Pacemakers and Defibrillators

An implantable cardioverter-defibrillator is a device that resuscitates the heart by attempting to restore a normal heartbeat in a patient whose heart is beating rapidly and in a disorganized way. This is a lifesaving therapy and is similar to the machines ambulances bring to patients in the midst of cardiac arrest when the heart stops. In patients with significant heart disease who are determined to be at risk of sudden cardiac death, implantable cardioverter-defibrillators are placed to shock the heart and resuscitate the patient. An implantable cardioverter-defibrillator is about the size of a Zippo lighter. It is attached to a wire placed in the right side of the heart much like a pacemaker. An implantable cardioverter-defibrillator has the capacity to pace the heart like a pacemaker, but it also has the capability to shock the heart and resuscitate or stop a cardiac arrest.

The procedure is performed in the electrophysiology laboratory. Under light sedation, a 5-centimeter incision is made either on the left or right side of the chest, just below the collarbone. The battery is placed under the skin, and a vein located underneath the collarbone is isolated. Then, the wires are placed through that vein to allow entry to the right side of the heart. The wires are attached to the device and the wound is closed. 

When the patient undergoes implantation of an implantable cardioverter-defibrillator, the patient also will need testing of the device, which requires sedation while the physician puts the patient into arrhythmia. Under monitored conditions, the device treats the arrhythmia and places the patient back into normal rhythm. An overnight stay in the hospital is expected for this type of procedure.

In patients who experience fatigue, dizziness or fainting due to a slow heartbeat, a mechanical generator called a pacemaker is necessary to pace the heart to allow normal blood flow. Pacemakers are small computers that are about the size of two stacked half-dollars. The generator, which is placed under the skin by the left or right collarbone, is attached to either one or two small wires that are placed in the vein and the right side of the heart. Pacemakers are programmed by the physician and the batteries usually last 5-10 years.

A patient who needs a pacemaker will be admitted to the hospital. In the electrophysiology laboratory under conscious sedation, the pacemaker generator is placed under the skin. Veins that run underneath both sides of the collarbone are used to access entry to the right side of the heart. The wires are placed in these veins, called subclavian veins. The wires are then attached to the generator and the wound, which is about 4 centimeters long, is closed and the patient stays overnight in the hospital. 

After a pacemaker is placed, there are few limitations for the patient other than decreased movement of the arm on the side where the pacemaker was placed for 1-2 weeks. Pacemakers are covered in titanium which prevents abnormal function from environmental electrical signals. Patients with pacemakers can use household appliances, cellular telephones and microwave ovens. Large magnetic fields can be dangerous for pacemaker patients, such as during an MRI, but CT scans, ultrasounds and other medical imaging devices are still allowable after receiving a pacemaker.