Unexplained Fainting
- Spells too rare to catch
- Other tests came back normal
- Looks for pauses or fast rhythms
- Guideline-recommended choice
Names & Terms You Will Hear
Plain-language meanings for the terms your care team may use.
| Term | Meaning |
|---|---|
| Implantable loop recorder (ILR) | A small heart monitor placed just under the skin. It records your heart rhythm for up to about 3 years. |
| Insertable cardiac monitor (ICM) | The same device. This is the newer name many companies use. |
| Loop recorder | The everyday short name patients and staff use most. |
| Reveal LINQ, Confirm Rx, BioMonitor | Brand names of common loop recorders. They work the same basic way. |
| Long-term ECG monitor | A device that records the heart's electrical signal (ECG) over months, not minutes. |
| Ambulatory monitoring | A general term for recording your rhythm while you go about daily life. |
It records, it does not treat. A loop recorder is a monitor only. It cannot pace your heart or give a shock. If it finds a problem that needs treatment, that is a separate step — for example a pacemaker or ICD for dangerous pauses, or a blood thinner for atrial fibrillation.
What Is the Implantable Loop Recorder?
- An implantable loop recorder (ILR) is a small monitor about the size of a key. A doctor places it just under the skin over the upper-left chest.
- It records the heart's electrical signal (the ECG) all day and night. It keeps a rolling memory, so it can save the beats right before, during, and after a symptom.
- It is not a pacemaker. It does not treat the heart or give shocks. It only watches and records.
- The battery lasts up to about 3 years. When the answer is found, or the battery runs low, the device is taken out in a quick visit.
- It sends data to your care team. Many models connect to a small bedside unit or a phone app that uploads recordings while you sleep.
- You also get a way to mark your own symptoms. Pressing a small handheld marker (or a phone button) flags the moment so your team can look right there.
Four Common Reasons a Loop Recorder Is Used
Palpitations
- Racing or skipping heart
- Comes and goes unpredictably
- Shorter monitors kept missing it
- Links the feeling to a rhythm
Stroke, No Cause Found
- Searches for silent AF
- AF often has no symptoms
- Catching it allows a blood thinner
- Aims to prevent the next stroke
Known AF Follow-Up
- Measures how often AF happens
- Checks if treatment is working
- Tracks rhythm after an ablation
- Guides medicine decisions
Why It Matters
- Fainting and palpitations often come and go. A short test like a 12-lead ECG lasts seconds. A Holter lasts a day or two. The problem may simply not happen during that short window.
- A loop recorder watches for up to 3 years. That long window is why it finds answers that shorter tests miss. The chart below compares how long each monitor watches.
- For unexplained fainting, finding the cause matters. A long pause or a dangerous fast rhythm changes treatment — some patients need a pacemaker or other care.
- After a stroke with no clear cause, the worry is silent atrial fibrillation (AF). AF often has no symptoms, so it slips by. Catching it lets us start a blood thinner to prevent the next stroke.
- In the CRYSTAL-AF trial, a loop recorder found AF in 12.4 percent of stroke patients by 12 months. Usual care found it in only 2.0 percent. The gap grew even wider over 3 years.
- Most of the AF the device catches causes no symptoms at all. Without a long-term monitor, it would go unnoticed until it caused harm.
Heart Monitors Side by Side — How Long Each One Watches
| Monitor | How long it records | Best for | On the body |
|---|---|---|---|
| 12-lead ECG | A few seconds | A symptom happening right now | Stickers, then off |
| Holter | 1 to 2 days | Daily symptoms | Worn on the skin |
| Patch or event monitor | 2 to 4 weeks | Symptoms every week or so | Worn on the skin |
| Loop recorder (ILR) | Up to 3 years | Rare spells; silent AF | Under the skin |
Risk Factors
Knowing your personal risks helps your care team take extra precautions.
| Risk Factor | Why It Increases Risk |
|---|---|
| Unexplained fainting (syncope) | When other tests are normal and spells are too rare to catch, a loop recorder is often the next step. It is a guideline-recommended choice. |
| Palpitations with no diagnosis | A racing or skipping heart that comes and goes, when shorter monitors keep missing it. |
| Stroke with no clear cause (cryptogenic) | To search for silent atrial fibrillation that may have caused the stroke. |
| Known or suspected atrial fibrillation | To measure how often AF happens, or to check how well treatment is working. |
| Possible slow heart rhythm or pauses | When we suspect the heart pauses or slows but cannot prove it on a short test. |
| Spells that may be heart-related seizures or falls | To tell a fainting spell from a seizure or a non-heart cause when the picture is unclear. |
Treatment Options
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
- Getting a loop recorder is a short, low-risk procedure. It is done while you are awake, with numbing medicine, usually in under 10 minutes. The diagram below shows the steps.
- It is placed as an outpatient. You go home the same day. Most people return to normal activity within a day or two.
- After placement, you do almost nothing day to day. The device watches on its own. You only mark a symptom if one happens.
- Your team reviews uploads on a schedule. If the device flags a serious rhythm, the team is alerted and contacts you.
- When an answer is found, treatment is matched to it: a pacemaker for dangerous pauses, a blood thinner for AF, an ablation or medicine for a fast rhythm, or simple reassurance if the rhythm is benign.
- The device is removed in a brief visit once it has done its job, or when the battery runs low after about 3 years. Removal is as quick as placement.
What to Expect — Day of the Procedure
- You check in as an outpatient. You can usually eat a light meal beforehand unless told otherwise. Bring your medication list.
- The skin over the upper-left chest is cleaned and numbed with a small shot. You stay awake the whole time.
- A cut under half an inch is made. The slim device slides just under the skin. No stitches go into the heart.
- The cut is closed with a small strip or a single stitch. A light dressing is placed. The whole thing takes about 10 minutes.
- Your team checks that the device is recording and uploading before you leave. You go home the same day, often within an hour.
What to Expect — The Weeks and Years After
- Soreness and bruising fade over a few days. Keep the site clean and dry, and avoid heavy lifting on that side for about a week.
- Day to day, you do almost nothing. The device watches on its own. Press the marker when you feel a symptom.
- Keep the bedside unit plugged in near your bed, or the phone app installed, so recordings upload while you sleep.
- Your team reviews uploads on a set schedule and reaches out if anything needs attention. You will also have routine check-in visits.
- When the cause is found, or the battery runs low after about 3 years, the device is removed in a brief, low-risk visit.
Who Is a Good Candidate — and Who Decides
- Good candidates have rare but worrying spells — fainting or palpitations — that shorter monitors keep missing.
- It is also a strong choice after a stroke with no clear cause, to search for silent atrial fibrillation.
- It is less useful when symptoms happen every day; a Holter or patch monitor may answer faster and without a procedure.
- The choice is shared between you and your cardiologist or heart-rhythm specialist (electrophysiologist), weighing how often spells happen and how serious they might be.
- See our Holter and event monitor guide and our palpitations guide to compare the options.
Comfort Measures at Home (No Medication Needed)
These simple steps support healing and ease symptoms. Use them alongside any medication your doctor prescribes.
- Keep the small cut clean and dry for the first few days, just as your team instructs.
- Avoid heavy lifting or hard arm exercise on that side for about a week, so the device settles in place.
- It is safe to shower once your team says the site has sealed. Pat it dry; do not scrub.
- Keep the bedside monitor plugged in near where you sleep, or keep the phone app installed, so recordings upload on their own.
- Carry your device ID card. Airport scanners and store security gates are fine, but the card explains the device if asked.
- MRI scans are allowed with most modern loop recorders, but always tell the MRI staff you have one first.
Risks, Benefits, and Alternatives
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
Every choice has trade-offs. Use this table to start the shared decision conversation with your care team.
| Option | Risks | Benefits | Alternatives |
|---|---|---|---|
| Implantable loop recorder (ILR) | Small chance of bruising, a pocket infection (about 1 to 2 in 100), or the device shifting. Rare skin irritation over the site. | Watches for up to 3 years, so it catches rare spells short tests miss. Quick to place and remove. Uploads on its own. | External patch or event monitor. Holter monitor. Tilt-table or EP study, depending on the question. |
| External patch or event monitor (worn on the skin) | Skin irritation under the patch. Falls off or comes loose. Only watches for 2 to 4 weeks. | No procedure at all. Good first step when spells happen often. Quick to start and stop. | Loop recorder if spells are rarer than the patch window. Holter for a 1 to 2 day question. |
| Holter monitor (1 to 2 days of recording) | Bulky to wear. Only watches 1 to 2 days, so rare spells are easily missed. | Simple, no procedure, fast result. Good when symptoms are daily. | Patch monitor for a few weeks. Loop recorder for rare spells. |
| Tilt-table test or EP study | Tilt can cause a brief faint by design. An EP study is an inside-the-vein test with its own small risks. | Can pinpoint certain causes (reflex fainting, electrical short-circuits) that a monitor cannot. | Loop recorder when the spell itself must be captured as it happens. See our fainting and EP-study guides. |
Common Misconceptions
| Myth | Reality |
|---|---|
| A loop recorder is a kind of pacemaker. | No. A pacemaker treats the heart by sending electrical signals. A loop recorder only watches and records. It cannot pace, shock, or change your rhythm. It is purely a monitor. |
| The procedure is major surgery. | No. It is a quick outpatient procedure done while you are awake. Numbing medicine is used. It usually takes under 10 minutes, and you go home the same day. |
| It will set off airport scanners or stop me from getting an MRI. | Security gates are fine; carry your ID card. Most modern loop recorders are MRI-safe. Just tell the MRI team you have one before any scan. |
| I have to do something every day to make it work. | No. The device records on its own around the clock. You only press the marker if you feel a symptom. Recordings upload by themselves, often overnight. |
| If the device finds nothing, the test was a waste. | Not true. A clean recording during a real spell is a valuable answer. It can rule out a dangerous heart rhythm and point the search in a new direction. |
| It is permanent. | No. It is removed once it has answered the question, or when the battery runs low after about 3 years. Removal is a quick visit, much like placement. |
| It tracks my location or my private health all the time. | It records your heart rhythm, not your location. It sends only rhythm data to your care team through a secure link. |
Possible Complications
Knowing what can go wrong helps you spot problems early. Most complications are uncommon, especially with treatment.
| Where / What | What Can Happen |
|---|---|
| Insertion site | Mild bruising or soreness is common and settles in days. A small number of people get a pocket infection (about 1 to 2 in 100). Signs are redness, warmth, swelling, drainage, or fever. |
| Device position | Rarely, the device shifts a little or, very rarely, works toward the skin surface. If it feels like it is poking out, the team checks and can reposition it. |
| Skin reaction | Some people get mild irritation or itching over the site. True allergy to the device is rare. Keep the area clean and tell us if it worsens. |
| False or extra alerts | The device may flag a recording that turns out to be harmless (for example, motion or a loose signal). This is not dangerous; it just means an extra review. |
| Missed window (rarely) | If a spell never happens during the years of monitoring, the cause may still be unknown at the end. The clean recordings still help by ruling out dangerous rhythms. |
| Removal | Taking the device out is quick and low-risk. Minor bruising or brief soreness at the site is the usual extent. |
Points to Know
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you remember nothing else, remember these key points.
- A loop recorder is a small monitor placed just under the skin. It watches your heart rhythm for up to about 3 years.
- It is not a pacemaker. It only records. It cannot pace or shock your heart.
- Placement is a quick outpatient procedure, done awake, in under 10 minutes. You go home the same day.
- Its long watch window is the point: it catches rare fainting spells and silent atrial fibrillation that short tests miss.
- Press the marker (or phone button) when you feel a symptom. That flags the exact moment for your team to review.
- Keep the bedside unit plugged in or the app installed so recordings upload on their own.
- Serious risks are uncommon: infection or the device shifting happens in only about 1 to 2 in 100 people.
- When the cause is found, treatment is matched to it, and the device is removed in a brief visit.
When to Call Us — and When to Call 911
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you are not sure, call. We would rather hear from you twice than miss a real problem.
- You faint or nearly faint again after the device is placed — call us; if you were hurt or it followed chest pain, call 911.
- Chest pain, severe shortness of breath, or a fast heartbeat that will not settle — call 911.
- Redness, warmth, swelling, drainage, or fever around the insertion site — call us today (possible infection).
- The skin over the device opens, or the device feels like it is poking through — call us today.
- The bedside monitor shows an error for several days, or recordings stop uploading — call us this week.
- You are scheduled for an MRI or any procedure — tell that team you have a loop recorder first.
- You feel a symptom and pressed the marker — call us if it was severe or did not pass quickly.
Office: (727) 943-5200
Fainting can be an emergency. If someone collapses and is not breathing normally, call 911, start CPR, and use an AED if one is nearby. Push hard and fast in the center of the chest, about 100 to 120 pushes a minute (the beat of the song "Stayin' Alive"). An AED will not shock a normal heart, so it is safe to use. The free PulsePoint app shows the nearest AED. Learn more in our fainting guide.
Trusted Resources
Independent, evidence-based pages we recommend for deeper reading.
- Cleveland Clinic — Implantable Loop Recorder — Plain-language overview of the device, the insertion, and what it detects.
- British Heart Foundation — Implantable Loop Recorder — Patient explainer on living with a loop recorder and how it captures fainting and palpitations.
- MedlinePlus — Holter Monitor and Ambulatory ECG — NIH/NLM background on heart monitoring, helpful for comparing external monitors with an ILR.
- American Heart Association — Arrhythmia Monitoring — AHA patient hub on irregular heart rhythms and the tests used to find them.
Sources Used to Build This Guide
- Cleveland Clinic — Implantable Loop Recorder [clinical] — Patient overview of the small under-skin monitor, the insertion, and what it detects.
- British Heart Foundation — Implantable Loop Recorder [clinical] — Patient explainer of how the long-term ECG monitor captures unexplained fainting and palpitations.
- CRYSTAL AF — Cryptogenic Stroke and Underlying AF (NEJM 2014) [clinical_trial] — Pivotal trial: ILR found AF in 12.4 percent at 12 months versus 2.0 percent with usual care after cryptogenic stroke.
- MedlinePlus — Holter Monitor / Ambulatory ECG [clinical] — NIH/NLM context distinguishing implantable from external/Holter monitoring.
- 2018 ESC Guidelines for the Diagnosis and Management of Syncope [guideline] — Class I recommendation for an ILR in recurrent unexplained syncope without high-risk features.
- 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Syncope [guideline] — U.S. guidance on when prolonged monitoring with an ILR is reasonable for infrequent unexplained syncope.
- Implantable Loop Recorder — StatPearls (NCBI Bookshelf, NIH) [clinical] — Device overview: indications, insertion, battery life (about 3 years), and monitoring period.
- Reveal LINQ Registry — Real-World ILR Performance (JAHA) [clinical_trial] — Large registry confirming low complication and infection rates (about 1 to 2 percent) with the modern small ILR.
