External Monitor

A standard EKG records about ten seconds of your heart's rhythm. If your symptoms come and go, that snapshot will usually be normal — not because nothing is wrong, but because nothing was happening at that moment. An external monitor solves this by recording continuously while you go about ordinary life, so the rhythm during a symptom can finally be captured.

The device is worn on the skin with adhesive sensors and records to memory, transmits automatically, or both. You press a button or note the time whenever you feel a symptom, and that marker lets the physician line up exactly what your heart was doing against what you felt.

Which device you are given depends on how often your symptoms occur:

• Holter monitor — records every beat for 24 or 48 hours. Best for symptoms that happen daily or nearly so, and for measuring the overall burden of an arrhythmia already known to be present
• Patch monitor — a single adhesive patch worn continuously for up to about 14 days. Comfortable, showerable and the most common choice for intermittent palpitations
• Event monitor — worn for up to about 30 days, recording when triggered or when it detects an abnormal rhythm. Suited to symptoms that occur only every week or two
• Mobile cardiac telemetry — transmits continuously to a monitoring center that can alert your physician promptly. Used when a significant rhythm problem is suspected

If symptoms are rarer still — a fainting episode every few months — an implanted loop recorder becomes the better answer, since it monitors for years.

• Palpitations, skipped beats or a racing heart
• Fainting, near-fainting or unexplained dizziness
• Detecting atrial fibrillation, including after a stroke of unclear cause
• Measuring how much atrial fibrillation is present and whether rate control is adequate
• Checking whether a medication or an ablation is working

The recording is only as good as the contact between sensor and skin. A few things help:

• Skin is prepared and sometimes lightly shaved so the adhesive holds
• Avoid lotions, oils and powders on the chest for the duration
• Follow the specific device's guidance on showering — patches are typically water-resistant, while older Holter units are not and must be kept dry
• Keep the symptom diary. A recording with no notes shows the rhythm but not which moment mattered; the diary is what makes the study interpretable
• Return the device or its data promptly, as nothing is read until it comes back

The full recording is processed and then reviewed by a cardiologist, who correlates any abnormal rhythms against your diary entries. A monitor that captures a symptomatic episode and shows a normal rhythm is a genuinely useful result — it points the search elsewhere rather than leaving the question open.