24 or 48-hour Holter monitor
A continuous recording of heart rhythm across one or two full days. This is the test for palpitations that come and go.
What it measures
- What it measures
- Records every heartbeat for 24 or 48 consecutive hours while you go about your normal routine. It finds intermittent arrhythmias, pauses in rhythm, and whether a symptom lines up with what the heart was doing electrically at that moment.
- Duration
- 24 or 48 hours
- Preparation
- No fasting. Bring any previous test results and the list of medicines you take.
- What it feels like
- You wear adhesive electrodes on the chest and a small recorder all day. It does not hurt; sleeping with it is awkward, and it cannot get wet.
- Referral from another doctor
- No
- Results
- Same day
- Where it is done
- Fitted at the office, then worn at home
What it shows
The axis is to scale and can be counted: the marks are every six hours. The window of an office electrocardiogram fits 8640 times into the day, which is why at this scale it is narrower than the line itself. The single mark is illustrative: the diagram does not say how many episodes anyone has, or of what kind. The drawing is the 24-hour recording; the 48-hour one is the same test worn for longer, and the ratio between the window and the day is unchanged.
- 01
- The office window. It is all a normal electrocardiogram gets to see, at the same scale as the drawing. It is there, and it cannot be seen.
- 02
- A symptom that comes and goes. It falls outside that window, which is exactly why this test exists.
- 03
- The whole day. The device goes with you and records without stopping: while you work, while you walk and while you sleep.
The Holter exists because arrhythmias do not keep appointments. A patient can feel palpitations three times a week and still arrive with a flawless electrocardiogram, simply because the heart behaved during those ten seconds.
A symptom diary comes with the recorder. Writing down the exact time a symptom occurred is what turns the recording into a diagnosis: it lets the tracing from that minute be matched against what you felt.
A normal Holter in a patient with frequent symptoms does not close the case. When episodes are more sporadic, longer recordings are available.