A Holter monitor is a kind of ambulatory monitoring device which makes a continuous recording of a patients’s echocardiogram (ECG) for a period of twenty four hours. The Holter is named after Norman J. Holter, who invented the first ambulatory ECG monitor in 1963. It is widely used in diagnosis and monitoring of heart arrhythmia and cardiac ischemia.
Other common applications include the evaluation during drug therapy of heart rhythm, rate and interval changes, the identification of asymptomatic atrial fibrillation or dysrhthmia, and evaluating specific clinical situations such as postcoronary bypass surgery, post-pacemaker implant recovery, implanted defibrillator or pacemaker malfunction, or postmyocardial infarction.
The Holter’s light weight, noninvasive design, and ease of use allow it to be worn by a patient all through his normal daily activities. The device is thus able to record and capture whatever intermittent irregularities and arrhythmias occur during that time, and to correlate them with subjective reports of dizziness, chest pain, palpitations, shortness of breath and so on. The Holter can pick up events that happen less frequently, compared to a regular ECG, which only records for less than one minute.
Holter Monitor System
The Holter monitoring system consists of a portable, lightweight echocardiogram recorder with three or more lead wires and a Holter scanner analyzer unit. Modern day Holter units have improved functions and portability in the 4 plus decades since the fists ones were created.
The portable ECG recorder can be either the traditional cassette tape based type, or the now more common digital type, which records onto a flash memory card. The tape type of recorder has a more limited data capacity, and the analog nature of the tape, which needs to be physically delivered to the analyzing physician’s office, where it is analyzed with the Holter scanner, or converted to digital form for computer processing, all of which takes longer to produce a final report from.
Digital recording has higher capacity that can extend the recording period past 24 hours if required. The main advantage, of course, is that recorded data can be instantly downloaded and transmitted to the analyzing physician via e-mail, wireless or phone line. Reports are therefore available much sooner, and if needed, treatment can be begun or modified immediately.
A more recent form of digital cardiac monitoring is the Cardiac Event Monitoring (CEM) system. CEM is like a Holter monitor except that it only records a patient’s ECG when certain pre-defined events occur, for example, if the patient experiences palpitations or other irregularities. This means even longer period can be monitored and recorded more cost-effectively.