Pacemaker and Defibrillator Lead Extraction
Surgically implanted cardiac devices play an important role in the treatment of heart disease. Approximately 400,000 devices are implanted in patients each year in the United States, with more than three million patients implanted with these devices currently.
One part of the device system is the pulse generator, a metal container which surrounds electrical circuits and a battery, which is usually placed under the skin on the chest wall beneath the patient’s collarbone. The device’s wires (or leads) run between the pulse generator and the heart. In a pacemaker, the leads allow the device to increase the patient’s heart rate by delivering small bursts of electrical energy to make the heart beat faster. In a defibrillator, the lead has special coils which deliver a high-energy shock to convert a dangerous heart rhythm (such as ventricular tachycardia or fibrillation) back to a normal heart rhythm.
In order to work correctly, the leads from a traditional cardiac device must be in contact with heart tissue. Most leads pass through a vein under the collarbone and into the right side of the heart (right atrium and right ventricle).
To hold the lead in place inside of the heart, most leads have either a small screw or hooks at the end. Within a few months of implantation, the body forms scar tissue along the lead and at its tip, which helps keep it securely in place inside the patient’s body.
Leads usually last longer than device batteries, so existing leads can often be reconnected to each new pulse generator (battery) at the time of the replacement.
Although implantable cardiac devices are designed to be permanently implanted in the body, occasionally it is necessary to remove (extract) the leads. The most common reasons for lead extraction include: infection, a broken lead or a lead which is not functioning properly or (rarely) a mechanical lead failure which could prove dangerous to the patient, such as a protruding wire.
Sometimes a lead can be left inside the body, with a new lead implanted alongside it. However, veins can only contain a limited number of leads due to space constraints. As a result, sometimes non-functioning leads must be extracted in order to make space for a new lead.