Cardiac physiology plateau phase. The remaining Ca for contraction is released from storage in the sarcoplasmic reticulum. The pattern of prepotential or spontaneous depolarization, followed by rapid depolarization and repolarization just described, are seen in the SA node and a few other conductive cells in the heart. Since the SA node is the pacemaker, it reaches threshold faster than any other component of the conduction system. It will initiate the impulses spreading to the other conducting cells. The SA node, without nervous or endocrine control, would initiate a heart impulse approximately 80–100 times per minute. Although each component of the conduction system
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