Pacemakers are small electric devices, about the size of a pocket watch. They are put under the skin below the collarbone near the heart. Implantable cardioverter-defibrillators (ICDs) are also small, pager-sized devices. They’re also put below the skin on the left side of the chest. Both devices control abnormal heartbeats (arrhythmias). Pacemakers send signals to the heart to speed up a slow beat. One-chamber pacemakers have one wire connected to the heart. Two-chamber pacemakers have wires to both top and bottom heart chambers (atria and ventricles). Another kind, biventricular, stimulates both bottom chambers. ICDs send electric shocks to the heart to make the heart rhythm normal.
Pacemakers and ICDs have two parts: a pulse generator (including battery and computer) and wires connecting the device and heart.
Almost all pacemakers are used for slow heartbeats (bradycardia, heart block). These abnormal heartbeats are caused by aging, heart disease, or medications. People with fainting, dizziness, and shortness of breath due to heart rate abnormalities may need pacemakers. Other reasons for pacemakers are heart muscle damage, drugs, and genetic conditions. People with dangerously fast heartbeats (ventricular tachycardia) or fast, irregular heartbeats (ventricular fibrillation) may need ICDs. ICDs are also used for weakened hearts (e.g., from heart attacks), heart conditions involving abnormal heart muscle, and inherited heart disorders.
Before surgery, the health care provider may order electrocardiography (ECG), 24-hour Holter monitoring (ECG), echocardiography, and stress tests. People getting ICDs may also need to have electrophysiology studies done.
Minor surgery to put in pacemakers and ICDs is usually done under local anesthesia. Surgery usually takes 1–3 hours. During the operation, a flexible, insulated wire is put into a large vein near the collarbone and guided to the heart. One end is attached to the heart, and the other ends go to the device.
Complications from surgery are rare (in less than 5% of people). They may include infection at the place of the incision and allergic reactions to anesthesia. Swelling, bruising or bleeding, damage to blood vessels or nerves near the pacemaker, and collapsed lungs may occur.
Cell phones, security systems (such as at airports), and power-generating equipment might cause problems. Medical procedures, including magnetic resonance imaging, might also. However, people with these devices need not worry about microwave ovens, televisions, remote controls, radios, toasters, and electric blankets, shavers, and drills.
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