A wearable cardioverter defibrillator (WCD) is a non-invasive medical device designed to protect individuals at risk for sudden cardiac arrest (SCA). This external device, often resembling a vest, continuously monitors the heart’s electrical activity. Its primary function is to detect life-threatening irregular heart rhythms, such as ventricular tachycardia or ventricular fibrillation, and deliver a corrective electrical shock if needed. The WCD provides a temporary layer of protection, allowing healthcare providers time to assess a patient’s long-term cardiac risk and determine appropriate next steps.
How a Wearable Defibrillator Works
The WCD system consists of a fabric vest worn against the body, an electrode belt, and a separate monitor unit. The vest contains dry, non-adhesive sensing electrodes that continuously detect the heart’s electrical signals. These signals are transmitted to the monitor unit, which houses the battery and advanced algorithms to analyze the heart’s rhythm.
When the monitor identifies a life-threatening arrhythmia, it initiates an alert sequence to notify the patient. This sequence involves vibrations felt on the back, followed by audible alarms and voice prompts. If the patient is conscious and responsive, they can press a button on the monitor to prevent the shock delivery, indicating the detected rhythm is not a true cardiac arrest.
Should the patient become unconscious and fail to respond to the alerts, the device proceeds with therapy. Conductive gel is automatically released from the therapy electrodes within the vest to ensure proper contact with the skin. Subsequently, a defibrillating electrical shock is delivered to the heart to restore a normal rhythm. This entire process, from arrhythmia detection to shock delivery, occurs within one minute.
Medical Indications for a WCD
A WCD serves as a temporary protective measure for patients with a heightened, but potentially transient, risk of sudden cardiac arrest. It acts as a bridge solution while their underlying heart condition is being managed or assessed. One common scenario for its use is following a recent major heart attack, particularly if the heart muscle is significantly weakened with a low ejection fraction.
Patients newly diagnosed with conditions like cardiomyopathy or myocarditis may also be prescribed a WCD as they undergo treatment and their long-term risk profile becomes clearer. The device can be used while awaiting a heart transplant. It also provides a safeguard for individuals who require an implantable cardioverter-defibrillator (ICD) but cannot immediately receive one, such as due to an active infection.
Daily Life with a Wearable Defibrillator
Living with a WCD involves adhering to specific routines to ensure its effectiveness. The vest is designed to be worn nearly continuously, 24 hours a day, seven days a week, with the main exception being short periods for bathing or showering. Proper fit of the vest is important for accurate monitoring and comfortable wear.
Patients are instructed on the daily routine of changing and charging the device’s batteries. Most systems come with two batteries, allowing one to charge while the other is in use. Many normal daily activities, including light exercise, spending time with family, and chores, can be continued while wearing the WCD. Patients should discuss specific activities like driving with their doctor and be aware of any local regulations.
Education for both the patient and their family is important regarding the device’s alerts and how to respond. Understanding the different sounds and messages helps in distinguishing between routine notifications and a potential life-saving event. This preparedness helps ensure the device functions as intended.
Distinctions from an Implantable Defibrillator
The wearable cardioverter defibrillator (WCD) and the implantable cardioverter-defibrillator (ICD) both deliver electrical therapy for dangerous heart rhythms, but they differ fundamentally. The WCD is an external, non-invasive device. An ICD, by contrast, is a small, battery-powered device surgically placed under the skin, usually in the chest, with leads extending into the heart.
The duration of use is another distinction; the WCD is a temporary solution, worn for weeks to several months. An ICD is a long-term or permanent device, intended for patients with a persistent, high risk of sudden cardiac death. ICDs also possess pacing capabilities to help regulate slow heart rhythms, a feature not present in WCDs.
A notable difference lies in patient interaction during an event. The WCD incorporates an alert sequence that allows a conscious patient to prevent a shock by pressing a button if the alarm is not a true cardiac emergency. Conversely, an ICD delivers a shock automatically once a life-threatening rhythm is detected, without this interactive step. The WCD often serves as a transitional measure to determine if a patient’s risk is temporary or if a permanent ICD is required.