American Medical Association Family Medical Guide - American Medical Association [341]
Symptoms
In most people, first-degree and second-degree heart block usually do not produce symptoms. Third-degree heart block may cause sudden loss of consciousness, seizures, or stroke. In some people, third-degree heart block may produce symptoms of heart failure (see page 570), such as shortness of breath or fatigue. If you are an older person and you have episodes of dizziness, weakness, or confusion, see your doctor as soon as possible. Although these symptoms have many possible causes, early detection and treatment of heart block may save your life.
Diagnosis
To diagnose heart block, your doctor will examine you and will probably order an electrocardiogram (ECG; see page 559), an examination of the electrical activity of the heart. You may need to wear a portable electronic ECG device called a Holter monitor (see page 580) to record the electrical activity of your heart for 24 hours or longer.
Treatment
If the doctor has determined that your heart’s natural pacemaker is causing your symptoms, he or she may recommend temporary or permanent insertion of an artificial pacemaker (see next page) to regulate the heartbeat.
Paroxysmal Atrial Tachycardia
In healthy adults, the heart beats from 60 to 100 times per minute, and increases to about 160 beats per minute during physical activity. In an episode (or paroxysm) of atrial tachycardia, the heart rate suddenly jumps to 160 or more beats per minute without physical exertion. An episode of paroxysmal atrial tachycardia can last from about 1 minute to several days.
Symptoms
Palpitations (heartbeats that you’re aware of) are the main symptom of paroxysmal atrial tachycardia. If you suddenly become aware of your rapid heartbeat, you may become anxious or frightened. Some people who have paroxysmal atrial tachycardia say they have a feeling of impending death. Other symptoms can include shortness of breath, fainting, angina (chest pain), or frequent urination. Despite the anxiety or fear it may cause, paroxysmal atrial tachycardia is not life-threatening, although sometimes it can lead to congestive heart failure (see page 570). If you have recurring symptoms of paroxysmal atrial tachycardia, see your doctor.
Pacemakers and Implantable Defibrillators
An electronic pacemaker is a battery-operated device that is often used to treat severe arrhythmias. A pacemaker may be temporary or permanent. A temporary pacemaker is usually inserted under the skin of the chest after a heart attack has disturbed the heart’s normal rhythm. The pacemaker produces electrical impulses that keep the heart beating at a normal rate. In most people, the heart rate returns to normal in a few days and the temporary pacemaker is removed.
A permanent pacemaker is implanted under the skin of the chest to regulate an abnormally slow heart rate. When the heart rate slows, or when the heart misses a beat, the pacemaker produces electrical impulses that restore a normal heart rate. After the heart rate returns to normal, the pacemaker stops producing the impulses until they are needed again. The pacemaker also can produce electrical impulses at a constant rate, depending on a person’s needs.
Pacemaker
A pacemaker is an electronic device that is implanted just beneath the skin and attached to the heart with very thin wires. The device delivers an electrical impulse (at a fixed rate or whenever it is needed) to an electrode placed in one of the ventricles of the heart. A pacemaker is powered for 8 to 10 years by a tiny battery that a doctor can easily replace in a minor surgical procedure.
During the Procedure
Implanting a pacemaker is a minor surgical procedure that is performed while the person is awake. To implant a pacemaker, the doctor numbs the chest with a local anesthetic, makes a 2-inch incision just below the collarbone, and inserts a catheter (a thin, flexible tube) through