Editing Holter monitor (section)

==Components==
Each Holter system has hardware (called monitor or recorder) for recording the signal, and software for review and analysis of the record. There may be a "patient button" on the front that the patient can press at specific instants such as feeling/being sick, going to bed, taking pills, marking an event of symptoms which is then documented in the symptoms diary, etc.; this records a mark that identifies the time of the action on the recording. Advanced Holter recorders are able to display the signal, useful for checking the signal quality.

===Recorder===

The size of the recorder differs depending on the manufacturer of the device. The average dimensions of today's Holter monitors are about 110x70x30&nbsp;mm, but some are only 61x46x20&nbsp;mm and weigh&nbsp;99 g.<ref>[http://www.superecg.com/en/hearthbug/reliable-and-accurate/ HeartBug technical specifications] {{webarchive|url=https://web.archive.org/web/20131004213531/http://www.superecg.com/en/hearthbug/reliable-and-accurate/ |date=2013-10-04 }}</ref>

Most Holter Monitors monitor the ECG via two or three channels. Depending on manufacturer, different lead systems and numbers of leads are used; the number of leads may be minimised for patient comfort. Two or three channel recording has been used for a long time in the Holter monitoring history; 12-channel Holters were introduced later, using either the standard 12-lead electrocardiograph or the modified (Mason-Likar) [[Cardiac stress test|exercise lead]] system.<ref>{{cite journal | last1=Papouchado | first1=M. | last2=Walker | first2=P. R. | last3=James| first3=M. A. | last4=Clarke | first4=L. M. | title=Fundamental differences between the standard 12-lead electrocardiograph and the modified (Mason-Likar) exercise lead system | journal=European Heart Journal | publisher=Oxford University Press (OUP) | volume=8 | issue=7 | date=1 July 1987 | issn=0195-668X | doi=10.1093/eurheartj/8.7.725 | pages=725–733| pmid=3653124 }}</ref> 

These Holters can occasionally provide information similar to that of an [[ECG]] stress test examination. They are also suitable when analyzing patients after [[myocardial infarction]]. Recordings from these 12-lead monitors are of a significantly lower resolution than those from a standard 12-lead ECG, and in some cases have been shown to provide misleading ST segment representation, even though some devices allow setting the sampling frequency up to 1000&nbsp;Hz for special-purpose examinations such as detection of "late potential".

Another innovation is the inclusion of a triaxial movement sensor, which records the patient's physical activity and, on examination and software processing, extracts three movement statuses: sleeping, standing, or walking. Some modern devices can record spoken patient diary entries that can be listened to.

===Analyzing software===

[[File:Cubeholter.jpg|thumb|250px|Screenshot of Holter ECG software]]
After the recording of ECG signal for typically 24 hours, the signal must be analysed. A person would have to listen for the full 24 hours; instead integrated automatic analysis determines different sorts of heart beats, rhythms, etc. The success of the analysis is closely associated with the signal quality, which mainly depends upon the attachment of the electrodes to the patient's body. Incorrect attachment allows electromagnetic disturbance to add noise to the record, particularly with rapid patient movement, impeding processing. Other factors can also affect signal quality, such as muscle tremors, sampling rate and resolution of the digitized signal (high quality devices offer higher sampling frequency).

The automatic analysis commonly provides the physician with information about heart beat morphology, beat interval measurement, [[Heart rate monitor|heart rate variability]], rhythm overview and patient diary (moments when the patient pressed the patient button). Advanced systems also perform spectral analysis, ischemic burden evaluation, graph of patient's activity or PQ segment analysis. Also possible is the ability to monitor and analyse [[pacemaker]] impulse detection, useful for checking pacemaker function.