Event Monitor
Recording The Heart's Electrical Impulses

Heart medical testing devices


Event Monitor


What Is A Heart Event Monitor?
What Are The Different Types of Monitors?
How Does An Event Monitor Work?
Who Needs Event Monitoring?

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Heart Disease in Women
Heart Disease Testing

What Is A Heart Event Monitor?

Event Monitors are medical devices which are used for heart disease testing and the diagnosis of chest pain. They record a person's heart electrical activity (ECG) and are usually prescribed by a doctor to diagnose a heart arrhythmia. Where a Holter Monitor records ECG continuously over a 24 to 48 hour period, an Event Monitor records intermittently over a few weeks or months. This may be necessary because a standard external electrocardiogram (EKG or ECG) or a 24 hour Holter Monitor has not managed to capture relevant data for a diagnosis. Some patient may only show symptoms of a heart problem infrequently and unpredictably.

Although an Event Monitor can be taken off for bathing it should be worn 24 hours a day. Event monitors tend to be smaller than Holters because they need to store less information - they only record when an incidence occurs as opposed to continual recording. There are different types of Event Monitors, some which require sticking patches with wires to the chest area and linking the wires to a recording device. Others do not require patches but are worn like a bracelet or watch. People who only experience symptoms a few times a year may be recommended an implantable device which is inserted in the chest for up to 18 months.

What Are The Different Types of Monitors?

Postevent Recorders

These are the smallest of the Event Monitor devices and they can be worn like a bracelet or wristwatch. Alternatively there is a version which can be carried in a pocket and is about the size of a standard beeper. Postevent recorders do not connect with wires and sensors to the chest. Instead, when symptoms occur the person places the device against their chest and clicks the record button. Devices worn on the wrist simply require pushing a button on the monitor to start recording. Postevent recorders only start recording when the patient pushes the record button. If they have difficulties doing so at the onset of symptoms the event will not be recorded, or vital parts of the information may be missed if there are any delays. The information is stored on a digital chip in the monitor which can then be transmitted via telephone to the cardiologist's office where it is recorded on paper. This is known as Transtelephonic Monitoring (TTM). Typically TTMs are worn for 30 days and help detect arrhythmias and assess symptoms such as palpitations, dizziness and fainting spells. They may also be used to test the effectiveness of anti-arrhythmia drugs. Many hospitals loan the monitors to patients for the duration of the testing period. A technician will clearly explain how the device works and the patient will be given an opportunity to practice using it before going home. A cardiologist assesses the information as it comes in over the 30 days and then forwards the information to the patient's doctor.

Event Monitor (Loop Recorder)

This is the most common type of event device and it is similar to a Holter Monitor. It is worn 24 hours a day but may be removed briefly for showering or bathing. It is used to capture data from arrhythmias which may not occur regularly. Small electrodes are attached to the chest and wires leading from the sensors are attached to a recording device which is worn on a belt or shoulder strap. When symptoms occur the patient pushes a button on the monitor which triggers a memory of what was recorded 60 seconds before the 'event', the event itself is recorded and up to 40 seconds after. A monitor can record several events which can then be transmitted by telephone or bought to the doctor's office directly. If the reading indicates an emergency, the patient will be contacted immediately and advised to go straight to A&E.

Autodetect Recorders

Similar to a standard loop recorder, autodetect recorders require placing sensors on the chest which hook up to a recording device. However, the difference is that autodetect recorders do not need to be manually started. Instead, as soon as they detect an abnormal heartbeat (whether the patient feels it or not), it starts instantly recording and transmits the information directly to a cardio center which is operated around the clock by cardiac technicians. The technicians analyze each transmission and give diagnostic reports to the patient's doctor. If the patient feels another symptom such as dizziness or fainting, they can press a special button on the monitor to indicate this so that the cardio center can rule cardiac causes in or out. CardioNet is one of the leading so-called Mobile Cardiac Outpatient Telemetry (MCOT) companies which provide this ambulatory ECG monitoring service to many hospitals in America.

Implantable Loop Recorders (ILR)

This is an implantable device which was developed for people who only experience symptoms a few times a year. It may be that an external ECG or 24 hour Holter Monitor was not able to capture relevant information. An ILR is about the size of pack of gum and it is inserted under the skin of the chest and can be worn for up to 18 months (with a battery life between 15 and 18 months). However it may be removed sooner if the physician makes a diagnosis. The procedure to implant the device is simple. A local anesthetic is injected into the area of skin where the implant is to be placed (usually the left side of the chest), a small incision is made and the device is inserted. The skin is then closed with dissolvable stitches. The procedure takes about 15 minutes and a course of antibiotics may be prescribed to prevent infections. An ILR is used to diagnose patients experiencing palpitations, dizziness or loss of consciousness (fainting or blackouts). The device continuously records the heart's activities, similar to an ECG. The recordings can then be evaluated by a cardiac physiologist. To capture the data from a recorded episode the patient needs to place a hand held activator over the ILR and press a button to save the information. Ideally this should be done while experiencing the symptoms or soon after. The hand device needs to be carried at all times.

Know The Risks: Risk Factors for Heart Disease.
Stats: Heart Disease Statistics and UK Heart Disease Statistics.

How Does An Event Monitor Work?

Loop recorders are the most commonly prescribed type of Event Monitor, so we will discuss their preparation and use here.

Attaching Electrodes
Small sticky pads called electrodes will need to be securely attached to the chest skin to get a clear recording. To do so:
• Wipe the area of skin with an alcohol swab and dry with gauze pads provided by your doctor.
• Attach the lead wires to the electrodes before attaching the electrodes to the chest.
• Attach the electrodes to the chest; you will be given a diagram to show where exactly.
• Change the electrodes every day or more often it they stop sticking.
• Plug the wires into the top of the recorder and secure the recorder to a belt or strap.

• When you feel a symptom such as chest pain (see chest pain in women), palpitation, shortness of breath then press the RECORD button on the monitor.
• Try to relax and remain still while it is recording.
• You will hear a series of beeps when it finishes recording.
• After recording you will see a sign in the display window to indicate that the monitor is full and ready for transmission.
• The information is transmitted by a regular landline phone. The patient is given a specific phone number to call. Once dialed, they unplug the lead wire and then place the monitor next to the mouthpiece of the phone. They press the SEND button and the monitor will emit a whistling sound while it is transmitting information. The noise will stop when the transmission is completed. The home telephone number is always the patient's identification number.
• Cell phones and iPods can interfere with the transmission so keep them well away from the monitor.

Who Needs Event Monitoring?

Common reasons include:

• People who are suspected of having arrhythmia but where an external ECG or 24 monitoring have failed to pick up evidence for diagnosis.
• Patients with episodes of chest pain, shortness of breath or fatigue which cannot be explained.
• To monitor how patients are reacting to arrhythmia treatments or coronary heart disease treatment, including coronary bypass surgery.
• Patients who need to be evaluated for arrhythmia before major surgery.
• To diagnose atrial fibrillation.
• To diagnose tachycardia (fast heartbeat).
• To diagnose bradycardia (slow heartbeat).
• To uncover evidence of heart block.
• To uncover evidence silent myocardial ischemia.
• To monitor people with sleep apnea.
• To diagnose why a patient is fainting regularly. See, why do I feel faint?
• To determine if a pacemaker or an implantable cardioverter defibrillator is necessary.


Related Articles on Heart Event Monitors

For more heart disorders, see the following:

Nuclear Heart Scan / Echo Test / Exercise Stress Test
Chemical Stress Test / Heart Catheterization /Calcium Score Test

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