The ECG in patients with palpitations and syncope
Ambulatory ECG monitoring
Although sometimes a baseline ECG between episodes can provide supporting evidence for a potential diagnosis, the only way to be certain that a patient’s symptoms are due to an arrhythmia is to show that an arrhythmia is present at the time of the symptoms. This may require ECG monitoring for longer periods than the 12-lead ECG, and in this chapter we will describe some of the technological options available for ambulatory monitoring of the ECG.
Types of ecg monitors
There is an expanding range of ECG monitoring technologies available to aid diagnosis (Tables 3.1 and 3.2). Selecting the best options depends on local availability and the nature and frequency of patient episodes. If symptoms occur frequently – say two or three times a week – a 24- to 72-h tape recording (called a ‘Holter’ record after its inventor) may show the abnormality. Traditional lead-based monitors (Table 3.1a) are being replaced by disposable patch adhesive monitors (Table 3.2b) which are water resistant to allow the patient to shower. These will often enable monitoring for a week or more if longer periods are needed. The latest wireless enabled devices can send data to a small device or hub, which can then relay data via the mobile phone network to the analytical centre for assessment.
TABLE 3.1
| Monitoring device | Mode of use | Duration and mode of recording | Applications | Comments |
|---|---|---|---|---|
(a) Holter monitor   | Usually three electrodes placed on chest wall for maximal signal; activation button can be used in association with patient diary to highlight symptomatic events | Usually 24 h, but up to 7 days Usually 1–2 channels, but up to 12 leads possible | Suitable for palpitations, syncope or presyncope occurring fairly frequently (e.g. daily) | Analysis time-consuming, but aided by software |
(b) Cardiac memo   | Device placed directly on to the skin by patient when symptomatic, or can be adapted to use with electrodes; traces can be downloaded by telephone | 10–20 recordings of 30–60 s | Suitable for palpitations lasting for several minutes, enabling patient to apply device and record trace | Not suitable for syncope, because patient activation required |
(c) Loop recorder   | Usually three electrodes placed on chest wall; position of electrodes may require rotation, especially if there is skin reaction | Recording period programmable; usually 4 min pre-and post-activation Can record 2000–3000 periods (‘loops’) of ECG records, including patient-activated and autoactivated episodes Autoactivation function programmable, based on heart rate and on QRS complex duration and irregularity | Increasingly replacing memo devices Useful for diagnosis of palpitations or syncope | Can be kept in place for long periods, although batteries may need replacing periodically |
(d) Implantable loop recorder Get Clinical Tree app for offline access 
|
