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Arrhythmia
The heart is the chief organ of the cardiovascular system. It is a muscle that is responsible for pumping blood to all parts of the body. The heart is divided into four chambers: two atria and two ventricles. The normal sequence of the heartbeat is known as the sinus rhythm (1). This begins in the atria after an electrical impulse is sent from the heart's natural pacemaker. The impulse then travels down special fibers to the ventricles. The left ventricle is the primary pump of the heart, delivering blood to all points south of the heart. The heart beats normally at a pace of 60 to 100 beats per minute and never stops beating as long as a person is alive. However, interruptions in the normal heartbeat are known to occur.
The arrhythmia describes any abnormal electrical impulse that causes an irregular heart rhythm (1). Moreover, the efficiency of the heart's ability to pump blood to vital organs may be adversely affected. Fortunately, the majority of arrhythmias are harmless and affect most people occasionally. It is common for arrhythmias to cause noticeable symptoms such as: palpitations, chest pain, shortness of breath, feeling faint, and dizziness (2). Doctors frequently detect arrhythmias during a routine examination that are present without symptoms. Typical causes of arrhythmias include: heart disease, hypertension, diabetes, smoking, alcohol or caffeine abuse, drug abuse, stress, certain medications, and dietary supplements.
The two major types of arrhythmias are classified based on the speed they cause the heart to beat (2). Tachycardia refers to a heart rate greater than 100 beats per minute, while bradycardia describes a heart rate of less than 60 beats per minute. Tachycardias may be either atrial or ventricular in origin. Bradycardias are often seen in the hearts of athletes due to extreme cardiac efficiency. Age and genetics are known to naturally increase the risk of developing arrhythmias.
- American Heart Association. "What are arrhythmias?" 2007.
- Mayo Clinic. "Heart Arrhythmias." Mayo Foundation for Medical Education and Research. February 16, 2007.