The, 'LifeVest,' is a personal defibrillator that is worn by a person at risk for sudden cardiac arrest (SCA). The vest monitors the person's heart on a continual basis and if the person goes into a life-threatening arrhythmia, the LifeVest delivers a shock to restore the person's heart to a regular rhythm.
A common treatment for life-threatening cardiac dysrhythmias, ventricular fibrillation and pulse-less ventricular tachycardia. Defibrillation consists of delivering a therapeutic dose of electrical energy to the heart with a device called a defibrillator. This depolarizes a critical mass of the heart muscle, terminates the dysrhythmia and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart. Defibrillators can be external, transvenous, or implanted (implantable cardioverter-defibrillator), depending on the type of device used or needed. Some external units, known as automated external defibrillators (AEDs), automate the diagnosis of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully with little or no training at all.
What is an, 'arrhythmia'
An arrhythmia, also referred to as, 'dysrhythmia,' is an irregular or abnormal heartbeat. There are different kinds of arrhythmias. For example:
Ventricular Arrhythmias: Ventricular arrhythmias are ones that start in the ventricles.
Bradycardia: Bradycardia is a slow heart rhythm with a rate under 60 beats per minute.
Tachycardia: Tachycardia is a fast heart rhythm with a rate of greater than 100 beats per minute.
Bradyarrhythmias: Bradyarrhythmias are slow heart rhythms that might be caused by disease in the heart's conduction system, such as the sinoatrial (SA) node, HIS-Purkinje network, or atrioventricular (AV) node.
Supraventricular Arrhythmias: Supraventricular arrhythmias are ones that start in the, 'atria,' or the heart's upper chambers. 'Supra,' refers to above while, 'ventricular,' refers to the lower chambers of the heart or ventricles.
What causes arrhythmias
They may be caused by a number of things. Arrhythmias may be caused by things such as:
How the LifeVest Works
The LifeVest is comprised of two main components - a monitor and a garment. The garment is lightweight and comfortable and is worn underneath a person's clothing. It contains electrodes to pick up the person's electrocardiogram (ECG). The monitor is about the same size as a paperback book and is worn around the person's waist, or from a shoulder strap.
The monitor constantly reads the person's ECG. If the person has, 'ventricular tachycardia,' or rapid heartbeat or, 'ventricular fibrillation,' which is a rapid, uncontrolled and ineffective heartbeat, the device will sound an alarm to verify whether or not the person is responsive. If the person is conscious, they have time to respond to the alarms by pressing two buttons to stop the treatment sequence.
If the person does not respond, the device warns people nearby that a shock is about to be delivered. If the arrhythmia continues and the still does not respond to the warnings, a treatment shock is administered through the electrodes in the garment. After the shock has been administered, if the person's heartbeat returns to an acceptable rate the alarms stop and the LifeVest returns to its usual monitoring mode. If the person's heartbeat does not return to an acceptable rate; however, and the arrhythmia continues - the treatment cycle repeats. Up to five treatment shocks may be administered.
The Difference between the LifeVest and an Automatic External Defibrillator (AED)
An AED requires a bystander to witness an arrhythmia event such as ventricular fibrillation, then operate the device and administer treatment to the person who is experiencing arrhythmia. To be effective, the treatment must be delivered within a few minutes of the event. The person's chances of survival drop by around 10% for every minute after the onset of fibrillation, so it is vital that a bystander take action quickly.
In contrast, people who use the LifeVest do not require intervention from a bystander. The device constantly monitors the person's ECG and if a lethal arrhythmia happens, the LifeVest administers a treatment shock commonly within a single minute. The LifeVest protects the person, even when the person is sleeping or by themselves. An AED is unable to provide the same kind of protection.
The Difference between the LifeVest and an Implantable Cardioverter Defibrillator (ICD)
The ICD, as well as the LifeVest, provide continual protection to the person. The device may provide protection as a bridge to ICD implantation or cardiac transplantation. It may be useful in higher risk people who are being considered for ICD implantation but who may not meet the criteria for implantation. For example; people who have had large myocardial infarctions, or undergone coronary re-vascularization with decreased left ventricular function may be candidates for ICD implantation if their ventricular function does not improve after 1 to 3 months.
The LifeVest can provide protection during this period of time. People who have an infection or malfunction of their ICD and are waiting for re-implantation may also use the LifeVest during the time they are waiting as their infection clears, or until the ICD procedure is performed. It can be potentially used in place of hospitalization for people undergoing anti-arrhythmic drug loading for other arrhythmias, such as atrial fibrillation, to protect against worsening of ventricular arrhythmias during the early drug initiation phase.
Keeping a Doctor Aware
People transmit information from their devices by connecting them to a regular telephone line. The LifeVest then sends the information over the phone line to a secure and password protected database that is part of a web site called, 'LifeVest Network.' Doctors can access LifeVest Network any time and view the person's information, to include ECG recordings - both automatic and manual, compliance information such as how long the person wears the device, noise information and additional device-related data.