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Symptoms

Arrhythmias, whether mild or severe, do not always cause symptoms. Because of this, even a life-threatening arrhythmia can go undetected. Possible symptoms of an arrhythmia include palpitations (heartbeats that you’re aware of), dizziness, fainting, shortness of breath, and angina (chest pain). An arrhythmia can sometimes be a symptom of a serious underlying disorder. If you have symptoms of an arrhythmia, see your doctor.

Diagnosis

Your doctor will examine you, check your pulse, and listen to your heart through a stethoscope. He or she will probably order an electrocardiogram (ECG; see page 559) to evaluate your heart rate and rhythm. If the arrhythmia seems to come and go, you may need to wear a Holter monitor for 24 hours or longer. A Holter monitor is a portable ECG device that you wear over your shoulder, around your neck, or at your waist, with electrodes attached to specific areas of your chest. While you go about your daily routine, the monitor records your heart’s electrical activity on a special cassette tape. After 24 hours, the doctor reviews the recorded information to make a diagnosis.

Sometimes a person may use a smaller device called an event recorder, which is used only at the time the arrhythmia occurs. A person who has a severe arrhythmia may need to be hospitalized for continuous ECG monitoring. In some cases, a person is placed on a table that tilts from horizontal to vertical while an ECG is performed to diagnose some forms of arrhythmia.

The cause of some arrhythmias can be determined by examining the heart in a cardiac catheterization procedure (see page 592), in which a thin, flexible tube is inserted into the heart through an artery or vein in the groin or in the arm. When diagnosing arrhythmias, doctors may also perform blood tests to check for chemical imbalances or thyroid problems.

Treatment

Mild arrhythmias often do not require treatment. More severe arrhythmias and those that produce intolerable symptoms may be treated with beta blockers (see page 562), calcium channel blockers (see page 563), or medications that slow the heart’s electrical impulses. You may need to try several drugs before finding the medication that works best for you.

Some severe arrhythmias are treated surgically. Coronary artery bypass surgery (see page 564) and coronary angioplasty (see page 565) are sometimes used to treat arrhythmias that result from heart disease. A procedure called catheter ablation uses radiofrequency energy to destroy or remove a spot on the heart that is causing an arrhythmia. This procedure is similar to cardiac catheterization (see page 592); a catheter is threaded into the heart, and the radiofrequency therapy is delivered through the catheter.

Many severe arrhythmias are treated by temporarily or permanently implanting an electronic pacemaker (see page 584) beneath the skin of the chest. A pacemaker is a battery-powered device that produces electrical impulses that regulate the heartbeat.

Cardiac Arrest

Cardiac arrest means that the heart is beating ineffectively or has stopped beating. Possible causes of cardiac arrest include ventricular tachycardia (a rapid, ineffective heartbeat originating in the ventricles), ventricular fibrillation (a disorganized, ineffective attempt by the ventricles to contract), or cardiac asystole (cessation of heartbeat). When cardiac arrest occurs, the heart cannot beat effectively, the brain does not get enough blood, and loss of consciousness occurs immediately. Cardiac arrest in a person who seems healthy usually results from undetected heart disease (see page 558). Cardiac arrest can begin with ventricular tachycardia and degenerate into ventricular fibrillation.

WARNING!

Cardiac