The heart is essential for life, pumping blood through the body with an average of 100,000 beats a day, 60-100 beats per minute. The muscle is made of the myocardium, specialized muscle fibers that rhythmically contract when working properly, resulting in the heartbeat. Primary myocardial diseases are the forms of heart disease based on problems with the myocardium and not secondary to other problems, such as a lack of oxygen, a current infection, hypertension, or diabetes. (Secondary heart disease is discussed in another article.)
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