Cardiac pacemaker discharge at about 40-60 beats per minute, and are called the "secondary pacemaker". Further down the electrical conducting system of the heart is the Bundle of His. The left and right branches of this bundle, and the Purkinje fibres, will also produce a spontaneous action potential at a rate of 30-40 beats per minute, so if the SA and AV node both fail to function, these cells can become pacemakers. It is important to realize that these cells will be initiating action potentials and contraction at a much lower rate than the primary or secondary pacemaker cells. The SA node
Cardiac muscle cell by disruptions to cardiac muscle cell growth and / or organization. Presentation can range from asymptomatic to sudden cardiac death. Cardiomyopathy can be caused by genetic, endocrine, environmental, or other factors. Cardiac muscle cell Cardiac muscle cells or cardiomyocytes (also known as myocardiocytes or cardiac myocytes) are the muscle cells (myocytes) that make up the cardiac muscle (heart muscle). Each myocardial cell contains myofibrils, which are specialized organelles consisting of long chains of sarcomeres, the fundamental contractile units of muscle cells. Cardiomyocytes show striations similar to those on skeletal muscle cells. Unlike multinucleated skeletal cells, the majority of cardiomyocytes contain