An implantable defibrillator is a small, battery-powered electrical generator that is fixed just underneath the skin in the chest. Wires run from the defibrillator through a large vein and into one or both of the right chambers of the heart. When a patient's heart rhythm becomes too fast or too slow, the device emits a low-energy electrical pulse to restore normal contraction rates. The implantable defibrillator can also emit a higher energy shock if heart rate slows to a life-threatening level or stops completely. Most modern devices record patterns, allowing doctors to periodically check the heart's performance and make decisions about whether further treatment is necessary.
A doctor may decide to implant a defibrillator if a patient has frequent arrhythmia problems or is at risk of sudden cardiac failure. A similar device called a pacemaker, which only emits low-energy pulses, can be used if the risk of heart failure is low. There are few risks associated with the surgery itself, and most defibrillators continue to work for about five years before they need to be replaced.
The procedure to embed an implantable defibrillator is relatively simple and quick, and it can usually be performed while the patient is under a gentle sedative. A local anesthetic is injected into the chest and a small incision is made in the skin. With the aid of real-time x-rays, the surgeon affixes the generator underneath the skin and runs wires through a vein to the right atrium and ventricle. The surgeon tests the wires to make sure they are working properly before suturing the skin incision. Patients are generally kept in the hospital overnight so doctors can monitor recovery.
A person may need to limit physical activity for several days after receiving an implantable defibrillator. Frequent checkups with the surgeon or a cardiologist in the first few weeks after surgery are important to make sure the device works. Regular activity levels can be resumed after about a month if complications do not arise. The doctor can also explain what types of medications are safe to use with the defibrillator in place.
An implantable defibrillator constantly monitors and records heart function. It only emits pulses when the generator detects an abnormality. A series of low-energy pulses cause heart chambers to contract and pump blood at a steadier rate when necessary. In the case of sudden heart failure, the generator delivers a painful shock similar in intensity to external defibrillators used in hospitals. It is essential to call an ambulance after receiving a shock, even if symptoms get better, to receive proper treatment and monitoring.