Under normal, healthy conditions the human heart beats 60 to 100 times a minute. In the course of a day, the heart pumps an equivalent of 2,000 gallons of blood, carrying essential oxygen and other nutrients to all of the body's cells. Ultimately, the brain coordinates this complex process, but the heart also has its own semi-independent power station. Most of this electrical activity is carried out by pacemaker cells located in the upper right-hand portion of the heart muscle known as the sinus node. From the sinus node, beat impulses are relayed to other areas of the heart via special groups of interlocking relay cells.
To have a properly functioning heart, all four of the heart's chambers must receive the beat signal in the proper sequence. The chambers are divided into the right atrium and ventricle and the left atrium and ventricle. The pair on the right side of the heart pumps oxygen-depleted blood coming back from the rest of the body into the lungs for fresh oxygen. The pair on the left side moves freshly oxygenated blood returning from the lungs to the many organs of the body.
Many factors affect the heart rate, or the number of heartbeats per minute. The rate goes up when we exercise or are emotionally aroused, and goes down when we rest or sleep. Irregularities, however, also can originate within the heart itself. This type of disturbance is known as an arrhythmia, and it can not only affect the rate at which the heart beats but also its pattern of beating.
Most people experience skipped beats or minor palpitations from time to time; these generally are of no medical significance. Other types of arrhythmias, however, are potentially quite serious.
Sinus Rhythm Disturbances
Some rhythm disturbances are due to a malfunction of the heart's pacemaker cells. These commonly occur in one of two forms: bradycardia, in which the heart beats at an abnormally slow rate, and tachycardia, in which it pulsates at 100 or more beats per minute. In itself, neither condition is particularly worrisome. In fact, a slow heart rate is often found in highly trained athletes whose hearts have been conditioned to beat more slowly, pumping a greater volume of blood per beat. In some older people, however, an abnormally slow beat may be a sign of an underlying disease. In such cases, there is usually a telltale rhythm of fast beats followed by slow ones. And while this pattern is not necessarily a cause for concern, in some individuals it can lead to loss of consciousness or dizziness due to poor output of blood from the heart. In these cases, an artificial pacemaker may stabilize the heartbeat.
Tachycardia arising in the pacemaker cells also may be harmless. The exceptions include an accelerated rapid heartbeat, which may indicate congestive heart failure, or conditions in which there is both a rapid beat and some other problem involving the heart and blood vessels.
Atrial Rhythm Disturbances
Though the relay cells in the atrium chamber are designed to pass on beat impulses sent out by the pacemaker cells, sometimes they acquire the ability to produce a beat on their own. Since such beats occur just before the "true" heartbeat, they are known as atrial premature beats. Commonly associated with the heavy use of tobacco, alcohol and coffee, these beats disappear once the stimulants are removed. However, when they are accompanied by palpitation, fluttering in the chest, rapid heartbeat, dizziness or shortness of breath, they may indicate underlying heart disease. In such cases, treatment with drugs may be indicated.
Potentially far more serious is atrial fibrillation, a condition in which the muscles of he atrium contract in an erratic, uncoordinated fashion. In most instances, it can be corrected by drugs; at times, it may be necessary to employ a technique called cardioversion, a type of electrical shock designed to restore normal rhythm. One major complication of atrial fibrillation is blood clotting. Usually, these clots from in the left atrium and then move out into the general circulatory system, where they can produce a potentially serious blockage. Anti-clotting drugs are therefore often prescribed for people with this condition.
In persons with narrowed coronary arteries, the onset of atrial fibrillation may produce chest pain, particularly if the heart rate speeds up dramatically. This combination of symptoms is frequently a warning sign of pending heart failure or a heart attack. The rapid beat must therefore be slowed immediately with either drugs or a medical procedure.
Another significant rhythm disturbance is atrial tachycardia, in which the muscles of the atrium beat much faster than those of the ventricle, producing an erratic heart rate. Symptoms such as a sense of fullness in the chest, light-headedness and chest flutters are also common. Problems often associated with this disturbance include rheumatic heart defects, hyperthyroidism, pneumonia and blood clots in the lungs. Drug therapy is often the most effective treatment.
Ventricular Rhythm Disturbances
The relay cells in the ventricles, like those in the atria, also may acquire the ability to produce a heartbeat on their own. Called a ventricular premature beat, this condition may be traceable to excessive use of caffeine, cigarettes or alcohol. But since it can also be the sign of a serious cardiac disorder, it should be investigated. Prompt medical attention is crucial in cases of ventricular tachycardia. As its name implies, this problem involves rapid beating of the ventricles (usually over 100 to 120 beats per minute), and the danger is that the rate may increase even further, leading to ventricular fibrillation and possibly death.
Summing Up
Disturbances in heartbeat and heart rhythm are among the most common forms of cardiac disorders. While not all such disturbances have medical significance, some can be extremely serious unless they receive proper medical attention. Drug therapy is often used to treat various forms of arrhythmias, strict adherence o the dosage instructions given by your doctor is most important.
Hospitalization - Admission Procedures
The procedures you follow on admission to a hospital vary from one hospital to another, but basically the process is the same in most institutions in the United States.
Care of the Dying - Role of Friends
The friend can show appreciation of the work being done by the family and offer to stay with the patient if the family needs a little time away from home.
Care of the Dying - Death of an Older Child or an Adolescent
From the age of three years onward, a child begins to understand the concept of death and dying. The dying child feels protective toward his or her parents. Although the child desperately needs to talk about what is going to happen, he or she may never get close to the subject. The child may attach himself or herself to a nurse or physician while still relying on the parents. By doing this, the child is sharing the emotional responsibility. The parents may find this difficult to accept, but must realize that someone else can perhaps give more help by listening dispassionately to the child's fears and anxieties.
