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
Heart failure acute respiratory distress. High-output heart failure can occur when there is an increased cardiac output. The circulatory overload caused, can result in an increased left ventricular diastolic pressure which can develop into pulmonary congestion (pulmonary edema). Heart failure is divided into two types based on ejection fraction, which is the proportion of blood pumped out of the heart during a single contraction. Ejection fraction is given as a percentage with the normal range being between 50 and 75%. The two types are: 1) Heart failure due to reduced ejection fraction (HFrEF). Synonyms no longer recommended are "heart failure due to