The heart’s pumping process during the cardiac cycle

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①Atrial systole: At the end of ventricular diastole, the atria contract, causing the pressure within them to rise, which in turn pushes more blood into the ventricles. Subsequently, the ventricles begin to contract, entering the next cardiac cycle. ②Isovolumetric contraction phase: When the ventricles begin to contract, the pressure inside them rises rapidly. Once this pressure exceeds that in the atria, the atrioventricular valves close. At this point, the aortic valve is also closed, so the ventricles remain in a state of isovolumetric contraction with continuously increasing pressure. When the intracardiac pressure exceeds the aortic pressure, the aortic valve opens, marking the onset of the ejection phase. ③Rapid ejection phase and reduced ejection phase: During the first roughly 1/3 of the ejection phase, ventricular pressure rises rapidly and a large volume of blood is ejected; this is known as the rapid ejection phase ； Subsequently, ventricular pressure begins to drop and the ejection velocity slows down; this period is known as the deceleration phase of ejection. ④Isovolumetric diastole: The ventricles begin to relax, with the aortic valve and atrioventricular valves remaining closed; thus, the ventricles are in an isovolumetric state with continuously decreasing pressure. When the ventricle relaxes until the intraventricular pressure falls below the atrial pressure, the atrioventricular valve opens, marking the onset of the ventricular filling phase. ⑤Rapid filling phase and slow filling phase: At the beginning of filling, due to the large pressure difference between the ventricle and the atrium, blood fills the ventricle rapidly; this is known as the rapid filling phase. Subsequently, the pressure difference between the ventricle and the atrium decreases, and the speed at which blood fills slows down; this period is called the slow filling phase. For more information, please visit the China Pump Industry Network.