A Holter monitor is a small, portable device that continuously records the heart's rhythms as well as the electrical activity of the heart. A Holter monitor may be used to capture information and check an individual's heart rhythm if results of other tests, such as an electrocardiogram (EKG), have been inconclusive. The monitor is worn for 24 to 48 hours during normal activity, and it it records the heart's electrical activity during that time period.
Because patients are only hooked up to an EKG machine for a short time, it may not detect any irregularities in the heart rhythm. If symptoms suggest that an individual may be experiencing an irregular heart rhythm, a doctor may recommend wearing a Holter monitor for one to two days. Over that time, the Holter monitor may be able to detect irregularities in the heart rhythm that an electrocardiogram was unable to detect. A Holter monitor may also be used to monitor heart rate after a heart attack or to monitor the effectiveness of new heart medication.
How a Holter Monitor Works
Electrodes are placed on the patient's chest. The electrodes are attached by wires to a small recording monitor. The Holter monitor runs on batteries and is carried in a pocket or pouch worn around the neck or waist. The Holter monitor, worn for 24 to 48 hours and records the heart's activity throughout that time period. This consistent monitoring may detect arrhythmias that only occur at certain times, such as after physical exertion. While wearing the Holter monitor, individuals are asked to record any symptoms and activities, so the doctor can link them to the results of the Holter monitor. This information is often helpful in identifying the cause of heart rhythm problems
Results of Holter Monitoring
After the Holter monitor is removed, the doctor will review the results of the test and compare them with any information that the patient recorded while wearing the monitor. A diagnosis may be determined from the results of this test, however in some cases, additional testing may be necessary. There is no risk involved in using a Holter monitor and the tests is painless.
Implantable Cardioverter Defibrillator
An implantable cardioverter defibrillator (ICD) is an electronic device that is implanted under the skin, and is used to detect an abnormal heartbeat. An ICD is often implanted in individuals with arrhythmias (irregular heartbeats). This device uses electrical impulses to control dangerous arrhythmias that may lead to heart attack or sudden cardiac arrest. If an abnormal heartbeat is detected, the ICD will deliver an internal electric shock to the heart, restoring a normal heart beat as needed.
Candidates for an ICD
Individuals at risk for ventricular arrhythmia may include people who have:
- Had a heart attack
- Experienced cardiac arrest
- Congenital heart disease
- Brugada syndrome
- Existing ventricular arrhythmia
When ventricular arrhythmias occur, the heart cannot properly pump the blood. This may cause a person to lose consciousness within seconds and die within minutes if not treated. The ICD can prevent life-threatening ventricular arrhythmias with an electric shock to the heart.
How an ICD Works
An ICD is a small, battery-operated device that is implanted under the skin, below the left collarbone, to help maintain a regular heartbeat. The ICD sends electronic signals to the heart to help it pump properly when needed. The ICD consists of two flexible parts: the lead and the pulse generator. The lead monitors and treats the heart, while the generator contains a battery and tiny computer. When a very fast or abnormal heart beat is detected, the ICD sends energy to the heart to shock it and help it return to a normal rhythm.
The ICD Implantation Procedure
A cardioverter defibrillator is surgically implanted and the procedure is performed in a hospital. A small incision is made under the collarbone, and the lead is placed in a vein and led to the heart chamber, while the generator remains attached to it and is placed under the skin of the upper chest. After the ICD is implanted, the doctor programs it to treat the individual's specific heart rhythm problem.
Considerations of ICD Implantation
Although rare, complications of an ICD implant may include infection, bleeding, damage to veins or puncture of the heart or lung. Patients should avoid strong electric or magnetic fields after the implantation of the cardioverter defibrillator. An ICD battery lasts an average of 7 to 10 years and should be checked regularly and replaced by a doctor when necessary.