BACKGROUND: Sudden cardiac arrest (SCA) is a condition in which the heart suddenly stops beating. When it happens, blood stops flowing to the brain and other organs. The heart has an electrical system that controls the rhythm and rate of the heartbeat. The problems with the heart’s electrical system can lead to irregular heartbeats, known as arrhythmias. During an arrhythmia, the heart can beat too slow, too fast, or with an irregular rhythm. Arrhythmias can cause the heart to stop pumping blood to the body; these are the ones that cause sudden cardiac arrest. SCA is not the same as a heart attack. A heart attack doesn’t usually cause the heart to stop beating suddenly. However, SCA can happen during or after recovery from a heart attack. (Source: www.nhlbi.nih.gov)
CAUSES: Ventricular fibrillation (v-fib) causes most sudden cardiac arrests. V-fib is a type of arrhythmia that causes the ventricles to beat irregularly, causing the heart to pump too little or not enough blood to the body. Certain diseases and conditions can also cause the electrical problems that lead to SCA, like coronary heart disease. Physical stress, like intense physical activity and severe lack of oxygen, is another cause of electrical system failure. Structural changes in the heart can have an impact on the electrical system. Examples can include an enlarged heart due to high blood pressure or advanced heart disease. Heart infections can also cause structural changes in the heart. Finally, arrhythmias can run in the family. Members of families with arrhythmias are at a greater risk. (Source: www.nhlbi.nih.gov)
NEW TECHNOLOGY: When a person experiences sudden cardiac arrest (SCA) while asleep, the chance of survival is minimal. The LifeVest is a personal defibrillator worn by the patient who is at risk for SCA. It monitors the heart constantly. So, if a patient goes into an arrhythmia, the LifeVest delivers a shock treatment to restore the patient’s heart to normal. The two major components of the LifeVest include: a garment and a monitor. The garment is lightweight and is worn underneath clothing and contains electrodes to pick up the patient’s electrocardiogram. The monitor is about the size of a paperback book and is worn around the waist or from a shoulder strap. The monitor reads the patient’s ECG continuously. If the patient experiences ventricular fibrillation (rapid, uncontrolled heartbeat) or ventricular tachycardia (rapid heartbeat), the LifeVest makes an alarm sound to verify that the patient is nonresponsive. If the patient is conscious, then they can respond to the alarms by pressing two buttons to stop the treatment. If they do not respond, then the device warns bystanders that a chock is about to be delivered. If the arrhythmia continues and the patient is still nonresponsive, then the shock will be delivered through the garment electrodes. If the patient’s heartbeat then returns to normal, the alarms stop and the LifeVest returns to monitoring. However, if the patient’s heartbeat is still abnormal and the arrhythmia continues, then the treatment cycle will repeat itself (up to five treatment shocks are possible).
The difference between a LifeVest and an automatic external defibrillator (AED) is that an AED requires a bystander to witness an arrhythmia event and operate the device and administer treatment to the patient. The LifeVest does not need bystander intervention. Patients can transfer information from their devices by connecting them to a normal telephone line so that their doctor can evaluate the data. The LifeVest sends the data over a secure phone line, password protected database that is part of a website called LifeVest Network. Physicians can access the website at any time and view patient information, which includes their ECG recordings, noise data, compliance data, and other information related to the device. (Source: http://my.clevelandclinic.org/heart/services/tests/procedures/lifevest.aspx)