Stroke volume

這是什麼

Stroke volume is the amount of blood ejected from the ventricle with one systolic contraction. A common textbook example is about 70 mL in a 70 kg adult male.^[1]

為什麼重要

Stroke volume is the per-beat half of cardiac output. If heart rate stays similar, changing stroke volume changes how much blood the heart delivers per minute.^[2,1]

發生異常的根本原因

• Core relation: Stroke volume rises when the ventricle fills more, the myocardium contracts harder, or outlet load is lower; it falls when preload is low, contractility is weak, or afterload is high.^[1,3]
  Cardiac preloadVenous returnCirculating blood volumeMyocardial contractilityCardiac afterload
• Filling time: Very fast or disorganized rhythm can reduce ventricular filling time, so each beat may eject less blood even if the heart is beating more often.^[3,4]
  Heart rate and rhythmCardiac preload

它會影響哪些判斷

• It links preload, venous return, circulating blood volume, contractility, afterload, cardiac output, blood pressure, and perfusion.^[1,2]

解讀陷阱

• Stroke volume is not usually known from a pulse or blood-pressure reading alone.^[1]

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