An implantable loop recorder is a tiny, thin device roughly the size of a small USB flash drive or an AAA battery cut in half lengthwise. It sits just beneath the skin on your upper left chest, where it continuously monitors your heart rhythm. Most people are surprised by how small it actually is.
Size and Shape of the Device
Modern loop recorders are narrow, flat rectangles with slightly rounded edges. The most widely used model, the Medtronic Reveal LINQ, measures about 45 millimeters long, 7 millimeters wide, and 4 millimeters thick. That’s roughly the length of a standard paperclip and about as wide as a pencil. Other models are somewhat larger: the Abbott Confirm Rx measures 49 by 9 by 3 millimeters, while the Biotronik BioMonitor 2 is noticeably bigger at 88 by 15 by 6 millimeters.
These devices have gotten dramatically smaller over the years. Earlier generations of loop recorders were closer in size to a lighter or a pack of gum and required a more involved surgical placement. Current models are small enough to be inserted through a tiny incision in a procedure that takes only a few minutes.
What It Looks Like Under Your Skin
The device rests just beneath the skin, not deep in the body. After healing, you might notice a faint outline of the recorder if you look closely or press on the area, but it’s not visible to other people in normal situations. The device is placed on the left upper chest, typically over the breastbone area or slightly to the left.
The incision used to insert it is small, closed with either dissolving stitches or surgical glue, and covered with a small bandage. Once healed, the scar is minimal. If surgical glue is used, it peels off on its own within about seven days. The result is a very small, faint line that fades over time. For most people, the cosmetic impact is negligible.
The External Equipment You’ll Have
The implanted device is only one part of the system. You’ll also receive two pieces of external equipment that live outside your body.
The first is a patient activator, a handheld gadget about the size of a computer mouse. You carry this with you and use it when you feel symptoms like palpitations, dizziness, or fainting spells. When something happens, you hold the activator over the recorder on your chest and press a button. A blue light flashes while it searches for the device, and a green light confirms the symptom has been marked. It has a small connection slot so you can attach it to a keychain or lanyard, making it easier to keep nearby at all times.
The second piece is a bedside monitor, often called a CareLink monitor. This is a wireless unit roughly the size of a small clock radio that you plug in next to your bed, ideally on a nightstand. It communicates with the implanted recorder and automatically transmits your heart rhythm data to your medical team using a mobile phone signal. You don’t need to do anything with it beyond keeping it plugged in and nearby while you sleep.
What the Device Actually Does
A loop recorder continuously records your heart’s electrical activity, storing data in a loop. It overwrites older data unless something triggers it to save a segment permanently. That trigger can come from you pressing the patient activator, or the device itself can detect irregular rhythms automatically and flag them for review.
The recorder contains two small sensing electrodes built into its surface that pick up electrical signals from the heart through the surrounding tissue. Because it records continuously for up to three years, it’s especially useful for catching heart rhythm problems that happen infrequently, the kind that a standard 24-hour or even 30-day external monitor might miss entirely.
How It Compares to Other Heart Monitors
If you’ve worn a Holter monitor (the kind with sticky patches on your chest connected by wires to a small box clipped to your belt), a loop recorder is a completely different experience. There are no external wires, no patches that irritate your skin, and nothing visible. Once the small incision heals, the device is essentially invisible. You can shower, exercise, and go about daily life without adjusting anything.
Compared to a pacemaker, which is implanted deeper in the chest and connected to wires threaded into the heart, a loop recorder is far smaller and simpler. It only monitors; it doesn’t deliver any electrical signals to your heart or change how your heart beats. The implantation is a minor outpatient procedure rather than a full surgery.