Cardiac Holter
The holter is a portable device uninterrupted allowing the recording electrocardiogram during at least 24:00
History
Its name comes from the name of Dr. Norman Holter, biophysicist American who created this technique in 1949, in the form of a portable valisette of a little more than 30 kg. The recording of the cardiac electrical signal was then made in an analogical way on a simple audio cassette 60 minutes, idling. End of the year 80 saw appearing the first numerical recordings, initially on chips, then on removable memory cards.
Material
The holter comprises two parts:- a case of recording entrusted to the patient and connected to this last by electrodes (five generally, allowing to record two about orthogonal derivations, the last electrode acting as neutral) fixed at the skin by an adhesive. This case comprises a button which the subject can actuate if it feels something during the recording (Palpitation S, thoracic pains or other): a reference mark will be registered then on the recording, making it possible to the doctor to directly go to consult the layout at this time and to thus make the diagnosis of it.
- a console of treatment: it is about a Ordinateur provided with a software allowing visualization and the semi-automatic analysis with the recording.
The patient must ideally hold up to date a sheet where it describes his activity during the recording.
It is about a completely painless and nondangerous examination. One should not obviously wet the case during the recording (nor even after…).
Contrary to the techniques of medical imagery (DICOM), there currently does not exist of data-processing standard of storage allowing the exchange of information between various systems.
Interpretation
The holter is a useful examination for the diagnosis of the Troubles of cardiac conduction and the rhythmic turbid , especially if they are paroxystic (i.e. intermittent), and sometimes asymptomatic (not felt by the patient).
One can thus know the heart rate maximum and minimal, the existence or not Bradycardie, of Tachycardie, the number and the type of Extrasystole S.
The analysis of the disorders of the repolarization (segment ST) makes it possible to evaluate the presence of a cardiac Ischémie and can be revealing of a coronary disease of the S
The holter makes it possible to also evaluate the effectiveness of a treatment given against the rhythmic disorders.
Limitations
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the recording does not exceed a few days for reasons of size memory of the case, but also of quality of the electrical signal which is degraded if the electrodes are left a long time in place.
- the essential problem remains the computerized management of the artefacts (background noises), badly managed by the current software, and which can obstruct the interpretation of the examination considerably.
Various types of holters
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the modern holters can record between two and twelve tracks. One is in this last case limited by the number of electrodes (ten) and by the cable becoming handy with more difficulty.
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Certains cases comprises their own system of analysis what theoretically makes it possible to do without the console of reading and to have thus a result as of the end of the recording. The reliability of these systems is however limited.
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One finds Holter cases now which can go more than one week and having an automatic release in the event of crisis. (Example R.Test Evolution or the Vista More at Novacor), the problem being to find a doctor practitioner this type of examination.
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the plantable holter consists of a metal case of the size of a small lighter which is established under the skin (in general under a Clavicule), under local anesthesia. It allows a recording which can go up to one year.
In any rigor, the name of holter indicates an only electrocardiographic recording. By extension, one speaks about holter tensionnel (whose true name is ambulatory MAPA = monitoring of the blood pressure) or about other type of holters recording over one long period of other medical data.