Holter Monitors, Event Monitors, Ambulatory Monitors, and Implantable Loop Recorders

Chapter 8


Holter Monitors, Event Monitors, Ambulatory Monitors, and Implantable Loop Recorders





1. What are the major indications for ambulatory electrocardiography (AECG) monitoring?


    AECG monitoring allows the noninvasive evaluation of a suspected arrhythmia during normal daily activities. It aids in the diagnosis, documentation of frequency, severity, and correlation of an arrhythmia with symptoms such as palpitations, lightheadedness, or overt syncope. AECG monitoring can be extremely helpful in excluding an arrhythmia as a cause for a patient’s symptoms if there is no associated event during monitoring. AECG can also be used to assess antiarrhythmic drug response in patients with defined arrhythmias. Occasionally AECG is also used in other situations. The current major indications for AECG monitoring, from the American College of Cardiology/American Heart Association (ACC/AHA), are given in Box 8-1.



Box 8-1   SUMMARY OF THE AMERICAN COLLEGE OF CARDIOLOGY/AMERICAN HEART ASSOCIATION GUIDELINES FOR AMBULATORY ELECTROCARDIOGRAPHY





Class IIb (Usefulness/Efficacy Is Less Well Established by Evidence/Opinion)



image Patients with episodic shortness of breath, chest pain, or fatigue that is not otherwise explained


image Patients with symptoms such as syncope, near syncope, episodic dizziness, or palpitation in whom a probable cause other than an arrhythmia has been identified but in whom symptoms persist despite treatment


image To assess rate control during atrial fibrillation


image Evaluation of patients with chest pain who cannot exercise


image Preoperative evaluation for vascular surgery of patients who cannot exercise


image Patients with known coronary artery disease and atypical chest pain syndrome


image To assess risk in asymptomatic patients who have heart failure or idiopathic hypertrophic cardiomyopathy or in post–myocardial infarction patients with ejection fraction less than 40%


image Patients with neurologic events, when transient atrial fibrillation or flutter is suspected


2. What are the different types of AECG monitoring available?


    The major types of AECG monitoring include Holter monitors, event monitors, ambulatory telemetry, and implantable loop recorders (ILRs). The type and duration of monitoring is dependent on the frequency and severity of symptoms. Most modern devices have the capability for telephonic transmission of electrocardiography (ECG) data during or after a detected arrhythmia. Each system has advantages and disadvantages; selection must be tailored to the individual. With any system, however, patients must record in some fashion (e.g., diary, electronically) symptoms and activities during the monitored period.



image A Holter monitor constantly monitors and records two to three channels of ECG data for 24 to 48 hours. It is ideal for patients with episodes that occur daily.


image An event monitor constantly monitors two to three channels of ECG data for 30 to 60 days. However, it will only record events when the patient experiences a symptom and presses a button that triggers the event monitor to store ECG data 1 to 4 minutes before and 1 to 2 minutes after the event. Some event monitors will also store arrhythmias that are detected by the monitor itself, based on preprogrammed parameters. An event monitor is appropriate for patients with episodes that occur weekly or monthly.


image Ambulatory real-time cardiac monitoring has various monikers. it has been termed ambulatory telemetry, real-time continuous cardiac monitoring, or mobile cardiac outpatient telemetry (MCOT). Ambulatory telemetry is a monitoring system that continuously records a 1- to 3-lead strip for 14 to 30 days. Depending on the vendor, the ECG data is either stored for offline interpretation or instantaneously transmitted for interpretation by a monitoring technician. In cases where the rhythm is monitored by a technician in real time, the patient or physician can be contacted immediately after an arrhythmia has been detected, to minimize delays in treatment. No patient action is necessary for an arrhythmia to be stored, and patient compliance can easily be assessed. These features facilitate the detection of silent or asymptomatic arrhythmias.


image An implantable loop recorder (ILR) is an invasive monitoring device allowing long-term monitoring and recording of a single ECG channel for over a year. It records events similarly to an event monitor, based on patient’s symptoms or automatically based on heart rate. It is best reserved for patients with more infrequent episodes occurring greater than 1 month apart from each other.


3. How does an ILR work?

Related posts:

  1. Exercise Stress Testing
  2. Nuclear Cardiology
  3. Endomyocardial Biopsy
  4. Pulmonary Hypertension

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Jun 5, 2016 | Posted by in CARDIOLOGY | Comments Off on Holter Monitors, Event Monitors, Ambulatory Monitors, and Implantable Loop Recorders

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