Holter Monitoring (24-Hour ECG)

Your heart races for ten minutes in the middle of the market, then settles. By the time you reach the clinic it's beating normally and the ECG shows nothing, because a standard ECG records only about 10 seconds.

A Holter monitor records your heart rhythm continuously through an ordinary day. Sticky electrodes on your chest connect by thin wires to a recorder the size of a mobile phone, worn on a belt or in a pouch. It logs every beat, usually for 24 or 48 hours, while you keep a diary of what you were doing and feeling.

The test works well when symptoms happen most days. If they come once a month, a 24-hour recording will probably miss them and a longer monitor makes more sense. A clear result still helps: if you felt your usual palpitations and the rhythm was normal at that moment, a dangerous rhythm is very unlikely to be the cause.

Holter monitors for 24-hour rhythm tracking are part of our cardiology unit, and a cardiologist reads your recording and diary side by side.

A Holter recording is used when symptoms suggest a rhythm problem, or when a known rhythm problem needs checking.

The report lists your fastest, slowest and average heart rates, with the times they happened. A rate that dips into the 40s during sleep is often normal. It also counts extra beats from the upper chambers (atrial ectopics) and lower chambers (ventricular ectopics, often written VPCs). A few hundred a day is common in healthy people. A very high count, more than roughly 1 in 10 beats, may need an echo to check the heart muscle.

The findings that matter most are runs of abnormal rhythm, such as atrial fibrillation, supraventricular tachycardia (SVT) or ventricular tachycardia, and pauses of 3 seconds or more while awake, especially if their timing matches your diary.

Depending on the result, the next step may be reassurance, rhythm medicines, a blood thinner if atrial fibrillation is found, an echocardiogram, or a pacemaker for significant pauses or heart block. Some fast rhythms respond well to a catheter procedure called ablation, for which you may be referred.