Heart rate variability are needed to address the LF component (with a lower bound of 0.04 Hz). Although time domain methods, especially the SDNN and RMSSD methods, can be used to investigate recordings of long durations, a substantial part of the long-term variability is day–night differences. Thus, long-term recordings analyzed by time domain methods should contain at least 18 hours of analyzable ECG data that include the whole night. Although cardiac automaticity is intrinsic to various pacemaker tissues, heart rate and rhythm are largely under the control of the autonomic nervous system. The parasympathetic influence on heart rate is mediated via release of
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