When doctors speak of cardiac arrhythmia, they mean a category of conditions manifested by the irregular heartbeat that is faster or slower than normal. Some forms can be life-threatening because they can lead to cardiac arrest and sudden death. Other forms can bring about aggravating symptoms. These include an acute awareness of an increase or decrease in the heart rate or heart palpitations.
A moderately fast heartbeat followed by slowing of the normal rhythm is referred to as sinus arrhythmia. The normal adult heart rate ranges from 60 beats per minute to 100 beats per minute. A small area in the upper chamber of the heart known as the sinoatrial node or sinus node controls it.
A fast heartbeat of above 100 beats per minute is called tachycardia. The heart rate of a person changes with age, which means that a younger person's heartbeat is naturally faster than that of an older person. The sinus node increases its rate of electrical activity to accelerate the heart rate during exercise. The normal heart rate resulting from exercise is called sinus tachycardia. It is caused by fast, abnormal electrical activity, and it can result in dangerous tachycardia disorders.
There can be severe problems if the ventricles of the heart experience one of these tachycardia conditions for a prolonged period. Patients often perceive a tachycardia as a pounding sensation of the heart known as heart palpitation. If a tachycardia results in lowered blood pressure, it sometimes causes lightheadedness, dizziness, or even fainting. A overly fast tachycardia can impede the pump function of the heart, and this can cause sudden death.
A slow rhythm, i.e., a heart rate of less than 60 beats per minute is called bradycardia. This is usually not a life-threatening problem, but it can result in symptoms that may require implantation of a permanent pacemaker. Both tachycardia and bradycardia call for medical attention, since a doctor must evaluate the risks associated with them.
This is one of the more serious types of abnormal heart muscle contractions. In fibrillation, the heart's muscle begins a quivering motion caused by a lack of coordination in contractile cell function. This type of cardiac arrhythmia can affect the atrium and cause atrial fibrillation. It can also affect the ventricle and cause ventricular fibrillation, which is imminently life-threatening.
Doctors call a quivering, chaotic motion in the upper chambers of the heart as atrial fibrillation. The causative factor is usually a serious underlying medical condition, which needs medical evaluation. However, it does not always qualify as a serious medical emergency. Another variant is ventricular fibrillation, which happens in the lower chambers (or ventricles) of the heart. Without timely administration of medical treatment, it can lead to death within minutes. Effective pumping of blood stops when a heart goes into what doctors call 'V-fib', a condition considered as a form of cardiac arrest.
Patients suffering from it are unlikely to survive unless they receive cardiopulmonary resuscitation and defibrillation immediately. In the last few minutes of life, almost all persons go into ventricular fibrillation because the heart muscle reacts to diminished oxygen or general blood flow, trauma, irritants, or depression of electrical impulses from the brain.
Disclaimer: This article is for informative purposes only, and should not be used as a replacement for expert medical advice.