidity and depressive symptomatology in patients with permanent pacemakers The most frequent symptoms included difficulty with work and daily activities, anxiety, loss of energy, and trouble sleeping. Women and patients with less education about the device tended to report more psychological distress, suggesting that fear and lack of understanding amplify the problem.
Younger patients may be especially vulnerable. A large study following young recipients of cardiac implantable electronic devices found that both pacemaker and defibrillator recipients had a significantly higher risk of developing mental health disorders compared to matched individuals without devices. The elevated risk was most pronounced in the first two years after implantation but persisted beyond that window as well.23PubMed Central. Mental Disorders After Cardiac Implantable Electronic Device Implantation in Young Individuals This suggests that the psychological burden of device dependency deserves more attention in follow-up care than it traditionally receives.
Generator Replacement and Long-Term Upkeep
A pacemaker battery lasts roughly 7 to 15 years depending on how heavily the device paces. When it runs low, the generator is swapped out in a procedure simpler than the original implant, since the existing leads are usually left in place. Still, generator replacement is not risk-free. The REPLACE registry, a large multicenter study, found major complications in about 4% of pacemaker generator replacements.24PubMed. Complication rates associated with pacemaker or implantable cardioverter-defibrillator generator replacements and upgrade procedures: results from the REPLACE registry Rates climbed substantially when the procedure also involved adding new leads or upgrading the device type. Infection is the complication physicians worry about most during replacements, because the old pocket is being reopened and manipulated.25EP Europace. Complications related to elective generator replacement of the subcutaneous implantable defibrillator
For very thin or frail patients, the device pocket itself can become a long-term problem. Erosion occurs when the generator gradually wears through the overlying skin, creating an opening that invites infection. One case report described a thin, elderly patient whose pacemaker eroded through the skin four years after a generator change, aggravated by a small pocket and superficial anchoring sutures.26PubMed Central. Risk Mitigation of Pacemaker Pocket Erosion in Thin Patients Submuscular placement, where the generator sits beneath the chest muscle rather than directly under the skin, is one strategy used to prevent this in patients with little subcutaneous tissue.
Allergic and Inflammatory Reactions
Rarely, the body reacts to the materials in the pacemaker itself. The generator casing is typically made of titanium, and the leads contain various metals and polymers. True allergic reactions are uncommon. Data from two high-volume centers spanning thousands of implants estimated the incidence of allergic reactions at around 0.05%.27PubMed Central. Allergic reaction to pacemaker compounds: Case reports The challenge is that the skin changes caused by allergy, including redness and erosion, look very similar to those caused by infection, making accurate diagnosis tricky. Patch testing for metal sensitivity can help sort this out, and in confirmed cases the device may need to be replaced with one made from a different alloy or coated to prevent contact.
How Leadless Pacemakers Change the Risk Profile
Leadless pacemakers, small capsules implanted directly inside the heart through a vein in the leg, eliminate leads and the subcutaneous pocket entirely. That changes which complications you are exposed to. A comparative study found that leadless devices had significantly fewer complications overall, with lower rates of lead dislodgement, lead fracture, and pocket-site infection.28PubMed Central. Complications of leadless vs conventional (lead) artificial pacemakers – a retrospective review Another study of more than 2,000 patients confirmed that leadless pacemakers had lower short- and mid-term complication rates, though they did show a higher rate of pericardial effusions in the acute period after implant.29Heart Rhythm. Comparative study of acute and mid-term complications with leadless and transvenous cardiac pacemakers Leadless devices also completely avoid thoracic trauma complications like pneumothorax, since nothing goes through the chest veins. The tradeoff is that current leadless pacemakers are limited to single-chamber pacing, so they are not suitable for all patients.
Conduction system pacing, including left bundle branch pacing, is another evolving approach. By targeting the heart’s natural electrical highway rather than the right ventricular muscle, this technique aims to avoid the dyssynchrony that leads to pacing-induced cardiomyopathy.30PubMed. Left Bundle Branch Pacing: JACC Review Topic of the Week Early results are encouraging, with stable pacing thresholds and good lead stability, though lead-related complications still occur at rates around 12% in some series.31PubMed. Pros and Cons of Left Bundle Branch Pacing: A Single-Center Experience The approach is newer and less standardized than conventional pacing, so its long-term complication profile is still being defined.32PubMed. Left bundle branch pacing: A comprehensive review
End-of-Life Device Decisions
A side effect few people think about at the time of implantation is the question of what happens to the pacemaker at the end of life. Professional guidelines affirm that deactivating a pacemaker at a patient’s or surrogate’s request is both ethically and legally permissible.33PubMed. Deactivation of Cardiac Devices at the End of Life: Clinical and Ethical Challenges But the decision is more emotionally and clinically complicated than it might sound. Some patients have had their heart’s own conduction system intentionally disrupted as part of their treatment, meaning that turning off the pacemaker would cause the heart to stop. In those cases, the physician who performed the original procedure may feel a profound sense of responsibility, and the conversation requires sensitivity from everyone involved.34Journal of Pain and Symptom Management. Pacemaker Deactivation at the End of Life Despite guidelines recommending that deactivation be discussed before the device is even implanted, these conversations remain infrequent in practice.33PubMed. Deactivation of Cardiac Devices at the End of Life: Clinical and Ethical Challenges If you or a family member are facing a pacemaker implant, it is worth raising the topic early, even though it feels premature, so that preferences are documented while everyone is thinking clearly.